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BIOLOGY UNIT 1 - HOW DO ORGANISMS REGULATE THEIR FUNCTIONS?, Chapter 1 -…
BIOLOGY UNIT 1 - HOW DO ORGANISMS REGULATE THEIR FUNCTIONS?
Key Knowledge Powerpoint 30,1,23
Everything that is classified as living is MRS GREN
Movement
Reproduction
Response to stimuli
Growth
Respitration
Energy produced ATP
Anarobic
aerobic
Excretion
Nutrition
Cellular respiration
Cell utilises oxygen and glucose to produce energy
water and carbon dioxide are biproducts
Reproducing
Mitosis
produces two genetically identical daughter cells
from a parent cell
Miosis
Produces genetically unique cells from parents
Ends up with only half the amount of DNA
Cell composition
Carbohydrates
Proteins
Fat/lipids
Nucleic acids
Minerals/ions
SA:V Ultra structure of cells Powerpoint 09/02/23
Ultrastructure
the organelles of a cell
Surface area to volume ratio
important factor in explaining the limitation of cell size and need for internal compartments (organelles) with specific cellular functions
SA:V
What is a micelle?
help body absorb lipophilic substances
vitamins
from small intestines
absorb vitamins from
liver
gall bladder
loosely aggregated combination of lipid molecules
Chapter 1 - Cellular Structure
1A - Living or non living
Cells
types
eukaryotes
prokaryotes
Cell theory
biotic things are
made up of at least one cell
basic unit of life
came from pre-existing cells
Single celled organisms are called protists
Things can be
biotic
living
made up of at least one cell
abiotic
non-living
Common factors for ALL ORGANISMS
Genetic material
contains
hereditary (passed on) information
genes that code for protiens
Cytosol
Liquid in cells
80% water + salts + organic molecules
surrounds organelles
not including them
site of many cellular reactions
contains dissolved nutrients
breaks down waste products
moves material and organelles around the cell
Ribosome
site of protein synthesis
non membrane-bound organelle
not bound by a lipid bilayer membrane
Plasma membrane
separates interior and exterior environments
selects what enters and exits cell
made up of two layers of phospholipids
bilayer
lipids that contain phosphate
a class of fatty compounds
encloses cell contents
Organism
Something that is living
made up of at least one cell
Structure of the plasma membrane
ultrastructure of eukaryotic cells
1B - Plasma membrane
also known as cell membrane
boundary between internal and external cell environment
One of the common factors
semi permeable
only lets certain substances cross it
can also be called
partially permeable
differentially permeable
it can select what goes through
selectively permeable
consists of components
phospholipid bilayer
phospholipids
arranged in two layers
hydrophilic glycerol + phosphate heads facing outwards to both the intracellular and extracellular environments
hydrophilic
attracts water
so that water can easily can get in and out
dissolves easily in water
also called lipophobic
repels fat
things that are hydrophilic
Carbon dioxide
Oxygen
lipids
have a polar and non polar end
water
hydrophobic fatty acid tails face inwards towards each other
Hydrophobic
repels water
does not dissolve readily in water
also called lipophilic
attracts fat
polar
things that are hydrophobic
ions
big molecules
1 of 2 main components of cell membrane
can split and merge with other phosoholipids
phospholipids with shorter tails
interact less with others
make the membrane more fluid
protiens
purpose
transport
signalling
cell-to-cell recognition
the ability to distinguish a nearby cell
1 of 2 main components of cell membrane
transmembrane proteins
span the width of the membrane
integral proteins
peripheral proteins
present to only one side of the membrane
Types
transporter
transport molecules through the membrane
receptor
Enzyme
Anchor
Keep the membrane strong and structured
carbohydrates
help with
adhesion between cells
cell recognition
when attached to
protein
called glycoprotein
head of phospholipid
called glycolipid
cholesterol
helps to
increase stability of plasma membrane
without affecting membranes fluidity
(ability to move)
Fluid mosaic model
plasma membrane is made up of a mosaic of molecules (different types)
it is also fluid
phospholipids and proteins are able to move around within each layer
Phospholipids
fatty acids
single bonds between carbon atoms
saturated
double bonds
unsaturated
packed together less tightly
increased fluidity of plasma membrane
model
represents plasma membrane as a mosaic of phospholipids, proteins, cholesterol, carbohydrates
that give the membrane fluid nature
Diffusion
Osmosis
Movement of solvent molecules from lower concentration to a higher concentration of solution through a semipermeable membrane
higher conc of water to lower
associated with diffusion of water
special class of diffusion
movement of water particles
movement of BOTH solute and solvent particles across a barrier
such as membrane
net movement of particles from high concentration to low concentration
Water potential
measure of the relative tendency for water to move from one area to another
force
set up by the amount of particles on either side of membrane
more salt on one side to less on the other
water will move from less concentrated to more concentrated
produced by comparison of
Turgidity
plant cells
permanent vacuole
Water moves out of plant (coming out of the permanent vacuole)
cells lose turgidity if no water is replacing
1C - Cell types
Bacteria
first type of organism on earth 3.5 billion years ago
now most prevalent organism on earth
Organisms can be classified into two groups
Prokaryotes
single celled organism
made up of prokaryotic cells
do not contain membrane bound organelles
Contains ribosomes
Genetic material
one circular DNA chromosome
found free in cytosol
located in nucleoid
irregularly shaped area of a prokaryote where the genetic material is located
many contain small rings of double-stranded DNA called plasmids
Plasma membrane surrounded by cell wall
cell wall made out of Chitin
Bacteria
Some have capsule around cell wall for extra protection
some have flagella for movement
singular: flagellum
Some have pili for attaching to surfaces
singular: pilus
bacteria and archea
Archea
anaerobic
does not use oxygen to respire
bacteria
anaerobic
aerobic
should not be in blood or muscles
First ones on earth
Means: before the nucleus
eukaryotes
protists, fungi, plants and animals
protists
some are photsynthetic
malaria
plasmodium plasmipharum
can be found diseases to humans
plasmodium needs to be in the red blood cells for them to multiply
fungi
heterotrophic
use other organisms to feed their respiration
plants
mosses
have an asexual and sexual part of their lifecycle
flowering plants
most complicated
sexual reproduction
non-flowering plants
animals
large group
group them in bilateral symmetry
arm legs
radial symmetry
starfish
made up of Eukaryotic cells
single celled
or multicellular
contains membrane bound nucleus
contains ribosomes
Genetic material
linear DNA chromosomes
contained in nucleus
membrane bound
plasma membrane encloses cytoplasm
all of the contents inside the cell
includes cytosol and organelles
not including cytosol
Fungi and some protists
Cell wall
Many cell types (not fungi)
movement
flagella
cilia
With a nucleus
1D - Organelles
Symbiosis
A beneficial relationship between two organisms
Endosymbiosis
Symbiosis where one organism lives inside another
Mitochondrion
believed to have risen as a result of one prokaryote engulfing the other, aerobic, prokaryote
aerobic prokaryotes: able to use oxygen to respire
respire
biproducts: water and carbon dioxide
create energy from oxygen and glucose
Therefore first prokaryote was able to take on the respiratory function
it didnt break it down
it retained it and gained its aerobic function
symbiotic relation
have a double membrane
their own ribosomes
own DNA
Compartmentalisation within cells
benefits
allows various chemical reactions to occur simultaneously without interfering with each other
If the reactants are in a smaller compartment, then they are more likely to bump into each other and react
enzymes and reactants can be in high concentration
allows for processes that require different conditions to proceed at the same time
the separation of a eukaryotes elements to form cellular compartments which divide the elements into different regions
Organelles in plant and animal cells
Nucleus
double-membrane bound organelle that contains genetic material (DNA, RNA)
Messenger RNA is created through transmission
structure
Enclosed in a double-membrane nuclear envolope
Contains chromatomin
DNA and protein
Nucleus inside contains RNA
Nuclear pores
allow RNA and other materials to leave the nucleus
Make the nucleus semi-permeable
Function
Stores and executes the genetic code in the DNA
RNA carries codes to ribosomes
to synthesise proteins
that control the cells activities
DNA is passed on to daughter cells
mitosis
meiosis
Creates messenger RNA
Endoplasmic reticulum (smooth and rough
Smooth
organelle that synthesises and transports lipids
structure
no ribosomes studded
function
lipids
synthesis
transport
Rough
Transports proteins in vesicles to Golgi apperatus
structure
studded with ribosomes
function
transports
protiens
in vesticles
to Golgi Apperatus
Structure
Membrane bound
with system of tubules
Ribosome
Structure
non-membrane-bound
made up of
protein
ribosomal RNA
they are in 2 pieces and they come together around the RNA to translate it
See 1A for definition
Function
translation
(synthesis of proteins)
ribosomes in cytosol
proteins for use inside cell
ribosomes on rough ER
proteins for outside
RNA carries code to make proteins
translate code from RNA into sequence of amino acids
into a long chain called primary polypeptide
Golgi aperatus
Organelle consisting of layers
modifies and packages proteins
Structure
layers of membrane bound stacks
Function
Proteins
Modifies and packages
into secretory vesicles
for exporting from cell through exocytosis
Vesicle
Transports materials between organelles
within cell
Structure
Membrane-bound sac
Function
Transports materials
e.g. proteins
between organelles
between cell
exocytosis
exports molecules from cell
endocytosis
brings molecules into cell
produced and absorbed by
ER
Golgi apperatus
Lyosome
organelle containing enzymes
Structure
Membrane-bound sacs
containing digestive enzymes
lyozomes
related to vesicles
similar structure
but not found in plants
Function
enzymes break down foreign matter/materials no longer needed
Vacuole
Organelle that stores substances
important in maintaining structure
(in plant cells)
Structure
Membrane (tonoplast-bound sac
Develop from vesicles
Function
Storage of substances
water
ions
Larger in plants than animals
water regulator
Mitochondrion
Organelle
stages of aerobic respiration occur
releasing energy (ATP)
Structure
Has double membrane
inner membrane folded
forms cristae
forms matrix
spaces enclosed by the inner membrane
contains own
genetic material
ribosomes
Function
site of
stages 2 and 3
of Aerobic cellular respiration
releases useful energy
in form of ATP particles
Cell wall
Is a structure
Surrounds plan cell
provides
support
protection
Structure
surrounds plant cell
lies outside plasma membrane
Contains cellulose
Function
Provides cellular structure and protection
animal cells DO NOT HAVE
Cell wall
plants need structure to be rigid so that they can grow out
animal cells are flexible so they can move more
Chloroplasts
Different types
Main ingredient
Plants
Cellulose
polysaccharids
many sugars
made up of long chains of glucose monomers
C_6 H_12 O_6
Bacteria
peptidoglycan
Fungi
Chitin
Chloroplasts
Chloroplast
in plants only
organelle
photosynthesis
contains chloraphyll
Structure
Double membrane
comprised of
Grana
stacks of membrane discs called thylakoids
contains chloraphyll
stroma
fluids
Function
site of photosynthesis
converts carbon dioxide and water
with assistance of light
to glucose and oxygen
It is a plastid
plastids all have different functions
Cilia and Flagella
Cilia
Short microtubules
projecting from a cell
move to provide
motility
movement of cell
movement of fluid
Flagella
Long microtubules
projecting from a cell
move to provide
motility
movement of cell
movement of fluid
Structure
not found in fungi or plants
Function
Provide movement of cell or fluid
Centrioles
cylindrical structures
usually in animal cells
shoot out tubercular structures to form a spindle
Comparison of plant and animal cells
Plant
Photosynthesis
not all cells (root cells dont)
Aerobic cellular respiration
all cells
organelles
mitochondria
chloroplasts
Cell wall
aid with structural support
Permanent vacuole
stores
water
minerals
ions
structural support
through turgure (pressure)
large
Animal
Do not photosynthesis
organelles
no chloroplasts
Bones or exoskeleton
provides structural support
Vacuole
small
not permanently present
no structural support
any of a number of organised or specialised structures within a living cell.
cell ultrastructure
Chapter 2 - Cellular functioning
2A - The nature of substances and their modes of transport
Movement of substances into and out of cells
essential for survival
nutrients
water
oxygen
amino acids
lipids
sugars
various ions
wastes
carbon dioxide
excess water
nitrogenous waste from proteins
urea
Different modes
Passive
simple diffusion
most basic way for substances to move in and out of cell
occurs in biotic and abiotic systems
biotic
diffusion takes place across plasma membrane
substances that move by simple diffusion
oxygen
urea
carbon dioxide
alcohol
steroid hormone
water
molecule can cross membrane without a channel
rate of diffusion
cell conditions can affect
diffusion is neccessary for cell survival
different factors can affect the rate of diffuion
osmosis
See 2B
facilitated diffusion
molecule needs a channel to pass through membrane
assistance from protein
Carrier
transmembrane
bind to substance
change shape to move it across membrane to other side
hydrophilic substances
glucose
2 more items...
amino acids
1 more item...
selective
specific to the substance they transport
some molecules transported, others not
Channel
transmembrane
hydrophilic substances
move from high to low conc
also called protein-mediated transport
moving hydrophilic/polar substances
that can't diffuse through bilayer
does not require energy to be supplied to the cell (in form of ATP)
high to low concentration regions
down concentration gradient
Active
active transport
Requires input of energy
ATP
adenosine triphosphate
Bulk transport
endocytosis
substance (including fluid) moves closer to membrane
portion of plasma membrane is invaginated
turned on itself
membrane pinches off
forming membrane-bound vesicle, containing substance
into cell
exocytosis
out of cell
substance to be exported (usually protein molecules)
enclosed in vesicle from golgi apperatus
vesicle moves towards and fuses with PM
vesicle releases contents into extracellular fluid
required if substance are too large for previous transport
movement of large particles or volumes of liquid across plasma membrane
requires ATP
vesicle -mediated
uses membrane-bound structures
cholesterol is important for PM
allows membrane to be broken and remade as substances enter and leave cell
if transpoted substance is
solid
phagocytosis
phago=eating
food or pathogen
liquid or dissolved
pinocytosis
occurs continuously in almost all cells
pino = drinking
Needs aid of transport membrane
low to high concentration regions
reverse of the way substances naturally move and become disturbed
See 2D for more information
moves against concentration gradient
Protein mediated
like facilitated diffusion
protien CARRIERS
can be used in active transport
every plasma membrane has carrier proteins
akak protein punps
use ATP as fuel
some transport one substance and others 2 simultaneously
all are for specific substances
still considered selective
e.g.
sodium-potassium pump
action potential
active transport of positive ions into and out of the axon of a neuron by carrier protiens
allows neuron to send messages
nature of substances
don't all have same characteristics
molecules of substances can either be
large or small
charged or uncharged
polar or non polar
polar = can dissolve in water
non-polar = dissilve in lipids
different components of plasma membrane allow different substances to enter and exit
Structural elements of plasma membrane
Phospholipid bilayer
lipophilic (hydrophobic) substances
move freely through bilayer due to hydrophobic tails
dissolve in the non-polar portion of the tails
dissolve easily in lipids
diffuse directly across bilayer
water
gases
other small hydrophobic, polar molecules
Protein channels/carriers
polar or hydrophilic substances
pass through channel proteins
pass through carrier proteins
molecules diffuse into lipid tails and dissolve and then diffuse again and dissolve into the cytosol.
semi-permeable
differentially permeable
it is selective about what goes in and out
see table of the nature of substances in book
2B - Osmosis
Define
way of transporting water across PM
special case of diffusion
simple diffusion
net passive movement of substance to reach equilibrium
from region of high substance conc to low
osmosis
net passive movement of free water to reach equilibrium
across semi-permeable membrane
from region of high free water conc to low
diffusion of water
Tonicity
Water is medium of which many chemical processes of cells take place
bc it is excellent solvent
can transport a lot of substances (solutes)
moves easily through plasma membrane
water content of extracellular fluid will affect internal cell environment
tonicity
definition
the the concentration of solutes in extracellular solution can determine direction and rate of osmosis
therefore also determine the volume of cell
measured as
hypotonic
less molecules/solutes outside of cell
more water outside of cell
isotonic
equal amount of molecules inside and outside of cell
hypertonic
lots of molecules/solutes outside of cell
less water outside of cell
In red blood cells (example of an animal cell)
Environment
isotonic
no concentration gradient
concentration gradient = difference in concentration between two regions
no net movement of net movement of water or solvent in either direction
net movement = total amount of water moved by subtracting amount in from amount out
although no net movement still equal amounts of water flowing in and out at times
hypertonic
Osmosis
water runs from inside high conc to low conc
typically water will move outside of the cell
crenation
cell shrinks
edges become crinkled
low free water outside of cell
hypotonic
Osmosis
water runs from high to low conc of water
typically will move into cell
cell will expand
haemolysis (it can burst)
high free water outside of cell
Kidney dialysis
diffusion and osmosis work together
diffusion
transfer from blood to dialysis solution through semi-permeable membrane
toxins
metabolites (waste products)
Osmosis
Dialysis solution is continuously replaced to allow the concentration gradient to stay going into the solution
electrolytes transfer
In plant cells
when in isotonic environment
no net movement is happening
plant cell is in equilibrium
when in hypertonic environment
free water exits cell
cell initially becomes limp
plant wilting
becoming flaccid
plasmolysis
plasma membrane pulls away from cell wall
contracts while vacuole shrinks
when in hypotonic environment
free water enters cell
turgid (adjective)
when plasma membrane pushes against cell wall
vacuole expands
plant cell will not burst
rigid cell wall
things that can happen
crenation
any cell
shrinkage
haemolysis
red blood cell
ruptures
cytolysis
any cell
bursts
plasmolysis
plant cell
cell membrane pulls away from cell wall
Flaccid
plant cell
limp
Turgid
plant cell
expanded
2C - Surface area to volume ratio
cells of organisms need
oxygen and nutrients
to move in from surroundings
allowing processes to occur
growth
repair
reproduction
waste products
to be removed
to prevent build up of dangerous substances
urea
carbon dioxide
maintain certain conditions in internal environment
pH
temperature
need to be maintained within a narrow range
Relationship between surface area and volume
exchange of substances in and out of cell needs to be efficient enough so the cell survives
more surface area (SA) per unit of volume (V)
= more exchange
efficiency of exchange is affected by
area of plasma membranes surface that is exposed to external environment
larger SA = more substances
volume of cells cytoplasm
larger V = more nutrients that are required
The impact of size on cells
larger cells = less surface area available per unit of volume
large cells
more oxygen and nutrients needed
have a lot of wastes
eventually a growing cell reaches a point
exchange isn't fast enough
cant support volume of cell
cant keep internal conditions within safe range
cell will eventually die
when a certain size is reached
growing cells tend to divide to make two smaller cells
maintains a sustainable SA:V ratio
cells have adapted to be more efficient
by having
flattened shape
thin, flat cells have greater SA:V ratio
than spherical or cubic cells of same volume
compartments
folds
not all cells exist on their own
multicellular systems spread different duties across cells so that they can be smaller
Compartments
As discussed in 1B
organelles compartmentalise cells
eukaryotic
each membrane bound organelle is
self contained unit
with right conditions for the specialised function
allows cell to be more efficient
Folds
increase SA:V ratio
plasma membranes
Example
plant roots
covered in tiny folds
root hairs
digestive system
villi and microvilli
tiny projections in intestines
each villus increases SA by 30-fold
each microvillus is said to increase the SA of the small intestine by 600-fold
the size of a tennis court
Definition
Surface area
the area on the outside of an object that is exposed to the external environment
In a cell this is the plasma membrane
Volume
the amount of space inside an object
in a cell this is the cytoplasm
SA:V ratio
the amount of surface area per unit of volume
2D - Role of chloroplasts and mitochondria
energy
capacity to do work
link between life and energy
organisms
energy
survival
originates from sun
form of light energy
transformed into other forms of energy
example
photosynthesis
2 more items...
Autotrophs and heterotrophs
categorised by the way they gain energy and obtain organic compounds that are crucial to their survival
autotrophs
self-feeders
make own organic materials
take energy from environment
e.g.
green plants
light energy from sun
used to convert inorganic compounds to organic
(photosynthesis)
heterotrophs
cannot make own food
through
photosynthesis
chemosynthesis
obtain organic materials
feeding on autotrophs
feeding on other organisms
their products
used to make energy available
ATP
cellular respiration
such as
animals
fungi
troph = energy
Chloroplasts and photosynthesis
most autotrophs
photosynthetic
capture sun's light energy in chloroplasts
to convert inorganic compountds
water
ccarbon dioxide
into organic ones
glucose
oxygen
photosynthesis
many steps
biochemical pathways
each controlled by different enzyme
see book for word equation
light dependent stage: light energy and chlorophyll
needed for the reaction to occur
chlorophyll
1 more item...
light energy
1 more item...
light independent stage
Inside the chloroplasts
structure and shape of leaves
helps photosynthesise
photosynthesis produces some ATP
chloroplasts
organelle
double membrane
ribosomes
own DNA
arose via endosymbiosis
beneficial relationship between organisms
one lives off the other
chloroplast initially prokaryotic cell
engulfed by a larger one
phagocytosis
contain chlorophyll
essential for photosynthesis
splitting of water (In thylakoid)
Create H+
Create O2
NADPH
stacks of grana (granum)
look like stacks of pancakes
thylakoid membranes
membranes
interconnected
folded
location of pigment
chlorophyll
1 more item...
more thylakoid
= more surface area
capturing energy
exchange of
1 more item...
inside chloroplasts
plant cells
algae cells
light dependent stage of photosynthesis occur
remaining space
stroma
gel-like fluid
contains a lot of ribosomes
as large number of enzymes are needed
second stage of photosynthesis
light independent stage
location of light independent stage
Calvin Cycle
H+ + CO2
2 more items...
role of chlorophyll
absorb most wavelengths
sun's light energy
red and blue
absorbed most
used for photosynthesis
reflects green
assisted
accessory pigments
absorb different wavelengths
light energy
examples
carotenoids
orange
red
xanthophylls
yellow
Mitochondria: cellular respiration
cellular respiration
in order to access chemical energy
stored in bonds
glucose molecules
turn into
ATP
adenosine triphosphate
both autotrophs and heterotrophs
the energy shuttle
glucose produced in photosynthesis
used as raw fuel by mitochondria
make ATP
ATP
energy stored
needed for biochemical processes
cell growth
repair
muscle movement
dransmission of nerve impulses
moving molecules by active transport
synthesising molecules
proteins
acts as energy shuttle
transports energy
chemical reactions occur all over cell
when cell needs energy
high-energy bond in ATP is broken
3 more items...
consists of
andenosine
an adenine molecule attached to a ribose sugar
three phosphate groups
Cellular respiration
stages/steps
aka biochemical pathway
each step controlled by different enzyme
Glycolysis
occurs in cytosol
does not require oxygen
breaks down glucose
10 different reactions
each step catalysed by different enzyme
overall
two molecules produced
pyruvate
biproduct (ATP) produced
potential energy released by glycolysis
used to phosphorylate ADP to form ATP
meaning
glyco
carbohydrate glucose
lysis
something being broken down
Aerobic
glucose broken down
presence of oxygen
to produce
water
ATP
Carbon dioxide
Stage 2 and 3 occur in mitochondria
Krebs Cycle
(Citric acid cycle)
occurs in mitochondria
fluid matrix
produces 2 ATP molecules
Electron transport chain
occurs on CRISTAE
inner membrane of mitochondria
most of the ATP is produced at this stage
Anaerobic
glucose broken down
absence of oxygen
to produce
ethanol
plants
yeast
lactic acid
animals
far less efficient than Aerobic
only produces 2 ATP molecules per glucose molecule
also called fermentation
glucose
glycolysis
2 pyruvate molecules
Plants and yeast
alcoholic fermentation
1 more item...
Animals
lactic acid fermentation
1 more item...
Inside the mitochondrion
shares features of chloroplasts
as result of endosymbiosis
ribosomes
DNA
double membrane
inner membrane
folded over and over
forms layered structure
cristae
more cristae
more SA
better for carrying out important reactions of ELECTRON TRANSPORT CHAIN
matrix
remaining space in cristae
contains many ribosomes
due to large number of enzymes (made of protein) needed for
reactions that occur during
Krebs cycle
Electron transport chain
Comparing aerobic and anaerobic cellular respiration
Both include glycolysis
first stage
Differ in what happens after glycolysis
Location
Aerobic
Cytosol
Mitochondria
Anaerobic
Cytosol
Oxygen required
Aerobic
Yes
Anaerobic
No
total ATP yield
Aerobic
36 or 38 ATP
Anaerobic
2 ATP
Energy production speed
Aerobic
Slow ATP production
Anaerobic
Rapid ATP producion
Reactants
Aerobic
Glucose + oxygen
Anaerobic
Glucose
Products
Aerobic
Carbon dioxide + water + energy (ATP)
Anaerobic
Plants and yeast
Ethanol + carbon dioxide + energy (ATP)
Animals
Lactic acid + energy (ATP)
Stages
Aerobic
Glycolysis
Krebs cycle
Electron transport chain
Anaerobic
Glycolysis
Fermentation
Chapter 3 - Cellular regeneration and regulation
3B - The cell cycle
DNA structure
DNA
Deoxyribonucleic acid
Structure
Many repeating sunbits (monomers)
nucleotides
five-carbon deoxyribose sugar
one of four nitrogenous bases
adenine (A)
cytosine (C)
guanine (G)
thymine (T)
negatively charged phosphate group
nitrogenous bases
purines
two ring structure
Adenine
Guanine
larger
pyrimidines
single ring structure
Thymine
Cytosine
smaller
complementary properties
a purine will always pair with a pyrimidine
helps to strengthen and stabilise DNA helix
Therefore
adenine + thymine
guanine + cytosine
Helix ladder
strands formed
alternating
phosphate
deoxyribose sugar groups of nucleotides
giving rise to sugar-phosphate backbone
rungs formed
nitrogenous bases
orientating themselves towards centre of molecule
hydrogen bonds
form between complementary nitrogenous bases
of two opposing strands
hold molecule in double helix form
Packaging of DNA
body of a human contains around 37.2 trillion cells
housed within nucleus:
more than 2 metres of DNA
within 6 micro-metres in diameter (nucleus)
accomplished through DNA packaging
chromatin
thread-like mass
2 substances
DNA
Proteins
histones
nucleosomes
DNA wraps tightly around 8 histones
is the sunbit of the chromatin
Chromatin to chromasomes
DNA is packaged into the nucleus in the form of a chromatin
division stage
chromatin condenses further
most condensed stage
X-shaped structure
chromasomes
The purpose of cell division
what?
a parent cell divides into 2 identical daughter cells
why?
replicate
pass on genetic material to next generation of offspring
types
prokaryotes
binary fission
for reproduction
eukaryotes
mitosis
for growth and repair
growth
all forms of life begin from a single cell
multicellular develop into a complex organism
consist of 37 trillion cells
mitosis responsible for division and development of 37 trillion cells into 210 specialised types of cells in body
repair
mitosis replaces all dead or harmed cells in the body
Cell division in eukaryotes
membrane bound organelles
make the process of cell division more complicated
cell cycle
process that most eukaryotic cells undergo to multiply
parent cell gives rise to 2 genetically identical daughter cells
human cell takes 24 hours to go through the cycle
phases
Interphase
most time
95%
consists of
G1
S
some cells G0
G2
several important changes
growth
replication
produce 2 sets of chromosomes
multiply organelles
ready to move out of interphase
into division portion
cultured mammalian cells typically divide once every 18-24 hours
increasing cell mass
G1
first gap phase
grows larger
doubles in size
organelles copied
daughter cells will be equipped to sustain their own survival.
important for conservation of cell size
longest stage
most cells seen in this stage when looked at under microscope
8-11 hours
G0
Not all cells progress through the whole cycle
exit cycle
lack of nutrients
reached a stage where they can no longer divide
enter G0 stage
resting phase
eventually rejoin cycle
some permanently stay
neurons
damage is not quite as easy to repair
S
Following G1
Synthesis phase
DNA is replicated
two identical copies of DNA
Chromosomes not present
easier to explain with them present
DNA replication
single chromosome becomes double chromosome
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G2 phase
second gap phase
final stage of the inter phase
period of growth
increase energy store
prepare for division
metabolic activity increases
proteins synthesised
needed for division
M phase
Following G2
Mitosis
nucleus of parent cell splits into 2
responsible for organisms
growth and development
replacement
damaged and outworn cells
10% of the cell cycle
the human body typically has 46 chromasomes
counted by the number of centromeres
46 chromosomes can be
46 chromatids
92 chromatids
chromatic = a single chromasome
Stages (PMAT)
Prophase
nucleus is still there
Early: chromosomes condensing
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pro = before
Late
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Metaphase
M for middle
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Nucleus has been disassembled
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chromosomes appear stationary
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Anaphase
A = away
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chromatids separated
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chromosomes moving
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Telophase
chromosomes at complete opposite ends
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T = two
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spindles disassemble
end of chromatids are called telomeres
contractile ring forms
prior to division
each parent cell
contains diploid number of chromasomes
2n
one from each parent
homologous chromosomes
contains its own set of distinct phases
C phase
Cytokinesis phase
cytoplasm splits
forming 2 identical daughter cells
important
restores original size of the cell
maintains SA:V ratio
divides organelles equally between daughter cells
so that cells can survive once separated
at the end of cytokinesis
parent cell completed cell cycle
marked by two identical daughter cells
animal cells
PM pinches on both sides
cleavage furrow
keeps splitting until cells are separate
plant cells
cell wall prevents cleavage
new cell must be formed
cell plate
formed of vesicles
from golgi apperatus
forms on midline of cell
new plasma membrane and cell wall formed by end of cytokinesis: two new daughter cells formed
contractile ring contracts
regulation
multiple checkpoints
to see if the process has been carried out correctly
otherwise errors could be passed on to daughter cells
could effect the whole organism
examples
g1
structure of DNA
any damage?
sufficient nutrients
cell size
normal growth patterns
if standards not met
chemicals released
stop cell progression
initiate DNA damage control
import nutrients
if cannot be satisfied
apoptosis
g2
proper chromosome duplication
DNA is screened for damaging errors
cell size checked
if damage found - cell will stop to allow for repair
failure to repaire = apoptosis
m
attachment of each centromere to a spindle fibre
measured by gatekeepers
chemicals
promote cell progression
stop the cell cycle
signal for apoptosis
signalled cell death
apoptosis
programmed cell death
steps
cell shrinks
chromatin condenses
membrane starts "blebbing"
organelles disintergrate
nucleus and organelles collapse
membrane continues to bleb
apoptotic bodies form
macrophages phagocytose the apoptotic bodies
3A - Where do new cells come from?
Early development
8 weeks
From embryo to foetus
32 more weeks
from foetus to fully functional child
called gestational period
40 weeks total
humans
variation between gestational period length between different animals
development of an embryo
contraception
all human life begins
occurs in fallopian tubes
female
when sperm from a male fertilises ovum (egg)
produces zygote
complete cell
in a number of hours
zygote undergoes mitosis
no longer identified as a zygote
by day 3 there are 16 cells
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Morula
in uterus
cleavage of cells in morula cells continues
day 4
58 cells
cell mass
blastocyst
day 5
100 or more cells
2 different types
trophoblast
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inner cell mass
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6-7 days after fertilisation
blastocyst
implants to uterine wall
gastrulation
3 layers of tissue are formed
lasts for 5 days
end result
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by beginning of week 3
gastrula becomes an embryo
marked by formation of
critical organs
critical body structures
start of week 9
embryo resembles human
is called foetus
foetal stage continues until birth
30 weeks
critical structures develop
become fully functional
Gatrulation
Germ layer development
occurs shortly after implantation of the blastocyst into the uterine wall
result
single layered blastocyst
turns into
3 layered gastrula
how
inner cell mass
subdivides
by folding in on itself
gives rise to 3 primary embryonic germ layers
ectoderm
outer layer
mesoderm
middle layer
endoderm
inner layer
supported by 2 membranes
amnion
gives rise to amniotic sac
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yolk sac
surrounds yolk
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each of the 3 primary germ layers
gives rise to own unique specialised cells
will form tissue and organ system of baby
developmental milestone
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steps
cells of inner cell mass begin to differentiate as the amnion forms
gastrula develops when cells begin to migrate inward forming an indentation
cells continue to push inward, forming the endoderm cells that remain on the outer surface of the gastrula are called the ectoderm
mesoderm is formed, as additional cells migrate inward between the endoderm and ectoderm
Cell specialisation
inner mass of blastocyst
contains true embryonic stem cells
capable of forming all different types of specialised cells
specilised cells to form all functioning body systems of foetus
each layer of inner cell mass forms different specialised cells
Ectoderm
pigment cells
Neuron
epithelial cells
melanocyte
Mesoderm
Smooth Muscle
Cardiac muscle
cardiomyocytes
Red blood cells
Skeletal muscle
Osteocyte
Endoderm
Alveolar cells
Liver cells
stomach cells
Lung cells
Pancreatic cells
Critical periods of development
40 week gestation period
3 stages
Germinal stage
Begins at fertilisation
lasts until blastocyst implants into uterine wall
2 weeks
Embryonic stage
Begins at end of germinal stage
lasts until the 8 week mark after fertilisation
all major organs form
cell mass is considered an embryo
particularly fragile
Foetal stage
last stage
begins 2 months after fertilisation
concludes at birth
foundation laid by previous processes is progressed
the embryo is now classified as a foetus
the longer a systems period of development, the more susceptible it is to abnormalities
Stem cells
definition
type of cell
capable of giving rise to any type of specialised cell in the body of a multicellular organism
not yet have a specific role within the organism
it differentiates into almost any type of cell when body needs it
capable of self-renewal
can replicate themselves
regenerate
giving rise to exact copies of themselves
Sources
classified into two types
Embryonic stem cells
found in embryo
prior to implantation into uterus
(from the zygote to blastocyst stage)
before the blastocyst implants into the implants into the cell wall
occurs at blastocyst stage
at day 5 cells are arranged to be blastocysts
where blastocyst turns to gastrula
stem cells can differentiate into all types of cells
once implanted the gastrulation happens and the 3 primary germ layers of inner cell mass become more specialised.
Adult stem cells (Somatic stem cells)
undifferentiated cells
found in certain tissues
throughout life of the individual
locations include
Brain
bone marrow
skin
liver
blood vessels
spinal cord
heart
hair follicles
primary purpose
repair
of damaged or old body tissue
maintenance
more specialised than embryonic stem cells
give rise to a more limited variety of cells
For example
bone marrow
contains haematopoietic stem cells
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Types of stem cells
Totipotent
can differentiate into all possible cell types
examples
embryonic stem cells
zygote through to morula
only ones
can even produce an embryo
Pluripotent
Can differentiate into almost any type of cell
examples
embryonic stem cells
form inner cell mass
as they form the 3 primary germ layers
not considered totipotent
can't form embryonic membrane or placenta
these are formed by the trophoblast (outer layer of blastocyst)
Multipotent
can differentiate into a variety of closely related types of cells
examples
Haematopoietic stem cells
found in bone marrow
only produce a variety of blood cells
stem cells of the differentiated germ layers
Unipotent
can only produce one type of cell: their own
still considered stem cells as they are capable of self-renewal
examples
all somatic cells
skin
muscle
as they are able to repair tissue
Stem cell therapy
treatment and prevention of disease through the use of stem cells
diseases and conditions that could be treated by it
baldness
blindness
deafness
stroke
traumatic brain injury
learning defects
Alzheimer's disease
Parkinsons disease
missing teeth
wound healing
diseases affecting the bone marrow
spinal cord injury
Arthritis
Myocardial infarction
muscular dystrophy
Diabetes
Multiple sites: Cancers
requires infinite amounts of stem cells
sourced
embrionic
harvested from early embryos that have been donated
then manipulated by scientists to grow specific cell types by
changing chemical composition of medium that cells are grown in
altering nutrients provided to cell
directly modifying stem cells by inserting genes
adult
bone marrow
haematopoietic stem cells
most commonly obtained from donor bone marrow
placed under general anaesthetic
doctor inserts hollow needle into hip or pelvic bone
or injections into donor cause them to release stem cells into blood
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will form all types of blood cells
umbilical cord
same stem cells as bone marrow
if a baby's cord blood is stored
then they can use it if a transplant is needed in their lifetime
less likely to be rejected
Induced pluripotent stem cells
iPSCs
typical adult cells that have been genetically reprogrammed to revert to an embryonic stem cell state
Applications
regenerative medecine
new field of medecine
replaces, regenerates or engineers human cells, tissues or organs to restore normal function
tissue regeneration
Cell deficiency treatment
Organ transplants
Research
some applications are believed not to be ethically right
embryonic stem cells
harvesting can be percieved as killing a baby
harvesting techniques have advanced and scientists can now harvest only one stem cell by isolating it
3C - Cell cycle regulation and apoptosis
monitor the division of the cell
G1 checkpoint
aka restriction point
between G1 and S phase
checks that all conditions are favourable for division
monitors wide range of internal and external signals
cell size
nutrient/energy stores
DNA damage
Growth factors
if not
cell wont progress to S phase
either
attempt to rectify issue
place into G0 state
cell cycle arrest
if fabourable conditions do not eventuate
cell will stay in G0 permanently
receiving 'all clear'
irreversible
unless extenuating circumstances occur
G2 checkpoint
second checkpoint of the cycle
before enters mitosis
Checks
DNA
Damage
replication accuracy
complete replication
cell size
if not
cell progression halted
until
replication complete
damage repaired
if still not
cell is tagged
for apoptosis
M checkpoint
aka spindle checkpoint
checks
spindle attachment to chromosomes
correct formation of kinetochore
complex of proteins that assembles on the centromere
spindle microtubules attach to during mitosis
essential for accurate separation of double chromosome
how
scan cell for loose chromosomes
if not
cease mitosis
gives spindles time to attach
then anaphase will proceed
if alignment still doesn't occur
apoptosis
occurs in mitosis portion
after Metaphase
Before Anaphase
Regulatory proteins
Group of proteins
operate at cell cycle checkpoints
allow healthy cells to progress in cycle
each cell has a core set
control system
respond to environmental and internal signals
Signals activate them
they tell cell to progress
if signals don't activate them
they become inactive
blocking progression of cell to next stage in cell cycle
Apoptosis and programmed cell death
Form of cellular suicide
purpose
performs 3 key functions
Development
normal development of organism
sculpt the body
during gestation
e.g fingers and toes
if fails to occur then condition occurs
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other examples
removal of tadpoles tail
shedding of females uterus lining at beginning of menstrual cycle
removal of immune cells that could attack healthy cells that belong to the organism
elimination of excess neurons
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Balance
maintain balance
old cells make way for new cells
some cells only needed for a temporary role
certain cells removed
prevent traffic
organs and tissues retain desired size
Protection
remove cells
if checkpoint detects that they are faulty
cells that may become cancerous
cells infected with viruses
crucial for our immune system
Apoptosis in action
correct combination of signals from internal and external environment
signals
positive
necessary for continued survival of cell
negative
indicate need to activate the apoptosis pathway
correct combination results in apoptosis
Pathways
two major types
intrinsic pathway
internal signal
intracellular stress signals
as a result of
radiation
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toxic chemicals
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absence of important growth factors
received by mitochondria
how
healthy cell
Bcl-2
in mitochondrial membrane
specific regulatory protein
inhibits apoptosis
unhealthy cell
receives intracellular stress signal
Bax
2 more items...
extrinsic pathway
external siganal
death signals bind to death receptors
on plasma membrane of target cell
transmits death signal
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due to
diseased
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extreme heat exposure
important aspect
IMMUNE DEFENCE
result is always the same
complete systematic destruction of cell
recycling of it's material
Necrosis
uncontrolled cell death
trauma
injury
process
swells
bursts
spilling cellular contents into extracellular environment
causes inflammation
detrimental to health and wellbeing of organism
Cell cycle malfunction and apoptosis
regulatory proteins
detect errors
only if it is structurally sound
if damaged
not longer detect errors
cannot signal for apoptosis
malfunction of cell cycle
division of defective cells
cancer
master regulatory protein
p53
operates at checkpoints
G1
G2
role
detect damaged DNA
in healthy cells
levels are low
levels only increase for 3 major purposes
Enzyme repair of DNA
Activation of apoptosis
Halting of cell cycle
If damaged
abnormal protein
cannot perform it's role
division of damaged cells
rapid accumulation of mutated cells
example
UV radiation can cause
defected p53 proteins
1 more item...
for cancer to develop
p53 proteins must be shut down
causes of regulatory protein malfunction
UV radiation
cigarette smoke
prolonged exposure to pollution
genetics
age
cancer development
faulty regulatory proteins
acquired mechanisms allowing the cell to
bypass protective measures of regulatory proteins
tumour forms
benign
lacks ability to invade neighbouring tissue
malignant
further DNA mutations
invade neighbouring tissue
impair organ function
classified as cancerous
caused by DNA mutations
develops in a series of stages
progressive steps
cancer cells
possess 60 different mutations
later on
genomes experience significant changes
chromosomes completely lost
Vascular system
Xylem
carry water
phloem
carry glucose
Chapter 4 - Functioning systems
4A - From cells to systems
Types of cells
Specialised cells
210 types
share the load
different functions
give structure
transport nutrients
more...
more efficient
but large size can be difficult to operate
requires a highly organised framework of cells
for example
red blood cells
concave disc shape
increase SA:V ration
more efficient in diffusing oxygen
quicker transport of oxygen
levels of organisation
Specialised cell
Tissue
Organ
System
Organism
what do specialised cells do?
Exchange
intestinal cell with villi
exchange of nutrients from digestive tract into bloodstream
root hair cells
absorption of water from soil
Transport
Red blood cells
the protein haemoglobin carries oxygen to body cells and tissues
for aerobic respiration
Tracheid in xylum
transport water and mineral salts
from roots to shoots of plant
Support/structure
bone cells
collagen
protein
structure and support to organism
Xylem and phloem cells
vascular tissue networks
transport water and nutrients
roots to other parts
structure and support
Defence
White blood cells
help body to defend pathogens
Epidermal cells with thickened cell walls
prevent pathogens from entering leaves and stems
What is a tissue?
group of specialised cells working together to perform a specific function
for example
cardiac muscle tissue
cardiomyocytes
strength and endurance needed to pump blood
all animals are made up of 4 types of tissue
muscle
nervous
epithelial
connective
Organs
two or more types of tissues act together to perform one or more specific functions
For example
heart
cardiac muscle tissue
works with
epithelial tissue
connective tissue
nerve tissues
Animal organs
brain
lungs
stomach
liver
more
plant organs
leaves
stems
flowers
roots
Systems
group of organs working together to perform a complex task vital to an organisms survival
For example
heart belongs to circulatory system
to provide body with oxygen and nutrients
Organism
in complex multicellular organisms
many systems working together to ensure organism can thrive in it's environment
Mammilian systems
10 systems
Nervouse
Endocrine
Lymphatic
Urinary
Musculoskeletal
Respiratory
Immune
Circulatory
Digestive
Reproductive
work together
functions overlap
we rely on their cooperation
balance
4C - The endocrine system
Hormones
two categories
libid based
for example
testosterone
can diffuse through PM
bind to intracellular receptors
hydrophobic
steroid
protein based
for example
insulin
cannot diffuse through PM
send signal to carry out action
bind to specific complementary receptor
surface
hydrophilic
peptide
longer lasting effects
widely distributed
far-reaching effects
sustained balance
slower to act
all follow same communication principles
specialised cells in endocrine gland secrete the hormone
binds to a specific receptor on target cell
which initiates a response
travel in bloodstream to target cells in a particular tissue
What is it?
Helpts to maintain homeostasis
maintenance of a constant internal environment
despite changes in external environment
Influence growth and development of
behaviour
reproduction
cellular metabolism
body parts
collection of glands
secretes hormones directly into bloodstream
travel through blood to target cell
cell with complementary receptor for signalling molecule/hormone
to initiate response
chemical messengers
organ
Glands
See Year 9 science