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Patterns In Nature (Cell Membrane # (Structure (Made up of double layers…
Patterns In Nature
Cell Membrane
#
surrounded by a cell membrane, each cell has own internal environment
functions:
control flow of substances in and out at cell
separates internal and external environment
allows substances to exchange places between internal and external environment
composed of lipids and proteins
lipids = phospholipids
contains large phosphate groups and 2 hydrocarbon chains
dual properties
phosphate group: hydrophilic, easily interacts with water
hydrocarbon: hydrophobic, do not interact with water
Fluid Mossaic Model
Structure
Selectively permeable
Semi-permeable
Made up of double layers of phospholipids
Proteins positioned in complex patterns within those layers, controls transport of substances in one out of layer
carbohydrates may be attached outside of cell membrane
role in recognition
'glycolipids' or 'glycoproteins' depending on where they are attached
Microtubules attached inner surface
Endocytosis
#
particles larger than individual molecules need to enter cells, animal all able to surround and engulf particle
Exocytosis
it is opposite: vesicles can be transported to surface of all and emptied out
plants need water for photosynthesis
it is are used in other ways
dissolve minerals
transport of substances amount plant
keep it upright and rigid
keep it cool
allow other chemical reactions to occur
Diffusion
spreading out of particles from many to fewer
gases diffuse easily and more randomly to arrange equally within limits of space they occupy
Rate of diffusion depends on:
concentration gradient
temperature
Facilitated Diffusion
larger molecules and electrically charged molecules more too slowly by simple diffusion
proteins in membrane act is membrane transporter accelerating movement at molecules
carrier protein
Transport Tubes
xylem
water and dissolved mineral salts
movement of water 'transpiration stream'
phloem
sugars produced in leaves
'translocation'
glucose to sucrose then into starch for storage
companion cells lying next to phloem help support phloem walls
contained in stems and be in of leaves
clumped together in vascular bundles
Cells
all living things one made from cells, all have similar characteristics
Cell Theory
2- fails are basic structural and functional unit of organisms
3- All cells come from pre-existing cells
1- all living things are made of cells (Can be unicellular or multicellular)
History
discovery of cells depended on development of technology
magnifying lens and use of light microscope
before invention of lenses and microscopes it was believed living matter could come from non-living matter
e.g. maggots from dead meat
theory of Spontaneous generation
prediction of living creatures arise from inanimate material
disproved by observation -Francesco Redi, 1688
Contributors
Malpighi - first to use lenses
Leeuwenhoek - constructed microscopes that were better than others at the time
Hooke
designed compound microscope (more than one lens) to observe cells in cork, first to use
cells
Brown
recognised
nucleus
regular feature in plant cells and named it
Ruska, Zworykin, Hillier, and others- developed election microscope to give greater magnification
Schleidn and Schwann - discussing results of microscopic studies of lively things
Schleiden - regular placement of nuclei he had observed in plant cells
Schwann - similarity to animal cells he'd been studying
Virchow - his studies led to third statement it
Cell Theory
Organelles
Cytoskeleton
Lysomes
Centrides/Centromes
Osmosis
#
flow of water though semi-permeable membrane
water more from weak solution to strong solution
osmosis rate depends on:
Solute concentration
opposing physical pressure or tension excreted on water
Technology Advances
Light Microscope
can see:
chloroplast
central vacuole
chloroplasts
cell wall
Special staining techniques, parts of cell or cell organelles are coloured, used to improve examination
Election Microscope
uses beam of electron
limitation- preparing tissues, walls are preserved, function cannot be observed
Cell Structure
generally divided into 2
Prokaryote
(no internal structure)
unicellular
e.g. bacteria
Eukaryote
(has internal structure)
unicellular or multicellular
e.g. amoeba or humans
Parts of a Cell
cell membrane, nucleus, endoplasmic reticulum, ribosomes, cytoplasm, golgi apparatus, mitochondria, cell wall, chloroplast, vaculoes
Plant Roots and Leaves
Roots
roots long, have large SA
root hair increase SA
roots and root hair absorb war from soil by osmosis
#
obsorbs minerals by diffusion
if inadequate, facilitated diffusion and active transport may also be involved
Leaves
Role
Pore in least surface
cells inside that contain chloroplasts
water transport system
Food transport system
Large SA
Differences In
shape and size
size of intercellular spaces
size and no. of photosynthesising cells
number and location of stomates
cuticle thickness
fleshiness
amount of strengthening tissue
special structures
Epidermal cells
is a protective layer
protects inner tissues and prevents evaporation
Guard cells
Control both exchange of gases and loss of water
within epidermal
spongy Mesophyll
in middle layer
2 types of cells:
palisade
spongy
Vascular Tissue
distributed throughout leaf
ensures no cells too for away from source of transport
Substances in Cells
#
Chemicals in Cells
chemical substances fit into 2 groups
organic
synthesised by living things
contain carbon and hydrogen together
long chains
lipids (fats and oils)
More efficient store of cell energy
structural part of all membrane
some are essential structural parts of hormones
proteins
Made up of amino acids
controls cell metabolism because on games are proteins
structural components of cells
nucleic acid (DNA and RNA)
also contains nitrogen and phosphorous
found in all living things
made of large number at nucleotides
information storage molecules
Vitamins
carbohydrates (sugars and starch)
Monosaccharides
Disaccharides
Polysaccharides
inorganic
not part of living world
do no to contain carbon and hydrogen together
not long chains
mineral salts (calcium salts, section chloride and phosphorous)
water
Main inorganic compound in living things
important solvent used in transporting substances
source of hydrogen an oxygen
some gases (carbon dioxide and oxygen)
Other inorganic substances
may dissolve in water and present in cells in forms of ions
many has specific purposes
calcium important for bone functions
iron important componentof red blood al carry oxygen
every living cell has water in it and surround by fluids
Passive Transport
movement of water through semipermeable membrane from areas of higher to lower concentration
#
movement of moleules from higher to lower concentration
#
similarities
passive movements of-particles, requires no energy
particles move along concentration gradient
occur until equilibrium is reached
differences
diffusion = movement of molecules, occurs without membrane
osmosis: movement of water through semi-permeable membrane
Animals
Circulatory
involves system of pumps, tubes, fluids
pump -heart
lubes-arteries, veins, capillaries
fluids-blood, lymph
transport gases, nutrients, water, maintains constant internal environment, immunity, temp regulation
Respiratory
3 processes
breathing: inhalation to exhalation
gaseous exchange: diffusion it oxygen and carbon dioxide across cell membrane in lung
respiration: biochemical process breaks down nutrients in pressure of oxygen to release energy
large SA, moist, g la transport system
excretory
removes metabolic wastes from body
metabolism it proteins produces type of metabolic waste 'nitrogenous waste'
3 types: ammonia (fish), uric acid (birds), area (mammals)
3 systems regulate transport
circulatory, respiratory, excretory
Active Transport
#
movement of molecules from low to high concentration
requires imput at energy
requires carrier protein
Mitosis
plants 'meristematic'
occurs in root/stem tips=increase length
cambium between xylem and phloem: increase thickness
insects 'metamorphosis'
changes from larvae into adult
pupal stage
Animals
skin/hair/naiI cells
Autotrophs
Photosynthesis
light dependent phase
involves splitting of water using energy of light
photolysis
light independent phase
involves using carbon dioxide to make sugar
carbon fixing
makes organic material from water, carbon dioxide and inorganic material using energy from sun light
Heterotrophs
#
depends an autotrophic organisms
red blood cells = no nucleus