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Cell structure and organisation Biology chapter 1 - Coggle Diagram
Cell structure and organisation
Biology chapter 1
A Cell
Cell is the
basic unit
of structure in an organism
It is the basic block of life.
All organisms are composed of one(
unicellular
) or more cell(
multicellular
)
Protoplasm
Includes nucleus
Its a
jelly like substance
made up of
70% water
and
other substances,proteins
and
fats.
The composition of protoplasm varies from cell to cell.
Protoplasm is made up of the
nucleus and cytoplasm
Cell surface membrane
Also known as
plasma membrane
Partially permeable membrane
to control substances
entering
and
leaving
the cell.
Surrounds organelles within cell
and keeps them in place
Nucleus
Controls cell activity(e.g.
protein
synthesis, cell division)
Contains
long thread-like structures
called
chromatin
(contains hereditary materials)
Chromatin threads condense to form thicker
chromosomes
before the cell divides.
Chromatin contain
genetic information
and instructions for cell metabolism
Nuclear membrane
To
separate nuclear membrane from surrounding cytoplasm
Cytoplasm
Jelly-like substance surround the nucleus and forms larger part of the cell.
Emends many cell organelles:
Endoplasmic reticulum
Ribosomes
Golgi apparatus
Mitochondria
Chloroplasts
Vacuoles
Centrioles
Endoplasmic reticulum
Endoplasmic
= within the cytoplasm
Reticulum
= network
Two types:
Rough ER
What is it?
Outer surface appears
rough
and is
continuous with nuclear envelope
Functions
Site of protein synthesis
(translation stage)
Transport network
/ System of tubes that moves proteins from the
ribosomes
to the Golgi body for secretion out of the cell.
Smooth ER
What is it?
More
tubular
and may or may not be connected to RER
Functions
Synthesis of fats and steroids
Ribosomes
Small round structures that are either
attached to RER or lie freely in cytoplasm
They are needed to
make proteins in the cell
Golgi Apparatus
Stack of
flatted, membrane-bound sacs
together with
associated vesicles called Golgi vesicles
Functions
Secretes substances made at ER out of the cell, store and modifies substances for secretion.
Forms membrane-bound(Golgi vesicles) vesicles containing modifies substances for export from the cell
(e.g. nerve cells secrete neurotransmitters, endocrine glands secrete hormones, digestive glands secrete enzymes)
Pathway taken by secretory vesicles in the cell
Vesicles pinch off the rough endoplasmic reticulum and fuse to form flattened sacs
The Golgi body-stack of flattened sacs lined with smooth endoplasmic reticulum
Vesicles fuse with the cell surface membrane and release the secretions
Mitochondrion
Singular - mitochon
drion
Plural - mitochon
dria
Looks like a
sausage-shaped
organelle
Function
Site of
aerobic respiration
(=where food substances are
broken down
by
oxidation
during cellular respiration)
where energy is released
for
cellular activities
(e.g. cell division)
Vacuoles
In Animal cells
Small
and usually
temporary
in animal cells
Function as mainly
storage
, e.g. dissolved food substances, water,
wastes
, (metabolites,soluble pigment)
In plant cells
Function as mainly
storage
, e.g. dissolved food substances,water,waste products
Large,
sap-filled
in plant cells
Increase cell size through
water uptake
, to provide support(
turgid
) in plant cells
Cell wall
Rigid wall made of
cellulose
Cell wall is
fully permeable
Protects the cell from injury and gives plant cell a
fixed shape
Found in
plant cells
Chloroplasts
Contain a green pigment called
chlorophyll.
May contain
starch grains
Carry out
photosynthesis
Cell differentiation
There are many different groups of cells which have different groups of cells which have different structure,shapes and sizes
They are adapted to perform
specific
roles
Differentiation:
A process by which a cell becomes specialised for a specific function
Examples of specialized cells:
Root hair cells, Red blood cells, Xylem vessels
Red blood cell
No nucleus
.Can carry more
hemoglobin
and thus more oxygen
Contains Hemoglobin.
Combines with oxygen to form
oxy-hemoglobin
which transports oxygen from lungs to all parts of the body.
Circular Biconcave shape.
Increase
surface area to volume ratio
of cell for diffusion of oxygen into and out at a faster rate
Function
Transport
oxygen
from lungs to all parts of the body.
Root hair cell
Function
Absorbs
water
and
mineral salts
from the surrounding soil solution
Long and narrow protrusion
Increases
surface area to volume ratio
of cell so that water and mineral salts can be efficiently absorbed from the soil
Presence of sap vacuole
Central vacuole contains
cell sap. Lowers
its water potential so that water can be absorbed by
osmosis
Xylem Vessel
Function
Support
the plant
Transport
water
and
mineral salts
from the roots to the leaves
Long,
hollow
tubes formed from xylem cells laid end to end
Allows water and mineral salts to be conducted from
roots
to
stem
and
leaves
Xylem vessels
bundled
together
Provides
mechanical
support to plant
Absence
cross wall
or
protoplasm
Enables
water
to move easily through the
lumen
Lignin
deposited on walls of xylem vessels
Levels of organisation
Cells
The
basic unit
of living things. e.g. muscle cell
Tissues
A group of
similar
or
different
cells work together for a
specific function
. e.g cardiac muscle
Organs
Different
tissues
work together for a
specific function
. Division of labour among organs.e.g heart
Systems
Different
organs
work together to
support
the whole
system
. e.g circulatory system.
Organism
Different
systems
work together to support the whole
organism
. e.g human