E X T E N D E D

CELL STRUCTURE AND ORGANISATION

ORGANISMS ARE MADE OF CELLS

Some organisms are made of a single cell – like this Amoeba

When you look at a section of a plant stem

under a microscope you will see it is made of

many cells

Plant and Animal cells are similar in many ways

but also have some differences

Let’s begin with a generalised animal cell...

This is a generalised animal cell such as

a liver cell

All cells are surrounded by a partially

permeable cell surface membrane – this

allows some substances to move in and

out of the cell

Cell surface membrane

Most of the cell is filled with a jelly like cytoplasm.

This is where all the cell activity happens.

It contains small organelles where specific activities occur

Cytoplasm

All cells have a nucleus (there are a few exceptions but they

began with a nucleus that then breaks down).

It is surrounded by a membraneThe nucleus controls all the activity in a cell.It contains genetic material in chromosomes.Chromosomes are made of DNAThere is a dark region called the nucleolus that is sometimes visible

Nucleus

Nucleolus

All cells need energy from RespirationThis energy is stored in a molecule called ATP.Aerobic Respiration occurs in organelles called mitochondriaVery active cells, like muscle cells, have many mitochondria so they can make a lot of energy from respiration

mitochondria

Proteins are made on small structures called ribosomesThe proteins are then modified in organelles called Endoplasmic Reticulum.When ribosomes are found on the surface of Endoplasmic Reticulum it is called Rough Endoplasmic Reticulum

Ribosomes

Endoplasmic

Reticulum

Rough Endoplasm

ic

Reticulum

Sometimes the proteins and other substances made in a cell are stored and moved around in vesicles.These are small sacs with a membrane around them.Vesicles may move to the cell surface membrane and empty their contents out of the cell

vesicles

This is a generalised plant cellSuch as a palisade mesophyll cell from a leaf

There are some

features plant

and animal

cells have in

common

The cell surface

membrane allows

certain substances in

and out of the cell

because it is partially

permeable

Cell surface

membrane

There is cytoplasm in

which there are

organelles

cytoplasm

The nucleus contains

the genetic material in

organelles

A nucleolus may be

visible

Nucleus

Nucleolus

There are

mitochondria to

release energy

from respiration in

the form of ATP

mitochondrion

There is Rough

Endoplasmic

Reticulum for

making and

maturing proteins

Rough Endoplasmic

Reticulum

Photosynthesis takes

place in chloroplasts

They contain the

green pigment

called chlorophyll

This captures light

energy

They are only found

in plant cells that

photosynthesise

chloroplasts

Plant cells have a large

central vacuole

It is filled with cell sap

This is a solution of

dissolved substances

There is a membrane

around the vacuole

Large, central

vacuole

Cell sap

All plant cells are

surrounded by a

cellulose cell wall

This provides support

for the cell and the

plant.

The cellulose may

become further

thickened with other

substances like lignin

Cellulose cell wall

Learn all the parts of these cells

and know their functions

Complete the table in your notes

to show the similarities and

differences between plant and

animal cells

Prokaryotes are single celled

organisms

Bacteria are prokaryotes

Prokaryote cells are very small

They are about the size of a mitochondrion

10µm

Prokaryote cells have no nucleus

The DNA is free in the cytoplasm

Strand of

DNA

cytoplasm

Prokaryote cells have a cell surface

membrane

This is surrounded by a cell wall that is not

made of cellulose but of a protein substance

Cell surface

membrane

Cell wall

Prokaryote cells do not have organelles but

there are some small ribosomes

ribosomes

Prokaryote cells may have a slime capsule to

protect them

They may have tails or other structures for

movement

tail

Slime capsule