Introduction to plant, animal
and bacteria TYPES of CELL STRUCTURE
and the FUNCTIONS of their components
including sub-cellular structures and differences between plant, animal and bacterial cells
and unicellular organisms
IGCSE AQA GCSE Biology Edexcel
GCSE Biology OCR Gateway Science Biology OCR 21st Century Science
Biology Doc Brown's
school biology revision notes: GCSE biology, IGCSE biology, O level
biology, ~US grades 8, 9 and 10 school science courses or equivalent for ~14-16 year old
students of biology. Some
of these revision notes on cell structure, types of cells, organelle
functions are suitable for UK KS3 Science-Biology
(~US grades 6-8)
What features do animal cells and plant
cells have in common? In what way do plant cells differ from
animal cells? Can you correctly draw and label an animal cell
and a plant cell? What are subcellular structures? What is their
function in cells?
Sub-index for this page
(a)
Introduction to cells
- prokaryotes and eukaryotes
(b)
Animal cells including humans! (eukaryotes, eukaryota)
(c)
Plant and algal cells (eukaryotes, eukaryota)
(d)
Bacteria are prokaryotes - prokaryotic cells, prokaryota
(e)
Fungal cells (eukaryotes)
(f)
Yeast cells (eukaryotes)
(g)
A note on the
structure of viruses (NOT
classified as living organisms)
(h)
The scale of things and orders of magnitude
(i)
Protists
(j)
Some more examples of
unicellular organisms
See also
CELL SPECIALISMS - an introduction to cell
specialisation is on another
page
and
Microscopy and cells: the development and use of microscopes in biology
- optical and electron
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(a)
Introduction to CELLS and types of cells
The majority of living things are made up of cells,
the building blocks of life.
You can think of most cells as a unit of life surrounded and
enclosed by an outer membrane of some sort.
Appendix 1.
Viruses
can be considered a 'non-cellular' form of life.
Why is cell biology important?
Cell biology is very important t
understand the structure and function of cells e.g. what do the various
sub-cellular structures do? and how does a cell function as a living unit.
Knowledge of cells helps us understand
how organisms develop and interact with other organisms e.g. sexual
reproduction or our bodies own defences in fighting bacteria.
Knowledge of cell chemistry is also
important in the diagnosis of disease and developing drugs to counteract
adverse medical conditions e.g. anti-cancer drugs.
What is a cell?
A cell is the smallest unit of life able
to control its own activities, BUT, it relies on the rest of the
organism (if multicellular) or the surroundings (if unicellular) to
provide it with raw materials i.e. nutrients and removal of waste
material.
The different parts of a cell are referred to
as subcellular structures.
The term
organelle refers to
specialized sub-cellular structure within a cell that perform a specific
function (e.g., mitochondria, ribosomes, chloroplasts).
Organelles in unicellular organisms
are the equivalent of organs in multicellular organisms.
You should know and understand that the structures of different types of
cells are related to their functions.
You should know and understand the similarities and
differences between animal cells, bacteria and plant cells.
See Appendix 2. for the
scale of things and
order of magnitude
The
two main groups of cells
Cells can be either
eukaryotic or prokaryotic in character.
Eukaryotes are organisms made of
eukaryotic cells, which are complex cells, and all plants and animals are
made up of such cells.
Eukaryotes are usually multi-cellular organisms, but can
consist of one cell e.g. yeast or algae (unicellular).
Plant and animal cells (eukaryotic cells)
all have a
cell membrane, cytoplasm and genetic material
enclosed in a true nucleus in the cytoplasm (compared to prokaryotic
cells described below) and other sub-cellular structures called
organelles e.g. mitochondria, chloroplasts, ribosomes etc.
However there are significant
differences between eukaryotic plant and animal cells (see later).
Watch out for adaptations in both unicellular and
multicellular organisms that help them survive and reproduce.
See also
Classification - domain, kingdom, phylum, class, order, family,
genus, species, Linnaeus naming
of organisms
Prokaryotes, are smaller
and
simpler single celled organisms (unicellular prokaryotic) eg bacteria
and archaea are prokaryotic cells.
Prokaryotic cells do NOT
have a true nucleus containing the DNA - the DNA is in free floating
loops/strands in the cytoplasm.
Archaea are now considered as a
separate domain of single celled organisms (see diagram below) even
though they are like bacteria
See
classification
and evolutionary trees gcse biology revision notes
Prokaryotic cells are more primitive than
eukaryotic cells and the oldest fossil evidence suggests that bacteria were
evolving as much as 3.5 billion years ago.
Planet Earth is reckoned to be about 4.5
billion years old (4.5 x 109 years from radiometric data - using
the half-lives of elements in rocks - the calculations are VERY complex).
The early bacteria probably existed as
thin purple or green coverings on shorelines.
These early bacteria used photosynthesis
but produced sulfur instead of oxygen as a waste product.
See also
Classification - domain, kingdom, phylum, class, order, family,
genus, species, Linnaeus naming
of organisms
including the
three domain system
Sections
(b) and (c) give a detailed comparison of animal
cells, plant cells and bacteria cells
All plant and animal cells have
similarities in basic structure, BUT, there are important differences
between them.
Both eukaryotic and prokaryotic cells
contain various subcellular structures, of some are referred to as
organelles - a subcellular structure performing a particular function, on a
larger scale, rather a like an organ in an animal.
There are also important differences
between prokaryotic cells (single celled archaea and bacteria) and (usually)
multicellular) eukaryotic cells (plants and animals)
Using diagrams and explanatory notes, their similarities and differences in
sub-cellular structures will be described and their functions explained.
Note that an organelle is a specialised sub-cellular
unit that performs a specific function. It has its own membrane and
examples include mitochondria (organelle of energy production molecules) in both plants and animals which have their
own
DNA and in plant cells, chloroplasts, the organelle of photosynthesis..
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and sub-index
(b)
ANIMAL CELLS including humans! (eukaryotes, eukaryota)
Most animal cells
have the following five parts in these eukaryotic cells - the so called subcellular structures, and, remember,
plants cells usually have the same five components too (1.
to 5. below).
The diagram shows the principal subcellular
structures of an animal cell.
1. Cell membrane
Usually from/to blood vessels (in animals), the cell
membrane controls what enters the cell (oxygen, glucose, other
nutrients) and controls what leaves the cell (carbon dioxide and
other waste products).
Transport in plants is
via the xylem and phloem systems.
The cell contents i.e.
the sub-cellular structures like cytoplasm, nucleus, (small vacuoles in
animal cells), mitochondria etc. are
all held together
and enclosed, by
the very thin soft cell membrane which controls the passage of substances in and out of the
cell.
Because not everything can pass through the membrane, it is described
as a semi-permeable or a partially permeable membrane.
The cell membrane allows the free passage of water and gases but may
act as a selective barrier to other chemicals.
The cell membrane also
contain receptor molecules that are used in cell communication e.g. by
hormones.
Through the cell membranes, specific substances can
diffuse out of one cell and diffuse into another neighbouring cell, from a
cell of higher concentration to a cell of lower concentration.
Reminder: Diffusion is due to the random movement of ions
and molecules in the fluid, from a region of higher concentration to a
region of lower concentration, in this case the regions are separated by the
semi-permeable cell membrane.
e.g. usually, for an animal ...
outside a cell the concentrations of oxygen and glucose
are higher in the blood, so both will diffuse into a cell,
and inside the cell the concentration of carbon dioxide
and other waste products are higher, so these will diffuse out of a cell
through the cell membrane into the blood for disposal via lungs or
kidney.
2.
Mitochondria
(an example of an organelle - a subcellular structure performing a particular
function)
A mitochondria organelle has a double
membrane, the inner one is folded in a complex way
Most of the aerobic energy releasing
chemistry of
respiration occurs in the mitochondria, which is where
most energy is released in respiration - eg the aerobic 'burning' of glucose to release
energy.
e.g. glucose + oxygen == via enzymes ==> carbon dioxide +
water + energy
The equation of aerobic respiration, an exothermic
chemical reaction and catalysed by the appropriate enzymes.
glucose + oxygen ===>
carbon dioxide + water
C6H12O6(aq)
+ 6O2(g) ===> 6CO2(g) + 6H2O(l)
+ energy
RESPIRATION - aerobic and anaerobic in plants, fungi and animals,
conditions, substrates etc. gcse
biology revision notes
Mitochondria are the power house of the cells
and contain all the enzymes needed for the chemical reactions that provide the chemical energy for any of the cells functions.
Liver cells carry out lots of metabolic reactions
so lots of energy needed, so they contain a lot more mitochondria.
The energy releasing molecule ATP is made in the mitochondria.
Similarly, muscle cells need lots of energy eg to
contract, so again, they have a lot more mitochondria than other cells
to supply the energy for the physical work animals perform.
Mitochondria have their own DNA in the form of circular
chromosomes, which is inherited from the mother only.
It is believed that mitochondria where once separate
microorganism - an ancient purple bacteria, that somehow became
incorporated and used by another unicellular organism.
3. Cytoplasm
Cytoplasm is a jelly like
fluid (gel-like) in which most of the cells chemical reactions take place
and most of these reactions are catalysed by enzymes (biological catalysts)
which facilitate and control the rate of these reactions.
Anaerobic respiration (glycoyslis,
fermentation) take place
in the cytoplasm, but most aerobic respiration takes place in the mitochondria,
another specialised organelle.
4. Nucleus
The cell nucleus contains
all the genetic material, the deoxyribonucleic acid (DNA codes) of the genes in the
chromosomes which control the cells
functions and the cell division in replication.
The nucleus controls the
activities of the cell by sending instructions to the cytoplasm.
The genetic
material is organised into chromosomes and the
chromosomal DNA
contains the instructions for making proteins e.g. that make up tissue or
enzymes.
Therefore the nucleus is where RNA is made from the double
helix DNA template.
5. Ribosomes
Ribosomes are involved in the translation
of the genetic material from the chromosomes, they can decode the DNA to
carry out various chemical synthesis e.g. ribosomes are where protein synthesis
takes place -
from amino acids in the cytoplasm of the cell - the protein 'factory'!
This organelle is a tiny structure
and can just be seen as a dot with a
light microscope.
They can be free to move in the
cytoplasm or attached to an internal network of channels in the cell.
6. Other features
Glycogen granules
Stored food for
respiration.
Small vacuoles - much smaller than
in plant cells
Some animal cells may have several small vacuoles
of water containing various dissolved substances - might be food or
waste products.
7. Some differences between animal, plant and
bacteria cells
Animal cells are much larger than bacterial
cells, with important differences from plant cells.
Animal cells, unlike plant cells, do not have
(i) an
outer rigid cell wall for strength, (ii) a large permanent
vacuole and (iii) chloroplasts (for photosynthesis).
Reminder note: What is an
organelle?
An organelle is a specialized part of a cell having some
specific function, a sort of cell organ. Organelles are only found in eukaryotes
(plant and animal cells). The nucleus, mitochondria, ribosomes and chloroplasts
are examples of organelles.
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and sub-index
(c)
PLANT and algal CELLS (eukaryotes, eukaryota)
Plant cells are much larger than bacterial
cells, with important differences from animal cells.
The diagram shows the principal subcellular
structures of a plant cell.
Like animal cells, plants cells have (1) a
cell membrane, (2) mitochondria, (3) cytoplasm, (4) nucleus and (5) ribosomes,
all of which perform the same functions as in the animal cells.
All of these five are described in section (b)
animal
cells.
The three extra principal different
sub-cellular structures that plant cells have, and animal cells do not are: (i) a rigid cell wall, (ii) chloroplasts and (iii) a
large permanent
vacuole - animal cells do NOT have these three features, but some have small
vacuoles.
You need to be able to describe the function
of the components of a plant cell including chloroplast, large vacuole, cell
wall, cell membrane, mitochondria, cytoplasm and nucleus (see diagram and notes
below) and know the differences between plant and animal cells.
(i)
Plant and algal cells have a
more
rigid cell wall made of
cellulose, which strengthens the cell, supports it and therefore the plant's structure
as a whole.
The plant cell wall is effectively an
additional layer outside of the cell's inner membrane.
It is made from cellulose fibres that
provide strength to the cell and collectively the strength of a whole
multicellular plant.
Unlike the cell membrane, the cell wall
does not control what materials can enter or leave the cell.
(ii) Chloroplasts the sites of
photosynthesis
Chloroplasts (an organelle) has a complex
internal membrane structure.
Chloroplasts can absorb light energy to
make food via chlorophyll in photosynthesis
The chloroplasts contain green chlorophyll molecules which are involved in the energy absorbing
process of
photosynthesis. The chlorophyll molecules absorb the light energy
from the sun to promote the endothermic reaction below. The chloroplasts
must also contain all the enzymes to catalyse the whole series of complex
reactions to make sugars - the equation below is a greatly simplified
summary!
sunlight energy + carbon dioxide + water ==>
sugars (e.g. glucose) + oxygen
6H2O(l)
+ 6CO2(g) ====> C6H12O6(aq) + 6O2(g)
Therefore chloroplasts are the site of food
production for the plant. The sugars may be used directly as a source of
energy or converted to starch grains - the plant's food store (and part of
our food store as well!).
Chlorophyll absorbs mainly in the violet-blue and
orange-red regions of the visible spectrum, hence it appears green, the
light NOT absorbed.
(iii)
Large permanent vacuole
Most plant cells have a single large permanent vacuole
surrounded by a membrane containing cell sap, a dilute solution of
mineral salts and sugars. It maintains the internal pressure to support the
cell.
The central vacuole is a cellular organelle
found in plant cells. It is often the largest organelle in the plant cell.
The central vacuole's membrane's functions
is to hold useful materials and wastes.
It also
functions to maintain the proper internal pressure within the plant cells to provide
structure and support for the growing plant.
Other features
Starch grains
Stored food for
respiration from the glucose made by photosynthesis.
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(d)
BACTERIA (prokaryotes - prokaryotic cells, prokaryota)
The diagram shows the principal subcellular
structures of an bacterial cell.
Bacterial cells, single-celled microorganisms, are
much smaller than plant
or animal cells with some quite distinct and different sub-cellular features.
A
prokaryotic
bacterial cell consists of cytoplasm within a
membrane surrounded by a cell wall.
Bacteria do NOT have a real nucleus,
chloroplasts or mitochondria.
Cell wall and inner membrane
The cell contents i.e. the
cytoplasm, DNA etc. are all held together within the cell wall by the surface
membrane which controls
the passage of substances in and out of the cell.
The surrounding outer cell wall gives
a bacterium extra structural support.
The cell wall can also be surrounded by a
capsule.
Note, unlike plant cells, animal cells do not have a cell
wall.
Cytoplasm
The jelly like
fluid in which most of the cells chemical reactions take place with the aid
of enzyme catalysts.
Although they do not have mitochondria, bacterial cells
can still respire aerobically in the cytoplasm.
Chromosomal DNA - the genetic material
is not confined in a nucleus which doesn't exist in bacteria
The genes are not in a distinct true
nucleus, the genetic material is a sort of jumbled cluster comprising of one
long circular strand (loop) of DNA floating free in the cytoplasm sometimes accompanied
by
one or more small rings of DNA called plasmids. As with any other cells the
string of DNA controls the cell's activities and cell division for
replication.
This single chromosome controls the
cells functions and the cell division in replication.
The chromosomal DNA moves freely around in the
cytoplasm and is not confined in a distinct nucleus as in plant and animal
cells.
Plasmid DNA, not part of the
chromosome
Plasmids are small hoops
of extra DNA that are separate from the chromosomal DNA.
Plasmids contain genes that help tolerance
against drugs and this drug resistance can be passed from one bacteria to another
- a problem in dealing with bacterial infectious diseases.
This is how the bacteria MSRA have
evolved and become so dangerous because of their antibiotic resistance.
Not all prokaryote cells contain
plasmids.
Shape
and Flagella (flagella plural, flagellum singular)
Bacteria come in all sorts of shapes e.g. rods, spirals
etc. and some have a tail!
The flagellum is a long
thin tail, a hair-like structure that projects out of the body of the cell, and can
rotate to move the bacteria along.
Some bacterial cells have more than one
flagella (flagellum) protruding from the outer layers of the
bacterium.
The 'tail' flagellum can be driven by a
tiny biochemical electric motor with moving parts, mostly made of proteins!
A rotating flagellum is quite a remarkable piece of
biochemical engineering - bioengineering!
The flagellum enables a bacterium away
from harmful substances (e.g. toxins) and move towards beneficial materials
like nutrients or oxygen.
Ribosomes
As with other cells, the place of protein
synthesis from decoding genetic material from chromosomes.
Other comments on prokaryotes like
bacteria
Unlike eukaryotic cells, prokaryotic
cells do not contain a defined nucleus nor do they contain mitochondria or
chloroplasts.
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(e)
FUNGAL CELLS (eukaryotes)
Fungal cells share some similarities with
plant and animal cells, but are different to both these groups.
Fungi include yeasts and mushrooms.
In common with plant and animal cells,
fungal cells have a nucleus and contain mitochondria and have a cell
membrane.
Some differences are:
fungal cells have a cell wall like
plant cells,
they have no chloroplasts like animal
cells, but unlike plant cells, which do have chloroplasts for
photosynthesis.
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(f)
YEAST CELLS (eukaryotes)
Yeast is used in the production of
alcoholic beverages eg beer, wine etc. and in bread making.
A yeast cell has the same organelles as a
mature eukaryotic cell.
A yeast cell, a single-cell microorganism, has a nucleus, cytoplasm,
mitochondria enclosed in a
cell membrane which is surrounded by a cell wall.
Yeast can be regarded as a single celled
fungus.
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(g) A note on the
structure of viruses (which are NOT
classified as living organisms)
The basic structure of a virus
Viruses are not considered to be a living
organism such as a plant, animal, bacteria or archaea.
Viruses are not considered to alive
because they do not fulfil the seven life processes, namely: movement,
respiration, sensitivity, nutrition, excretion, reproduction and growth.
Biological science uses the phrase 'strains' of virus and not species.
Viruses are the smallest agents of
infectious disease and are exceedingly small (about 20 - 500 nm diameter)
and essentially round in shape.
Viruses are consist of a relatively short
length of genetic material (DNA or RNA) which is enclosed in a thin protein coat,
which is sometimes surrounded by an extra thin fatty coating or envelope.
A typical size of a virus is about 1/50th
of a red blood cell, but they can vary in size from 20 to 500 nm).
Within the protein shell the DNA/RNA
nucleic acid can be single- or double stranded.
The entire infectious virus particles are unable to grow or reproduce
without a host.
They have non of the usual sub-cellular structures seen in
most plant or animal cells described above.
Viruses are different from all other
infectious microorganisms because they are the only group of microorganisms
that cannot replicate outside of a host cell.
Viruses do not consume food, but they
obtain materials and energy from host cells by hijacking their host
cell's cellular machinery.
Specific types of viruses only infect specific cells and
persuades them to reproduce the invading virus.
Some scientists argue that they are
more like complex molecules than living creatures.
Viruses are known to infect nearly
every type of organism on Earth and some viruses, called bacteriophages,
even infect bacteria - nothing is safe from some virus or other!
For more on virus infection
mechanism see
communicable diseases -
pathogen infections
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(h) The
scale of things and orders of magnitude
Object |
Size |
|
Object |
Size |
a common ladybird |
~7 mm, 7000
µm |
|
HIV virus |
~0.1
µm,
~100 nm |
diameter of a
human hair |
~0.1 mm, ~100
µm |
|
thickness of cell
membrane |
~0.007
µm, ~7 nm |
typical plant leaf
cell |
~0.07 mm, ~70
µm |
|
diameter of DNA
strand |
~2.5 nm |
diameter of red
blood cell |
~0.007 mm, ~7
µm, 7000 nm |
|
diameter of a
carbon atom |
~0.34 nm |
When comparing the size of small
objects like cells, scientists refer to differences in sizes as an order
of magnitude.
This means that an object is described as
being greater of smaller by a factor of 10.
For example, the leaf cell size is
one order greater (10 x) in size than a red blood cell.
The common ladybird is two orders
greater (100 x or 10 x 10) in size than a plant leaf cell.
The thickness of the cell membrane is
three orders smaller {1/1000 or 1/(10 x 10 x10)} in size than the
diameter of a red blood cell.
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(i) Protists
Protists
are single celled organisms
e.g. protozoan pathogens like those causing malaria, but this diverse group of
organisms includes simple single celled algae and amoebas.
An amoeba is a classification of protist
(single-celled eukaryotic organism that is neither plant, animal, bacteria,
nor fungus) that are amorphous in shape. They move via forming 'feet-like'
pseudopodia, which are also used for feeding.
(j) Some more examples of eukaryotic
unicellular organisms
The simplified diagram shows the structure of three singled cell
organisms found in fresh water.
The cell membrane encloses the cytoplasm and the usual cell
features like the nucleus.
The diagram also illustrates some structural adaptations to help
the organism to survive e.g.
flagellum to move towards food or away from predators,
chloroplasts for photosynthesis, so the organism can make
its own food.
Dinoflagellate
Dinoflagellates are protists, and in this case, it contains
chloroplasts for photosynthesis and can manufacture its own food.
It also
has flagellum that enables it to move at will in a forward direction with a
'swimming' action.
Other
dinoflagellates do not have chloroplasts and feed on other microscopic
creatures. feed on
Amoeba
The amoeba is a single celled primitive organism that does
not contain chloroplasts, so cannot photosynthesize its own food and must
scavenge for smaller organisms or waste decayed organic material.
The
nucleus, mitochondria and vacuoles are shown.
The amoeba has a very flexible shape and can surround a food
source and 'digest' it.
The amoeba can use a contractile vacuole to collect excess
water and expel it out through the cell membrane.
Amoeba
feed on algae and bacteria and tiny fragments of dead plant or animal
material.
Euglena
Euglena are microscopic protists containing chloroplasts to
photosynthesize sugars for food, but they can also ingest bacteria and small
microbes for food too.
They has have flagellum to enable independent
movement.
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Some typical learning objectives for this page on cell structure and function
Eukaryotes and
prokaryotes :
Know that plant and animal cells (eukaryotic cells) have a
cell membrane, cytoplasm and genetic material
enclosed in a nucleus.
Know that bacterial cells (prokaryotic cells) are much
smaller and simpler in comparison. They have cytoplasm
and a cell membrane surrounded by a cell wall.
The genetic material is not enclosed in a
nucleus. It is a single DNA loop and there may
be one or more small rings of DNA called
plasmids.
Know the similarities and differences between
animal, plant and bacterial cells.
You should be able to explain how the
main sub-cellular structures, including the
nucleus, cell membranes, mitochondria,
chloroplasts in plant cells and plasmids in
bacterial cells are related to their functions.
Know that most animal cells have the following parts: a nucleus, which controls the activities of the
cell, cytoplasm, in which most of the
chemical reactions take place, a cell membrane, which controls the passage
of substances into and out of the cell, mitochondria, which is where aerobic
respiration takes place, ribosomes, which are where protein
synthesis occurs.
Be able to recognise,
draw and interpret images of cells.
Know the parts found in animal cells
(listed above)
Know that plant cells often have: chloroplasts, which absorb light to make food
by photosynthesis a permanent vacuole filled with cell sap.
Know that plant and algal cells have a
more rigid cell wall made of cellulose, which strengthens the cell.
The
diagram above illustrates some of the basic features to recognise, without the
key below!
More detailed diagrams of typical
animal cells
and plants
cells are in sections (b) and (c).
L = mitochondria, N = chloroplasts, O = cilia hairs, P = cell
wall, R = cell membrane, T = vacuole, W = nucleus, Z = cytoplasm
Cell 1: Ciliated cell - mucous membrane cell with cilia
hairs to move mucous along, found in nose, throat, stomach and lungs.
Cell 2: Plant cell - nucleus, chloroplasts, cell
membrane, cell wall, large vacuole, nucleus, mitochondria
Cell 3: Red blood cell - has no nucleus, but important
carrier of oxygen for respiration in all cells with mitochondria.
Cell 4: Non-specific cell - just showing cytoplasm, cell
membrane, nucleus and mitochondria.
Cell 5: Sperm cell - showing swimming tail and nucleus.
Cell 6: Plant root hair cell - cytoplasm, nucleus,
mitochondria, cell wall, cell membrane, (NO chloroplasts!)
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General CELL BIOLOGY and GENETICS revision notes index
Introduction to plant and animal cell structure and
function - comparison of subcellular structures gcse biology revision notes
Stem cells and medical uses, and introduction to cell
differentiation and specialisation gcse biology revision notes
Cell division - cell cycle - mitosis, meiosis, sexual/asexual reproduction,
binary fission gcse
biology revision
Microscopy - the development and use of microscopes in biology
- optical and electron gcse biology revision notes
Diffusion - including demonstration, factors &
Fick's Law, osmosis investigation and active transport gcse biology
Examples of surfaces for the exchange of substances in
animal organisms gcse biology revision notes
Respiration - aerobic/anaerobic in plants, fungi & animals,
substrates/products, experimental investigations
Enzymes - structure, functions, optimum conditions,
investigation experiments, digestion gcse
biology revision
See also
Enzymes and Biotechnology
(gcse chemistry notes)
Culturing microorganisms like bacteria - testing
antibiotics and antiseptics gcse
biology revision notes
DNA and RNA structure and Protein Synthesis gcse
biology revision notes
An introduction to genetic
variation and the formation and consequence of mutations
gcse biology revision notes
Introduction to the inheritance of characteristics and
genetic diagrams (including Punnett squares) including technical terms, Mendel's work and inherited
genetic disorder, genetic testing gcse biology revision notes
The human GENOME project - gene expression, chromosomes, alleles, genotype, phenotype, variations,
uses of genetic testing including 'pros and cons' gcse biology revision notes
Inherited characteristics and human sexual
reproduction, genetic fingerprinting and its uses gcse biology
Genetic
engineering: uses - making insulin, medical applications, GM crops & food
security gcse biology
More complicated genetics: Sex-linked genetic
disorders, inheritance of blood groups gcse biology revision
See also section on
Cloning -
tissue culture of plants and animals gcse biology revision notes page
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