Introduction

The purpose of this illustrated report is to look at the structure of living cells and their biological
characteristics. It will explore the differences between prokaryotic and eukaryotic cells and how viruses
impact cells. The report will then focus on the organelle of eukaryotic cells.

The report will investigate cellular metabolism by explaining the role of the cell membrane and how
nutrients support the growth, reproduction, and movement of animal cells. It will then look at the role of
nucleic acids within the nucleus and cytoplasm and how proteins are synthesised.

The concluding section of this report will explore embryotic stem cells and how they generate specialist
cells, the process of interphase that initiates cell division and how normal cells and cancer cells differ.
Cell Structure
by Lorraine Mullins

5th February 2021

Contents Page

Living Characteristics of a Cell and Prokaryotic cell 1

Eukaryote Cell & comparison table for Eukaryotes and prokaryotes 2
How Virus’s impact cells 3
Membrane bound organelle 4-5
How molecules are transported across membrane – 6
Endocytosis and Exocytosis 7
Cellular Respiration – Glycolysis & Fermentation 8
Cellular Respiration – Krebs Cycle & Electron Transport Chain 9
Nucleic Acid – Compare DNA & RNA 10
DNA Structure 11
RNA & Protein Synthesis 12
Codon Table for Amino acids 13
Stem Cells 14
Cell Reproduction 15
Compare normal cells and cancer cells 16
Conclusion and recommendation 17
Reference List 18-19
Bibliography 20-21
Living Characteristics of a Cell

‘Cells are the basic building blocks of all animals and plants. They are so small, you need to use
a light microscope to see them’ (BBC Bitesize, 2021)
All living things are made from cells regardless of their physical appearance , they can work independently
but they also work together to form tissue and organs that create entire organisms, including plants,
animals, and humans.

Cells must have several biological characteristics to function and survive. The following characteristics
decides whether something is living.

Movement – The cells must be able to move around so that they can avoid danger and cross cell
membranes to perform their functions

Respiration – They must be able to break food down to produce energy. This is done via a series of
chemical reactions that will be explored later in the report.

Sensitivity – They must be able to adapt to surroundings and go where they are required to be to maintain
the health of the organism. This includes changes in temperature, PH Levels, and nutrient levels

Growth – They increase in size to reach maturity and develop in complexity

Reproduction – This must happen to avoid extinction and repair damaged cells.

Excretion & Nutrition – All living cells require nutrients to survive and must be able to clear unwanted
toxic products and waste.

Figure 1 – Prokaryotic Cell (Astarbiology.com, 2021

Prokaryotic cells are simple single cells like bacteria

and archaea. They are unicellular, meaning they
work on their own.
They do not have a true nucleus or membrane
bound organelle.
They reproduce by Binary Fission; this means that
the cell replicates itself and then divides to form two
identical cells.
Respiration takes place in the cytoplasm; it does not
require oxygen.
Eukaryotic cells are more complex cells that have evolved from prokaryotes. The main difference from
prokaryotes is that they have membrane bound organelle, including a nucleus that contains the cell's
DNA.

‘All living things, plant

and animal, are made up
of strikingly similar
microscopic building
blocks called cells, the
basic structural and
functional units of life.’
(Shields, 2019)

Figure 2 – Eukaryotic
Cell (science.howstuffworks.com, 2019)

Eukaryotes are more complex and around 10 times larger in diameter. They reproduce by mitosis,
which is when they split to make an identical copy of themselves or meiosis, which is sexual
reproduction.

Comparison table for Prokaryotic and Eukaryotic Cells

Feature Prokaryotic cell Eukaryotic cell

Unicellular Multicellular (mainly)
Size 1-10µm 10-100µm
Cell membrane YES YES
Cytoplasm YES YES
Centrioles NO YES
DNA YES YES
DNA Stored Free floating in cytoplasm Membrane bound nucleus

Chromosomes Circular multiple single strands

Cilia/flagella YES, simple YES, complex
Endoplasmic reticulum NO YES
Golgi body NO YES
Lysosomes NO YES
Mitochondrion NO YES
Nucleus NO YES
Peroxisomes NO YES
Ribosomes YES YES
Chloroplast NO plant cell only
Cell wall YES Plant cells only
Vacuoles YES YES
How do Virus’s impact cells?

Lodish et al describe a virus as a small parasite that cannot reproduce by itself.

Viruses are not classified as living as they

do not have their own genetic material to
perform the characteristics of a living cell.

Instead, they must take over a host cell

and use their cell machinery.

Figure 3 - Structure of a virus (A-level

Biology AQA Notes, 2021)

There are two reproductive cycles for viruses:

1. Lytic Cycle – The virus binds to specific receptors on the surface of the host cell and injects its
DNA into the host. The virus's DNA breaks down the host DNA and takes control of the cellular
machinery which it uses to build new virus particles. As this happens virus enzymes cause the
host to become weaker. Lysis occurs when the host cell bursts and goes on to infect more cells.
You are then infected straight away
2. Lysogenic Cycle – Viral DNA gets injected into the host DNA, but it does not kill it. Instead, it
stays within the host cell in a dormant state and duplicates when the cell replicates. When
conditions are favourable the virus then enters the Lytic Cycle and takes over the cell's DNA.

Figure 4 – The stages of the Lytic Cycle. (Luman Learning, 2021)

Membrane bound organelle are only present in eukaryotic cells. Some organelles have a single layered
membrane, whilst the organelles that are protecting the genetic information of the cell are protected by
a double layered membrane, called an envelope.
Figure 5 - Membrane bound organelle (Norman, 2021)

The Nucleus is the largest organelle, it holds and protects

tightly packed strands of DNA within the Chromatin.

The Nucleolus produces Ribosomes that are the smallest

and most numerous organelles. The Nuclear Pore allows
for molecules to leave and enter the nucleus.

Figure 6 – Structure of the nucleus and endoplasmic

reticulum (Hagler, 2019)
The Endoplasmic Reticulum (ER) is a transporting system
that is connected to the nuclear envelope. It has two
parts: The Rough Endoplasmic System (RER) and the
Smooth Endoplasmic System (SER). The RER is shown above with the membrane covered in ribosomes.
Ribosomes are packets of RNA and protein that are used for protein synthesis. They have a large subunit
and a small subunit, both consisting of proteins that hold ribosomal RNA (rRNA) which speeds up protein
synthesis.
The SER carries out different function depending on the cell type , including the metabolism of
carbohydrates, lipids, or steroid synthesis. It can also detoxify harmful chemicals such as alcohol and
drugs.
The Golgi Body changes proteins into useable shapes that are used as part of the membrane or in cell
secretion, such as antibodies.
Lysosomes are also known as suicide bags and are the waste disposal system for the cell. They dispose
of worn-out cells and unwanted toxic chemicals.

The Mitochondrion manufactures the energy

molecule adenosine triphosphate (ATP) from
glucose and other nutrients in a process known
as respiration.

It also stores a small amount of DNA.

’’Mitochondria have many other functions as

well. They can store calcium, which maintains
homeostasis of calcium levels in the cell. They
also regulate the cell’s metabolism and have
roles in apoptosis (controlled cell death), cell
signaling, and thermogenesis (heat
production).’’ (Biology Dictionary, 2021)

Figure 7 – The structure of a Mitochondria (Biology Dictionary, 2021)

The cell membrane,

also known as the
plasma membrane, is
a double layer of
lipids and proteins
that surrounds a cell.
(Katy McLaughlin,
2021)

The cell membrane

controls what
molecules can enter
and leave the cell,
making it selectively permeable.

Figure 8 - Structure of the membrane (Hagler, 2019)

Small molecules such as steroids, oxygen and carbon dioxide can freely cross the cell membrane by
diffusion. Osmosis is the process that allows water to cross the membrane. They are known as a passive
process, as no energy is required.

Limitations are that

molecules can only move
from areas of high
concentration (hypertonic)
to areas of lower
concentration (Hypotonic)
to create balanced
concentration (isotonic).

Figure 9 - Passive Transport

( Dbriers.com, 2021)

Another passive process is facilitated diffusion, where protein channels are used to transport larger
molecules across the membrane.
A protein channel transports specific molecules, such as sodium and potassium ions.
Carrier proteins allows for larger molecules, such as glucose.

As this is another passive process, substances only travel from areas of high concentration to low
concentration.

Figure 10 – Facilitated
Diffusion ( Dbriers.com, 2021)

Active transport is where

the protein channels are
used to transport
molecules against the
concentration gradient,
from areas of low to high
concentration. To do this
they require energy. The phosphorate molecule from ATP (Adenosine triphosphate) binds to the protein
pump to allow it to open and cross the membrane.
Some molecules are too large to move through a protein channel, so another form of active transport
gets these macromolecules across the membrane. Endocytosis is the process of substances entering the
cell and Exocytosis is how waste products, such as hormones and digestive enzymes leave the cell.

Figure 11 shows how a molecule can be folded into the membrane. It forms a closed vesicle, that
pinches shut and is absorbed into the membrane for transportation.

Figure 11 Exocytosis and Endocytosis. (ck12, 2021)

When the materials or vesicles being transported are small this is called Pinocytosis, this is comparable
to cell drinking. When large molecules are absorbed it is known as phagocytosis and is comparable to
cell eating.
Adenosine triphosphate (ATP) is the energy molecule that is created during cellular respiration that
enables cells to synthesis, move and reproduce.

‘Cellular respiration is critical to any living organism since it is this process that essentially turns food into
energy that the body needs to survive’ (Puiu, 2020)

There are three stages to cellular respiration.

Glycolysis is the first stage of respiration; it is an aerobic or anaerobic process that occurs in the
cytoplasm.

Glucose is a 6-carbon molecule.

ATP is hydrolysed into ADP; the two phosphate

molecules lost from ATP are added to the glucose,
forming a Hexose Bisphosphate.

This splits into 2 x 3-carbon molecules known as

triose phosphates, with 1 phosphate molecule
attached to each.

Oxidation occurs when dehydrogenase enzymes

remove the hydrogen atom, which NAD take away to
form NADH, this is used later in the process.

The phosphates leave, creating two ATP molecules

each.

The result of 1 glucose molecule =

2 ATP (net),
2 NADH,
2 pyruvate molecules.
Figure 12 – Glycolysis (Khan Academy,2021)

Fermentation happens after glycolysis if there is no oxygen available. The anaerobic process turns the
pyruvic acid into lactic acid. NAD+ molecules go back into the glycolysis cycle, to generate 2 ATP.

If Oxygen is present, Pyruvic acid is actively transported across the mitochondrial envelope, where it
loses a carbon & hydrogen molecule. NAD accepts the hydrogen to form NADH and the resulting 2-
carbon molecule combines with Coenzyme A to form Acetyl coenzyme A (AceytylCoA).
 The Krebs cycle performs a series of
chemical reactions that break down
the Acetyl COA.

The result of 1 glucose molecule =

2 ATP,
6 NADH,
2 FADH2
4 CO2

Figure 13 Krebs Cycle (Khan

Academy, 2021)

The final process is the electron transport chain where around 36 molecules of ATP are made per molecule
of glucose. The NADH and FADH2 made earlier in the process are oxidised. These transfer electrons are
used to synthesis the ATP as they pump hydrogen across the matrix to the inner membrane .

Figure 13a Electron

Transport Chain
(Khan Academy,
2021)
Nucleic acids are found in the nucleus and cytoplasm. ‘A nucleotide is an organic molecule that is the
building block of DNA and RNA’ (Nucleotide, 2019). They are made up of the 3 parts, shown here.

The Phosphate energy molecule

always binds to the pentose sugar,
to form the sugar phosphate back
bone.

Figure 14 - Structure of a nucleotide

- (A-level Biology OCR Notes, 2021

RNA sugar molecule is shown on

the left, DNA on the right.

DNA has lost an oxygen atom, so it

is Deoxyribose (DNA) rather than
just Ribose (RNA).

Figure 15 - Pentose sugar (Mackenzie, 2020)

Deoxyribonucleic Acid - DNA Ribose nucleic Acid-- RNA

Purpose Stores genetic information that is replicated Copied from DNA. These are the
in every cell. This information defines messenger molecules that are
physical traits and encodes proteins used to manufacture proteins
Strands Two polynucleotide strands, running in Single polynucleotide strand
opposite directions (5’-3’ and 3’-5’)
Length Very long Short
Sugar Deoxyribose Ribose
Nitrigeonous bases - Adenine Adenine
Pyrimidine Guanine Guanine
Nitrigeonous bases Cytosine Cytosine
Purine Thymine Uracil
Location Nucleus of every cell and a small amount in Copies DNA in nucleus, lives in
mitochondria Cytoplasm

‘DNA encodes all genetic information and is the blueprint from which all biological life is created.’ (Mackenzie,
2020)
The sugar back bone binds to the nitrogenous bases in a specific bonding pattern, determined by their
molecular arrangements shown below. To maintain the structure the complementary paring must
consist of 1 purine and 1 pyrimidine. The structure of the 5 different organic bases is shown below.

Figure 16 -Five nitrogenous bases of DNA and RNA -

purines and pyrimidines. (ResearchGate. 2021)

Chargaff’s rule dictates that because of specific

bonding patterns there must always be equal
numbers of purines to pyrimidines present in DNA.

C % = G% = 30% each = 60% in total

A % = T% = 20% each = 40% in total

DNA is a double helix with has two

polynucleotide strands running in the
opposite directions, that form the rungs
on the ladder.

The direction is read according to the

position of the 5th and 3rd carbon atom on
the sugar molecule.
5 prime direction (shown on the left) is
also known as the sense/coding strand.

3-prime direction (right) is also known as

the anti-sense/template strand.

Figure 17 - DNA Double Helix Structure

(NCBI, 2021)

Every cell has a complete set of DNA that

is copied in cell division, it never leaves
the nucleus. Instead, a section of the DNA’s genetic code is copied onto RNA that is used for protein
synthesis.
There are two stages to protein synthesis; Transcription and Translation and there are three separate
roles RNA need to carry out - Messenger RNA (mRNA), Transfer RNA (tRNA), Ribosomal RNA (rRNA)

Transcription occurs in the nucleus when a section of the DNA’s genetic code is unzipped by the enzyme
DNA Helicase. This breaks the hydrogen bonds between the bases. The RNA nucleotides read the
strands of the DNA in the 3’-5’ direction, forming the same complementary base pairs as the sense
strand.

Figure 18 – Transcription ( lumenlearning.com.

2021)

Thymine is only found in the DNA strand, when

it is read by the RNA it is replaced with Uracil.

Once copied RNA leaves the nucleus through

the nuclear pore and Translation starts when
ribosomes attach in the cytoplasm.

A small subunit of the ribosome binds to the

mRNA at the start codon, AUG. The tRNA then brings the complementary anticodon, UAC which releases
the correct amino acid, always methionine.

Once the first amino acid is attached, the

large subsection of the ribosome
attaches to the mRNA and a second
tRNA comes in. The first tRNA is then
released and the ribosome moves along
the mRNA waiting for the next tRNA to
bring the next anticodon that carries the
correct amino acid.

rRNA catalysis the process of translation.

The process continues until there is no
complementary anticodon, so a stop
code is reached. The polypeptide chain is
released and folds to form the coded
protein.

Figure 19 – Translation process (Biologos, 2021)

There are 64 codon combinations that the tRNA
can read. They translate into the 20 amino acids
available for protein synthesis.

Figure 20 – Codon Table, wikipedia,2021.

Embryonic stem cells

A zygote (fertilised cell) divides by mitosis to form a mass of cells. After 4-5 days these cells form a
blastocyst with an outer layer known as a trophoblast and an inner layer, the embryoblast. The former
will become the placenta and the latter are embryonic stem cells. At this early stage, these cells are
undifferentiated. As they develop into a foetus, they will differentiate into specialised cells that carry out
a specific function and create an entire organism.

Embryotic stem cells are pluripotent, meaning

they can develop into any type of specialised cell,
except embryotic membranes & placenta.

Once the cells have differentiated, they are no

longer pluripotent.

Figure 21 - Pluripotent Cells (Bio-Rad, 2021)

Scientists create a stem cell line by removing

embryotic stem cells from the embryoblast. These
are usually donated by woman who have
undergone fertility treatment and the embryo
would otherwise be destroyed. These cells enable scientists to study how pluripotent cells develop and
are aiding medical research.

In 2001, Professor Christine Mummery used stem cells to create heart cells outside the body for the first
time. (10 breakthroughs in stem cell research, 2021)

Stem cell research is controversial as it prevents the blastocyst developing into a human, however it has
also developed treatments for chronic diseases such as cancer, Alzheimer's, Parkinson's, diabetes, and
many others that have saved lives.
Living cells must reproduce to grow and survive. The cell cycle is shown in Figure 22 (University of
Leicester, 2021)

Some cells such as brain and nerve cells are

unable to reproduce, these cells will leave the
cycle at G0.

Most cells will continue through the interphase

cycle performing its intended function whilst
preparing for cell division by mitosis. Cells are
in the interphase section for most of their
time.

In preparation for division, the cell replicates

its organelle. The DNA is then unzipped and
copied so that each cell has all 23
chromosomes pairs replicated. In the final
stage of interphase, the cell stores energy, and
duplicates centrioles.

As the cell has now replicated itself, it can move into the Mitosis phase.

This is the process of moving the

chromosomes to the opposite ends
of the cell in preparation for them
to separate in the final phase,
Cytokinesis.

The result is two identical daughter

cells are created from one cell,
these daughter cells then enter the
cell cycle and can divide again.

In healthy cells, cell signalling will

control this process to maintain the
correct number of cells. Increasing
signalling when a wound need
repairing, or old cells need
replacing and reducing signalling
when repair is complete.

Figure 23 – Mitosis and Cytokinesis

(University of Leicester, 2021)
 If cell signalling becomes faulty, the
correct number of cells are no longer
maintained, resulting in the cells
becoming damaged and different growth
patterns emerging, this can cause
harmful tumours to grow.
These mutated cells replicate, and cancer
can develop

Figure 24 - A tumour forming (cancer

cells, 2021)

As they take over, they can break away

into the blood stream and spread to
other areas of the body.

The differences between cancer cells and healthy cells can be compared here.

Figure 25 - The
Difference Between
Normal and Cancer
Cells (DrJockers.com,
2021)

If caught early
cancer cells can be
removed and
healthy cells will
replace them.
Unfortunately, if
the cancer has not
been found before
the cells have
spread to other
areas or have
grown too large to be removed the cancer cells will need to be treated in othe r ways.
Conclusion

All living things start from just one cell that can reproduce to form a vast network of cells that function
together creating an organism. Human beings are made up of around 30 trillion cells. Understanding
how cells reproduce from a single cell into this complex network of cells that then work together is
fundamental for the increased life expectancy of humans.

Studying cell biology has enabled scientists to understand what happens when cells go wrong, and
disease and illness occur. Medical science has evolved over the past 70 years, diseases that would have
previously caused loss of life are now easily treatable, and some previously terminal viruses such as
smallpox and polio have been bred out of society completely by immunisation.

Living in the developing world where lifestyles change, and we are exposed to different environmental
factors the study of cell biology will continue to be of paramount importance to ensure we continue to
understand how health can be maintained and diseases prevented in our ever-changing world.

Recommendation

The structure of the report starts quite simple and becomes more complex as it progresses into how
cells function and reproduce. It is important to fully grasp the initial topics of cell types and organelle
before moving into the more complex subject of how they perform important roles, such as protein
synthesis and respiration. The process of compiling this report has been to explore a subject in detail
and then condense back into a short word count, picking out the key aspects. This has been a very
thorough and enjoyable learning experience.

There is a lot of information out there across various channels. It has been confusing at times as there
can be several names for the same thing, particularly if something becomes plural or loses an atom. A
basic understanding of chemistry is also useful.
Reference List
A-LEVEL NOTES. 2021. A-level Biology AQA Notes: Structure Of Prokaryotic Cells & Viruses. [online] Available
at: <http://www.a-levelnotes.co.uk/biology-aqa-as-notes-cells-structure-of-prokaryotic-cells-and-
viruses.html> [Accessed 4 February 2021].
Astarbiology.com. 2021. [online] Available at: <http://astarbiology.com/ib/1-2-prokaryotic-cells/> [Accessed
18 January 2021].
BBC Bitesize. 2021. Cells - Cells To Systems - KS3 Biology Revision - BBC Bitesize. [online] Available at:
<https://www.bbc.co.uk/bitesize/guides/z9hyvcw/revision/2> [Accessed 18 January 2021].
BioLogos. 2021. Biological Information and Intelligent Design. [online] Available at:
<https://biologos.org/articles/biological-information-and-intelligent-design> [Accessed 4 February 2021].

Biology Dictionary. 2019. Nucleotide. [online] Available at: <https://biologydictionary.net/nucleotide/

[Accessed 26 January 2021].
Biology online. 2021. Cell Respiration. [online] Available at: <https://www.biologyonline.com/tutorials/cell-
respiration> [Accessed 25 January 2021].

Biology Dictionary. 2021. Mitochondria. [online] Available at: <https://biologydictionary.net/mitochondria/>

[Accessed 30 January 2021].

Bio-Rad. 2021. Pluripotent & Early Differentiation Antibodies. [online] Available at: <https://www.bio-rad-
antibodies.com/pluripotent-early-differentiation-antibodies.html [Accessed 31 January 2021].

Briers, D., 2021. What Is Passive Transport Simplified - Dbriers.Com. [online] DBriers.com. Available at:
<http://www.dbriers.com/tutorials/2012/11/what-is-passive-transport-simplified/> [Accessed 24 January
2021].

British Heart Foundation. 2021. 10 breakthroughs in stem cell research. [online] Available at:
<https://www.bhf.org.uk/informationsupport/heart-matters-magazine/research/breakthroughs-in-stem-cell-
research> [Accessed 31 January 2021].

Cancer Research UK. 2021. Cancer cells. [online] Available at: <https://www.cancerresearchuk.org/about-
cancer/what-is-cancer/how-cancer-starts/cancer-cells> [Accessed 2 February 2021].

CK-12 Foundation. 2021. Exocytosis and Endocytosis. [online] Available at:

<https://www.ck12.org/c/biology/exocytosis-and-endocytosis/lesson/Exocytosis-and-Endocytosis-BIO/>
[Accessed 24 January 2021].

Courses.lumenlearning.com. 2021. The Viral Life Cycle | Microbiology. [online] Available at:
<https://courses.lumenlearning.com/microbiology/chapter/the-viral-life-cycle [Accessed 19 January 2021].

Courses.lumenlearning.com. 2021. Prokaryotic Transcription. [online] Available at:

<https://courses.lumenlearning.com/suny-osbiology2e/chapter/prokaryotic-transcription/> [Accessed 27
January 2021].

DrJockers.com. 2021. The Difference Between Normal and Cancer Cells - DrJockers.com. [online] Available at:
<https://drjockers.com/cancer-cells/> [Accessed 2 February 2021].

Hagler, J., 2019. 4.3 Eukaryotic Cells. [online] Biology.andover.edu. Available at:
<https://biology.andover.edu/Joomla/index.php/content_page/item/618-4-3-eukaryotic-cells> [Accessed 27
January 2021].
Khan Academy. 2021. Cellular respiration. [online] Available at:
<https://www.khanacademy.org/science/biology/cellular-respiration-and-fermentation> [Accessed 30
January 2021].

Khan Academy. 2021. Cellular respiration and fermentation. [online] Available at:
https://www.khanacademy.org/science/biology/cellular-respiration-and-fermentation/pyruvate-oxidation-
and-the-citric-acid-cycle/a/the-citric-acid-cycle [Accessed 30 January 2021].

Lodish H, Berk A, Zipursky SL, et al. Molecular Cell Biology. 4th edition. New York: W. H. Freeman; 2000.
Section 6.3, Viruses: Structure, Function, and Uses. Available from:
https://www.ncbi.nlm.nih.gov/books/NBK21523/

Mackenzie, R., 2020. DNA vs. RNA – 5 Key Differences and Comparison. [online] Technology Networks.
Available at: <https://www.technologynetworks.com/genomics/lists/what-are-the-key-differences-between-
dna-and-rna-296719> [Accessed 27 January 2021].

McLaughlin, K., 2021. Cell Membrane. [online] Biology Dictionary. Available at:
<https://biologydictionary.net/cell-membrane/> [Accessed 23 January 2021].

Ncbi.nlm.nih.gov. 2021. Molecular Biology Review. [online] Available at:

<https://www.ncbi.nlm.nih.gov/Class/MLACourse/Modules/MolBioReview/dna2.html> [Accessed 4 February
2021].

Norman, H., 2021. organelles. [online] Quora.com. Available at: <https://www.quora.com/What-is-an-

example-of-a-single-and-double-membrane-bound-cell-organelles> [Accessed 4 February 2021].

Puiu, T., 2020. What Is Cellular Respiration: From Food To ATP. [online] ZME Science. Available at:
<https://www.zmescience.com/science/what-is-cellular-respiration-052533/> [Accessed 25 January 2021].

ResearchGate. 2021. Figure 1-Five Nitrogenous Bases of DNA And RNA -Purines and Pyrimidines.. [online]
Available at: <https://www.researchgate.net/figure/Five-nitrogenous-bases-of-DNA-and-RNA-purines-and-
pyrimidines_fig1_235921296> [Accessed 26 January 2021].

Shields, J., 2021. Here's How Plant and Animal Cells Are Different. [online] HowStuffWorks. Available at:
<https://science.howstuffworks.com/life/cellular-microscopic/plant-cells-animal-cells.htm> [Accessed 20
January 2021].

University of Leicester. 2021. The Cell Cycle, Mitosis and Meiosis. [online] Available at:
<https://www2.le.ac.uk/projects/vgec/highereducation/topics/cellcycle-mitosis-meiosis> [Accessed 1
February 2021].

Wikipedia. 2021. DNA and RNA codon tables. [online] Available at:
<https://en.wikipedia.org/wiki/DNA_and_RNA_codon_tables> [Accessed 4 February 2021].
Bibliography

A-LEVEL NOTES. 2021. A-level Biology AQA Notes: Structure Of Prokaryotic Cells & Viruses. [online] Available at:
<http://www.a-levelnotes.co.uk/biology-aqa-as-notes-cells-structure-of-prokaryotic-cells-and-viruses.html>
[Accessed 4 February 2021].
Astarbiology.com. 2017. 1.3 – Eukaryotic Cells. [online] Available at: <http://astarbiology.com/ib/1-3-eukaryotic-
cells/> [Accessed 18 January 2021].
Astarbiology.com. 2021. [online] Available at: <http://astarbiology.com/ib/1-2-prokaryotic-cells/> [Accessed 18
January 2021].
BBC Bitesize. 2021. Cells - Cells To Systems - KS3 Biology Revision - BBC Bitesize. [online] Available at:
<https://www.bbc.co.uk/bitesize/guides/z9hyvcw/revision/2> [Accessed 18 January 2021].
BioLogos. 2021. Biological Information and Intelligent Design. [online] Available at:
<https://biologos.org/articles/biological-information-and-intelligent-design> [Accessed 4 February 2021].

Biology Dictionary. 2019. Nucleotide. [online] Available at: <https://biologydictionary.net/nucleotide/ [Accessed 26

January 2021].
Biology online. 2021. Cell Respiration. [online] Available at: <https://www.biologyonline.com/tutorials/cell-
respiration> [Accessed 25 January 2021].

Biology Dictionary. 2021. Mitochondria. [online] Available at: <https://biologydictionary.net/mitochondria/>

[Accessed 30 January 2021].

Bio-Rad. 2021. Pluripotent & Early Differentiation Antibodies. [online] Available at: <https://www.bio-rad-
antibodies.com/pluripotent-early-differentiation-antibodies.html [Accessed 31 January 2021].

Briers, D., 2021. What Is Passive Transport Simplified - Dbriers.Com. [online] DBriers.com. Available at:
<http://www.dbriers.com/tutorials/2012/11/what-is-passive-transport-simplified/> [Accessed 24 January 2021].

British Heart Foundation. 2021. 10 breakthroughs in stem cell research. [online] Available at:
<https://www.bhf.org.uk/informationsupport/heart-matters-magazine/research/breakthroughs-in-stem-cell-
research> [Accessed 31 January 2021].

Cancer Research UK. 2021. Cancer cells. [online] Available at: <https://www.cancerresearchuk.org/about-
cancer/what-is-cancer/how-cancer-starts/cancer-cells> [Accessed 2 February 2021].

CK-12 Foundation. 2021. Exocytosis and Endocytosis. [online] Available at:

<https://www.ck12.org/c/biology/exocytosis-and-endocytosis/lesson/Exocytosis-and-Endocytosis-BIO/> [Accessed
24 January 2021].

Courses.lumenlearning.com. 2021. The Viral Life Cycle | Microbiology. [online] Available at:
<https://courses.lumenlearning.com/microbiology/chapter/the-viral-life-cycle [Accessed 19 January 2021].

Courses.lumenlearning.com. 2021. Prokaryotic Transcription. [online] Available at:

<https://courses.lumenlearning.com/suny-osbiology2e/chapter/prokaryotic-transcription/> [Accessed 27 January
2021].

Courses.lumenlearning.com. 2021. Ribosomes and Protein Synthesis. [online] Available at:

<https://courses.lumenlearning.com/boundless-biology/chapter/ribosomes-and-protein-synthesis/> [Accessed 26
January 2021].

DrJockers.com. 2021. The Difference Between Normal and Cancer Cells - DrJockers.com. [online] Available at:
<https://drjockers.com/cancer-cells/> [Accessed 2 February 2021].
Hagler, J., 2019. 4.3 Eukaryotic Cells. [online] Biology.andover.edu. Available at:
<https://biology.andover.edu/Joomla/index.php/content_page/item/618-4-3-eukaryotic-cells> [Accessed 27
January 2021].

Grade 11 Biology Study Guide. 2021. Viruses. [online] Available at:

<https://3ubiostudyguide.weebly.com/viruses.html> [Accessed 19 January 2021].

Khan Academy. 2021. Cellular respiration. [online] Available at:

<https://www.khanacademy.org/science/biology/cellular-respiration-and-fermentation> [Accessed 30 January
2021].

Khan Academy. 2021. Cellular respiration and fermentation. [online] Available at:
https://www.khanacademy.org/science/biology/cellular-respiration-and-fermentation/pyruvate-oxidation-and-the-
citric-acid-cycle/a/the-citric-acid-cycle [Accessed 30 January 2021].

Khan Academy. 2021. Steps of Cellular Respiration. [online] Available at:

<https://www.khanacademy.org/science/ap-biology/cellular-energetics/cellular-respiration-ap/a/steps-of-cellular-
respiration> [Accessed 25 January 2021].

Khan Academy. 2021. Structure of The Plasma Membrane (Article) | Khan Academy. [online] Available at:
<https://www.khanacademy.org/science/high-school-biology/hs-cells/hs-the-cell-membrane/a/structure-of-the-
plasma-membrane> [Accessed 23 January 2021].

Lodish H, Berk A, Zipursky SL, et al. Molecular Cell Biology. 4th edition. New York: W. H. Freeman; 2000. Section 6.3,
Viruses: Structure, Function, and Uses. Available from: https://www.ncbi.nlm.nih.gov/books/NBK21523/

Mackenzie, R., 2020. DNA vs. RNA – 5 Key Differences and Comparison. [online] Technology Networks. Available at:
<https://www.technologynetworks.com/genomics/lists/what-are-the-key-differences-between-dna-and-rna-
296719> [Accessed 27 January 2021].

McLaughlin, K., 2021. Cell Membrane. [online] Biology Dictionary. Available at: <https://biologydictionary.net/cell-
membrane/> [Accessed 23 January 2021].

Ncbi.nlm.nih.gov. 2021. Molecular Biology Review. [online] Available at:

<https://www.ncbi.nlm.nih.gov/Class/MLACourse/Modules/MolBioReview/dna2.html> [Accessed 4 February 2021].

Norman, H., 2021. organelles. [online] Quora.com. Available at: <https://www.quora.com/What-is-an-example-of-a-

single-and-double-membrane-bound-cell-organelles> [Accessed 4 February 2021].

Puiu, T., 2020. What Is Cellular Respiration: From Food To ATP. [online] ZME Science. Available at:
<https://www.zmescience.com/science/what-is-cellular-respiration-052533/> [Accessed 25 January 2021].

ResearchGate. 2021. Figure 1-Five Nitrogenous Bases of DNA And RNA -Purines and Pyrimidines.. [online] Available
at: <https://www.researchgate.net/figure/Five-nitrogenous-bases-of-DNA-and-RNA-purines-and-
pyrimidines_fig1_235921296> [Accessed 26 January 2021].

Shields, J., 2021. Here's How Plant and Animal Cells Are Different. [online] HowStuffWorks. Available at:
<https://science.howstuffworks.com/life/cellular-microscopic/plant-cells-animal-cells.htm> [Accessed 20 January
2021].

University of Leicester. 2021. The Cell Cycle, Mitosis and Meiosis. [online] Available at:
<https://www2.le.ac.uk/projects/vgec/highereducation/topics/cellcycle-mitosis-meiosis> [Accessed 1 February
2021].

Wikipedia. 2021. DNA and RNA codon tables. [online] Available at:
<https://en.wikipedia.org/wiki/DNA_and_RNA_codon_tables> [Accessed 4 February 2021].