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MODELLING PROTEIN SYNTHESIS
INTRODUCTION
This exercise aimed to demonstrate how protein synthesis works by modelling the transcription and translation
processes that the proteins and DNA undergo in a cell
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RNA, or ribonucleic acid, is a polypeptide amino acid chain which, in protein
synthesis, is formed from the DNA – deoxyribonucleic acid – strand within a cell nucleus
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This aside, a large alteration from DNA is that thymine in DNA is replaced by Uracil in
RNA
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The principal role of RNA is to act as a messenger for DNA, which contains
genetic information
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e
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This is done by transcription of
the base pairs on the DNA to form mRNA, which later translates them to form a protein
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FIGURE 1: RNA STRAND AND
DNA STRAND

TABLE 1: COMPARISON BETWEEN DNA AND RNA
Name
Function
Structure

Location

DNA
Deoxyribonucleic Acid
Contains genetic information which is used to form
proteins in an organism to allow it to function
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Double nucleotide strands forming a helical structure
from 2-deoxyribose sugar with phosphate group and 4
nitrogenous bases adenine, thymine, guanine and
cytosine
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Formation Replication from cell cycle
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Single nucleotide strand formed from ribose
sugar with phosphate group and 4
nitrogenous bases adenine, uracil, guanine
and cytosine
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Depends on
type of RNA
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There are many types of RNA, three of which are involved in the process of protein synthesis
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Transcription is the formation of mRNA from the DNA
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This copy is formed from the connection of complementary nucleotides to
that of the unzipped DNA, where the DNA double helix is separated by RNA polymerase disrupting the hydrogen
bonds between its own complementary base pairs
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The formed mRNA then leaves the nucleus through the nuclear pore and serve as the basis for translation:
Translation is the process where ribosomes in the cytoplasm form proteins
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This occurs when the ribosome surrounds the mRNA, attaching a tRNA to the start codon of the mRNA
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This
repeats, eventually forming the full polypeptide chain when a stop codon is reached
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e
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This is known as mutation, where the base
sequence of the polypeptide is artificially altered, resulting in a different protein formed
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Exposure to mutagens:
o The DNA is damaged and an error is made when attempting to repair the DNA
o Alteration of chemicals which form the nucleotides results in a different/different number of
nucleotides:
 Substitution/Point – the changing of one base into another one (e
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G into A)
 Insertion – the formation and addition of extra base pairs into the sequence
 Deletion – the removal of bases

Mutagens include physical mutagens, such as ionising radiation that can break or damage DNA; UV radiation that is
absorbed by bases, altering them; and decay of elements such as carbon-14 into nitrogen
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g
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Biological mutagens are biological elements or
‘organisms’ (viruses, bacteria) that can alter the codon structure
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As this is all a complex process, which can’t be seen directly, a model has been used to represent it
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It’s only necessary that a model is used as actual protein synthesis isn’t observable – there is no
option of visibly performing or demonstrating the real thing, hence an imitation is needed
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HYPOTHESIS
The model is theoretically sound, and should be able to successfully represent the process of protein synthesis and
become sufficiently accurate when all the representations are understood
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2
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4
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RESULTS
DNA Code: TAC TTT TTG TTA ACG TGC ATC
mRNA Code: AUG AAA AAC AAU UGC ACG UAG
Sentence: your mother dresses you funny
note: I don’t have the other results

TABLE 3: REPRESENTATIONS OF PARTS OF THE MODEL
MODEL PART
TEACHER
PAPER STRIP
REWRITTEN STRIP
DESK
STUDENT
LAB
BENCH
SQUARE PAPERS
SENTENCE
FLOOR

REPRESENTATION
Transcription Factor
DNA section
mRNA
Nucleus
Enzymes
Cell
Cytoplasm/Ribosomes
Codons/tRNA
Proteins
Cell Membrane

The sentences formed shared in common the fact that they were statements
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This resulted in a sentence which made literal sense
but was very strange
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The model showed how protein synthesis works within a cell by simulating the processes of transcription and
translation
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This is modelled in the flow chart by the steps (right) lining up with
the real steps (left) showing the equivalence of each part
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The accuracy is still high as the
steps that are present align well, and – at the very least – the key steps are there including the start and finish, with
lesser details omitted
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With no start codon present, the ribosome will never attach the first tRNA and translation would never occur
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Overall the model is accurate as far as it goes
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Essentially, the model fulfils its purpose perfectly in
serving as an example demonstrating the process of protein synthesis and, with a little thought involved, allows the
real process to be envisioned and remembered easily
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