Cambridge (CIE) AS Biology Your notes
Protein Synthesis
Contents
From Gene to Polypeptide
The Universal Genetic Code
Constructing Polypeptides
Transcription
Gene Mutations
© 2025 Save My Exams, Ltd. Get more and ace your exams at savemyexams.com 1
, From Gene to Polypeptide
Your notes
From Gene to Polypeptide
A gene is a sequence of nucleotides that forms part of a DNA molecule (one DNA
molecule contains many genes)
This sequence of nucleotide bases (the gene) codes for the production of a specific
polypeptide (protein)
Protein molecules are made up of a series of amino acids bonded together
The shape and behaviour of a protein molecule depend on the exact sequence of these
amino acids
The initial sequence of amino acids is known as the primary structure of the protein
molecule
The genes in DNA molecules, therefore, control protein structure (and as a result,
protein function) as they determine the exact sequence in which the amino acids join
together when proteins are synthesised in a cell
A gene is a sequence of nucleotides that codes for the production of a specific protein
molecule (polypeptide)
Examiner Tips and Tricks
© 2025 Save My Exams, Ltd. Get more and ace your exams at savemyexams.com 2
, One gene codes for one mRNA molecule, which codes for one polypeptide. This is
known as the central dogma of molecular biology.
Your notes
Remember – each chromosome in a human cell nucleus contains one very long DNA
molecule. This DNA molecule is made up of thousands of specific nucleotide
sequences called genes that code for specific proteins. Even though these genes are
all found within the same DNA molecule and are therefore all linked up, each individual
gene has a specific start and stop point. This ensures that the DNA is read correctly
and that the correct protein molecules are produced that are required by the cell to
function properly.
© 2025 Save My Exams, Ltd. Get more and ace your exams at savemyexams.com 3
Protein Synthesis
Contents
From Gene to Polypeptide
The Universal Genetic Code
Constructing Polypeptides
Transcription
Gene Mutations
© 2025 Save My Exams, Ltd. Get more and ace your exams at savemyexams.com 1
, From Gene to Polypeptide
Your notes
From Gene to Polypeptide
A gene is a sequence of nucleotides that forms part of a DNA molecule (one DNA
molecule contains many genes)
This sequence of nucleotide bases (the gene) codes for the production of a specific
polypeptide (protein)
Protein molecules are made up of a series of amino acids bonded together
The shape and behaviour of a protein molecule depend on the exact sequence of these
amino acids
The initial sequence of amino acids is known as the primary structure of the protein
molecule
The genes in DNA molecules, therefore, control protein structure (and as a result,
protein function) as they determine the exact sequence in which the amino acids join
together when proteins are synthesised in a cell
A gene is a sequence of nucleotides that codes for the production of a specific protein
molecule (polypeptide)
Examiner Tips and Tricks
© 2025 Save My Exams, Ltd. Get more and ace your exams at savemyexams.com 2
, One gene codes for one mRNA molecule, which codes for one polypeptide. This is
known as the central dogma of molecular biology.
Your notes
Remember – each chromosome in a human cell nucleus contains one very long DNA
molecule. This DNA molecule is made up of thousands of specific nucleotide
sequences called genes that code for specific proteins. Even though these genes are
all found within the same DNA molecule and are therefore all linked up, each individual
gene has a specific start and stop point. This ensures that the DNA is read correctly
and that the correct protein molecules are produced that are required by the cell to
function properly.
© 2025 Save My Exams, Ltd. Get more and ace your exams at savemyexams.com 3
