IB Biology SL B1.2.4 Infinite Variety of Peptide Chains Questions

Practise IB Biology SL B1.2.4 by connecting codon order to polypeptide sequences and using gene-expression contexts to explain cell proteomes.

Exam points

Trace how codon order specifies amino-acid order and how sequence variation creates many polypeptides.
Define a proteome as a cell’s expressed proteins and distinguish it from the shared genome.
Interpret why one genome can produce different proteomes or more protein types than gene count.

[Maximum number: 7]

Cells produce a large variety of proteins with different sequences of amino acids. Explain how this is done.

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a	protein is produced when a gene is expressed / switched on;
b	genetic code/codons consists of three nucleotides/bases/base triplet;
c	genetic code in DNA is transcribed/transcription (to mRNA);
d	mRNA exits the nucleus;
e	mRNA (code) is translated/translation into a polypeptide/protein;
f	amino acid sequence/polypeptide formation occurs at a ribosome;
g	one codon translates to one amino acid;
h	tRNA carries code for specific amino acids;
i	tRNA anticodon matches with specific codon in mRNA;
j	amino acids joined (by peptide bonds) to form polypeptide;
k	sequence of amino acids determined by order of bases/nucleotides/codons in DNA/mRNA;
l	proteins vary based on which amino acids are used and their order OR protein variety increases by mutations to DNA;