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CAIE A-Level Biology AS 6.2.6 Gene Mutations Questions

Use real CAIE Biology questions to define a gene mutation, trace replication or repair errors, and judge when a changed sequence does or does not alter a polypeptide.

Syllabus
2028–2030
Course
Biology 9700
Level
AS

Exam points

  • Define or identify a gene mutation as a change in the base-pair or nucleotide sequence of DNA.
  • Trace how DNA damage, replication or repair errors can introduce a changed sequence and form a new allele.
  • Explain that a changed DNA sequence may alter a codon and polypeptide, but can also be silent or have no effect on protein function.

CAIE A-Level Biology AS 6.2.6 Gene Mutations Questions question 1

[Maximum number: 2]

Smooth muscle is a tissue composed of smooth muscle cells. The cells contain cytoplasm packed with proteins that are involved in contraction and relaxation.

Caldesmon is a large protein with a number of binding sites to attach to other proteins.

Caldesmon exists in two different forms, H-caldesmon and L-caldesmon.
H-caldesmon helps to regulate contraction and relaxation in smooth muscle cells.
L -caldesmon is found in some non-muscle cells, where it also acts as a regulatory protein.
- Caldesmon is coded for by a gene known as CALD1.
- CALD1 has 17 exons.
- The primary structure of H-caldesmon has a repeating sequence in the middle of the amino acid chain that is not present in L-caldesmon.

Researchers have discovered that a gene mutation is not the cause of the two different forms of caldesmon.

Explain what is meant by a gene mutation.

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