B13.6 Gene expression and mutation

Question 1

What does it mean when a gene is expressed?

Answer 1

When a genes code for a protein that is synthesised in the cell

Question 2

What does the non-coding part of the DNA do?

Answer 2

Involved in switching genes or part of genes on and off

Question 3

What are mutations?

Answer 3

New forms of genes result from changes in existing genes and these changes are called mutations

Question 4

Why are mutations caused?

Answer 4

Mistakes made in copying DNA for new cells as they reproduce

Question 5

What might a mutation in an amino acid cause?

Answer 5

Result in the substrate not longer fitting the active site

Question 6

What can mutations do to offer an advantage?

Answer 6

Can produce a more efficient enzyme or a stronger structural protein

Question 7

What happens when mutations in the non-coding DNA takes place?

Answer 7

Does not directly affect the phenotype
However variants in the non-coding DNA can affect which genes are switched on or off
By changing the genes that are expressed - can cause a big effect on the phenotype

Question 8

Suggest ways in which the expression of a gene may be controlled?

Answer 8

Non‑coding regions of DNA
involved in switching genes on so they are expressed,
switching them off so they are not expressed,
or switching only part of gene on so different protein is expressed.

Question 9

How can a mutation can change the appearance of an organism?

Answer 9

If mutation alters DNA bases, this may change amino acids joined together to form protein.
This affects the way in which protein folds and functions. If an enzyme cannot work, certain chemicals will not be made and this
can affect organism appearance.

If mutation affects non-coding DNA, gene expression is affected, which
would also affect appearance.