Protein Synthesis & Mutations

Where are proteins synthesised? = On ribosomes.

Describe protein synthesis. = Proteins are synthesised on ribosomes according to a template. Carrier molecules bring specific amino acids to the ribosome, where they are added to the growing protein chain in the correct order.

What happens when the amino-acid chain is complete? = It folds into a unique shape, allowing the protein to perform its specific function.

Why is a protein's shape important? = Its unique shape enables it to perform its function, for example as an enzyme, hormone or structural protein.

What is a mutation? = A change in the DNA.

How often do mutations occur? = Mutations occur continuously.

Do all mutations affect phenotype? = No. Most mutations have no effect on phenotype; some influence phenotype and very few determine phenotype.

How can a mutation affect a protein? = A mutation may change the DNA base sequence, which may change the amino-acid sequence, causing the protein to fold into a different shape.

How can a mutation affect an enzyme? = It may alter the enzyme's shape, so the substrate no longer fits the active site, reducing or preventing enzyme activity.

Can mutations occur in non-coding DNA? = Yes. Non-coding DNA can switch genes on and off, so mutations may affect how genes are expressed.