chapter 5 section 6

Question 1

What is a common type of post-translational modification not typically in sequence databases?

Answer 1

Proteolytic cleavage – removal of amino acids from a protein.

Question 2

What is the purpose of N-terminal signal sequences in proteins?

Answer 2

They direct the protein to specific subcellular compartments.

Question 3

What happens to N-terminal signal sequences after the protein reaches its destination?

Answer 3

They are usually removed (clipped off).

Question 4

How can proteolytic cleavage regulate protein activity?

Answer 4

Proteins can be synthesized in inactive forms and activated by removing certain amino acids, as seen in some hormones and proteases.

Question 5

What is a common post-translational modification that is often not listed in databases?

Answer 5

Proteolytic cleavage – removal of specific amino acids from a protein.

Question 6

What is the role of N-terminal signal sequences in proteins?

Answer 6

They direct proteins to their correct subcellular compartment.

Question 7

What typically happens to N-terminal signal sequences after the protein reaches its destination?

Answer 7

hey are removed (clipped off) during or after transport

Question 8

How does proteolytic cleavage regulate protein activity?

Answer 8

Some proteins are synthesized in inactive forms and are activated by removing amino acids, as in certain hormones or proteases.

Question 9

What are simple proteins?

Answer 9

Proteins composed only of amino acids with no additional chemical groups (e.g., ribonuclease, actin).

Question 10

What are post-translational modifications (PTMs)?

Answer 10

alterations of amino acid side chains after protein synthesis.

Question 11

Give an example of a post-translational modification.

Answer 11

Formation of a disulfide bond between two cysteine residues.

Question 12

What is a functional role of many post-translational modifications?

Answer 12

They can act as “on–off switches” to regulate protein activity or localization.