Chapter 7.4: What Mutations Tell Us About Gene Function

Question 1

What is a missense mutation?

Answer 1

 Geneticists use the term missense mutation to describe a genetic alteration that causes the substitution of one amino acid for another

Question 2

What refers to a wild-type cell that can grow on minimal medium alone?

Answer 2

prototroph

Question 3

Describe the primary structure of a protein

Answer 3

 The linear sequence of amino acids within a polypeptide is its primary structure

Question 4

Describe the tertiary structure of a protein

Answer 4

 Primary structure is also responsible for other folds and twists that together with the secondary structure produce the ultimate 3-D tertiary structure of the entire polypeptide

Question 5

Define prototroph

Answer 5

refers to a wild-type cell that can grow on minimal medium alone

Question 6

What is o A nutritional mutant microorganism that requires supplementation with substances not needed by wild-type strains ?

Answer 6

auxotroph

Question 7

Why is one end of a polypeptide called the N terminus and the other the C terminus?

Answer 7

 One end of a polypeptide is called the N terminus because it contains a free amino group that is not connected to any other amino acid
 The other end of the polypeptide chain is the C terminus, because it contains a free carboxylic acid group

Question 8

What is an oligopeptide?

Answer 8

 Several amino acids linked together constitute an oligopeptide

Question 9

What is the basic formula for amino acids?

Answer 9

 Basic formula: NH2-CHR-COOH

Question 10

Describe the Quaternary structure of a protein

Answer 10

 The 3-D configuration of subunits in a multimer is a complex protein’s quaternary structure

Question 11

Define auxotroph

Answer 11

o A nutritional mutant microorganism that requires supplementation with substances not needed by wild-type strains

Question 12

When does a branching pathway occur?

Answer 12

o A branching pathway occurs if different enzymes act on the same intermediate to convert it into two different products

Question 13

Describe the secondary structure of a protein

Answer 13

 The primary structure determines 3-D shape by generating secondary structure: localized regions with a characteristic geometry

Question 14

What is a dipeptide?

Answer 14

 A pair of amino acids is a dipeptide

Question 15

What is polypeptide?

Answer 15

 Thousands of amino acids linked together is a polypeptide