6.1.1 Cellular control

Question 1

What is a mutation?

Answer 1

Change in sequence of of bases in DNA

Question 2

What is a point mutation?

Answer 2

Only one nucleotide is affected

Question 3

What three things causes a mutation?

Answer 3

Insertion
Deletion
Substitution

(of one or more nucleotides or base pairs)

Question 4

What is a mis-sense mutation?

Answer 4

Different amino aicds in the sequence: two types are conservative and non-conservative

Question 5

What is a conservative mis-sense mutation?

Answer 5

Changed amino acid is chemically similar to the the previous amino acid so secondary and tertiary structure is unaffected

Question 6

What is a non-conservative mis-sense mutation?

Answer 6

Changed amino acid is chemically different to the previous amino acid and so secondary and tertiary structure is affected

Question 7

What is a non-sense mutation?

Answer 7

Protein is truncated (due to STOP codon) so it is no longer functional

Question 8

What is a silent mutation?

Answer 8

Shape of the protein/amino acid sequence is unaffected

Question 9

Why does a silent mutation occur?

Answer 9

Due to the degenerate nature of the genetic code (multiple codons code form one amino acid)

Question 10

What is an example of a silent mutation?

Answer 10

Base substitution

Question 11

What is a frameshift mutation?

Answer 11

Every adjacent base shifts from the point of mutation

Question 12

Why does a frameshift mutation occur?

Answer 12

Due to the non-overlapping nature of the genetic code (each codon is read separately)

Question 13

What is an example of a frameshift mutation?

Answer 13

Base deletion
Base insertion

Question 14

What are the types of chromosome mutations?

Answer 14

• Deletion: section breaks off and is lost
• Duplication: section gets duplicated
• Translocation: section breaks off and joins another non-homologous chromosome
• Inversion: section breaks off, is reversed and then joins back onto the chromosome

Question 15

What is an example of a beneficial mutation

Answer 15

Lactose digestion

Question 16

What is an example of a harmful mutation?

Answer 16

Cystic fibrosis

Question 17

What causes mutations in DNA?

Answer 17

• Mutagens (increases rate)
• Depurination (loss of purine base)
• Depyrimidination (loss of pyrimidine)

Question 18

What are regulatory genes?

Answer 18

Control transcription

Question 19

What are structural genes?

Answer 19

Controls structural and functional uses

Question 20

What is an exon?

Answer 20

Part of the gene which stays and gets expressed

Question 21

What is an intron?

Answer 21

‘Junk’ DNA which needs to be taken out