6.1

Question 1

what is a mutation

Answer 1

a random change in the genetic material of an organism

Question 2

what are the two main classes of DNA mutation

Answer 2

• point mutation, one base pair is substituted for another

- insertion or deletion, one or more nucleotides are inserted or deleted from a length of a DNA

Question 3

what are the three types of points mutations

Answer 3

• silent
• missense
• nonsense

Question 4

what is a silent mutation

Answer 4

a point mutation involving a change to the base triplet, where the triplet still codes for the same amino acid

Question 5

what is a missense mutation

Answer 5

a point mutation where a change in the base triplet that leads to a change in the amino acid sequence in a protein

Question 6

what is a nonsense mutation

Answer 6

a point mutation that may alter a base triplet so it becomes a stop codon

Question 7

what are indel mutation

Answer 7

insertion and deletion mutations the can cause frameshift

Question 8

what is a frameshift

Answer 8

when the dna is read incorrectly due to an insertion or deletion

Question 9

what are expanding triple nucleotide repeats and how do they increase

Answer 9

some genes contain a repeating triplet such as CAG CAG CAG, the number of CAG triplets increases at meiosis and again from generation to generation

Question 10

what are 2 examples of neutral mutations in humans

Answer 10

• inability to smell certain flowers like honeysuckle

- different shaped ear lobes

Question 11

what are exons

Answer 11

the coding regions of DNA

Question 12

what are introns

Answer 12

the non-coding regions of DNA

Question 13

what does the bacterium E.coli normally metabolise

Answer 13

glucose

Question 14

if lactose is present (glucose is absent) what 2 enzymes did lactose induce the production of

Answer 14

• lactose permease

- beta galactoside

Question 15

what does lactose permease do

Answer 15

allows lactose to enter bacteria cell

Question 16

what does beta galactoside do

Answer 16

hydrolyses lactose to glucose and galactose

Question 17

What does the lac operon contain

Answer 17

Regulatory gene 
Promoter region
Lac O
Lac Z
Lac Y

Question 18

What does the regulatory gene do when there is glucose present

Answer 18

Codes for a repressive protein that binds to the operator region preventing RNA polymerase from binding to the promoter region so lac Z and Lac Y are not expressed

Question 19

What does the regulatory gene do when there is lactose instead of glucose present

Answer 19

Regulatory gene produces a repressor protein and the lactose molecules binds to the repressor protein which changes its shape so it can’t bind to the operator region so RNA polymerase can bind to the promoter region which means lac Z and lac Y can be expressed

Question 20

What are transcription factors

Answer 20

Are proteins, or non coding pieces of RNA, that act within the cells nucleus to control which genes in a cell are turned on or off

Question 21

What do transcription factors do

Answer 21

They slide along a part of the DNA molecule, seeking and binding to their specific promoter regions and activate or suppress transcription of a gene

Question 22

What are introns

Answer 22

Non coding regions of DNA

Question 23

What are exons

Answer 23

Coding regions of DNA

Question 24

What needs to be done to mRNA before it is ready for translation and why

Answer 24

When DNA is turned into mRNA the resulting mRNA is called primary mRNA, however this is too big to leave the nucleus so the primary mRNA is spliced to remove introns and joining exons to make secondary mRNA which is small enough to leave nucleus

Question 25

How are proteins activated after translation

Answer 25

They are phosphorylated

Question 26

What is apoptosis

Answer 26

Programmed cell death