Lecture 19 and 20

Question 1

What are 2 types of mutations that can occur?

Answer 1

Somatic mutations

Germline mutations

Question 2

What is the rate of spontaneous mutations in phage and bacteria?

Answer 2

10^-8 to 10^-10 per base per generation

Question 3

What is the rate of spontaenous mutations in eukaryotes?

Answer 3

10^-7 to 10^-9 per base per generation

Question 4

what name is given to chromosomes that move?

Answer 4

Transposible elements

Question 5

What is euploidy vs aneuploidy?

Answer 5

Aneuploidy: changes in no. of individual chromosomes
Euploidy: changes in number of chromosome sets

Question 6

WHat are jumping genes called?

Answer 6

Transposons

Question 7

WHat are transposons?

Answer 7

Sequences of DNA that move from one location to another

Question 8

What are inverted repeats?

Answer 8

DNA sequences that are identical but run in opposite directions

Question 9

What is another way of moving genetic information around chromosomes?

Answer 9

RNA intermediate (for example, retroviruses) using reverse transcriptase

Question 10

What are RNA intermediates called?

Answer 10

Retroelements/ retrotransposons/retroposons depending on structure

Question 11

give an example of retrotransposition that isn’t caused by a retrovirus.

Answer 11

Alu family of repetitve sequences in humans, no apparent function

Question 12

what single ancestral gene did the alu family of sequences come from?

Answer 12

7SL RNA gene

Question 13

How many times has 7SL RNA gene been copied by retroposition?

Answer 13

more then 500,000 copies (around 5-6% genome)

Question 14

Why are tansposons there?

Answer 14

• Like parasites- there because they can (Selfish DNA theory)
• They offer some advantage

Question 15

What advantage might transposons give?

Answer 15

• Bacterial TE’s carry antibiotic resistance
• Greater genetic variability
• May cause insertion of exons into coding sequence

Question 16

What is the name of the TE in Drosophilia melangoster that only originated in the 1950’s?

Answer 16

P element

Question 17

What is the ames test?

Answer 17

Tests for the presence of mutation in the bacteria in the plate (the disc in the middle is covered in a mutagen)

Question 18

What are the bacteria on the ames test plate?

Answer 18

His-

Question 19

What removes the positive charges of histone proteins?

Answer 19

Acetylation of the lysine residues at the N terminus of histone proteins

Question 20

What does removal of the positive charge of histone proteins do?

Answer 20

Reduces affinity between histone protein and DNA

Question 21

What does reduced histone/DNA affinity cause?

Answer 21

RNA polymerase/ transcription factors get easier access to promoter region

Question 22

What enzyme catalyzes histone acetylation?

Answer 22

Histone acetyltransferase (HATs)

Question 23

What enzyme catalyses histone deacetylation?

Answer 23

Histone deacetylases (HDs)

Question 24

What type of RNA can alter expression?

Answer 24

MicroRNAs, by binding to RNA thats running around the cell

Question 25

What does adding methyl groups added to DNA do?

Answer 25

Prevent transcription, by changing magnetic patterns