Lecture 19 and 20 Flashcards
What are 2 types of mutations that can occur?
Somatic mutations
Germline mutations
What is the rate of spontaneous mutations in phage and bacteria?
10^-8 to 10^-10 per base per generation
What is the rate of spontaenous mutations in eukaryotes?
10^-7 to 10^-9 per base per generation
what name is given to chromosomes that move?
Transposible elements
What is euploidy vs aneuploidy?
Aneuploidy: changes in no. of individual chromosomes
Euploidy: changes in number of chromosome sets
WHat are jumping genes called?
Transposons
WHat are transposons?
Sequences of DNA that move from one location to another
What are inverted repeats?
DNA sequences that are identical but run in opposite directions
What is another way of moving genetic information around chromosomes?
RNA intermediate (for example, retroviruses) using reverse transcriptase
What are RNA intermediates called?
Retroelements/ retrotransposons/retroposons depending on structure
give an example of retrotransposition that isn’t caused by a retrovirus.
Alu family of repetitve sequences in humans, no apparent function
what single ancestral gene did the alu family of sequences come from?
7SL RNA gene
How many times has 7SL RNA gene been copied by retroposition?
more then 500,000 copies (around 5-6% genome)
Why are tansposons there?
- Like parasites- there because they can (Selfish DNA theory)
- They offer some advantage
What advantage might transposons give?
- Bacterial TE’s carry antibiotic resistance
- Greater genetic variability
- May cause insertion of exons into coding sequence
What is the name of the TE in Drosophilia melangoster that only originated in the 1950’s?
P element
What is the ames test?
Tests for the presence of mutation in the bacteria in the plate (the disc in the middle is covered in a mutagen)
What are the bacteria on the ames test plate?
His-
What removes the positive charges of histone proteins?
Acetylation of the lysine residues at the N terminus of histone proteins
What does removal of the positive charge of histone proteins do?
Reduces affinity between histone protein and DNA
What does reduced histone/DNA affinity cause?
RNA polymerase/ transcription factors get easier access to promoter region
What enzyme catalyzes histone acetylation?
Histone acetyltransferase (HATs)
What enzyme catalyses histone deacetylation?
Histone deacetylases (HDs)
What type of RNA can alter expression?
MicroRNAs, by binding to RNA thats running around the cell
What does adding methyl groups added to DNA do?
Prevent transcription, by changing magnetic patterns
