GIM 7&8 - Molecular genetics of inherited disease

Question 1

how is DNA differ to RNA

Answer 1

RNA is only different to the presence of the OH group on the deoxyribose group allowing it to form bonds with other molecules ie unstabele

Question 2

what direction is DNA sequences in

Answer 2

5’ - 3’

Question 3

what does interspersed repeats mean

Answer 3

copies of the same sequences located in many loci of the genes

Question 4

what does satellite DNA mean

Answer 4

large blocks of repetitive sequences

Question 5

what is pseudogene

Answer 5

when a gene is no longer activated as it no longer functional

Question 6

what is processed genes

Answer 6

intronless copies of genes - usually remote from parent gene

Question 7

what can processed gene?

Answer 7

Reverse transcription and reintegration

Question 8

what is pseudogene

Answer 8

it is gene which has lost their functions

Question 9

what are 2 examples of repetitive DNA

Answer 9

satellite DNA, interspersed repeats

Question 10

where is satellite DNA usually located ?

Answer 10

large block at centreomeres and heterochromatic chromosomal regions

Question 11

what are the different type of satellite DNA

Answer 11

centromere repeat, chromosome-specfic

Question 12

what is alphoid DNA?

Answer 12

A type of satellite DNA found at centromeres

Repeat unit sequence shows chromosome-specific sequence variation

Question 13

what is required for assembly of the centromere ?

Answer 13

alphoid DNA

Question 14

what is chromosome-specific alphoid DNA used for?

Answer 14

identifying individual human chromosomes

Question 15

what happen during formation of gametes

Answer 15

crossing over occuring between the paternal and maternal chromosome

In order for this to happen, the chromosome will need to recognise each other ie they line up

if fail - meiosis fail

Question 16

what happen when Alu repeats are present

Answer 16

cross over can happen leading to a mixture of chromosome

Question 17

how does Haemophilia A mutation happen at the DNA level?

Answer 17

Since the sequences are located at different position, when recombination take place within the same genes

Half of the F8C genes are being spliced into the other sequences at the different location and so they get inverted since they are upside down - inverted segment

Question 18

which mutation makes up 1/3 of all genetic mutation

Answer 18

CG - TG (methylation)

Question 19

what are some examples for trinucleotide repeat expansions

Answer 19

polyglutamine repeat (CAG) - neurodegenerative disorder- huntington’s disease,

large non-coding repeat expansions - Fragile X syndrome - transciptional silencing