Genomic DNA and Nucleic Acids Prework 2

Question 1

what percentage of DNA is repeated sequences?

Answer 1

50%

Question 2

what are the two types of repeats in DNA and how do they differ?

Answer 2

interspersed: repeated at different intervals on the chromosome
tandem: repeated over and over right next to each other

Question 3

what are the 4 classes of interspersed repeats in the human genome and what % do they make up?

Answer 3

LINEs- 20%
SINEs- 13%
HERVs- 8%
DNA transposon fossils- 3%

Question 4

what are LINEs?

Answer 4

transposons, move via RNA intermediates

6000 nt long, 850,000 copies

Question 5

what are SINEs?

Answer 5

inactive, but movement can be facilitated by active transposons
Alu repeats
280 nt long, 1.5 million copies

Question 6

what phenomenon can long interspersed repeats facilitate?

Answer 6

non-homologous recombination

Question 7

what are 3 types of tandem repeats?

Answer 7

satellite DNA: 3-5% of DNA in each chromosome
minisatellite DNA
microsatellite DNA

Question 8

where are satellite DNA sequences located at each chromosome?

Answer 8

centromere; binding sited for proteins involved in centromere structure

Question 9

what can micro- and minisatellite DNA repeats be used for?

Answer 9

DNA fingerprinting

Question 10

what are segmental duplications?

Answer 10

regions >1kb with greater than 90% identity, present more than once in the genome
duplications can be on the same or multiple chromosomes
5% of genome

Question 11

how do segmental duplications contribute to genomic rearrangements?

Answer 11

unequal crossing over in meiosis