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Flashcards in Ch 5.1 Deck (30):
1

What are the proteins that are regulated in DNA homologous recombination?

BRAC1
BRAC2
RAD51
they accumulate when damage is present

2

What is the purpose of BRAC1 and BRAC2?

They release RAD51 when it is needed for repair
BRAC1 and BRAC2 are breast cancer susceptible genes

3

What are Holliday junctions?

intermediate in the process of two DNA helices exchanging strands

4

What does holliday junctions do to different sequences?

once they are cut and ligased back together different sequences are created that are different from the original

5

What does meiotic recombination creates?

crossing over
gene conversions
Hybrid chromosomes are formed with genetic material from maternal and paternal chromosomes

6

What two proteins in yeast create double stranded breaks in recombining chromosomes?

Spo11
Mre11
Recombination occurs between maternal and paternal chromosomes rather than two identical duplexes

7

What may you have when forming two holliday junctions in meiosis recombination?

Chromosomes that are crossovers or
Chromosomes that are non crossovers

8

How many human recombinations are resolved as non crossovers?

90%
few Spo11 breaks become non crossovers

9

What do meiotic recombinants (crossover or non crossover have on their chromosomes?

a heteroduplex region

10

what is a heteroduplex?

a region where there is a mixture of DNA sequences from sister chromatids

11

What does gametogenesis yield during meiosis?

4 gametes containing 50% maternal and 50% paternal contributions
occasionally gametes may have 3 copies of maternal and one copy paternal

12

What is the divergence of expected distribution of gametes from mother and father known as?

gene conversion

13

What is transpositional recombination conservative site specific ?

DNA elements that move from one place in the genome to another. THis does not require substantial homology

14

What is the percentage of human genes that can be traced to mobile elements (jumping genes) ?

50%

15

What are mobile elements that move by the way of transposition?

transposons

16

What are transposase?

enzymes that act on the ends of transposons and catalyze their movement into different parts of the genome

17

What are the different types of transposons?

DNA- only transposons
retroviral- like retrotransposons
Nonretroviral retrotransposons

18

What are the enzymes for movement for DNA-only transposons?

tranposase

19

What is the mode of movement for DNA-only transposons?

moves as DNA either by cut and paste or replicative ways

20

Where are DNA-only transposons mostly predominant in?

Bacteria
spread antibiotic resistance in bacteria
penicillin is not effective against many bacterial strains

21

What is the antibiotic resistance in bacteria mainly a result of?

transposons that carry antibiotic-inactivating genes

22

What does the transposase gene do?

They make transposase monomers that recognize certain DNA sequences from donor transposons and cut and paste them into new acceptor genes

23

What do viruses code for in transposition Mechanism for viral integration?

Reverse transcriptase
Integrase (virus encoded transposase)

24

What do retroviral like retrotransposons resemble?

retroviruses but lack proteins

25

where are retroviral like retrotransposons?

yeast
mammals
fly

26

How do nonretroviral retrotransposons move in the genome?

only a few are mobile
Move via endonuclease and reverse transcriptase

27

What is the template that nonviral retrotransposons use?

RNA

28

What is conservative site-specific recombination?

mediates rearrangment of mobile DNA elements

29

What does site specific recombination?

integration
Excision
inversion

30

What are the specialized enzymes that are involved in conservative site specific recombination?

recombinase that resemble topoisomerase

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