Origins of Variation in Genomes Flashcards

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1
Q

What are the difference between mitosis and meiosis?

A

Mitosis
- somatic cells
- 2n -> 2n + 2n
- genetically identical daughter cells

Meiosis
- haploid gamete production
- 2n -> nx4
- genetically different daughter cells
- includes recombination

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2
Q

What is homologous recombination?

A

crossing over
occurs in meiosis
breakage and going of DNA
reciprocal
genetic rearrangement
creates new combination of alleles

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3
Q

Non-homologous strand break repair

A

cells quickly degrade bases around double strand
reform with ligase

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4
Q

Homologous strand break repair

A

bases around break are degraded to stop overhang
broken area accurately copied across from homologous source

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5
Q

double strand break repair

A

exonuclease creates 3 overhangs
strand invasion creates heteroduplex structure
D loop moves along copying it

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6
Q

What is heteroduplex formation?

A

synapsis
binds to 3’ single stranded end of damaged DNA
forms structure and searches for homology
unzips source of DNA and generates a heteroduplex structure
called a D loop

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7
Q

repair double strand breaks

A

break accurately repaired
mutations overwritten
universal process
non-reciprocal
basic mechanism of homologous recombination

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8
Q

How can homologous recombination generate crossovers?

A

occurs in meiosis
breakage and joining of DNA
reciprocal
genetic rearrangement

2 D loops are generated instead of 1

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9
Q

What is a Holliday junction?

A

4 double stranded arms joined in a square at the centre

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10
Q

What is linkage analysis?

A

Genes on chromosomes are linked physically and genetically

the further apart the linked genes are, the higher the likelihood of recombination

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11
Q

What is gene targeting?

A

introducing specific DNA in vivo
containing homologous sequences and selectable markers
recombination leads to the integration of DNA

can either be a single crossover and split the gene
or double and remove the gene completely

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12
Q

Homologous recombination in bacteria

A

bacteria don’t undergo meiosis
can alter and write more useful DNA
can edit out genes but double crossing over

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13
Q

Homologous recombination in bacteriophage

A

bacteriophages are bacterial viruses
create new versions of bacteriophages
creating recombinant phage within the bacteria

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