genetics 1 Flashcards

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1
Q

what are purines

A

DNA bases

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2
Q

what are pyrimidines

A

RNA bases

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3
Q

how are sugars attached to purines and pyrimidines

A

C-1 of sugar attached to N-9 of purine and N-1 of pyrimidines

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4
Q

where is the phosphoryl group attached too

A

5’ carbon atom of the sugar

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5
Q

where is the free hydroxyl group attached too

A

3’ carbon of sugar

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6
Q

what is the structure of DNA

A
  • antiparallel polynucleotide strands
  • right handed helix
  • sugar-phosphate backbone outside
  • bases inside
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7
Q

what do genes contain

A

exons - encoding
introns - connecting

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8
Q

where are the major and minor groves

A

major - when helix is away from you
minor - when helix is towards you

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9
Q

how are introns removed

A

splice out by spliceosomes to generate mature messenger RNA

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10
Q

what do single stranded DNA binding proteins do

A

cooperative protein binding straightens region of the chain so DNA polymerase can work

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11
Q

where does cytosine methylation take place

A

on DNA at CG motifs

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12
Q

how does cytosine methylation work

A
  • when DNA replicates only the original strands have methyl groups attached
  • one side not recognised by maintenance methylase
  • methyl group attached to CG motif
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13
Q

what causes damage to DNA

A
  • errors in DNA replication
  • mutagens
  • errors in DNA repair
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14
Q

what is a transition mutation

A

goes from one purine to another or one pyrimidine to another

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15
Q

what is a transverse mutation

A

goes from a purine to a pyrimidine or vice versa

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16
Q

what does deamination do

A

thymine and adenine base pair

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17
Q

what does oxidative damage do to DNA

A
  • adds oh to thymine and guanine
  • blocks DNA replication and transcription
18
Q

what does depurination do to DNA

A

N-glycosidic bonds are cleaved to release a corresponding adenine or guanine

19
Q

what does alkylating agents do to DNA

A

adds methyl groups - blocks DNA replication and transcription

20
Q

what does bulky adducts do to DNA

A

when binding results in abnormal DNA replication

21
Q

what does base analogues do to DNA

A

molecules which are substituted for bases of DNA

22
Q

what does intercalating agents do to DNA

A

intercalated molecule attaches to DNA helix causing base insertions and deletions

23
Q

what does uv light do to DNA

A
  • formation of dimers
  • creates photoproducts
  • generates free radicals
  • strand breaks
  • blocks DNA replication and transcription
24
Q

what does ionising radiation do to DNA

A
  • causes a double strand break
  • various mutations due to strand break repair and oxidative damage
25
Q

what is the components of an RNA nucleotide

A
  • ribose sugar
  • phosphate group
  • nitrogenous base
26
Q

what are the 3 types of functional RNA

A
  • transfer RNA
  • ribosomal RNA
  • ribozyme
27
Q

how many types of transfer RNA is there

A

over 50 types

28
Q

what are repeat sequences used for

A
  • genomes contain many repetitive sequences
  • structural binding sites
    used for - replication, recombination, repair and transcription
29
Q

types of secondary structure DNA repeats

A
  • hairpin
  • t-loop
  • cruciform
  • reverse fork
  • G-quartet
  • G-quadruplex
30
Q

what is DNA denaturation and what are the conditions

A

double stranded base pairs become separated
- 100 degrees or pH >13

31
Q

what is DNA renaturation and what are the conditions

A

reforming double stranded base pairs
- 55 degrees and neutral pH

32
Q

what is DNA hybridisation

A

double stranded base pairs with other DNA
- strict annealing —> more specific

33
Q

what does FISH stand for

A

fluorescence in situ hybridisation

34
Q

what does FISH do and what are the steps

A
  • detects nucleotide sequences
    1) denature target DNA
    2) bind labelled DNA to target
    3) label detection
35
Q

what does microarrays do

A
  • quantify gene expression
  • identify polymorphisms
  • quantify DNA
36
Q

what is the disadvantages of microarrays

A
  • low reproducibility
  • inaccurate
37
Q

in DNA chain-terminating fluorescently Sanger sequencing which nucleotides are labeled

A

Dideoxyribonucleotides

38
Q

how does ionising radiation damage DNA

A

sugar phsopahte backbone

39
Q

what mutation occurs due to UV light

A

formation of dimers

40
Q

what causes DNA strand breaks

A

ionising radiation

41
Q

how many nucleotide bases are in the human genome

A

3 billion