Unit 2 - DNA replication Flashcards

1
Q

what are the purines?

A

2 carbon-nitrogen rings

adenine/ guanine

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2
Q

what are the pyrimidines?

A

1 ring

cytosine/ thymine/ uracil

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3
Q

what does each nucleotide contain?

A
  • five carbon sugar
  • nitrogenous base
  • phosphate group
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4
Q

what are the four nucleotides found in DNA?

A

dAMP - deoxyadenosine monophosphate
dCMP - deoxycytidine
dGMP - deoxyguanosine
dTMP - deoxythymidine

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5
Q

what are the four nucleotides found in RNA?

A

AMP - adenosine monophosphate
CMP - cytidine
GMP - guanosine
UMP - uridine

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6
Q

what is the bond linking nucleotides between C3 and C5?

A

phosphodiester bonds

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7
Q

what are primers and what are they needed for?

A

short piece of nucleic acid base-paired template

starting point for DNA replication - requires 3’ - OH group

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8
Q

describe the DNA polymerase reaction

A

DNA partially unwound and RNA primers synthesised attach to the ends
DNA polymerase adds nucleotides to 3’ end
as the strand is further unwound the leading strand is synthesised continously but lagging strand synthesised as okazaki fragments
primers removed by nucleases and replaced with DNA

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9
Q

what is the role of telomerase in DNA replication?

A

extends the ends of chromosomes so prevents shortening of chromosomes
- found in germ-line cells

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10
Q

what attaches to the promoter region of gene?

A

RNA polymerase

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11
Q

how is gene expression controlled? - explain any components involved

A
  • controlling availability of regulatory proteins (transcription factors) that bind to promoters&enhancers
    (enhancers= DNA sequence in eukaryotes which varies in position and boosts transcription in nearby gene)
  • controlling strength of interaction between DNA & histones (euchromatin/ heterochromatin)
  • splicing
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12
Q

what are the initiation and termination codons?

A

initiation: AUG

termination codons: UGA, UAG, UAA

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13
Q

What are ribosomes composed of and what are its three tRNA binding sites?

A

protein/ ribosomal RNA

EPA - exit site/ peptidyl site/ aminoacyl site

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14
Q

what are the three main repeated cycle within translation?

A

binding of aminoacyl-tRNA (requires GTP)
peptidyl-transferase reaction (formation of peptide bonds)
translocation (movement of ribosome one codon along mRNA) - also requires GTP

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15
Q

which antibiotics inhibit peptidyl transferase reaction and translocation?

A

erythromycin/ clarithromycin

chloramphenicol

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16
Q

what is the effect of ricin ?

A

removes base from rRNA (ribosomal nucleic acid)

17
Q

At the end of transcription what are the promoter regions and stop codons replaced with?

A

promoter - Gppp cap

stop codon - poly A tail