proteinsynthesis + DNA Flashcards

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1
Q

DNA replication

A

semi conservative replication

  • DNA helices breaks hydrogen bonds between bases
  • strands unwinds, both act as templates
  • free DNA nucleotides diffuse into place by complementary base pairs
  • hydrogen bonds form between bases
  • DNA polymerase joins nucleotides by phosphodiester bonds
  • strand made of one parent and one new
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2
Q

transcription

A
  • DNA helices breaks hydrogen bonds between bases
  • strands separate, one acts as a template
  • free RNA nucleotides diffuse into place by complementary base pairing
  • RNA polymerase joins nucleotides y phosphodiester bonds
  • the pre-mRNA is spliced to remove introns to make mRNA
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3
Q

why are intron removed in splicing?

A

so they don’t affect amino acid order

(don’t code for amino acids)
not present in prokaryotic

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4
Q

difference between introns and multiple repeats

A

introns- non coding sections of DNA found WITHIN genes

non-coding repeats - DNA sequences that don’t code for amino acids, repeat BETWEEN genes

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5
Q

translation

A
  • mRNA leaves nucleus through pores
  • goes to ribosome
  • tRNA brings amino acids to the ribosome
  • specific tRNA molecules bring specific amino acids
  • anitocodon of tRNA is complementary to codon on mRNA, held by hydrogen bonds
  • means two amino acids are held close on ribosome
  • peptide bonds form between amino acids
  • tRNA detaches to get another amino acid from cytoplasm
  • ribosome moves along mRNA
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6
Q

role of DNA and RNA

A

DNA - stores genetic information

RNA - transfers genetic information from DNA to ribosomes

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7
Q

structure of nucleotide

A

pentose sugar (deoxyribose or ribose)
nitrogenous base (A,T,U,C,G)
phosphate group

join together by condensation reactions between sugar and phosphate

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8
Q

structure of DNA

A

two antiparallel polynucleotide strands, twisted into helix
= sugar phosphate backbone
joined by hydrogen bond between complementary bases
(A-T forms 2 bonds, C-G forms 3)

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9
Q

adaptations of DNA molecule

A

helix protects bases
weaker hydrogen bonds - easily broken to allow replication
strong phosphodiester bonds = strength of molecule

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10
Q

structure of RNA

A

single polynucleotide strand
A-U, C-G
shorter than RNA
ribose not deoxyribose

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11
Q

why does DNA polymerase only work in one direction?

A

active site only complementary to 3’ end
so only binds and moves one way

works antiparallel
- one polymerase on one strand moves different direction to one on the other

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12
Q

purpose of semi conservative replication

A

done before cell division
so each new cell has a full amount of DNA

semi conservative ensures genetic continuity between generations

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13
Q

Meselson and Stahl

A

two samples of bacteria grown
- one in heavy and one light nitrogen
(took up nitrogen into DNA)

sample taken and spun in centrifuge
- heavy nitrogen DNA settled lower than light nitrogen

heavy nitrogen bacteria allowed to replicate in only light nitrogen
- sample taken and spun

if conservative
- heavy strands settle lower and lighter higher

semi conservative
- contained a strand of heavy and light
- settled between, in middle

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14
Q

difference between transcription in eukaryotes and prokaryotes

A

eukaryotes - introns and exons both copied into mRNA
- spliced to remove introns

prokaryotes - mRNA directly from DNA
- no splicing as no introns in DNA

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15
Q

ribosomes

A

site of proteinsynthesis

found in cytoplasm of all cells
(RER of eukaryotic only)
larger (80s) in eukaryotic than prokaryotic
not membrane bound

made of proteins and rRNA
- small and large subunit

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