RNA and the Genetic Code Flashcards

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1
Q

What does degenerate mean?

A

allows multiple codons to encode for the same amino acid

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2
Q

Start codon?

A

AUG

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3
Q

Stop codons?

A

UAA
UGA
UAG

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4
Q

Wobble base?

A

allows mutations to occur without affecting the protein

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5
Q

Silent mutations?

A

mutations with no affect on protein synthesis

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6
Q

Nonsense (truncation)?

A

mutations which produce a premature stop codon

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7
Q

Missense?

A

mutations which produce a codon that codes for a different amino acid

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8
Q

Frameshift mutations?

A

result from nucleotide addition or deletion and change the reading frame

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9
Q

What makes RNA different from DNA?

A
  • substitution of a ribose sugar for deoxyribose
  • uracil instead of thymine
  • single stranded
  • 2’ OH group, more reactive
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10
Q

mRNA?

A

carries the message from DNA in the nucleus via transcription of the gene, travels from nucleus into cytoplasm

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11
Q

tRNA?

A

brings in amino acids, recognizes the codon on the mRNA using its anticodon

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12
Q

rRNA?

A

makes up much of the ribosome, enzymatically active

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13
Q

Steps of transcription?

A
  • Helicase unwinds, Topoisomerase relieves
  • RNA Pol II binds to TATA box within promoter region of gene (25 base pairs upstream)
  • hnRNA synthesized from DNA template (antisense) strand
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14
Q

Posttranscriptional modifications?

A
  • 7 methylguanylate triphosphate cap added to 5’ end
  • Poly A tail added to 3’ end
  • splicing done by spliceosome, introns removed and exons ligated together
  • alternative splicing combines different exons to acquire different gene products
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15
Q

Posttranslational modifications?

A
  • folding by chaperones
  • formation of quaternary structure
  • cleavage of proteins or signal sequences
  • covalent addition of other biomolecules (phosphorylation, carboxylation, glycosylation, prenylation)
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16
Q

Operons?

A

inducible or repressible clusters of genes transcribed as a single mRNA in prok

17
Q

Transcription factors?

A

search for promoter and enhancer regions in DNA

18
Q

Promoters?

A

within 25 base pairs of transcription start site

19
Q

Enhancers?

A

more than 25 base pairs away from transcription start site