chapter 17: from gene to protein Flashcards

1
Q

what is transcription?

A

the synthesis of RNA using a DNA template

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2
Q

what does transcription produce? what is used as a template?

A
  • it produces RNA
  • uses DNA strands as a template
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3
Q

what is translation?

A
  • the synthesis of a polypeptide using information in the mRNA
  • it occurs on ribosomes in the cytoplasm or ER
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4
Q

what does translation produce? what is used as a template?

A
  • it produces proteins
  • uses mRNA molecule as a template
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5
Q

what is mRNA?

A

“messenger RNA”, is a type of RNA, that attaches to ribosomes in the cytoplasm and specifies the primary structure of a protein

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6
Q

what are some of the differences between DNA and RNA?

A

DNA: double-stranded, uses thymine, contains 2 oxygen atoms, and contains a deoxyribose sugar
RNA: single-stranded, uses uracil, contains 3 oxygen atoms, and contains a ribose sugar

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7
Q

how many amino acids are there?

A

20 amino acids

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8
Q

what is a codon? how large is it?

A
  • a 3-nucleotide sequence of DNA or mRNA, that codes for a particular amino acid or termination sequence
  • each codon consists of 3 nucleotides
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9
Q

what are 3 important general notions about the “genetic code”?

A
  • the code is universal
  • the code is redundant
  • the code is not ambiguous (each codon signifies one amino acid)
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10
Q

what is a coding strand?

A

a strand of DNA that is not used for transcription and is identical in sequence to mRNA (except it contains thymine instead of uracil)

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11
Q

what is a transcription factor?

A

a regulatory protein that binds to DNA and affects transcription of specific genes

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12
Q

what is a promoter?

A

a specific nucleotide sequence in the DNA of a gene that binds RNA polymerase

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13
Q

what are the 3 subphases in transcription?

A

initiation, elongation, and termination

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14
Q

what is a TATA box? what attaches to a TATA box?

A
  • a DNA sequence found in eukaryotic promoters (helps build transcription initiation complex)
  • proteins, called transcription factors, can bind to the TATA box
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15
Q

what is RNA processing?

A
  • 5’ cap
  • poly A tail on 3’ end
  • cut out of introns and joining of exons
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16
Q

what is a “UTR”?

A

a DNA sequence that is not translated into a RNA sequence

17
Q

what are exons?

A

expressed sequence of DNA, coding for a protein

18
Q

do introns or exons code for a protein?

A

exons

19
Q

what is tRNA?

A

“transfer RNA”, a RNA molecules that carries amino acids to the ribosome

20
Q

what is rRNA?

A

“ribosomal RNA”, is a type of non-coding RNA that is the primary component of ribosomes (carrying out protein synthesis in ribosomes)

21
Q

where does translation occur?

A

in ribosomes in the cytoplasm

22
Q

where does transcription and RNA processing happen in a eukaryotic cell?

A
  • transcription, in eukaryotes, takes place in the nucleus
  • RNA process takes place in nucleolus
23
Q

what is the 5’ cap?

A

a modified form of guanine nucleotide added onto the 5’ end of a pre-mRNA molecule

24
Q

what is a poly-a-tail?

A

a sequence of 50-250 adenine nucleotides added onto the 3’ end of a pre-mRNA molecule

25
Q

RNA processing only happens where?

A

in eukaryotic cells

26
Q

what is a start codon? what is a stop codon?

A

start codon: marks the site at which translation into protein sequence begins
stop codon: marks the site at which translation ends

27
Q

what is a reading frame?

A

on mRNA, the triplet grouping of ribonucleotides used by the translation machinery during polypeptide synthesis

28
Q

what are the 3 active sites of a ribosome?

A

P site: protein binding site
A site: amino acid binding site
E site: exit site

29
Q

what is an anticodon?

A

a nucleotide triplet at one end of a tRNA molecule that base-pairs with a particular complementary codon on a mRNA molecule (3’ to 5’ direction)

30
Q

what is a polyribosome?

A

a group of several ribosomes attached to the same mRNA molecule

31
Q

what direction is mRNA building in?

A

5’ to 3’

32
Q

what is the link between genotypes and phenotypes?

A

proteins

33
Q

what are introns?

A

noncoding segments of nucleic acid that lie between coding segments (are removed by RNA splicing)

34
Q

list the start and stop codons

A

start: AUG
end: UAA, UAG, UGA