Unit 6 - topic 3 Flashcards

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1
Q

proteins

A

polypeptides made up of amino acids

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2
Q

amino acids are linked by

A

peptide bonds

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3
Q

gene expression

A
  • process by which DNA directs the synthesis of proteins
  • includes two stages: transcription and translation
  • occurs in all organisms
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4
Q

transcription

A
  • synthesis of RNA using information from DNA
  • allows for the “message” of DNA to be transcribed
  • occurs in nucleus
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5
Q

translation

A
  • synthesis of a polypeptide using information from RNA
  • a nucleotide sequence becomes an amino acid sequence
  • occurs at the ribosome
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6
Q

messenger RNA

A

synthesized during transcription using a DNA template

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7
Q

mRNA carries information from DNA (nucleus) to

A

ribosomes in cytoplasm

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8
Q

transfer RNA molecules are important in the process of

A
  • translation
  • each tRNA can carry a specific amino acid
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9
Q

tRNA can attach to mRNA via

A
  • their anticodon
  • a complementary codon to mRNA
  • allow information to be translated into a peptide sequence
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10
Q

ribosomal RNA

A
  • rRNA helps form ribosomes
  • helps link amino acids together
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11
Q

DNA contains the

A

sequence of nucleotides that codes for proteins
sequence is read in groups of three called the triplet code

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12
Q

during transcription

A

only one DNA strand is being transcribed
known as the template strand (aka the noncoding strand, minus strand, or antisense strand)

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13
Q

mRNA molecules formed are

A

antiparallel and complementary to the DNA nucleotides

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14
Q

base pairing

A

A-U and C-G

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15
Q

mRNA nucleotide triplets are called

A

codons

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16
Q

codons code for

A

amino acids

17
Q

amino acid chart

A

64 different codon combinations
61 code for amino acids
3 are stop codons
universal to all life

18
Q

redundancy

A

more than one codon codes for each amino acid

19
Q

reading frame

A

codons on the mRNA must be read in the correct groupings during translation to synthesize the correct proteins

20
Q

three steps in transcription

A
  • initiation
  • elongation
  • termination
21
Q

initiation

A
  • RNA polymerase molecules attach to a promoter region of DNA
  • do not need a primer to attach
22
Q

promoter regions are

A

upstream of desired gene to transcribe

23
Q

initiation eukaryotes

A
  • promoter region is called TATA box
  • transcription factors help RNA polymerase bind
24
Q

initiation prokaryotes

A

RNA polymerase can bind directly to promoter

25
Q

elongation

A
  • RNA polymerase opens the DNA and reads the triplet code of the template strand
    moves in the 3’ to 5’ direction
    mRNA transcript elongates 5’ to 3’
  • RNA polymerase moves downstream
    only opens small sections of DNA at a time
    pairs complementary RNA nucleotides
    growing mRNA strand peels away from the DNA template strand
    DNA double helix then reforms
  • a single gene can be transcribed simultaneously by several RNA polymerase molecules
    helps increase the amount of mRNA synthesized
    increases protein production
26
Q

termination prokaryotes

A
  • transcription proceeds through a termination sequence
  • causes a termination signal
  • RNA polymerase detaches
  • mRNA transcript is released and proceeds to translation
  • mRNA does NOT need modifications
27
Q

termination eukaryotes

A
  • RNA polymerase transcribes a sequence of DNA called the polyadenylation signal sequence
  • codes for a polyadenylation signal (AAUAAA)
  • releases the pre-mRNA from the DNA
  • must undergo modifications before translation
28
Q

three modifications that must occur to eukaryotic pre-mRNA

A
  • 5’ cap
  • Poly-A tail
  • RNA splicing
29
Q

5’ cap (GTP)

A

5’ end of the pre-mRNA receives a modified guanine nucleotide “cap”

30
Q

Poly-A-tail

A

3’ end of the pre-mRNA receives 50-250 adenine nucleotides

31
Q

both the 5’ cap and the poly-A tail function to

A
  • help mature mRNA leave nucleus
  • help protect mRNA from degradation
  • help ribosomes attach to the 5’ end of mRNA when it reaches the cytoplasm
32
Q

RNA splicing

A

sections of the pre-mRNA, called introns, are removed and then exons are joined together

33
Q

introns

A

intervening sequence, do not code for amino acids

34
Q

exons

A

expressed sections, code for amino acids

35
Q

alternative splicing

A

a single gene can code for more than one kind of polypeptide

36
Q

once all modifications have occurred, pre-mRNA is now considered

A

mature mRNA and can leave the nucleus and proceed to the cytoplasm for translation at the ribosomes