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BSCI330 SPRING > exam 2 the central dogma: translation > Flashcards

exam 2 the central dogma: translation Flashcards

(61 cards)

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1
Q

how does genetic information stored in chromosomes become useful

A

by being read and converted into proteins in the cytosol

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2
Q

where are mRNA molecules exported to and from

A

exported from nucleus to the cytosol

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3
Q

where do mRNA molecules get translated into proteins

A

cytosol, where they get translated into proteins by ribosomes

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4
Q

how many different combinations does the triple nucleic code allow for

A

4 x 4 x 4 = 64 - enough for the 20 amino acids

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5
Q

what is a codon

A

set of three nucleotides

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6
Q

how many codons does each amino acid usually have

A

more than one

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7
Q

what is the start codon

A

Met - AUG

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8
Q

what does degenerate mean

A

there are multiple codons that encode the same amino acid - no one-to-one correspondence

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9
Q

what is the result of the degenerate nature of the genetic code

A

for a given protein sequence there may be more than one RNA sequence

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10
Q

what happens with a degenerate code and the given RNA sequence

A

cannot determine 100% what the RNA sequence is from the protein sequence

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11
Q

why are intermediary required

A

amino acids cannot directly interact with mRNA

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12
Q

what does tRNA do

A

transfer RNA matches amino acids with codons

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13
Q

what are tRNAs

A

short RNAs with distinctive 3D structure

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14
Q

where does an amino acid get attached to a tRNA

A

covalently attached to 3’ end of tRNA

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15
Q

what is an anticodon

A

complementary to the appropriate amino acid’s codon

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16
Q

what are is the anticodon for CAG

A

CUG

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17
Q

what is the anticodon for AAA

A

UUU

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18
Q

is there an anticodon loop for every RNA

A

yes

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19
Q

what couples an amino acid to tRNA

A

aminoacyl-tRNA synthetase - each amino acid has a distinct one

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20
Q

what is an amino acid first activated by

A

conjunction to AMP

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21
Q

how is conjunction to AMP made

A

by taking ATP and chopping off phosphates

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22
Q

after being activated, what happens to amino acid

A

amino acid is transferred from AMP to tRNA

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23
Q

what does the resulting conjugate have for the amino acid transferred from AMP to tRNA

A

has a high-energy bond between amino acid and tRNA

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24
Q

what happens once the amino acid transfer to tRNA is complete

A

the synthetase proofreads for accuracy

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25
what direction does protein synthesis occur in
N-terminal to C-terminal direction (amino acid is added to C-terminal end of growing chain)
26
where is the peptide chain attached during protein synthesis
to the last tRNA that was added
27
how is the peptide chain extended by one residue
new aminoacyl tRNA replaces old tRNA
28
what is RNA message decoded by
ribosomes
29
what do rRNAs make up
structural and catalytic core
30
what makes up the structural and catalytic core
ribozyme
31
what is the ribozyme
enzyme where catalytic component is RNA, not protein
32
what are the two units of the ribozyme
large and small
33
which direction does ribosome read mRNA
5'->3', reading 3 bases (one codon) at a time
34
why can proteins translate while transcribing
because mRNA reads 5'->3'
35
how many reading frames does each mRNA have
3 - ribosomes must choose one and remain consistent or garbled translation occurs
36
what does AUG (Met) use
a special initiator tRNA - different than the Met tRNA used for the rest of translation
37
what is translation elongation facilitated by
elongation factors
38
what are the elongation factors in prokaryotes
Ef-Tu/Ef-G
39
what are the elongation factors in eukaryotes
EF1/EF2
40
what does GTPase activity allow for
they're used by elongation factors to allow proofreading and to speed up ribosome translocation
41
what do elongation factors do
convert GTP to GDP through hydrolysis, which uses it to regulate the process and proofread
42
what does hydrolysis do
puts energy back in the system because forming a peptide bond is energetically expensive
43
what is GTP hydrolysis in cells usually for
regulating things
44
when does translation termination occur
when the ribosomes encounters a stop codon
45
what happens with translation termination
a release factor binds to the ribosomes, causing the hydrolysis of the peptidyl tRNA, releasing the completed protein
46
what happens to the ribosome during translation termination
it dissociates into separate small and large subunits, releasing the mRNA, release factor, and remaining tRNA
47
does an in-frame stop codon always lead to termination of translation
no - there are circumstances where a stop codon is translated to insert an amino acid
48
what does protein translation occur on
polyribosomes
49
how many peptide chains can a ribosome synthesize at a time
one, but a cell may need many copies of a protein for every cell of the relevant mRNA
50
when does a next ribosome bind to a cap
once the first ribosome has moved far enough along
51
what is a polyribosome
a single mRNA may have several ribosomes translating simultaneously
52
what interacts with each other to recognize intact mRNA
5' cap and 3' tail interact with each other
53
what types of cells do antibiotics affect
prokaryotes
54
what are mitochondrial ribosomes like
prokaryotic ribosomes more than eukaryotic ribosomes
55
what can prokaryotic ribosomes do
cross mitochondrial membrane and effect mitochondrial protein synthesis
56
how are RNA and protein synthesis energetically costly
adding each subunit requires the conversion of an NTP into an NMP, the equivalent of hydrolyzing 2 ATPs to ADP
57
what does elongation steps consume
multiple ATP/GTP molecules
58
what are elongation steps
movement of ribosomes and proofreading
59
what is the info content at the protein sequence level
info for 3D structure, cellular location, and protein functions
60
what is the info content at mRNA level
same info as protein in code, plus info about initiating and terminating translation and sometimes mRNA stability
61
what is the info content at the DNA level
same info as in mRNA, plus info about initiating/terminating transcription, splicing, and anything useful in the introns themselves

BSCI330 SPRING (24 decks)

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