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Bio > Chapter 7 > Flashcards

Chapter 7 Flashcards

1
Q

Transcription

A

process in which RNA polymerase uses one strand of DNA as a template to synthesize a complementary RNA sequence

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2
Q

RNA polymerase

A

enzyme that catalyzes the synthesis of an RNA molecule from a DNA template using ribonucleoside triphosphate precursors

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3
Q

Do RNA polymerases need a primer?

A

no

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4
Q

Do RNA polymerases proofread their work?

A

no

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5
Q

messenger RNA (mRNA)

A

RNA molecule that specifies the amino acid sequence of a protein

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6
Q

each mRNA carries information transcribed for _____

A

just one gene which codes for a single protein

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7
Q

noncoding RNA

A

an RNA molecule that is the final product of a gene and does not code for protein
serve as enzymatic, structural, and regulatory components

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8
Q

ribosomal RNAs form the _______ of the ribosomes

A

structural and catalytic core

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9
Q

transfer RNAs (tRNAs)

A

act as adaptors that select specific amino acids and hold them in place as the ribosome links them to the growing protein

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10
Q

microRNAs (miRNAs)

A

regulate gene expression

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11
Q

small interfering RNAs (siRNAs)

A

provide protection from viruses and proliferating transposable elements

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12
Q

long noncoding RNAs (lncRNAs)

A

act as scaffolds and serve other diverse function, many of which are still being discovered

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13
Q

Promoter

A

DNA sequence that initiates gene transcription
includes sequences recognized by RNA polymerase and its accessory proteins

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14
Q

what does the sigma factor do

A

begins to open the DNA double helix to examine the exposed base pairs

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15
Q

which direction of DNA is used as its template

A

3’ to 5’ direction

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16
Q

general transcription factors

A

proteins that assemble on the promoters of eukaryotic genes near the start site of transcription and load the RNA polymerase in the correct position

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17
Q

RNA processing steps

A

capping
splicing
polyadenylation

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18
Q

RNA capping

A

modification of the 5’ end of a maturing RNA transcript by the addition of an atypical nucleotide

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19
Q

polyadenylation

A

the addition of multiple adenine nucleotides to the 3’ end of a newly synthesized mRNA molecule

20
Q

introns

A

noncoding sequence within a eukaryotic gene that is transcribed into an RNA molecule but is then excised by RNA splicing to produce an mRNA

21
Q

exon

A

segment of a eukaryotic gene that is transcribed into RNA and dictates the amino acid sequence of part of a protein

22
Q

RNA splicing

A

process in which intron sequences are excised from RNA molecules in the nucleus during the formation of a mature messenger RNA

23
Q

small nuclear RNA (snRNA)

A

RNA molecules that participate in RNA splicing

24
Q

spliceosome

A

large assembly of RNA and protein molecules that splices introns out of pre-mRNA in the nucleus of eukaryotic cells

25
Q

alternative splicing

A

production of different mRNAs from the same gene by splicing its RNA transcripts in different ways

26
Q

mRNA transport from the nucleus to the cytosol is _______ and is mediated by _______

A

highly selective
nuclear pore complexes

27
Q

what is true of eukaryotic mRNAs?
-they are synthesized and translated simultaneously
-they must always be folded into a complex three-dimensional shape before they can be translated
-they are subjected to processing only after being released by the polymerase
-they are translated after they are exported from the nucleus

A

they are translated after they are exported from the nucleus

28
Q

a RNA chain is synthesized in which direction

A

5’ to 3’ only

29
Q

in eukaryotes, which parts of a gene are transcribed into RNA?

A

introns and exons

30
Q

translation

A

process by which the sequence of nucleotides in a messenger RNA molecule directs the incorporation of amino acids into protein

31
Q

codon

A

group of 3 consecutive nucleotides that specifies a particular amino acid or that starts or stops protein synthesis

32
Q

reading frames

A

one of three possible ways in which a set of successive nucleotide triplets can be translates into protein, depending on which nucleotide serves as the starting point

33
Q

transfer RNA (tRNA)

A

small RNA molecule that serves as an adaptor that “reads” a codon in mRNA and serves as the source of the amino acid added to the growing polypeptide chain

34
Q

anticodon

A

set of 3 consecutive nucleotides in a tRNA molecule that recognizes, through base-pairing, the 3 nucleotide codon on a mRNA molecule

35
Q

aminoacyl-tRNA synthetase

A

during protein synthesis, and enzyme that attaches the correct amino acid to a tRNA molecule to form a “charged” aminoacyl-tRNA

36
Q

_____ are responsible for the ribosome’s overall structure and its ability to catalyze protein synthesis

A

rRNAs

37
Q

ribozymes

A

RNA molecules that possess catalytic activity

38
Q

initiator tRNA

A

special tRNA that initiates the translation of an mRNA on a ribosome
always carries methionine

39
Q

translation initiation factor

A

protein that promotes the proper association of ribosomes with mRNA and is required for the initiation of protein synthesis

40
Q

start codon

A

AUG codes for methionine

41
Q

stop codons

A

UAA
UAG
UGA

42
Q

protease

A

enzyme that degrades proteins by hydrolyzing their peptide bonds

43
Q

proteasome

A

large protein machine that degrades proteins that are damaged, misfolded, or no longer needed by the cell

44
Q

ubiquitin

A

major role is to mark target proteins for degradation by the proteasome

45
Q

how many different aminoacyl-tRNA synthetases do most organisms have?

A

one for each amino acid

46
Q

what is false regarding codons in mRNA molecules
-some codons do not code for amino acids
-in some cases, several different codons code for the same amino acid
-all codons contain three nucleotides
-some codons code for more than one amino acid

A

some codons code for more than one amino acid

47
Q

which reaction is catalyzed by a ribozyme in present-day cells?
-RNA polymerization during transcription in bacteria
-DNA polymerization during DNA replication
-peptide bond hydrolysis by the proteasome
-peptide bond formation during translation

A

peptide bond formation during translation

Bio (15 decks)

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