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Biology > Transcription And Translation > Flashcards

Transcription And Translation Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Takes place in the nucleus, and its end result is the creation of an mRNA copy of a gene that can be transported to the cytosol for translation into a protein

A

Transcription

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2
Q

DNA helix is unzipped in order for transcription to exist, similar to DNA replication. These enzymes are used for that purpose

A

Helical and topoisomerase

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3
Q

The enzyme responsible for RNA synthesis

A

RNA polymerase

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4
Q

The RNA polymerase in eukaryotes does not just start whenever it sees a start codon; instead, it binds to a ?

A

Promoter region upstream of the start codon with the assistance of transcription factors

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5
Q

What is the most important promoter in eukaryotes

A

TATA box

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6
Q

Similarly to DNA polymerase, RNA polymerase travels along the template strand in the _____________ direction, synthesizing an antiparallel complement in the ____________ direction.

A

3’->5’ , 5’->3’

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7
Q

The template strand is known as the _________ strand, and the opposite strand is known as __________ strand

A

antisense, sense

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8
Q

The default RNA polymerase that synthesizes hnRNA (the precursor to mRNA) and some nuclear RNA (snRNA)

A

RNA polymerase II

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9
Q

The precursor to mRNA. This is the immediate product of transcription, not mRNA. It must undergo a set of postranscriptional modifications to become mRNA.

A

hnRNA- heterogenous nuclear RNA

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10
Q

Small nuclear RNA

A

snRNA

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11
Q

Synthesizes ribosomal RNA (rRNA) in the nucleolus

A

RNA polymerase I

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12
Q

Synthesizes transfer RNA (tRNA) and some rRNA

A

RNA polymerase III

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13
Q

There post-transcriptional modifications that the hnRNA undergoes in order to become mRNA. These only occurs in eukaryotes as transcription and translation occurs simultaneously in prokaryotes

A
  1. 3’ poly-A-tail
  2. 5’ cap
  3. splicing
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14
Q

Adding a string of approximately 250 adenine nucleotides to the 3’ end of the hnRNA transcript. This protects mRNA transcript from rapid degradation in the cytosol.

A

3’ poly-A tail

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15
Q

What is the first step in mRNA degradation?

A

Deadenylation do the poly-A tail by a 3’ exonuclease

*the speed with which an mRNA molecule is degraded depends largely on how many A residues are left on it. - part of gene regulation to make sure mRNA stick around long enough to do it job, but not too long

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16
Q

Refers to a 7-methylguanylate triphosphate cap placed on the 5’ end of an hnRNA transcript.

A

5’ cap- prevents the transcript from being degraded too quickly in the cytosol, but it also prepares the RNA complex for export from the nucleus

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17
Q

No coding sequences (introns) are recited and coding sequences (exons) are ligated together.

A

Splicing

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18
Q

How can there be over 200, 000 proteins in the human body, but only approximately 20,000 genes?

A

Splicing!- each gene normally has multiple distinct exons, and they can be ligated in different combination

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19
Q

Splicing is carried out by?

A

Spliceosome, a combination of small nuclear RNAs (snRNAs) and protein complexes

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20
Q

When small nuclear RNAs (snRNAs) and protein complexes are combined they are known as?

A

Small nuclear ribonuclear proteins or snRNPs

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21
Q

T or F. Both introns and exons can be spliced out.

A

True.

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22
Q

The process in which an mRNA sequence is translated into a protein, with each codon corresponding to an amino acid. This takes place in the cytoplasm in both prokaryotes and eukaryotes.

A

Translation

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23
Q

A relatively small RNA molecule characterized by a hairpin structure that is responsible for “translating” between codons and amino acids

A

Transfer RNA (tRNA)

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24
Q

At the bottom of the hairpin structure, tRNA molecules contain an ________, which is specifically complementary to a certain codon of mRNA

A

Anticodon

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25
Q

Enzymes that do the work of “charging” tRNA molecules with the appropriate amino acids by attaching the C-terminus of the amino acid in question to the 3’ end of the tRNA molecule.

A

Aminoacyl-tRNA synthetases

26
Q

“Charging” the tRNA molecule requires the investment of ____ ATP bond, and this energy is then used to power the formation of a peptide bond during translation.

A

2

27
Q

T or F. Translation is a spontaneous process.

A

False. It is an energy consuming process. This means that it is disadvantageous to synthesize proteins that the cell doesn’t need.

28
Q

Major part of the structure of ribosomes, where translation takes place

A

Ribosomal RNA (rRNA)

29
Q

Ribosomes are composed of these 2 major components

A

Large subunit- 50S in prokaryotes and 60S in eukaryotes
Small subunit- 30S in prokaryotes and 40S in eukaryotes

*Overall- 70S for prokaryotes and 80S for eukaryotes

30
Q

Large and small subunits of ribosomes roles

A

Large- catalyzes the formation of polypetide chain

Small- reads the RNA

31
Q

3 steps of translation

A

Initiation, elongation, and termination

32
Q

Occurs when the mRNA sequence binds to the small ribosomal subunit, either at a region the 5’ untranslated region known as the Shine Dalgarno sequence (in prokaryotes) or to the 5’ cap in eukaryotes .

A

Initiation

33
Q

mRNA sequence in prokaryotes where the binding to small subunit of ribosomes occurs

A

Shine Dalgarno

34
Q

The first tRNA is known as the _________ tRNA , and it binds to the _________.

A

Initiator tRNA, start codon (AUG)

35
Q

What is the initial amino acid in eukaryotes? Prokaryotes?

A

Eu- methionine

Pro- N- formylmethionine

36
Q

Once the first tRNA binds to the start codon, initiation factors facilitate the binding of the small ribosomal subunit to the large ribosomal subunit, forming the?

A

Initiation complex

37
Q

Zymogens are activated by

A

Proteolytic processing- means they are cleaved at specific sites

The cleavage of a precursor protein (also called a zymogen) causes it to become active.

38
Q

During this step, the ribosome reads the mRNA in the 5’->3’ direction and synthesizes a polypeptide from its N-terminus to its C terminus.

A

Elongation

39
Q

Proteins that help move the elongation process along

A

elongation factors

40
Q

this site contains the aminoacyl-tRNA complex

A

A site

41
Q

at this site a peptide bond is formed between the growing polypeptide chain and the incoming amino acid

A

P site

42
Q

The tRNA which is now no longer charged, briefly pauses at this site and detaches from the mRNA.

A

E site

43
Q

The process continues until this step, when a stop codon on the mRNA is encountered at which point a release factor triggers ribosome disassembly and release of the polypeptide

A

termination

44
Q

what are the 3 stop codons

A

UGA, UAA, UAG

45
Q

a post-transcriptional modification where phosphates are added

A

phosphorylation

46
Q

enzymes that add phosphate

A

kinases- regulates the activity of enzymes

47
Q

a post-transcriptional modification where carbohydrates are added

A

glycosylation

48
Q

the effects of this post-transcriptional modification include improvements in protein stability, regulatory functions, and structural/ functional roles

A

glycosylation

49
Q

glycosylated molecules play a major role in these 2 cell functions.

A

cell adhesion and recognition- ABO blood system is based on glycoproteins

50
Q

another important post-translational modification that generally follows some large-scale principles regarding polarity, the details are very hard to predict

A

protein folding

51
Q

these proteins help guide protein folding

A

chaperones

52
Q

T or F. Formation of quaternary structures can be considered an example of a post-translational modification.

A

True

53
Q

a frequent occurrence in the synthesis and processing of peptide hormones

A

cleavage

54
Q

original transcript is a ____________, which is then cleaved to a _________________, which is finally cleaved to the active form of a hormone immediately before release from the cell.

A

preprohormone; prohormone

*the reason for this is to prevent hormones from inappropriately affecting the cells they are synthesized in

55
Q

Examples of covalent post-translational modifications

A

Phosphorylation, glycosylation, and ubiquination

56
Q

This is a post-translational modification that involves ubiquities addition. This targets proteins for transport and degradation in the proteosome

A

Ubiquination

57
Q

Ribosome docking is fulfilled by which post-transcriptional modification

A

5’ cap

58
Q

T or F. Each tRNA molecule corresponds to a specific mRNA codon

A

A single tRNA molecule may correspond to more than one codon, as multiple codons may encode the same AA, and thus be recognized by the same tRNA molecules

59
Q

Characteristics of transcription and post-transcriptional modifications in prokaryotes

A
  1. Transcripts are polycistronic- a single mRNA sequence may encode multiple proteins
  2. Transcription and translation may occur simultaneously
60
Q

Directionality of mRNA and peptide synthesis

A

During transcription, RNA polymerase reads the DNA strand in the 3’ to 5’ direction, synthesizing the complementary RNA strand in the 5’ to 3’ direction. During translation, the ribosome reads the mRNA sequence in the 5’ to 3’ direction and synthesizes a polypeptide sequences from it N-terminus to it C-terminus

Biology (16 decks)

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