BSI Lecture 5-6 Transcription/Translation Flashcards Preview

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Flashcards in BSI Lecture 5-6 Transcription/Translation Deck (78):
1

Define: transcription

The first step in gene expression when a segment of DNA is copied into mRNA by RNA polymerase.

2

What is the function of RNA polymerase?

Transcribe genes

3

Which RNA polymerase produces mRNA?

RNA Polymerase II

4

Promoter

A DNA sequence to which RNA polymerase binds to begin transcription

5

What are the three phases of gene transcription?

Initiation, Elongation and Termination

6

What is the role of the ribosome in translation?

Protein synthesis

7

What is the function of tRNA in the process of translation?

It carries amino acid to the ribosome

8

What is the role of the A-site in translation?

The A-site in translation is the entrance for tRNA to be tested for codon/anti-codon match with mRNA.

9

What is the role of the P-site in translation?

P-site receives amino acid from A-site and adds it to the end of the amino acid side chain.

10

What is the function of peptidyl transferase?

It forms peptide bond between carboxy terminal of polypeptide chain and amino group of new amino acid. Polypeptide grows from amino to carboxy terminus.

11

What is the function of elongation factors in the process of translation?

Elongation factors increase accuracy and speed of translational process

12

What are the stop codons?

UAA, UAG, UGA

13

Does just one codon code for a specific amino acid?

No, more than one codon can code for a specific amino acid.

14

What end of the mRNA is considered the beginning, 3' or 5'?

5'

15

Define the terms 5' untranslated region (5' UTR) and 3' UTR

5' UTR is the region of a mRNA that is directly upstream of the initiation codon. 3' UTR is the region that directly follows the translation termination codon.

16

Name 5 types of covalent post-translational modifications?

glycosylation, phosphorylation, acetylation, hydroxylation, methylation

17

Genes contain the instructions to:

Synthesize proteins as well as structural and enzymatic RNA molecules

18

What types of RNA are genes transcribed into?

mRNA, tRNA, and other RNA molecules.

19

Which is the only type of RNA that can be translated into a protein?

mRNA

20

What enzyme transcribe genes?

RNA polymerase I, II, and III

21

What are the functions of RNA polymerase I?

Transcribes most rRNA genes and produces rRNA.

22

What are the functions of RNA polymerase II?

Transcribes protein-coding genes and produces pre-mRNA

23

What are the functions of RNA polymerase III

Transcribes tRNA genes, transcribes some rRNA genes, and produces tRNA and rRNA.

24

The site where the polymerase starts transcribing the gene forming a pre-mRNA molecule is called the _______

Transcription start site

25

_______ sequence is the DNA sequence which stops transcription.

Termination

26

Define "sense" strand

The strand of DNA that is transcribed by the polymerase.

27

Define "anti-sense" strand

The strand that is not transcribed.

28

"Upstream" means toward the ______ end of the DNA strand in relations to a particular gene.

3'

29

T or F; 5' capping has a guanine nucleotide with a methyl group.

True

30

Series of repeated adenine nucleotides attached to 3' end is called ______

Polyadenylation

31

Capping and polyadenylation of mRNA are important for _____, _______, and ______

Nuclear export of mRNA, mRNA stability, translation of mRNA in cytoplasm

32

Removal of introns from pre-mRNA is called __________

splicing

33

________ recognizes a splicing sequence at 5' and 3' end of intron.

Spliceosome

34

T or F; RNA polymerase III excises introns and ligates exons together.

False, spliceosome

35

Spliceosome structure consists of _____________ and proteins.

small nuclear RNAs (snRNAs)

36

Where are ribosomes located?

Cytoplasm and Rough ER

37

Ribosomes subunits: Large (80s) and small (60s). T or F?

False, Large (60s) and small (40s)

38

Ribosomes are made up of ________ and ______.

Protein; rRNA

39

Ribosomes are made up of rRNA and 50 ________.

proteins

40

rRNa and proteins assemble into _____ and _____ subunits.

Large; small

41

The ______ subunit ribosome contains tRNA binding sites A, P and E.

Large (60s)

42

Small subunit contains ______ binding site.

mRNA

43

When an amino acid is attached to the tRNA it is considered "_______" and is called _________

charged; aminoacyl-tRNA

44

T or F? tRNA is highly folded, 3D structure which is essential for it's function.

True

45

____ contains acceptor arm that binds amino acid and an anticodon loop which must recognize codon from mRNA.

tRNA

46

________ __________ is when tRNMet binds to small ribosome.

Initiation complex

47

tRNAiMet is the "initiator" tRNA and only used at ______ codon.

start

48

tRNAmet is used to incorporate Met into the growing polypeptide during __________ phase.

elongation

49

Initial complex slides along the mRNA until it finds the first start codon which is _____

AUG

50

_______ sequence is thought to be an important DNA sequence surrounding AUG which helps the initiation complex recognize the first AUG

Kozak

51

Once the small subunit reaches start codon, eIF's dissociate to all the large subunit to assemble with tRNAiMet in which site?

P-site

52

Initiations factor (eIFs) are important because they recognizes 5' cap and also makes sure mRNA is ________ stranded at the start site.

single

53

What binds to the poly A tail which acts as a signal that the 3' end of the mRNA is intact.

Initiations factor (eIFs)

54

Some initiation factor acts as helicases to relax secondary structure allowing small subunit to scan along the mRNA to find the _____ _____.

start codon

55

T or F, tRNA with growing polypeptide in P-site is transferred to new amino acid on tRNA that just entered E-site?

False, just entered A-SITE.

56

Peptidyl transferase forms peptide bond between __________ and __________

carboxy terminal of polypeptide chain ; amino group of new amino acid.

57

Elongation: Polypeptide grows from ______ to ________ terminus.

Amino; carboxy

58

Elongation: Ribosome moves forward placing empty tRNA in ___-site and tRNA with growing polypeptide in ___-site, leaving ___-site open for incoming tRNA.

E, P, A

59

Elongation: Ribosome undergoes ______ _______ to shift the mRNA one codon at a time.

conformational change

60

Elongation factors (EFs) ______ accuracy and ______ of the translational process.

increase; speed

61

Termination: Releasing factors are called into play when stop codons ____, ____, or ____ appears in A-site.

UAA, UAG, UGA

62

Termination: ______ ______ bind to any ribosome with a stop codon in the A-site, which forces ____ _____ enzyme to transfer polypeptide to a molecule of H2O?

Releasing factors; peptydyl transferase

63

________ is required for many steps in initiation, elongation, and termination.

Energy

64

In most cells, ______ ______ consumes more energy than any other biosyntheic process.

protein synthesis

65

What are the two reasons why more than one codon can code for a specific amino acid?

Wobble and tRNA's with different anticodons can carry same amino acid.

66

What is wobble?

The ability of one tRNA with a specific anticodon to complementary base pair with more than one codon. Matching the 1st and 2nd codon.

67

Name the 5 regions of mRNA.

5' Caps, 5'UTR, Coding sequence (CDS); 3;UTR, 3' Poly A tail.

68

What are the 4 post-translational modifications:

Protein Folding; Co-factor binding; Covalent modifications; Assembly with other polypeptides to form quatenary structure

69

Once the protein is synthesized, most of the time, the first amino acid is _____, which is _____

Cleaved;methionine

70

The __________ has sequences that functions to regulate stabilization (half-life) of mRNA, length of the poly A tail, rate of which the poly A tail is degraded as well as sequences that regulate the translation of mRNA.

3' UTR

71

Introns

DNA sequences that do not contain coding for the amino acid sequence of protein

72

Exons

contain the coding sequence for the amino acid sequence of the protein

73

Transcription start site

the site where the polymerase starts transcribing the gene forming a pre-mRNA molecule

74

Termination sequence

the DNA sequence which stops transcription

75

Initiation phase

RNA polymerase II binds to promoter

76

Elongation phase

1. moves along DNA from 3' to 5'
2. reads single strand of DNA and adds complementary nucleotides to growing pre-mRNA
3. Pre-mRNA synthesized from 5' to 3'
4. contains uracil instead of thymine

77

Termination phase

RNA polymerase II recognizes termination sequence and releases DNA

78

Pre-mRNA processing

1. 5' capping - Guanine with methyl group gets added to the 5' end
2. Polyadenylation - series of repeated adenine nucleotides attached to 3' end (PolyA tail)
3. Splicing - introns removed by splicesosomes and ligates exons together

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