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Cell Bio > Exam 4 (Topic 15) > Flashcards

Exam 4 (Topic 15) Flashcards

1
Q

5’ UTR (untranslated region)

A

noncoding sequence

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2
Q

Coding sequence

A

only exons

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3
Q

Three important proteins for fully processing mRNA before it can be moved to the cytoplasm

A
  1. cap-binding protein
  2. poly-A-binding protein
  3. EJC - Exon junction complex
    (All are important for regulating mRNA export and initiating translation)
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4
Q

Important for initiating translation

A
  1. cap-binding protein
  2. poly-A-binding protein
  3. EJC - Exon junction complex
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5
Q

The code is redundant means

A

more than one triplet can code for the same amino acid

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6
Q

3 nucleotide sequence of mRNA that codes for an amino acid

A

Codon

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7
Q

Only codon that signals the start of translation

A

AUG (methionine)

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8
Q

Three codon signal termination of translation

A

UAA, UAG, UGA

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9
Q

Do not code for any amino acid

A

Termination of Translation

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10
Q

Number of codons

A

61 possible amino acid codons
3 termination condons
(1 for start, 3 to terminate, 60 code for 20 amino acids)

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11
Q

mRNA can have up to 3 different

A

reading frames

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12
Q

How the triple code is read

A

Reading frames

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13
Q

The correct reading frame is determined by the

A

start codon (AUG)

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14
Q

Adapter molecules (about 80 nucleotides long) that bind to amino acid and also bind to mRNA

A

tRNA

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15
Q

Two very important regions

A

Anticodon and 3’CCA end

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16
Q

Base pairs in the reverse complement direction with the codon of mRNA

A

tRNA anticodon

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17
Q

Covalently couple each amino acid to its specific tRNA molecule

A

Aminoacyl-tRNA Synthetases

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18
Q

There is _____ unique synthetases

A

20 (one for each amino acid)

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19
Q

Use ATP hydrolysis to create a high energy bond between the amino acid and the tRNA 3’CCA end

A

Aminoacyl-tRNA Synthetases (this high energy bond is later used to power peptide bond formation)

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20
Q

Complex of Ribosomal proteins and rRNA

A

Ribosome (ribonucleoprotein)

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21
Q

The ribosome is composed of

A 
Large subunit (catalyzes the formation of the peptide bond)
Small subunit (matches the tRNA anticodon to the codons of the mRNA)
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22
Q

Three tRNA binding sites

A

A site, P site, E site

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23
Q

Makes up the core of the ribosome and do most of its catalytic function

A

rRNAs

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24
Q

rRNA contains a

A

peptidyl transferase catalytic core

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25
Q

RNAs that can catalyze reactions

A

Ribozymes

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26
Q

Newly added tRNA binds to which ribosomal site?

A

P Site????

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27
Q

The small ribosomal subunit binds

A

Initator tRNA in the P site and additional proteins

28
Q

This binds Initiator tRNA and additional proteins

A

Small Ribosomal Subunit

29
Q

How do cells signal the start of translation?

A
  1. The small ribosomal subunit binds (initiator tRNA in the P site carries methionine (met) and additional proteins: translation initiation factors)
  2. The loaded small subunit binds to the 5’ cap of mRNA
  3. Initiator tRNA/small ribosomal subunit scans the mRNA in the 5’–> 3’ direction to look for AUG
  4. Once bound to AUG, Initiator factors dissociate from the small ribosomal subunit and then the larger ribosomal subunit attaches and completes the ribosome
  5. Translation then begins with addition of tRNA in the A site and the first peptide bond forms
30
Q

Translation Steps

A
  1. New tRNA is added to the A site (Old tRNA is ejected from the E site)
  2. Peptide bond is formed between new amino acids in P and A sites
  3. Large subunit move forward (translocates) on the mRNA
  4. Small subunit moves forward (translocates) creating empty A site
31
Q

When the peptide bond is formed between new amino acids in P and A sites tRNA in A site

A

Now holds the polypeptide

32
Q

When the large subunit moves forward on the mRNA

A

tRNA that was in P site is now in the E site and tRNA that was in A site is now in the P site

33
Q

When the small subunit moves forward it

A

Creates empty A site and Step one is repeated again

34
Q

Translation is terminated by

A

Three Stop Codons (UAG, UAA, UGA)

tRNA doesn’t bind to stop codons

35
Q

Proteins that bind to the A-site containing a stop codon

A

Release factors

36
Q

Release factors function

A

Catalyzes the addition of water molecule to the polypeptide, polypeptide released from the tRNA, then the ribosome dissociates from the mRNA

37
Q

How can we control gene expression?

A

mRNA production and degradation

Protein production and degradation

38
Q

What governs gene expression

A

The length of time mRNA is allowed to exist governs its gene expression

39
Q

When an mRNA is no longer needed

A

the mRNA gets degraded

40
Q

Enzymes that degrade RNA

41
Q

Lifetimes of mRNA are specified by

A

Specific sequence in the 3’ UTR of the mRNA

42
Q

Enzymes that degrade proteins

43
Q

Eucaryotes use

A

Proteosomes

44
Q

Cylinder (trash can) complex of many proteases

A

Proteosomes

45
Q

Proteosomes act primarily on proteins that are

A

Targeted for degradation by the addition of ubiquitin

46
Q

Ubiquitin

A

A small protein itself that s added to proteins for degradation

47
Q

The small ribosomal subunit binds

A

Initator tRNA in the P site and additional proteins

48
Q

This binds Initiator tRNA and additional proteins

A

Small Ribosomal Subunit

49
Q

How do cells signal the start of translation?

A
  1. The small ribosomal subunit binds (initiator tRNA in the P site carries methionine (met) and additional proteins: translation initiation factors)
  2. The loaded small subunit binds to the 5’ cap of mRNA
  3. Initiator tRNA/small ribosomal subunit scans the mRNA in the 5’–> 3’ direction to look for AUG
  4. Once bound to AUG, Initiator factors dissociate from the small ribosomal subunit and then the larger ribosomal subunit attaches and completes the ribosome
  5. Translation then begins with addition of tRNA in the A site and the first peptide bond forms
50
Q

Translation Steps

A
  1. New tRNA is added to the A site (Old tRNA is ejected from the E site)
  2. Peptide bond is formed between new amino acids in P and A sites
  3. Large subunit move forward (translocates) on the mRNA
  4. Small subunit moves forward (translocates) creating empty A site
51
Q

When the peptide bond is formed between new amino acids in P and A sites tRNA in A site

A

Now holds the polypeptide

52
Q

When the large subunit moves forward on the mRNA

A

tRNA that was in P site is now in the E site and tRNA that was in A site is now in the P site

53
Q

When the small subunit moves forward it

A

Creates empty A site and Step one is repeated again

54
Q

Translation is terminated by

A

Three Stop Codons (UAG, UAA, UGA)

tRNA doesn’t bind to stop codons

55
Q

Proteins that bind to the A-site containing a stop codon

A

Release factors

56
Q

Release factors function

A

Catalyzes the addition of water molecule to the polypeptide, polypeptide released from the tRNA, then the ribosome dissociates from the mRNA

57
Q

How can we control gene expression?

A

mRNA production and degradation

Protein production and degradation

58
Q

What governs gene expression

A

The length of time mRNA is allowed to exist governs its gene expression

59
Q

When an mRNA is no longer needed

A

the mRNA gets degraded

60
Q

Enzymes that degrade RNA

61
Q

Lifetimes of mRNA are specified by

A

Specific sequence in the 3’ UTR of the mRNA

62
Q

Enzymes that degrade proteins

63
Q

Eucaryotes use

A

Proteosomes

64
Q

Cylinder (trash can) complex of many proteases

A

Proteosomes

65
Q

Proteosomes act primarily on proteins that are

A

Targeted for degradation by the addition of ubiquitin

66
Q

Ubiquitin

A

A small protein itself that s added to proteins for degradation

Cell Bio (30 decks)

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