6.4: Translation Flashcards

1
Q

What is translation?

A

The synthesis of a polypeptide using information from mRNA (codon)

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2
Q

Where in the cell does translation occur?

A

Ribosomes

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3
Q

What occurs during translation?

A

A nucleotide sequence becomes an amino acid sequence

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4
Q

Which molecule translate mRNA to an amino acid sequence?

A

tRNA

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5
Q

 explain the process in which transfer RNA translates mRNA to an amino acid sequence

A
  1. transfer RNA has an anti-codon region which is complementary and anti-parallel to mRNA (codon)
  2. tRNA carries the amino acid that mRNA codon codes for
  3. The enzyme aminoacyl-tRNA synthesase is responsible for attaching amino acids to tRNA
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6
Q

A tRNA carrying an amino acid is ____

A

Charged

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7
Q

Ribisime have two subunits: small and large, but prokaryitic and eukarytic ribosomal subunits differ in size. Name the sizes for both projaryotes and Eukaryotes.

A

Prokaryotes: small subunits is 30s, large is 40s
Eukaryotes: small subunit is 40s, large is 60s

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8
Q

What are the three sites called on the large subunit?

A

A, P, E

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9
Q

What is the A site on the large subunit? (2)

A
  • amino acid site

- holds the next transfer RNA carrying an amino acid

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10
Q

What is the P site on the large subunit? (2)

A
  • polypeptide site

- holds the tRNA carrying the growing polypeptide chain

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11
Q

What is the E side of the large subunit?

A

Exit site

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12
Q

What are the three stages of translation?

A
  1. Initiation
  2. Elongation
  3. Termination
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13
Q

What occurs in initiation of translation?

A
  1. translation begins when the small ribosomal subunit binds to the mRNA and a charged tRNA binds to the start codon, AUG, on the mRNA.
  2. the tRNA carries methionine
  3. Next, the large subunit binds
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14
Q

What is the difference between the first transfer RNA carrying methionine, and every other transfer RNA?

A

the first tRNA carrying Met will go to the P site, while every other tRNA goes to rhe A site first

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15
Q

How does elongation start? (3)

A
  1. Elongation starts when the next tRNA comes into the A site
  2. MRNA is moved through the ribosome and its codons are read
    3. Each mRNA codon codes for a specific amino acid
    - codon charts used to determine the amino acid
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16
Q

Why do all organisms support the idea of common ancestry?

A

All organisms use the same genetic code, that’s why it supports the idea of common ancestry

17
Q

Name and describe the three steps in elongation.

A
  1. Codon recognition: the appropriate anticodon of the next tRNA goes to the A site
  2. Peptide bond formation: peptide bonds (polar covalent) are formed that transfer the polypeptide to the A site tRNA 3. Translocation: the tRNA is the A-site moves to the P site, the tRNA in the P-site goes to the E-site, ans the A site is open for the next tRNA
18
Q

How does termination start? (2)

A
  • termination occurs when a stop codon in the mRNA reaches the A site of the ribosome
  • note that dtop codons do not code for amino acids
19
Q

We know that termination begins when a stop codon in the mRNA reaches the A-site of the ribosome. What occurs after that? (4)

A
  1. The stop codon signals for a release factor
  2. this hydrolyzes the bond that holds the polypeptide to the P site (uses H2O to break the bond aka. Catabolic rxn))
  3. polypeptide releases, goes to the rough ER —> golgi —> vesicle —> stay in cell or leave via exocytosis
  4. all translational units (60s/40s) disassemble
20
Q

What occurs to the growing polypeptise chain as translation takes place?

A
  • The growing polypeptide chain begins to coil and fold
21
Q

What determines the primary structure in protein folding? What does the primary structure determine?

A
  • genes determine the primary structure

- The primary structure determines the final shape

22
Q

What do some polypeptides require to fold correctly?

A

Chaperone proteins

23
Q

What do some polypeptides required before it can be functional in the cell?

A

- modifications

24
Q

We know that all normal transcription is DNA —> RNA. Knowing this, what are retroviruses? (2)

A
  • Retroviruses like HIV are an exception to the standard flow of genetic information
  • information flows from RNA to DNA
25
Q

How do retroviruses work? (4)

A

- use an enzyme known as reverse transcriptase

  • couples viral RNA to DNA
  • DNA then becomes part of the RNA. (This RNA HAS VIRAL INFO IN IT)
  • using integrase, allows new viral DNA to integrate into helper T cell DNA
26
Q

Please please please study the steps in translation page 48-49

A

Please