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Term 1 > Biochemistry - Translation > Flashcards

Biochemistry - Translation Flashcards

1
Q

What is the mechanism of diptheria toxin and its relationship to protein translation?

A

Diptheria becomes infected by a bacterial virus.

ADP-ribose binds to the EF-2, which prevents elongation of the polypeptide chain.

Obviously, this is bad since we can’t synthesize proteins.

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2
Q

What is EF-2? What is EF-G

A

EF-2: Euks
EF-G: Proks

** EF is a GTPase protein. Hydrolysis of GTP is important for efficient translocation of the mRNA relative to the ribosome.

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3
Q

Why do we use less than 61 tRNA’s?

A

One tRNA can recognize multiple codons

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4
Q

What is the difference between 30/50/70s & 40/60/80s?

A

Prok vs. euk mRNA

Euk mRNA is more complex

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5
Q

What is the P site & A site in translation on a ribosome?

A

P site: has a free carboxyl end & holds the peptide [this is the charged site]
A: has the aminoacyl tRNA codon

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6
Q

What is ribozyme?

A

Peptide bond formation is catalyzed by the enzymatic activity of the RNA portion of the 50s ribosome

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7
Q

When does diptheria become toxic?

A

When it is infected with a lysogenic phage, aka a bacterial virus

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8
Q

What is the start codon(s)?

A

AUG

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9
Q

What is the stop codon(s)?

A

UGA, UAG, UAA

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10
Q

What is special about the “wobble position” on tRNA?

A

It can have an ionosine, which permits versatile base pairing, i.e. between two purines!

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11
Q

What do prokaryotes use as the first AA in a protein?

A

fMet

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12
Q

What diffuses into the A-site in order to terminate elongation?

A

RF, or release factor

Allows peptidyl transferase to cleave the ester bond between the RNA & the peptide

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13
Q

T/F Release factor (peptidyl transferase activity) is GTP dependent

A

True

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14
Q

What are the 4 major differences between prokaryotic and eukaryotic translation?

A
  1. Prok - polycistronic
  2. Prok - fMet
  3. Prok - multiple AUG start sites
  4. Prok - coupled transcription & translation
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15
Q

T/F Eukaryoties use a formylated-Methionine as its first codon in translation

A

False

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16
Q

What prevents abnormal protein folding during translation?

A

Chaperone proteins

17
Q

T/F Modifications to an antibiotic may alter bacterial resistance to the drug or change absorption or clearance patterns

A

True

18
Q

What is streptomycin?

A

Inhibitor of initiation

  • Aminoglycoside structure
  • Prevents assembly of ribosome (binds to 30s subunit)
19
Q

What is tetracycline? State 3 examples

A

Inhibitor of elongation
* 4-ring structure
* Prevent aminoacyl-tRNA access to the A-site
Examples: minocycline, doxorubicin, doxycycline

20
Q

What is erythromycin?

A

Inhibitor of elongation

  • Macrolide structure
  • Binds to 50s subunit of 70S ribosome
  • Blocks elongation by preventing ribosome movement relative to the mRNA (translocation)
21
Q

What is chloramphenicol?

A

Inhibitor of elongation

  • Inhibits peptidyl transferase activity
  • May inhibit mitochondrial activity [developing countries b/c it can damage the human – but it’s cheap!]
  • Important for meningitis
22
Q

What is cycloheximide?

A

Inhibitor of elongation

  • Same action as chloramphenicol, but is extremely toxic to eukaryotes
  • Prokaryotes and mitochondria not affected
  • Used widely in labs
23
Q

What is puromycin?

A

Inhibitor of elongation

  • Structural analogue to a portion of amino-acyl tRNA
  • Peptide can form -NH3 group, but gets stuck
  • Causes peptide to fall out of the ribosome P-site
  • Toxic to prokaryotes & eukaryotes
24
Q

Which 2 elongation drugs are similar (one toxic to proks & one toxic to euks)

A

Proks- Choramphenicol

Euks- Cycloheximide

25
Q

What is the difference between amino-acyl tRNA, ribozyme & peptidyl transferase?

A

Amino-acyl tRNA is bound to the A site with a free carboxyl end
Peptidyl transferase - forms peptide bonds (regulated by ribozyme)

26
Q

The insulin receptor has this type of modification

A

Protein phosphorylation by a tyrosine kinase

27
Q

What is O-linked glycosylation?

A

Adding a phosphate to an -OH group of Ser/Thr

28
Q

What is N-linked glycosylation? What are the 2 types?

A

Adding a phosphate to an asparagine residue (2 types: mannose or complex)

29
Q

The insulin receptor is this type of kinase

A

Tyrosine

30
Q

In lipid anchoring, the cell targets what in order to anchor it to the plasma membrane?

A

Ras

31
Q

When blood glucose is high, insulin will bind to this receptor.

A

Tyrosine kinase

Term 1 (10 decks)

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