Chapter 37- Translation

Question 0

How many nucleotides and coat proteins does the Tobacco necrosis satellite virus have?

Answer 0

Has 1200 nucleotides coding for 400 protein ( 1200/400 = 3)

Question 1

DNA polymerase that polymerizes DNA from an RNA template

Answer 1

Reverse Transcriptase

Question 2

What was the observation in bacteriophage T4?

Answer 2

That deletion of one or 2 base pairs resulted to synthesis of wrong proteins but deletion of 3 base pairs nagkukulang ng isang protein

Question 3

What is the codon for Start?

Answer 3

AUG = methionine

Question 4

What is the codon for STOP?

Answer 4

UAA, UAG, UGA

Question 5

What are the chars of Genetic Code?

Answer 5

1. Degeneracy - which can be found at 3rd bp
2. Unambiguous - codon codes for only ONE AA
3. Nonoverlapping - read in a continuous manner
4. Universal - except for (some) mitochondrial DNA

Question 6

What is the role of eIF 3 and eIF 1A?

Answer 6

delays the reassociation of the 43s to the 80s complex

Question 7

When is eIF-2alpha phosphorylated?

Answer 7

When the cell is stressed or when the energy expenditure required for protein synthesis is deleterious

Question 8

How does phosphorylation of eIF-2alpha blocks protein synthesis?

Answer 8

by binding tightly and inactivating the GTP-GDP recycling synthesis thus preventing formation of preinitiation complex

Question 9

Where does the 3’ acceptor binds to?

Answer 9

Binds to the amino acid

Question 10

What does the Ribothymidine pseudouridine cytidine arm binds to?

Answer 10

Binds the aminoacyl-tRNA to ribosomal surface

Question 11

What is the function of the D arm?

Answer 11

One of the sites needed for recognition of accurate aminoacyl-tRNA synthetase

Question 12

What is the function of the anticodon arm?

Answer 12

recognizes the codon of mRNA

Question 13

Importance of WOBBLE position

Answer 13

Since the 1st and 2nd bp are highly specific, wobble position allows recognition of different codons coding for the same protein

Question 14

Components of the cap binding protein complex (eIF-4F)

Answer 14

eIF -4E, eIF-4G-eIF4A complex

Question 15

Initiation sequence for translation

Answer 15

Kozak consensus sequence

Question 16

What is the action of peptidyltransferase?

Answer 16

Catalyzes peptide formation between alpha-amino group od new aminoacyl-tRNA in site A with the esterfied carboxyl group of the peptidyl-tRNA in the P site

Question 17

What is the function of release factor RF1?

Answer 17

Recognizes stop codon

Question 18

Component of RF1?

Answer 18

Release factor RF3 and GTP

Question 19

Function of the signal peptide?

Answer 19

it prompts the transport mechanism to bring it to its specific destination

Question 20

Multiple ribosomes on the same mRNA molecule?

Answer 20

Polysome

Question 21

Importance of the polysome?

Answer 21

The proteins they synthesize maybe free or bound to RER. This proteins are extruded into the cisternal space then exported.

Question 22

sdfs

Answer 22

sdfsdf

Question 23

How does eIF-2A regulate translation?

Answer 23

Tight binding to eIF-2B prevents GTP-GDP recycling thus no formation of preinitiation complex—> defence against viruses or energy conservation mech during stress or nutrient deprivation

Question 24

How does the Phosphorylation of 4E protein regulate translation?

Answer 24

Activation: increased binding of 4E to mRNA cap = enhanced protein synthesis *stimulated by synthesis + mitogenic growth factor

Inactivation via BP1(BP2 or BP3)

Question 25

Is the inactivation of 4E by BP1 reversable? if yes how?

Answer 25

Yes by insulin

Question 26

Rate limiting step in translation?

Answer 26

Recognition of mRNA cap by 4E

Question 27

What is the initiating amino acid of prokaryote? eukaryote?

Answer 27

pro: formyl-methionine
euk: methionine

Question 28

Differentiate Transition Mutation from Transversion

Answer 28

Transition = Mutation wherein one base pair is converted from a purine to a purine (or pyrimidine to pyrimidine)

Transversion = Mutation wherein one base pair is converted from a purine to a pyrimidine (or pyrimidine to purine)

Question 29

Type of mutation wherein the codon containing the changed base codes for the same amino acid

Answer 29

Silent mutation

Question 30

Changed base codes for a different amino acid?

Answer 30

Missense Mutation

Question 31

Cganged codon codes for a termination?

Answer 31

Nonsense mutation

Question 32

Differentiate acceptable, partially acceptable and unacceptable missense?

Answer 32

Acceptable = fully functioning protein
Partially acceptable = functioning but with abnormality
Unacceptable = protein is non-functional

Question 33

Define Splice Site mutation

Answer 33

Improper removal of introns could cause aberrant protein product

Question 34

Medicine used in cases of meningitis and typhoid fever? Mech of action?

Answer 34

Chloramphenicol - inhibits peptidyltransferase

Question 35

Med that prevents translocation (prevents movement of peptidyl-tRNA from the A to P site)

Answer 35

Erythromycin

Question 36

Medicine that distorts A site thereby initiating misreading of code? What is its complication?

Answer 36

Streptomycin. In high dosage can cause hearing loss

Question 37

A reversible drug that is concentrated on the gut rather than the intestine? Mech?

Answer 37

Tetracycline - prevents the binding of aminoacyl-tRNA to A site at 30s

Question 38

Medicine that irreversibly binds to 30s subunit?

Answer 38

Aminoglycosides

Question 39

What are interferons?

Answer 39

Proteins that are synthesized by virus-infected cells. They trigger antiviral protein