Translation

Question 1

What cellular components are involved in translation?

Answer 1

-Initiation, elongation and release factor proteins
-tRNA
-Synthetase enzymes
-rRNA
-Ribosomal proteins

Question 2

What is the function of synthetase enzymes

Answer 2

Facilitating the correct matching of tRNA and amino acids

Question 3

what is the function of tRNA?

Answer 3

Transfers amino acids from a pool of cystoplasmically situated amino acids to a growing polypeptide strand

Question 4

Each ____ is not ______ and can translate a specific mRNA _______ into a specific amino acid

Answer 4

tRNA, not identical, codon

Question 5

How many nucleotiddes are in a tRNA molecule?

Answer 5

70-90

Question 6

What are the different regions of the tRNA molecule?

Answer 6

-DHU loop
-Anticodon loop
-Amino acid attachment site

Question 7

In a tRNA molecule there are __ double helical segments and __ loops

Answer 7

4, 3

Question 8

What is an anticode region?

Answer 8

A specific nucleotide triplet taht forms complimentary base pairs with an mRNA codon for an amino acid
Written 3’-5’ and align with the codon 5’-3’

Question 9

What is located at the 3’ end of tRNA and what is it for

Answer 9

-The CCA sequence
-Terminal adenine is the point of attachment during tRNA activation with an amino acid

Question 10

Which enzyme allows tRNA activation? Describe how it works

Answer 10

-aminoacyl tRNA synthetases
-Specific to the type of tRNA and amino acid (there are 20)
-Active site of the enzyme recognizes the anticodon end
-Enzyme catalyzes the covalent attachment of the molecules from ATP hydrolysis

Question 11

How many tRNA molecule variations are there

Answer 11

45, some can bind to more than 1 codon due to wobble hypothesis

There are 64 codons and 20 amino acids

Question 12

What is the wobble hypothesis?

Answer 12

tRNAs always pair their anticodons with the first 2 bases of thee codon, but the third is more flexible

Question 13

How is translation initiated in eukaryotes?

Answer 13

-Translation initiation complex forms
-Forms towards 5’ cap
-mRNA is scanned until AUG is found

Question 14

How is translation initiated in prokaryotes?

Answer 14

-Forms at 1 or more ribosome binding sites called shine-dalgarno sequences located a few nucleotides upstream of AUG

Question 15

Define polycistrionic

Answer 15

2 or more separate proteins are encoded in 1 mRNA molecule; mRNA contains multiple genes controlled by a single promoter and terminator
(prokaryotic feature)

Question 16

What factors does translation initiation include?

Answer 16

-Large and small ribosomal subunits
-mRNA
-charged tRNA methionine
-Initiation factors (help assemble complex)

Question 17

How does the initiation complex assemble

Answer 17

-Initiation factors ind to 5’ cap
-Small ribosomal subunit joins
-Other initiation factors bind to methionine tRNA
-Partial compllex finds AUG on mRNA
-Large subunit binds using GTP hydrolysis

Question 18

Polypeptides are synthesized from the ___ end to the ____ end

Answer 18

amino end to the carboxyl end

Question 19

Where will methionine be located at the beginning of elongation

Answer 19

the peptidyl site

Question 20

Where do tRNAs enter and bind in the ribosome

Answer 20

The aminoacyl site

Question 21

What is a GTP elongation factor

Answer 21

-Delivered with each charged tRNA
-When codon pair is made, GTP is hydrolyzed and aminoacyl end of tRNA is released from the elongation factor

Question 22

Which site does the deacylated tRNA move to

Answer 22

The exit site

Question 23

What happens when the stop codon is reached on the mRNA

Answer 23

-GTP-bound release factors bind to the A-site
-Bond is broken between the terminal amino acid and the P-site tRNA
-GTP hydrolysis enables dissociation of the translation complex

Question 24

Which hypothesis was developed using Neurospora Crassa?

Answer 24

one-gene-one-enzyme hypothesis

Question 25

Can bread mold grow on a medium lacking arginine?

Answer 25

Yes, it can make its own from a series of steps requiring specific enzymes

Precursor–>ornithine–>citruline–>arginine