9.8 The Genetic Code and Translation

Question 1

________ is the process through which genetic information is converted to protein products

Answer 1

translation

Question 2

how many bases are there per codon?

Answer 2

3

Question 3

the code is _________ (redundant), some amino acids are coded by more than one _______

Answer 3

degenerate

codon

Question 4

_____ are proteins that read the codons and attach the right amino acid. They have non-standard __________ that are essential for enzymes to recognize which protein they are dealing with and attach the right aa.

Answer 4

t-RNAs

nucleotides

Question 5

what enzyme attaches the correct amino acid to the correct tRNA?

Answer 5

amino acyl-tRNA synthetase

Question 6

how many amino acyl-tRNA synthetases are there?

Answer 6

20, one for each amino acid

Question 7

amino acyl-tRNA synthetases are completely specific for both the _____ and _______

Answer 7

tRNA and amino acid

Question 8

The _____________ recognizes specific modified nucleotides within individual tRNAs, allowing correct addition of amino acids.

Answer 8

amino acyl tRNA synthetase

Question 9

are there the same amount of tRNAs as codons? (there are 61 codons not including stop codons). If not, how many tRNAs are there?

Answer 9

no. there are 48 tRNAs.

Question 10

some tRNAs need to recognize more than 1 codon. The non-standard base pairing between the third base of the codon and the corresponding anticodon in the tRNA is called:

Answer 10

wobble

Question 11

the most important modified nucleotide is _____ (closely related to guanine). Is is a purine or pyrimidine? What can it pair with?

Answer 11

inosine
purine
C, A, U

Question 12

a mutation in the mitochondrial gene encoding leucine tRNA causes _______, a human genetic disease that has mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like symptoms.

Answer 12

MELAS

Question 13

in MELAS, a mutation prevents the efficient recognition of the _____ by the appropriate ____________ and therefore interferes with synthesis of mitochondrial proteins.

Answer 13

tRNA

leucyl-tRNA synthetase

Question 14

___________________ disease is a common genetics disease that results in peripheral neuropathy. Associated with mutations in the gene encoding for glycyl-tRNA synthetase.

Answer 14

Charcot-Marie-Tooth disease

Question 15

Charcot-Marie-Tooth disease is caused by a mutation in the ____________, the _______ that attaches _____ to its appropriate _____.

Answer 15

glycyl-tRNA sythetase
amino acyl tRNA synthetase
glycine to its appropriate tRNA

Question 16

the ______ is the fundamental machinery for translation

Answer 16

ribosome

Question 17

translation always starts at the start codon ____, which codes for _____

Answer 17

AUG

methionine

Question 18

in order to begin translation, an initiation complex is formed from the following factors:

Answer 18

1. tRNAmet
2. GTP
3. small subunit of ribosome
4. initiation factors (ex. eIF-2)

Question 19

the initiation complex for translation recognizes the ____ structure at the 5’ end of an mRNA

Answer 19

cap

Question 20

after binding the cap structure at the 5’ end of an mRNA, the initiation complex moves along the mRNA until it comes in contact with the first ____ sequence. ____ provides unwinding for secondary structures in the mRNA

Answer 20

AUG

eIF-2

Question 21

In the process of translation: When the first AUG is located, ____ is hydrolyzed and ____ leaves the initiation complex. The large ribosomal subunit joins the complex and translation occurs.

Answer 21

GTP

eIF-2

Question 22

What is the enzyme that catalyzes peptide bond formation on the ribosome? (between P and A sites on the large ribosome)

Answer 22

peptidyl transferase

Question 23

a single mRNA translated by multiple ribosomes at the same time.

Answer 23

polysome

Question 24

what are the three stop codons?

Answer 24

UAA

UGA

UAG

Question 25

stop codons are not recognized by ____, thus when a stop codon is in vacant A site, a protein called a ___________ binds to the site. What does it do?

Answer 25

tRNA
release factor
attaches a water molecule to the end of the polypeptide chain - severing it.