Lecture 16: Translation

Question 1

What are the major molecules that take part in translation?

Answer 1

The major molecules are mRNA, tRNA, ribosomes and amino acids.

Question 2

What two molecules bind to the mRNA to initiate translation?

Answer 2

The small subunit of the ribosome and the aminoacylated tRNA both binds to the mRNA to initiate translation.

Question 3

Where does translation occur?

Answer 3

In the cytoplasm

Question 4

Briefly explain the translation mechanism

Answer 4

1. tRNA is aminoacylated
2. Initiation; small subunit, mRNA and tRNA bind together
3. large unit comes and binds
4. Elongation; polypeptide chain is made
5. termination: stop codon

Question 5

What is tRNA

Answer 5

decodes mRNA, turns it into the language of proteins

Question 6

What are the two important parts of tRNA?

Answer 6

1. Amino acid arm; binds to polypeptide chain

2. Anticodon; binds to codon chain

Question 7

What is an anticodon

Answer 7

Forms 3 base pairs with CODON; is complementry

Question 8

What attaches amino acids to tRNA? what kind of bond is this?

Answer 8

AMINOACYL-tRNA synthetases… Covalent bond

Question 9

How can tRNA read more than one codon?

Answer 9

Due to altered tRNA bases; WOBBLE in the third codon

Question 10

WOBBLE: which base?

Answer 10

3rd base in CODON, therefore 1st base in ANTICODON

Question 11

What is special about INOSINE?

Answer 11

it can bind to multiple bases; A, U, AND C

Question 12

What does AUG code for?

Answer 12

Codes for START codon AND methionine. Therfore every protein starts with METHIONINE

Question 13

Types of mutations?

Answer 13

1. Silent
2. Missense
3. Nonsense

Question 14

Describe silent mutation

Answer 14

No effect, although there is still a mutation

Question 15

Describe missense mutation

Answer 15

COULD have a drastic effect; really depends on the function of the protein and if it needs that particular AA

Question 16

Describe nonsense mutation

Answer 16

STOP codon; premature stop. affects protein function because missing a whole chunk

Question 17

Types of insertion/deletion?

Answer 17

2 types of frameshift and one non-frameshift

Question 18

describe the types of frameshift insertion/deletion of nucleotide-pair

Answer 18

1. nucleotide pair insertion causing immediate nonsense

2. nucleotide pair deletion causing extensive missense

Question 19

describe the non-frameshift deletion?

Answer 19

would just mean we are missing an amino acid

Question 20

How do we know where to start the 3 letter code?

Answer 20

START codon: AUG

Question 21

True/False: Ribosomes have both DNA and RNA

Answer 21

TRUE

Question 22

How do we know if it is START codon or Methionine?

Answer 22

SHINE-DALGARNO sequence

Question 23

What are the three sites in ribosome?

Answer 23

E, A, P
E: Exit of tRNA
A: aminoacyl-tRNA
P: poptodile-tRNA

Question 24

Which end of the polypeptide chain protrudes out?

Answer 24

Amino end. Carboxyl end is attached to tRNA