Week 19: Translation and Proteins, Genotype to Phenotype I

Question 1

what is translation

Answer 1

Translation is the process where the information carried by the mRNA is used to synthesize a corresponding protein

Question 2

where does translation occur

Answer 2

ribosomes

Question 3

describe what happens during translation

Answer 3

During translation, the sequence of nucleotides in the mRNA is translated into a sequence of amino acids, forming a polypeptide chain that folds into a functional protein.

Question 4

function of proteins

Answer 4

Catalyze (speed up) reactions

Transport: in a cell membrane OR throughout the body

Chemical signaling

Structure in cells & muscular contractions

Question 5

what are proteins made out of

Answer 5

amino acids

Question 6

what compounds and elements make up an Amino Acid

Answer 6

C (carbon)
NH2 (amino group)
COOH (carboxyl group)
H (Hydrogen)
R group

Question 7

what defines each of 20 different amino acids.

Answer 7

R group

Question 8

True or False: RNA can fold into protein-like shapes that do work in the cell

Answer 8

true

Question 9

what is tRNA

Answer 9

Transfer RNA, often abbreviated as tRNA

transfers amino acids to growing polypeptide strand.

Question 10

what is the “acceptor stem” in tRNA molecule

Answer 10

region of tRNA molecule where an amino acid will attach

Question 11

how long is a codon

Answer 11

A codon is a sequence of three nucleotides

Question 12

function of ribosomes

Answer 12

link amino acids together to make polypeptides.

Question 13

Initiation of tRNA steps:

Answer 13

1. Before translation can start, tRNA needs to be “charged” with an amino acid
2. The anticodon uses complimentary base pairing to match triplets, or codons, of mRNA bases

3.Small ribosomal subunit and tRNA Met interact with mRNA.

4. Scan the mRNA for an AUG (start) codon.
5. When the complex reaches an AUG, the large ribosomal subunit joins.

Question 14

practice question on pg 19

Question 15

practice question on pg 21

Question 16

practice question on pg 23

Answer 16

answer: Leucine

Question 17

Translation cannot start until a “_________” codon is read

Answer 17

start

Question 18

what allows the proper tRNA to bind to the correct codon

Answer 18

Complementary base pairing

Question 19

Elongation of tRNA:

Answer 19

1. The ribosome moves down one codon (reading mRNA in the 5’ to 3’ direction).
2. The anticodon of a charged tRNA molecule (complementary to the mRNA codon) binds to the mRNA codon in the A site (aminoacyl site) of the ribosome.
3. A peptide bond is formed between the amino acid carried by the tRNA in the A site and the growing polypeptide chain attached to the tRNA in the P site (peptidyl site).
4. The ribosome advances along the mRNA by one codon
5. The tRNA that was in the A site moves to the P site, and the tRNA that was in the P site moves to the E site (exit site).
6. The empty tRNA in the E site is released, and a new tRNA with its attached amino acid enters the A site.
7. this is repeated for each codon in the mRNA until a stop codon is encountered.

Question 20

summarize what initiation and elongation entails

Answer 20

In summary, initiation involves the assembly of the ribosome and the placement of the initiator tRNA at the start codon, while elongation involves the repeated addition of amino acids to the growing polypeptide chain.

Question 21

watch video on slide 33 to better understand intiation and elongation

or

watch that section of lecture

or

01:05:00 of lecture

Question 22

Describe the first, secondary, tertiary and quaternary structure of protein

(page 41 or watch section of lecture for better understanding)

Answer 22

1. protein formation (1st structure)
2. 1st structure folds into either alpha (α) helices or beta (β) sheets (2nd structure)
3. 2nd structure folds into into a tertiary structure
4. Quaternary structure occurs when 2 or more proteins bind together in order to function. (ex: hemoglobin)