Chapter 7.5

Question 1

TRANSCRIPTION

Answer 1

copies the information encoded in a DNA base sequence into complimentary language of mRNA

Question 2

TRANSLATION

Answer 2

Builds the protein. The actual construction of proteins.
Using the instructions from mRNA to build a protein by joining amino acid into a polypeptide sequence

It is the translation of the mRNA sequence into a sequence of amino acids

Question 3

GENETIC CODE

Answer 3

is the set of rules by which a cell uses the nucleotides in mRNA to assemble amino acids into a protein. It also contains direction for starting and stopping translation

Question 4

A CODON

Answer 4

is a group of 3 mRNA bases that corresponds to one amino acid or to a “stop” signal. Nearly all species use the same mRNA codons to specify the same protein

Question 5

How many amino acids in life

Answer 5

20

Question 6

What is typically the first codon of mRNA

Answer 6

AUG- the start codon ( methionine)

Question 7

the 3 stop codons in mRNA

Answer 7

UGA, UAA, UAG

Question 8

What participants are needed in translation

Answer 8

1. mRNA
2. tRNA
3. Ribosomes

Question 9

mRNA

Answer 9

product of transcription carries the genetic information that encodes a protein with each 3 base codon specifying a amino acid

Question 10

tRNA

Answer 10

This bilingual molecule binds to a mRNA codon and to an amino acid.It contains an ANTICODON that is complimentary to one mRNA CODON

Question 11

ANTICODON

Answer 11

is a 3 base loop that is complimentary to one mRNA codon

Question 12

What is on the opposite end of of the anticodon on a tRNA

Answer 12

it forms a covalent bond to the amino acid corresponding to that codon

Question 13

The anticodon for methionine

Answer 13

methionine codon on mRNA is AUG : on the transfer RNA the anti codon would be UAC with methionine attached to the opposite end.

Question 14

RIBOSOME

Answer 14

. built of rRNA and proteins
. Anchors mRNA during translation
.They consist of a large and small subunit at join at the initiation of protein synthesis

Question 15

Where are ribosomes in the cell

Answer 15

1. free in the cytoplasm or

2. attached to the rough endoplasmic reticulum

Question 16

The 3 steps of TRANSLATION

Answer 16

1. Initiation
2. Elongation
3. Termination

Question 17

INITIATION

Answer 17

1. The leader sequence at the 5’ end of the mRNA molecules bonds with a small ribosomal unit.
2. The first codon is usually AUG which attracts a tRNA that carries the amino acid methionine.
   The methionine signals the start of the the polypeptide chain

3, A large subunit of ribosome attaches to the small subunit to complete initiation

Question 18

ELONGATION

Answer 18

1.a tRNA molecule carrying the second amino acid , then binds ( a hydrogen bond) to the second codon on the mRNA
molecule.

2. The first and second amino cid align forming a covalent bond= a peptide bond
3. With the peptide bond in place the ribosome releases the first tRNA, which will pick up another methionine and be used again.
4. The ribosome moves down my one codon. The steps are repeated.

Question 19

ELONGATION FACTORS

Answer 19

are proteins that help the polypeptide to grow one amino acid at a time

Question 20

TERMINATION

Answer 20

Elongation halts at a stop codon ( UGA< UAG, or UAA). No tRNA molecule corresponds to these codons.

2. Instead proteins called RELEASE FACTORS bind to the stop codon prompting the release of the last tRNA from the ribosome.
3. The ribosomal sub units separate from each other
4. The polypeptide is released

Question 21

The stop codons

Answer 21

UGA, UAG, UAA

Question 22

. What happens in each stage of translation?

Answer 22

The steps of translation are initiation (ribosomal subunit binds to initiator codon), elongation of the polypeptide, and termination (release of the last tRNA from the ribosome, signified by a stop codon).

Question 23

Where in the cell does translation occur

Answer 23

Translation occurs at ribosomes, which are either free in the cytoplasm or attached to the rough ER.

Question 24

How are polypeptides modified after translation?

Answer 24

Polypeptides have to be folded into proteins; sometimes amino acids are cut out of the chain, and sometimes multiple polypeptides join together.

Question 25

What bonds are formed with the anticodon and the codon on mRNA

Answer 25

HYDROGEN BOND

Question 26

what bond are formed between the amino acids on the growing polypeptide chain

Answer 26

COVALENT PEPTIDE BONDS

Question 27

What stabilizes proteins

Answer 27

CHAPERONE proteins