17.4 Translation

Question 1

Genetic information flows from mRNA to protein through the process of what?

Answer 1

Translation

Question 2

A cell translates an mRNA message into protein with the help of what?

Answer 2

Transfer RNA (tRNA)

Question 3

tRNA transfer amino acids to the growing polypeptide in a what?

Answer 3

Ribosome

Question 4

Are molecules of tRNA identical?

Answer 4

NO

Question 5

Each carries a specific amino acid on one end

Answer 5

tRNA

Question 6

Each has an anticodon on the other end; the anticodon base-pairs with a complementary codon or mRNA

Answer 6

tRNA

Question 7

Consists of a single RNA strand

Answer 7

tRNA

Question 8

How long is a single strand RNA?

Answer 8

80 nucleotides long

Question 9

Flattened into one plane to reveal its base pairing; shaped like a cloverleaf

Answer 9

tRNA

Question 10

What causes tRNA to twists and fold into a 3-dimensional molecule?

Answer 10

The Hydrogen Bonds

Question 11

Roughly L-shaped

Answer 11

tRNA

Question 12

Step 1: correct match between tRNA & an amino acid done by ______

Answer 12

Accurate translation step; aminoacyl-tRNA synthetase

Question 13

Step 2: correct match between the tRNA anticodon an an mRNA codon

Answer 13

Accurate translation step

Question 14

Flexible pairing at the end of a codon is called _____; also allows some tRNA’s to bind to more than one codon.

Answer 14

wobble

Question 15

Aminoacyl-tRNA synthetase is an enzyme whose function is to ______.

Answer 15

Link a tRNA to its amino acid.

Question 16

Facilitates specific coupling of tRNA anticodons with mRNA codons in _______

Answer 16

Ribosomes; protein synthesis

Question 17

What are the 2 ribosomal subunits made of

Answer 17

proteins & ribosomal RNA (rRNA)

Question 18

Bacterial & Eukaryotic ribosomes are somewhat similar but have significant differences

Answer 18

Difference: Some antibiotic drugs specifically target bacterial ribosomes without harming eukaryotic ribosomes

Question 19

How many binding sites are there for tRNA?

Answer 19

3

Question 20

Holds the tRNA that carries the growing polypeptide chain

Answer 20

The P Site

Question 21

Holds the tRNA that carries the next amino acid to be added to the chain

Answer 21

The A Site

Question 22

The exit site, where discharged tRNA’s leave the ribosome

Answer 22

The E Site

Question 23

How many stages of translation are there?

Answer 23

3 - Initiation, Elongation, Termination

Question 24

What do all three stages require that aid in the translation process?

Answer 24

Protein “factors” & also energy for some steps

Question 25

Brings together mRNA, a tRNA with the first amino acid and the 2 ribosomal subunits

Answer 25

Initiation

Question 26

1. small ribosomal subunit binds with mRNA and a special initiator tRNA 2. small subunit moves along the mRNA until it reaches the start codon 3. Proteins called initiation factors bring in the large subunit that completes the translation initiation complex

Answer 26

Steps of Initiation

Question 27

During what phase are amino acids added one by one to the C-terminus of the growing chain

Answer 27

Elongation

Question 28

Each addition involves proteins called ____________

Answer 28

Elongation Factors

Question 29

Codon recognition, peptide bond formation, translocation

Answer 29

3 Steps of Elongation

Question 30

What steps does energy expenditure occur in

Answer 30

first and third steps

Question 31

Proceeds along the mRNA in a 5' ------> 3' direction

Answer 31

Translation

Question 32

Often translation is not sufficient enough to make a functional protein

Answer 32

Polypeptide chains are modified after translation or targeted to specific sites in the cell

Question 33

There are two populations of ribosomes evident in cells

Answer 33

Free ribosomes (located in cytoplasm) & bound ribosomes (attaches to the ER)

Question 34

Synthesize proteins that function in the cytosol

Answer 34

Free ribosomes

Question 35

Make proteins of the endomembrane system and proteins that are secreted from the cell

Answer 35

Bound Ribosomes

Question 36

Are identical and can switch from free to bound

Answer 36

Ribosomes

Question 37

During the synthesis of a _______ ________ begins to coil and fold spontaneously to form a ______ with a specific shape-------a 3-dimensional molecule with ______ & ______ structure.

Answer 37

polypeptide chain, protein, secondary, tetiary

Question 38

A ________ determines ________ structure and primary in turn determines shape.

Answer 38

Gene, primary

Question 39

May be required before the protein can begin doing its particular job in the cell-

Answer 39

Post-translational modifications