Topic 6.4 - Translation

Question 1

translation

Answer 1

the process by which an mRNA sequence is used to generate a polypeptide

Question 2

where does translation occur?

Answer 2

in the ribosomes

Question 3

what type of ribosomes do prokaryotes have?

Answer 3

cytosolic ribosomes

Question 4

what type of ribosomes do eukaryotes have?

Answer 4

cytosolic ribosomes and ribosomes bound to the rough ER

Question 5

how does translation occur in prokaryotes?

Answer 5

translation occurs while mRNA is being transcribed

Question 6

what are the steps for translation in eukaryotes (3)?

Answer 6

> initiation - where the process starts
elongation - where polypeptide starts
termination - where process starts

Question 7

is translation similar in all organisms? how?

Answer 7

yes. the nucleotides used to construct DNA/RNA molecules are common among organisms

Question 8

what is evidence of common ancestry?

Answer 8

the fact that the nucleotides used to construct DNA and RNA are common among organisms

Question 9

what allows host-cell translation mechanisms to work with viral genomes?

Answer 9

viral DNA molecules are chemically compatible with host-cell genomes, which allows host-cell translation mechanisms to work with viral genomes

Question 10

what is translation?

Answer 10

the final process in the flow of information from DNA -> RNA -> protein

Question 11

what does translation involve?

Answer 11

converting RNA information into a protein

Question 12

what is the first step of translation?

Answer 12

initiation - rRNA in the ribosome interacts with the mRNA at the first start codon

Question 13

how are mRNA nucleotides grouped?

Answer 13

they are grouped together and read in triplets called codons. each codon encodes a specific amino acid

Question 14

how many naturally occurring amino acids are there?

Answer 14

20, some are encoded for by more than 1 codon

Question 15

how is translation terminated?

Answer 15

via stop codons that do not code for amino acids but instead terminate translation

Question 16

what is the function of tRNA molecules?

Answer 16

bring the correct amino acid to the correct place, specified by the codon on the mRNA

Question 17

what is the second step of translation?

Answer 17

elongation - each newly arrived tRNA brings another amino acid to be added to a growing polypeptide chain

Question 18

what is the function of rRNA?

Answer 18

it adds the amino acids as the tRNA brings them

Question 19

what is the third step of translation?

Answer 19

termination - amino acids continue to be added to the growing polypeptide chain until a STOP codon is reached

Question 20

what happens when translation is stopped?

Answer 20

no more amino acids are added and the newly synthesized polypeptide is released

Question 21

when is translation initiated?

Answer 21

when the ribosomal subunits associate with an mRNA and read the first AUG codon

Question 22

why can prokaryotes quickly adapt to their environments?

Answer 22

because the ribosomes can bind before the mRNA molecule is even complete; translation can occur during transcription

Question 23

what needs to happen to polypeptides before they are functional?

Answer 23

they must be folded

Question 24

why does mRNA need modifications?

Answer 24

because the enzymes may remove amino acids from the interior of the chain