6.4: Translation

Question 1

Where does translation take place?

Answer 1

In the cytoplasm.

Question 2

How does the location of translation differ between a prokaryote and a eukaryote? How does the location of translation affect gene expression in a prokaryote?

Answer 2

In eukaryotes, it takes place in the in the cytosol as well as in the ER, while in prokaryotes it takes place only in the cytoplasm. This means that translation can occur at the same time as transcription for prokaryotic cells.

Question 3

What are the three steps of translation?

Answer 3

Initiation-start
Elongation-polypeptide grow
Termination-stop process

Question 4

What are the three sites found on a ribosome and what is their function?

Answer 4

• A site (aminoacyl tRNA)- allow tRNA to bind during translation
• P site- binds tRNAs to allow the polypeptide chain to grow
• E site- releases disassociated tRNAs so that they can be recharged with amino acids

Question 5

What happens in the initiation step of translation?

Answer 5

The rRNA interacts with the mRNA at the first start codon. (AUG or similar)

Question 6

What happens in the elongation step of translation?

Answer 6

tRNA brings the correct amino acid to the correct place by matching the anticodon to the codon on the mRNA strand.

Question 7

What happens in the termination step of translation?

Answer 7

When a stop codon is reached, then the polypeptide is released.

Question 8

What chemical process releases the growing polypeptide?

Answer 8

UAA, UAG, or UGA are the end codons that release the polypeptides.

Question 9

Where does translation start?

Answer 9

AUG codon

Question 10

What is a codon? How many nucleotides make up a codon?

Answer 10

A group of three nucleotides that are read together when translating mRNA into a protein.

Question 11

How are multiple codons able to code for the same amino acids?

Answer 11

There are only 20 amino acids, os some codons will code for the same amino acids.

Question 12

True or False: One codon can code for more than one amino acid.

Answer 12

False

Question 13

How does the genetic code demonstrate common ancestry?

Answer 13

Translation mechanisms are similar in all organisms and the nucleotides are also common.

Question 14

What is the central dogma? How does a retrovirus violate this process? Identify two examples of retroviruses.

Answer 14

DNA to RNA to protein is the central dogma, but in retroviruses, RNA uses reverse transcriptase to form DNA and into the host genome.

Question 15

What is the function of reverse transcriptase?

Answer 15

To transcribe RNA into DNA for retroviruses.

Question 16

How does a virus incorporate its viral genome into a host genome?

Answer 16

The RNA uses reverse transcriptase in order to transcribe itself into DNA. The DNA then becomes part of the host cell.

Question 17

How does a virus from progeny viruses?

Answer 17

When the DNA formed by reverse transcriptase is incorporated into the host cell and then gets replicated as normal.