4-5-3+4 Transcription and translation

Question 1

3 steps of transcription

Answer 1

1) initiation 2) elongation 3) termination

Question 2

transcription initiation

Answer 2

Step 1 of transcription: RNA polymerase binds to the gene promoter and unwinds the double helix, exposing the DNA nucleotides on each strand.

Question 3

transcription elongation

Answer 3

Step 2 of transcription: complementary RNA nucleotides are added, following the base-pairing rules U with A and C with G.

Question 4

transcription termination

Answer 4

Step 3 of transcription: Transcription stops when RNA polymerase comes upon a “stop” signal in the gene. The mRNA strand then detaches from the DNA, and the RNA polymerase detaches, too.

Question 5

Transcription follows the base-pairing rules for DNA replication, except that in RNA …

Answer 5

uracil (U) pairs with adenine (A).

Question 6

Where does RNA Polymerase bind to DNA

Answer 6

the gene’s promoter, which is a specific DNA sequence that acts like a “start” signal

Question 7

RNA polymerase

Answer 7

The enzyme that does transcription (from DNA to RNA)

Question 8

Uracil

Answer 8

the base that pairs with adenine (A) in RNA. (instead of thymine).

Question 9

When does transcription stop?

Answer 9

When RNA polymerase reaches the “stop” signal in the DNA.

Question 10

As RNA is being formed and RNA polymerase moves down the chain of the DNA molecule, what happens to the unzipped DNA strands behind the RNA polymerase?

Answer 10

They close up and form hydrogen bonds between the complementary bases.

Question 11

Does transcription make only mRNA?

Answer 11

No, it makes other kinds of RNA, too, inlcuding rRNA and tRNA.

Question 12

Translation

Answer 12

The step in protein synthesis in which cells use the different types of RNA created in transcription to put together the amino acids that make a protein.

Question 13

Before translation can begin, mRNA must leave _____ and enter _____.

Answer 13

leave the nucleus and enters the cytoplasm.

Question 14

Where in the cell and on which organelle does translation occur?

Answer 14

in the cytoplasm and on the ribosomes

Question 15

Ribosomes: what are they made of and what are they used for in the cell?

Answer 15

complex organelles used in translation that are made of rRNA (ribosomal RNA) and protein.

Question 16

codon

Answer 16

It is the “word” on mRNA that tells which amino acid to add or what action to take (such as “stop”). It is a 3-base sequence on mRNA that binds with the 3 base anticodon on the tRNA.

Question 17

anticodon

Answer 17

There is a three-base sequence on the tRNA that will bind with the three base codon on the mRNA.

Question 18

stop codon

Answer 18

a codon within messenger RNA that signals a termination of translation.

Question 19

4 steps of translation

Answer 19

steps that occur during translation: 1) activation 2) initiation 3) elongation 4) termination

Question 20

translation activation

Answer 20

first step of translation. The correct amino acids are linked to the correct tRNA molecules.

Question 21

translation initiation

Answer 21

Step 2 of translation. mRNA binds with the small subunit of the ribosome. Then, the initiator tRNA carrying methionine binds to the initiator codon (AUG) on the mRNA, forming the initiation complex consisting of the initiator tRNA, mRNA, and ribosome small subunit. The large ribosome subunit attaches to the initiation complex.

Question 22

translation elongation

Answer 22

Step 3 of translation. The next tRNA with its amino acid enters at the A site. A peptide bond is made between successive amino acids. The process repeats, and the protein chain gets longer. The tRNA molecules are ejected from the ribosome after losing their amino acid. (they can be reused).

Question 23

translation termination

Answer 23

Step 4 of translation: When the codon in the A site is a stop codon, a release factor binds to the site, translation stops, and the protein is separated from the ribosome.