1.3 - Control of gene expression

Question 1

A cell’s genotype is determined by what?

Answer 1

The sequence of DNA bases in its gene

Question 2

A cell’s phenotype is determined by what?

Answer 2

The proteins that are synthesized when the genes are expressed

Question 3

The structure and function of a protein (coded for by a gene) is determined by what?

Answer 3

The sequence of amino acids

Question 4

Amino acids are linked by ____ bonds to form ____

Answer 4

1. Peptide

2. Polypeptides

Question 5

Polypeptide chains fold to the three dimensional shape of a protein, what type of bond holds it together?

Answer 5

Hydrogen

Question 6

Sub-units that join together to form a polypeptide

Answer 6

amino acid

Question 7

Transcription and translation use 3 types of RNA, what are the types of RNA?

Answer 7

1. Messenger
2. Transfer
3. Ribosomal

Question 8

What are the three differences between DNA and RNA?

Answer 8

1. DNA - deoxyribose sugar, RNA - Ribose sugar
2. DNA - has thymine , RNA - has uracil
3. DNA - double stranded , RNA - single stranded

Question 9

What is transcription?

Answer 9

Transcription is the process in which a copy of DNA is made, This copy is known as mRNA and it occurs in the nucleus.

Question 10

What is stage one of transcription?

Answer 10

RNA polymerase moves along the DNA, unwinding the helix

Question 11

What is stage two of transcription?

Answer 11

Weak hydrogen bonds between the bases break

Question 12

What is stage three of transcription?

Answer 12

Free nucleotides pair up with complementary DNA bases

Question 13

What is stage four of transcription?

Answer 13

RNA polymerase enzyme controls the formation of the backbone between adjacent RNA nucleotides forming an RNA chain

Question 14

What is stage five of transcription?

Answer 14

The weak hydrogen bonds between DNA nad RNA break. This leaves a single strand of mRNA (primary transcript)

Question 15

What is stage six of transcription?

Answer 15

The two strands of DNA come together again and wind up

Question 16

What is RNA splicing?

Answer 16

Non-coding regions (introns) are removed from the primary transcript which forms the mature transcript.

Question 17

What is alternate splicing?

Answer 17

Different proteins exposed from one gene.

Question 18

What is translation?

Answer 18

Tranlation is when mRNA is translated into proteins by ribosomes in the cytoplasm.

Question 19

Which codons begin and end translation?

Answer 19

START and STOP codons.

Question 20

What happens during translation at the ribosome?

Answer 20

tRNA with complementary anticodons bond with codons on the mRNA by complimentary base pairing, translating the code into a sequence of amino acids. Peptide bonds form between amino acids.

Question 21

What is the ribosome composed of?

Answer 21

rRNA and protein

Question 22

Which process produces a primary mRNA transcript?

Answer 22

Transcription

Question 23

Which process is when the mature mRNA is used to direct the synthesis of a protein?

Answer 23

Translation

Question 24

What is the function of RNA polymerase?

Answer 24

Unwinds the double helix and breaks the hydrogen bonds between the bases. It synthesises a primary transcript of mRNA from RNA nucleotides by complementary base pairing.

Question 25

What is the function of tRNA?

Answer 25

Carries a specific amino acid to the ribosome and has an anticodon which is complementary to a codon.

Question 26

What is the function of mRNA?

Answer 26

It carries a complementary copy of the DNA code from the nucleus to a ribosome in the cytoplasm.

Question 27

Describe the structure of a tRNA

Answer 27

It folds due to complementary base pairing and has an amino acid attachment site at one end and an anti-codon at the other end.

Question 28

What is a codon?

Answer 28

A sequence of three bases on mRNA which codes for one specific amino acid.