Unit 1 - KA 3: Control Of Gene Expression

Question 1

Name the type of bonds that hold amino acids together.

Answer 1

Peptide bonds

Question 2

Name the structure created when many amino acids are joined together.

Answer 2

A polypeptide

Question 3

Describe how the polypeptide chain is altered to create a 3D protein shape.

Answer 3

Polypeptide chains fold to form the three-dimensional shape, held together by hydrogen bonds.

Question 4

Define the term gene.

Answer 4

A gene is a sequence of DNA that codes for a protein.

Question 5

Define the term phenotype.

Answer 5

The visible characteristics

Question 6

State how phenotype is determined.

Answer 6

Phenotype is determined by the proteins produced as the result of gene expression.

Question 7

State another factor that can influence phenotype.

Answer 7

Environmental factors.

Question 8

State another factor that can influence phenotype.

Answer 8

Environmental factors.

Question 9

State 3 differences between DNA and RNA.

Answer 9

DNA is double stranded; RNA is single stranded

DNA has thymine bases; RNA has uracil

DNA has deoxyribose sugar; RNA has ribose sugar

Question 9

State 3 differences between DNA and RNA.

Answer 9

DNA is double stranded; RNA is single stranded

DNA has thymine bases; RNA has uracil

DNA has deoxyribose sugar; RNA has ribose sugar

Question 10

What is mRNA?

Answer 10

Messenger RNA carries a copy of the DNA code from the nucleus to the ribosome.

Question 10

What is mRNA?

Answer 10

Messenger RNA carries a copy of the DNA code from the nucleus to the ribosome.

Question 11

What is tRNA?

Answer 11

Transfer RNA carries a specific amino acid to the ribosome.

Question 12

What is rRNA?

Answer 12

Ribosomal RNA combines with protein to form the ribosome.

Question 12

What is rRNA?

Answer 12

Ribosomal RNA combines with protein to form the ribosome.

Question 13

Define the term codon.

Answer 13

A triplet of bases on mRNA which codes for a single amino acid.

Question 13

Define the term codon.

Answer 13

A triplet of bases on mRNA which codes for a single amino acid.

Question 14

Define the term anticodon.

Answer 14

A triplet of exposed bases on a tRNA molecule.

Question 15

Describe transcription.

Answer 15

The genetic code on the DNA is used to create a complementary base sequence of mRNA called the primary transcript.

Question 16

Describe the order of events during transcription.

Answer 16

• The enzyme RNA polymerase moves along the DNA molecule unwinding the double helix and breaking hydrogen bonds between bases.
• RNA polymerase attaches RNA nucleotides to their complementary DNA bases on the template DNA strand. Hydrogen bonds form.
• RNA nucleotides are then joined together into a strand by strong chemical bonds forming the primary mRNA transcript.

Question 17

Define the terms introns and exons.

Answer 17

Introns are non-coding regions.

Exons are coding regions.

Question 18

Describe what happens to the introns following transcription of the mRNA.

Answer 18

The introns are removed from the primary mRNA transcript.

Question 19

Describe what happens to the exons during RNA splicing.

Answer 19

The exons are joined together, the order of exons always stays the same.

Question 20

Name the molecule that is formed after RNA splicing.

Answer 20

The mature mRNA transcript.

Question 21

What is translation?

Answer 21

Translation is a process that results in the formation of a polypeptide.

Question 22

State how translation starts and ends.

Answer 22

Translation begins at a start codon and ends at a stop codon.

Question 23

Explain how the mRNA determines the sequence of amino acids in the polypeptide.

Answer 23

The order of bases on mRNA determines the sequence of amino acids in a polypeptide.

Question 24

Describe how anticodons and codons join together.

Answer 24

They bond by complementary bade pairing, translating the genetic code into a sequence of amino acids.

Question 25

State what happens to each tRNA molecule as the polypeptide is formed.

Answer 25

The tRNA molecule leaves the ribosome to collect another specific amino acid

Question 26

Name the process that results in one gene producing many different proteins.

Answer 26

Alternative RNA splicing.

Question 27

Explain how different mature mRNA strands can be produced from the same primary transcript.

Answer 27

Different combinations of exons can be retained in the mature mRNA transcript. The order remains unchanged.