3.9 DNA Replication & Genetic Code

Question 1

What is the process of DNA replication?

Answer 1

The process of producing 2 new strands of DNA that are identical to the original.

Question 2

What are the products of DNA replication?

Answer 2

2 new molecules of DNA, each one consisting of one old strand of DNA and one new strand.

Question 3

Why is DNA replication considered to be “semi-conservative”?

Answer 3

Because each new DNA molecule contains one old strand of DNA and one new strand.

Question 4

What two enzymes control DNA replication?

Answer 4

DNA helicase and DNA polymerase

Question 5

What does DNA helicase do?

Answer 5

Catalyses reaction that break the H bonds between complementary base pairs. This causes the DNA to unwind and the 2 strands to separate.

Question 6

What does DNA polymerase do?

Answer 6

Catalyses the formation of phosphodiester bonds between nucleotides, forming a DNA strand.

Question 7

What is Genetic Code?

Answer 7

The sequence of amino acids that DNA codes for.

Question 8

What is an example of a replication error?

Answer 8

Incorrect base-pairing, leading to an incorrect sequence being produced

Question 9

What do replication errors lead to?

Answer 9

A change in the sequence of bases, AKA a mutation

Question 9

When do replication errors occur?

(Do they happen at any given time?)

Answer 9

Randomly and spontanteously

Question 10

Why is DNA considered a triplet code?

Answer 10

Because DNA is read in sets of 3. 3 bases = codon. Each codon codes for an amino acid.

Question 11

What is a codon?

Answer 11

3 bases

Question 12

What does each codon code for?

Answer 12

An amino acid.

Question 13

State the process of DNA replication.

Answer 13

• DNA helicase causes the two strands of DNA to separate, breaking the hydrogen bonds between the complementary bases
• Each strand is used as a template, and free nucleotides floating in the nucleoplasm pair their bases with the template strand
• The complementary bases are joined by hydrogen bonds, and DNA polymerase joins the nucleotides together, forming phosphodiester bonds.

Question 14

What is a gene?

Answer 14

The section of DNA that contains the complete sequence of bases (codons) to code for an entire protein

Question 15

What does “genetic code is universal” mean?

Answer 15

All organisms use the same code of C, G, A and T bases.

Question 16

What does “genetic code is degenerate” mean? What is the purpose of this?

Answer 16

• Different combinations of bases can code for the same amino acid.
• This is so that if there is a mutation, it might not make a difference.