Nucleic acids and DNA replication

Question 1

Describe the role of DNA polymerase in DNA replication

Answer 1

DNA polymerase connects the new nucleotides together through a condensation reaction to form phosphodiester bonds.

Question 2

Whats the name of the reaction that joins nucleotides together?

Answer 2

Condensation reaction

Question 3

Describe the role of DNA helicase in semi-conservative replication

Answer 3

DNA helicase unwinds the DNA and breaks the hydrogen bonds between complementary bases

Question 4

Describe the structure of DNA

Answer 4

-Deoxyribose sugar
-Adenine, thymine, cytosine, guanine
-double stranded
-holds genetic information

Question 5

Describe the structure of RNA

Answer 5

-ribose sugar
-adenine, uracil, cytosine, guanine
-single stranded
-transfers genetic information to ribosomes

Question 6

Explain how nucleotides join together to form a polynucleotide strand

Answer 6

Polynucleotides are formed when many nucleotides bond to form a long chain. The join together in a condensation reaction to form phosphodiester bonds between the phosphate on one nucleotide and the pentose sugar on the next using DNA polymerase

Question 7

Who discovered semi-conservative DNA replication?

Answer 7

Watson and Crick

Question 8

Explain how the structure of DNA relates to its function

Answer 8

1. Sugar-phosphate backbone- strength and stability and protects bases
2. long molecule- store a lot of info
3. Helix- compact
4. base sequence- codes for amino acids (3 bases= 1 amino acid) and polypeptides
5. double stranded- semi-conservative replication, each strand acts as a template
6. complementary base pairings- accurate replication
7. Hydrogen bonds are weak- unzipping and separation of strands for replication
8. many hydrogen bonds- strong and stable

Question 9

State why DNA replication is described as semi-conservative

Answer 9

Each new DNA molecule contains an original template strand and a new synthesised strand

Question 10

State the complementary base pairs in DNA

Answer 10

• adenine and thymine
• cytosine and guanine

Question 11

Describe the process of DNA replication

Answer 11

1. DNA helicase breaks the hydrogen bonds between complementary bases and strands separate
2. Both strands act as a template.
3. New DNA nucleotides are attracted to exposed complementary bases on template strands and complementary base pairing occurs.
   Adenine to thymine; thymine to adenine; cytosine to guanine; guanine to cytosine
4. DNA polymerase joins adjacent DNA nucleotides together through a condensation reaction forming phosphodiester bonds
5. Semi-conservative replication ensures that each new DNA molecule contains an original and a new strand of DNA.