From Study Guide

Question 1

What is the role of helicase? What is the role of DNA polymerase?
What is the role of DNA ligase?

Answer 1

• DNA helicase unwinds the double helix, separating the two strands so they may be replicated by DNA polymerase.
• DNA polymerase joins individual nucleotides to produce a new strand of DNA and it proof reads the strand
• DNA ligase is responsible for joining Okazaki fragments on the lagging strand during replication.

Question 2

With regard to the nitrogenous bases, what are purines and pyrimidines?

Answer 2

• Purines (adenine and guanine) are two-carbon nitrogen ring bases
• Pyrimidines (cytosine and thymine) are one-carbon nitrogen ring bases.

Question 3

How do nitrogenous bases pair off within DNA? i.e. Who pairs with whom?

Answer 3

Adenine pairs with thymine & cytosine pairs with guanine

• The ‘pairing’ occurs because the complementary bases form hydrogen bonds with each other

Question 4

What is the end product of transcription?

Answer 4

mRNA

The final product of transcription is mRNA which carries the code for making proteins to the cytoplasm

Question 5

What is the end product of translation?

Answer 5

Amino acid sequence (also known as polypeptide)

When the ribosome reaches a stop codon, it releases the mRNA strand and amino acid sequence
- The amino acid sequence is the final result of translation, and is known as a polypeptide

Question 6

How is RNA transcription different from DNA replication?

Answer 6

1. DNA replication consists of replicating the DNA, whereas RNA transcription consists of transcribing DNA into RNA or tRNA
2. DNA replication mostly uses DNA polymerase, whereas RNA transcription uses RNA polymerase
3. DNA replication produces a double stranded product, whereas RNA transcription produces a single stranded product.
4. The DNA produced in the DNA replication does not have uracil. The RNA produced in the process of transcription has uracil.