Question

errors in dna replication during mitosis can lead to:
a. mutations and diseases
b. chromosome pairing
c. increased genetic diversity
d. accurate cell division
how are okazaki fragments formed during dna replication?
a. by the action of ligase sealing gaps
b. by synthesizing short segments on the lagging strand
c. by continuous synthesis of the leading strand
d. by unwinding the dna double helix
what is the role of ligase in dna replication?
a. seals gaps between okazaki fragments
b. initiates replication
c. adds nucleotides to the growing strand
d. unwinds the double helix

Explanation:

First Question: Errors in DNA replication during mitosis can lead to:

• Option a: Errors in DNA replication can cause changes in the DNA sequence (mutations), and some mutations can lead to diseases.
• Option b: Chromosome pairing occurs in meiosis, not as a result of DNA replication errors in mitosis.
• Option c: Genetic diversity in mitosis - derived cells (somatic cells) isn't increased by replication errors; genetic diversity in meiosis comes from processes like crossing over.
• Option d: Errors in replication would likely disrupt accurate cell division, not promote it.

• Option a: Ligase seals gaps between Okazaki fragments, it does not form them.
• Option b: DNA replication is semi - discontinuous. The lagging strand is synthesized in short segments called Okazaki fragments because DNA polymerase can only add nucleotides in the 5' to 3' direction, and the lagging strand runs in the 3' to 5' direction relative to the replication fork movement.
• Option c: The leading strand is synthesized continuously, not related to Okazaki fragment formation.
• Option d: Helicase unwinds the DNA double helix, not related to Okazaki fragment formation.

• Option a: Ligase's role is to catalyze the formation of phosphodiester bonds between adjacent Okazaki fragments on the lagging strand, sealing the gaps between them.
• Option b: Replication is initiated by proteins that recognize the origin of replication, not ligase.
• Option c: DNA polymerase adds nucleotides to the growing strand, not ligase.
• Option d: Helicase unwinds the double helix, not ligase.

Answer:

a. Mutations and diseases

Second Question: How are Okazaki fragments formed during DNA replication?