DNA replication, Mitosis, Cell Cycle

Define DNA replication and its purpose

A biological process where a cell makes a complete identical copy of the DNA inside the nucleus before cell division.

Why must DNA replication occur before mitosis?

To ensure that each daughter cell receives a set of chromosomes identical to the parent cell, required to carry out its function properly.

What is the process of DNA replication?

DNA replication is assisted by various enzymes. The helicase unzips the DNA molecule by breaking the hydrogen bonds, into two separate DNA strand with exposed nucleotides. The DNA polymerase attaches to each original strand acting as a template, which adds complementary nucleotides. The DNA polymerase on the leading strand will add complementary nucleotides continuously. The DNA polymerase on the lagging strand adds complementary nucleotide in fragments, which are later joined up by the ligase. This makes DNA replication semi-conservative.

Why is DNA replication considered semi-conservative?

Because each replicated DNA molecule has an original strand and one newly synthesized strand. This preserves genetic information and ensures stability.

Define Mitosis and it's purpose

A process where the parent cell divides into two genetically identical daughter cells, producing new cells to replace damaged or old cells essential for growth and repair.

What are phases of Mitosis

IPMAT. Interphase, prophase, metaphas, anaphase, and telophase.

Interphase

The DNA inside the nucleus replicates, ensuring that there's enough genetic material for cell division.

Prophase

DNA condenses into chromosomes each with two sister chromatids. The nuclear membrane breaks and spindle fibers form.

Metaphase

Chromosomes line up across the equator (middle) of the cell. The spindle fibers attaches to the centromere of the chromosomes.

Anaphase

Sister chromatids seperate and the spindle fibres pulls them towards two opposite poles of the cell. Each separated chromatid is an individual chromosome.

Telophase

Spindle fibers disappear, new nuclear membranes form around each set of chromosomes, and the chromosomes uncoil.

Cytokinesis

The cytoplasm divides, producing 2 genetically identical daughters cells.