12.1 concepts

What is the main goal of cell division?

To distribute identical genetic material (DNA) into two daughter cells.

What is a genome

The complete set of an organism's DNA.

Chromatin

A complex of DNA and protein in a loose, uncondensed form found during interphase.

Chromosomes

Condensed forms of chromatin that become visible during cell division and carry genetic information.

Sister chromatids

Two identical copies of a chromosome joined by cohesins at the centromere.

Centromere

The narrow "waist" where sister chromatids are most tightly attached.

Cohesins

Protein complexes that attach along the length of chromatids to hold sister chromatids together.

Somatic cells vs. gametes

Somatic cells are diploid (2 sets of chromosomes); gametes are haploid (1 set).

Chromosomes in human somatic cells

46 chromosomes (23 pairs).

Chromosomes in human gametes

23 chromosomes (no pairs).

DNA replication timing

During the S phase of interphase, before mitosis.

Sister chromatids during cell division

They separate and move into two new nuclei, becoming individual chromosomes.

Ensuring identical genetic material in daughter cells

Accurate DNA replication followed by equal distribution during mitosis.

DNA condensation before division

To allow easier and more accurate movement during mitosis.

Importance of accuracy in cell division

To prevent mutations and ensure proper cell function and development.