Cell Reproduction

CELL REPRODUCTION

DNA is the cell's genetic material; chromosomes are the carriers of this genetic information. In proka-ryotes, the chromosome is a single circle of DNA. In eukaryotes, each chromosome is a complex of DNA and histone proteins found in the nucleus.

BINARY FISSION

Prokaryotic cells reproduce via binary fission. In this process, DNA Is replicated, and the cell splits in two roughly equal parts, each with a copy of the cell's DNA.

EUKARYOTIC CELL CYCLE

Eukaryotic cells reproduce via the creation of two identical diploid cells from one diploid cell. Diploid (2N) refers to the total number of chromosomes in autosomal (nonsex-ual) cells.

A. Interphase: The period between mitotic divisions during which chromosomes are not visible; comprise of three phases:

The four phases of a eukaryotic cell cycle

1. G1 phase: Major period of cell growth.

2. S phase: Chromosome replication takes place, pro-ducing pairs of sister chromatids (identical chromosomes) that are each connected by a centromere.

3. G2 phase: Synthesis of cell machinery in prepara-tion for cell division.

B. Mitosis (M) phase: The division of genetic material and cellular contents.

The stages of mitosis

1. Prophase: Replicated chromosomes condense. Spindle forms along cell equator. Nuclear envelope breaks down; spindle microtubules en-ter nuclear region, eventually attaching to cen-tromeres of chromosomes.

2. Metaphase: Chromosomes align along cell equa-tor called the metaphase plate but do not yet segregate to opposite poles. Centromeres divide, freeing sister chromatids.

3. Anaphase: Sister chromatids separate to oppo-site poles.

4. Telophase: Chromosomes uncoil at opposite