Cell Division

Cell Division

Cell Division

The process by which a single cell splits to form new cells called daughter cells.

Importance of Mitosis

1. To replace damaged or worn out cells

2. to facilitate growth of an organism

Based on functions, what are the types cells

Somatic cells and Gametes.

Somatic Cell

These are cells that are responsible for growth and regeneration. They are diploid cells. They undergo mitosis.

Gametes

These are sex cells. They are haploid cells. They undergo meiosis.

Cell Cycle

This refers to the regular sequence of growth and division that eukaryotic cells undergo.

Centromere

The part of the Chromosome where sister chromatids are held together.

Stages of the Cell Cycle

Interphase, Mitosis, Cytokinesis.

Interphase

This stage is where the cell grows and increases in size, makes a copy of its genetic material, and prepares for cell division.

Stages in interphase

G1, S, G2.

G1 Stage

In this stage, the cell develops and doubles its organelles.

S Stage

DNA synthesis occurs and DNA replication results in duplicated chromosomes.

G2 Stage

Cell synthesizes proteins needed for cell division.

Mitosis

The type of cell division that results in two daughter cells, each with the same number and kind of chromosomes as the parent nucleus.

Stages in Mitosis

Prophase, Metaphase, Anaphase, Telophase

Prophase

In this stage, the nuclear envelope disintegrates and spindle fibres form in the cytoplasm. Each replicated chromosome consists of two closely associated sister chromatids.

Metaphase

In this stage, sister chromatids line up in the middle of the cell.

Anaphase

Spindle fibres begin to shorten. The sister chromatids divide and are pulled to the opposite ends of the cell.

Telophase

The chromosomes begin to decondense, the spindle breaks down, and the nuclear membranes and nucleoli re-form.

Cytokinesis

During this stage, the cytoplasm is divided into two parts by a structure made up of actin and myosin filaments called a contractile ring.

Meiosis

a special cell division process that creates 4 haploid daughter cell from diploid cells.

Importance of Meiosis

It brings about variety

Stages of Meiosis

Meiosis I and Meiosis II.

Prophase I

Chromosomes condense, homologous chromosomes pair (synapsis), and crossing over occurs (genetic exchange). Nuclear envelope begins to break down.

Metaphase I

Homologous chromosomes align at the equator of the cell.

Anaphase I

Homologous chromosomes separate and move towards opposite poles. Sister chromatids remain attached.

Anaphase II

Sister chromatids separate and move towards opposite poles.