Cell Division

Cel l Division

Cell division involves the distribution of identical genetic material, DNA, to two daughters cells

Growth and development of somatic tissues of the organism

Regeneration of damaged tissues Production of new organs and tissues Replacement of old organs and tissues Asexual reproduction Sexual reproduction Maintains the size of cells within a limited range

The process of cell division which results in the production of two daughter cells

from a single parent cell.

The daughter cells are identical to one another and to the original parent cell.

• Interphase

• Prophase

• Metaphase

• Anaphase

• Telophase & Cytokinesis

DNA replicated Organelles replicated Cell increases in size

Interphase is the "resting" or non-mitotic portion of the cell cycle.

It is comprised of G1, S, and G2 stages of the cell cycle.

DNA is replicated during the S phase of Interphase

1. G1 phase:

The period prior to the synthesis of DNA.

The cell increases in mass in preparation for cell division.

G represents gap

2. S phase: The period during

which DNA is synthesized.

In most cells, there is a narrow window of time during which DNA is synthesized.

S represents synthesis.

3. G2 phase: The period after DNA

synthesis has occurred but prior to the start of prophase.

The cell synthesizes proteins and continues to increase in size.

Animal Cell Plant Cell

It the first stage of mitosis. The chromosomes condense and become visible

The centrioles form and move toward opposite ends of the cell ("the poles")

The nuclear membrane dissolves

Spindle fibers from each centriole attach to each sister chromatid at the kinetochore

Animal Cell Plant Cell

The Centrioles complete their migration to the poles

The chromosomes line up in the middle of the cell ("the equator")

Animal Cell Plant Cell

Spindles attached to kinetochores begin to shorten.

This exerts a force on the sister chromatids that pulls them apart.

Spindle fibers continue to shorten, pulling chromatids to opposite poles.

This ensures that each daughter cell gets identical sets of chromosomes

Animal Cell Plant Cell

The chromosomes decondense

The nuclear envelope forms Cytokinesis reaches

completion, creating two daughter cells

Animal Cell Cell wall pinches in to

form the 2 new daughter cells

Plant Cell New cell wall forms

between to nuclei to form the 2 new daughter cells

Animal Mitosis

Interphase

Prophase

Metaphase

Anaphase

Telophase

Interphase

Plant MitosisInterphase

Prophase

Metaphase

Anaphase

Telophase

Interphase

Meiosis is the type of cell division by which germ cells (eggs and sperm) are produced.

One parent cell produces four daughter cells.

Daughter cells have half the number of chromosomes found in the original parent

cell

During meiosis, DNA replicates once, but the nucleus divides twice.

Four stages can be described for each division of the nucleus.

First division of meiosis

Each chromosome duplicates and remains closely associated. These are called sister chromatids

Metaphase 1: Chromosomes align at the center of the cell.

Anaphase 1: Chromosome pairs separate with sister chromatids remaining together

Two daughter cells are formed with each daughter containing only one chromosome of the chromosome pair

Second Division of Meiosis

DNA does not replicate.

Metaphase 2: Chromosomes line up at the center of the cell

Anaphase 2: Centromeres divide and sister chromatids move separately to each pole.

Cell division is complete.

Four haploid daughter cells are formed.

MEIOSIS MITOSIS

Definition:

A type of cellular reproduction in which the number of chromosomes are reduced by half through the separation of homologous chromosomes, producing two haploid cells.

A process of asexual reproduction in which the cell divides in two producing a replica, with an equal number of chromosomes in each resulting diploid cell.

Function: sexual reproductionCellular Reproduction & general growth and repair of the body

Type of Reproduction: Sexual Asexual

Occurs in:Humans, animals, plants, fungi

all organisms

Genetically: different identical

Crossing Over:Yes, mixing of chromosomes can occur.

No, crossing over cannot occur.

Pairing of Homologues: Yes No

Number of Divisions: 2 1

Number of Daughter Cells produced:

4 haploid cells 2 diploid cells

Chromosome Number: Reduced by half Remains the same

Steps:

The steps of meiosis are Interphase, Prophase I, Metaphase I, Anaphase I, Telophase I, Prophase II, Metaphase II, Anaphase II and Telophase II.

The steps of mitosis are Interphase, Prophase, Metaphase, Anaphase, Telophase and Cytokinesis

Karyokinesis: Occurs in Interphase I Occurs in Interphase

Cytokinesis:Occurs in Telophase I & Telophase II

Occurs in Telophase

Centromeres Split:The centromeres do not separate during anaphase I, but during anaphase II

The centromeres split during Anaphase

Creates:Sex cells only: Female egg cells or Male sperm cells

Makes everything other than sex cells

Discovered by: Oscar Hertwig Walther Flemming