Cell division

Mitosis…

SM BLOSE

Cell CycleA process that takes place in the nucleus to divide a cell into two daughter cells with the same chromosomes and DNA. Mitosis involves four main phases: prophase, metaphase, anaphase, and Telophase.

MitosisMitosis is the division of the nucleus and is a continuous process that allows for the organized stribution of a cell’s copied DNA to offspring.

The process of mitosis is divided into four phases for easy understanding…

Prophase, Metaphase, Anaphase, and Telophase and Cytokenis.

Phases of Mitosis

Part of Interphase is also known as the G1 Phase of the Cell Cycle

(Growth Phase)

Interphase

Interphase

The longest stage of a Cell’s life

The time spent between divisions

Produces all materials required

for growth

Preparation for division

The Second part of Interphase is known as the S Phase of the Cell Cycle

(Synthesis Phase – when DNA duplicates)

The third part of the Cell Cycle, G2, is just a checkpoint to make sure the DNA is correct.

Next step –

Mitosis

Mitosis:Cell Division

The last part of the Cell Cycle is called Mitosis and has 4 phases during which the cell divides into 2 cells

Prophase• Prophase has three stages.

1. Early Prophase: The DNA and proteins condense and become visible. Centrioles begin to move apart, and the nuclear envelop starts to disappear.

2. Middle Prophase: The process keeps continuing, and everything keeps moving.

3. Late Prophase: Centrioles go to opposite poles of the nucleus. Microtubules (spindle fibers) begin to form. Chromosomes are put in homologous pairs, and the nuclear envelope is gone.

This shows Mitosis Prophase

Late Prophase happens when the Nuclear Envelope disintegrates and spindle fibers begin to move Chromosomes toward the center of cell.

Spindle Fibers

Chromosomes

Metaphase

The second stage. During this phase the spindle fibers move the chromosomes to the center of the dividing cell or metaphase plate. Once in the center of the cell, each chromosome is held by those fibers.

Spindle Fibers

AnaphaseThe centromeres split and chromosomes move to the different sides of the cell.Centrioles and spindle fibers help the chromosomes move.The beginning of Cytokinesis.

The Cell Plate begins to form

The Cell prepares for finial division

TELOPHASE

Cleavage Furrow

Telophase and CytokenisisThe nuclear envelope begins to reappear.The Chromosome lines disappear.Cell plate begins to form due to Cytokinesis.

Cytokinesis – The final stage of Mitosis

The cytoplasm, organelles, and nuclear material are evenly split and two new daughter cells are formed.

Cell Plate

The two new cells – each exactly like the other – are called Daughter Cells

Significance of MitosisDefinition: Mitosis is a replicative cell division involving one nuclear division to form 2 genetically identical daughter cells.Consequence of mitotic division: No variation in genetic information No variation in chromosome number due to

the semi-conservative replication of DNA and equal distribution of DNA.

The cell divide once. Two identical daughter cells are formed.

Why mitosis?• Growth. The number of cells

within an organism increases by mitosis and this is the basis of growth in multicellular organisms.

• Cell Replacement. Cells are constantly sloughed off, dying and being replaced by new ones in the skin and digestive tract. When damaged tissues are repaired, the new cells must be exact copies of the cells being replaced so as to retain normal function of cells.

• Regeneration. Some animals can regenerate parts of the body, and production of new cells are achieved by mitosis.

• Vegetative Reproduction. Some plants produce offspring which are genetically similar to themselves. These offspring are called clones

Red blood cells have short live spans of about 4 months and need to be replaced constantly by mitosis.

REFERENCE

All pictures from google. Campbell and Reece. (2010). Biology Hannah Hastings & Autumn Crosby