Cellular Reproduction

Mitosis

Cell reproduction occurs when parent cells divide. Two new daughter cells arise

from each parent cell.

The production of new cells serves several functions

• Early Development1. GROWTH: Increase the number of cells2. SPECIALIZE: Production of the many different cell

types that will make up the mature organism

• After Full Development1. Repair damage tissues2. Replace cells that are lost from the outer surface3. Resist disease

Small cells are better than large cells. There is more surface area for the cell

membrane to meet the cell’s needs

Cells stop growing or reproduce before they reach the point of:

• Starving because of a lack of nutrients

• Being poisoned because of waste buildup

Mitosis

The process by which chromosomes are duplicated and

distributed to daughter nuclei

Each daughter cell nucleus carries the same set of genetic information as the

parent nucleus

Interphase and Mitosis make up the cell cycle

Mitosis is a series of “phases” where the end of one phase blends

with the beginning of the next

Interphase (NOT part of mitosis)

• The in-between phase where chromosomes replicate

• Interphase begins when cell reproduction is completed.

• Interphase is a non-reproducing phase in which the cell spends most of its life

Early Interphase (still NOT mitosis)

• New parts such as ribosomes and mitochondria are produced– Animal cells: new centrioles

– Plant cells: new chloroplasts

Interphase

• Look for a. Complete nuclear membrane

b. Chromosomes NOT visible

chromatin

Nuclear membrane

Interphase

Prophase• Chromosome become dark and thick• Look for: a. Nuclear membrane

disappearingb. Chromosomes look like dark, thick

threadsNuclear Membrane

Chromosome threads

Mitosis - Prophase

Prometaphase

• Chromosomes move to the equator• Look for: a. Nuclear membrane is gone

b. Paired chromosomes attached with centromeres move toward the equator

Metaphase

• Chromosomes line up and attach to spindle fibers

• Look for: chromosomes lined up at the equator

Mitosis - Metaphase

Anaphase

• Chromosomes (chromatids) move to the poles• Look for: chromatids pulling apart at the

centromeres

Mitosis - Anaphase

Telophase• The cell splits and 2 new daughter cells are formed.

The nuclear membrane starts to reappear.• Look for: a. (animal) cleavage furrow b. (plant) equitorial plate

Mitosis – Late Telophase

Plant Cell – equatorial plate forming

Animal Cell – cleavage furrow forming

Daughter Cells

Mitosis

Anaphase

Metaphase Prophase

Prophase

TelophaseInterphase

Interphase

InterphaseTelophase

Prophase

It is estimated that 25 million cell division occur every second in the

human body

Different types of cells divide at different rates

• Red Blood Cell form in bone marrow and reproduce rapidly to keep up with the need for new cells

• Muscle and Nerve cells never reproduce once they mature

• Human Liver Cells divide only when new cells are needed to repair wounds.

If one type of cell grows too rapidly, the normal organization of the organism is disrupted.

Cancer is one kind of disruption. When there is a rapid, uncontrolled division of one kind of cell, it invades and disrupts cells in other tissue.

Genetic Uniformity = Mitosis

The genes in every daughter cell are identical to the genes in the parent cell

******BODY CELLS