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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