Chapter 9: Cell Chapter 9: Cell ReproductionReproduction9.2 – Mitosis9.2 – Mitosis

MitosisMitosis

The cell’s replicated genetic material The cell’s replicated genetic material separates and the cell prepares to split separates and the cell prepares to split into two daughter cells!into two daughter cells!

Can be used to replace damaged cells.Can be used to replace damaged cells.

Mitosis in Onion cellsMitosis in Onion cells

ProphaseProphase

The stage during The stage during which a dividing cell which a dividing cell spends the most spends the most time.time.

Chromatin tightens Chromatin tightens into chromosomes.into chromosomes.

ProphaseProphase

ChromosomeChromosome – A – A single structure that single structure that contains the genetic contains the genetic material that was material that was replicated in replicated in interphase. (x-interphase. (x-shaped)shaped)

ProphaseProphase

Sister chromatidsSister chromatids – – Structures that Structures that contain identical contain identical copies of DNA.copies of DNA.

CentromereCentromere – The – The structure at the structure at the center of the center of the chromosome where chromosome where the sisters are the sisters are attached.attached.

ProphaseProphase

Spindle ApparatusSpindle Apparatus – – Spindle fibers, Spindle fibers, centrioles, and aster centrioles, and aster fibers.fibers.

Important in moving Important in moving and organizing the and organizing the chromosomes before chromosomes before cell division.cell division.

ProphaseProphase

Nuclear membrane Nuclear membrane disintegratesdisintegrates

Nucleolus disappearNucleolus disappear Chromosomes Chromosomes

condensecondense Mitotic spindle Mitotic spindle

begins to form begins to form between the poles.between the poles.

MetaphaseMetaphase

Chromosomes attach Chromosomes attach to mitotic spindle and to mitotic spindle and align along equator align along equator of the cell.of the cell.

AnaphaseAnaphase

Chromatids are Chromatids are pulled apart by the pulled apart by the shortening of the shortening of the microtubules, microtubules, causing sister causing sister chromatids to chromatids to separate into two separate into two identical identical chromosomes.chromosomes.

TelophaseTelophase

Chromosomes reach Chromosomes reach poles of cellpoles of cell

Nuclear envelope re-Nuclear envelope re-formsforms

Nucleolus reappearsNucleolus reappears Chromosomes Chromosomes

decondensedecondense

CytokinesisCytokinesis

In animal cells, In animal cells, cytokinesis begins cytokinesis begins with a furrow that with a furrow that pinches the cell pinches the cell apart.apart.

Plant cells build a Plant cells build a cell plate that divides cell plate that divides the cell into daughter the cell into daughter cells.cells.

Section 9.3 – Cell Cycle Section 9.3 – Cell Cycle RegulationRegulation

Abnormal Cell Cycle: Abnormal Cell Cycle: CancerCancer

Cancer Cancer – – Uncontrolled growth Uncontrolled growth and division of cells – and division of cells – A failure in the A failure in the regulation of the cell regulation of the cell cycle.cycle.

Causes of Cancer:Causes of Cancer:

Cancer can occur in Cancer can occur in healthy people from healthy people from mutations in DNA mutations in DNA chains.chains.

CarcinogensCarcinogens - - Agents that are Agents that are known to cause known to cause cancer! (Sun, cancer! (Sun, asbestos, smoke)asbestos, smoke)

Cancer GeneticsCancer Genetics

DNA must undergo many changes to DNA must undergo many changes to develop cancer, thus the increase in develop cancer, thus the increase in having cancer at older ages.having cancer at older ages.

An individual who inherits changes from An individual who inherits changes from a parent is at a higher risk.a parent is at a higher risk.

Stem CellsStem Cells

Stem cells are unspecialized cells that Stem cells are unspecialized cells that can develop into specialized cells when can develop into specialized cells when under the right conditions.under the right conditions.

Remain in an organism for many years Remain in an organism for many years while undergoing cell division.while undergoing cell division.

Embryonic stem cellsEmbryonic stem cells

Adult Stem CellsAdult Stem Cells