CELL GROWTH & CELL GROWTH & REPRODUCTION REPRODUCTION Chapter 8, Section 2Chapter 8, Section 2

Cell SizeCell Size Small cells are more efficientSmall cells are more efficient Small cells have a greater Small cells have a greater Surface Area-Surface Area-

to-Volume Ratioto-Volume Ratio so that exchange of so that exchange of materials across the plasma membrane materials across the plasma membrane is more efficientis more efficient

Cell ReproductionCell Reproduction ChromatinChromatin = uncoiled = uncoiled

DNADNA ChromosomesChromosomes = =

condensed/coiled condensed/coiled DNA, form when cell DNA, form when cell is ready to divideis ready to divide

Made up of 2 halves Made up of 2 halves held together in the held together in the center by the center by the centromerecentromere

Cell Cycle (Interphase & Cell Cycle (Interphase & Mitosis)Mitosis) Cell CycleCell Cycle = sequence of growth & division of a = sequence of growth & division of a

cell, 2 partscell, 2 parts 1. Interphase1. Interphase 2. Cell Division2. Cell Division

MitosisMitosis CytokinesisCytokinesis

1. Interphase1. Interphase = growth period, majority of a cell’s = growth period, majority of a cell’s life (most of the pie)life (most of the pie) Cells grow (G1)Cells grow (G1) Chromosomes duplicate (S) [Chromosomes duplicate (S) [chromosomes look like an chromosomes look like an

XX]] Prep for division (G2)Prep for division (G2)

2. Mitosis2. Mitosis = period = period of division, (small of division, (small slice of the pie), slice of the pie), 2 2 daughter cells get daughter cells get formed, each w/ a formed, each w/ a complete set of complete set of chromosomeschromosomes Slice is divided into Slice is divided into 4 4

PhasesPhases

Phases of MitosisPhases of Mitosis 1. Prophase1. Prophase Chromatin (spaghetti Chromatin (spaghetti

shaped DNA)shaped DNA) coils into coils into chromosomeschromosomes

Sister ChromatidsSister Chromatids = two = two halves of the halves of the chromosome, chromosome, chromatids are chromatids are genetically identical genetically identical (chromosomes are (chromosomes are XX--shaped) shaped)

Nuclear EnvelopeNuclear Envelope & & NucleolusNucleolus break downbreak down

CentriolesCentrioles start sending start sending out out Spindle FibersSpindle Fibers

2. Metaphase2. Metaphase Spindle FibersSpindle Fibers attach attach

to the chromosomesto the chromosomes ChromosomesChromosomes line line

up in the center of up in the center of the cellthe cell

Chromosomes still Chromosomes still look like an look like an XX

3. Anaphase3. Anaphase Spindle fibers pull Spindle fibers pull

apart apart Sister Sister Chromatids Chromatids and they and they separateseparate

The chromosome The chromosome goesgoes from from XX-shaped to -shaped to looking like a looking like a VV

(X = 2 copies, (X = 2 copies, duplicated, V = 1 copy)duplicated, V = 1 copy)

4. Telophase4. Telophase ChromatidsChromatids pulled to pulled to

opposite ends of the opposite ends of the cell (chromosomes cell (chromosomes are shaped like a are shaped like a VV))

Nuclear Envelope Nuclear Envelope & & NucleolusNucleolus re-form re-form

CytokinesisCytokinesis = division of the cytoplasm = division of the cytoplasm Cleavage FurrowCleavage Furrow in animals in animals

Cell pinches off in the middleCell pinches off in the middle

Cell PlateCell Plate in plants in plants Cell forms new cell wall in the middleCell forms new cell wall in the middle

http://www.cellsalive.com/mitosis.htm

Cancer (Ch. 9, Sec. 3)Cancer (Ch. 9, Sec. 3)

Results from uncontrolled cell divisionResults from uncontrolled cell division If the DNA of a cell is damaged/altered, If the DNA of a cell is damaged/altered,

regulation of cell division can be affectedregulation of cell division can be affected Environmental factors can damage cellsEnvironmental factors can damage cells

PracticePractice

Lung cancer is the leading cause of Lung cancer is the leading cause of death by cancer for males and females. death by cancer for males and females. Explain what is happening to the lung Explain what is happening to the lung cells of smokers and how this statistic cells of smokers and how this statistic can be easily reduced.can be easily reduced.