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1Asexual ReproductionMitosis3 Questions will be asked in 3 minutes. Write a brief answer for each one. Be prepared to share your answer.13:00Mitosis is the process in which the nucleus divides to form two new nuclei. How does mitosis differ in plants and animals?

2:00WHY DO CELLS DIVIDE? Give me 2 reasons.

1:00HOW will YOU remember IPMAT?

TIMEs UP!

Genetics: Mitotic Cell Division

6How do little elephants grow up to be BIG elephants?

Why do animals shed their skin?

The process of asexual reproduction begins after a sperm fertilizes an egg.

Where it all beganYou started as a cell smaller than a period at the end of a sentenceAnd now look at you

How did you get from there to here?Three reasons why cells reproduce by asexual reproduction:

1. Growth 2. Repair 3. Replacement

Skin cancer - the abnormal growth of skin cells - most often develops on skin exposed to the sun.

Cells that reproduce by asexual reproduction reproduce constantly.

BUT FIRST.Use your book and define the following terms in your notes. You have 5 minutes.

1) Page 244CHROMOSOME (it is not in bold, so read carefully)CHROMATID

2)Draw a chromatid.

3) Page 245 CENTROMERE

4) Page 247SPINDLE

ChromosomesStrands of DNAEach human has 23 pair (diploid or 2n)One from your motherOne from your father

15Chromosome

One from MomOne from DadSister chromatidsDNA molecule with attached proteins16Chromosome numberEvery organism has its own specific number of chromosomes Examples: Human = 46 chromosomes or 23 pairs Dog = 78 chromosomes or 39 pairs Goldfish = 94 chromosomes or 47 pairs Lettuce = 18 chromosomes or 9 pairs

Phases and Sub-phases of Cell Division1. Interphase2. Mitosisa. G1b. Sc. G2Nuclear divisionb. Cytokinesis1. Prophase2. Metaphase3. Anaphase4. TelophaseFrom the Virtual Cell Biology Classroom on ScienceProfOnline.com18

Control of the Cell CycleInterphasePrior & After MitosisG1 period90% of cell life spent hereCell goes about its businessS periodDNA is duplicatedG2 periodCell prepares to divideCannot see DNA- uncoiled as chromatin

21Animated Mitosis Cycle

InterphaseProphaseMetaphaseAnaphaseTelophase & CytokinesisInterphase occurs before mitosis beginsChromosomes are duplicated (# doubles)Chromosomes appear as threadlike coils (chromatin) at the start, but each chromosome and its copy(sister chromosome) change to sister chromatids at end of this phaseCells are usually in interphaseCELL MEMBRANENucleusCytoplasmInterphase

Animal CellPlant CellPhotographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

Prophase 1st step in MitosisMitosis begins (cell begins to divide)Centrioles (or poles) appear and begin to move to opposite end of the cell. Spindle fibers form between the poles.Chromosomes coil up and become visible, thicker, and shorterNuclear envelope disappears

CentriolesSpindle fibers

Prophase

Animal CellPlant CellPhotographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htmSpindle fibersCentriolesProphase 1st step in MitosisMetaphase 2nd step in MitosisMetaphase = MiddleChromosomes attach to the spindle fibers.Chromosomes move to the middle of the cell.

Metaphase

Animal CellPlant CellPhotographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htmMetaphase 2nd step in MitosisAnaphase 3rd step in MitosisChromosomes separate and begin to move to opposite ends of the cell. Spindle fibers pull chromosomes to opposite poles

Anaphase

Animal CellPlant CellPhotographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htmAnaphase 3rd step in MitosisTelophase 4th step in MitosisChromosomes uncoil and appear as threads rather than rods.Nuclear membrane reforms around chromosomes.Two new nuclei form. Spindle fibers disappearMitosis ends.

Telophase

Animal CellPlant CellPhotographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htmCytokinesisoccurs after mitosis Cell membrane moves inward to create two daughter cells each with its own nucleus with identical chromosomes.Cytoplasm divides.

After mitosis and cytokinesis, the cell returns to Interphase to continue to grow and perform regular cell activities

Animal Mitosis -- Review

Interphase Prophase Metaphase Anaphase Telophase Interphase

Plant Mitosis -- Review

Interphase Prophase Metaphase Anaphase Telophase Interphase

REMEMBER!InterphaseProphaseMetaphaseAnaphaseTelophaseCytokinesisIPMATCI Pray More At The Church38A mnemonic to help remember the stages of mitosis.Summary of MitosisProphase: Chromosomes condenseNuclear envelope disappearscentrosomes move to opposite sides of the cellSpindle forms and attaches to centromeres on the chromosomes

MetaphaseChromosomes lined up on equator of spindlecentrosomes at opposite ends of cellAnaphaseCentromeres divide: each 2-chromatid chromosome becomes two 1-chromatid chromosomesChromosomes pulled to opposite poles by the spindleTelophaseChromosomes de-condenseNuclear envelope reappearsCytokinesis: the cytoplasm is divided into 2 cells

PhaseChromosome Appearance & LocationImportant EventsInterphaseProphaseMetaphaseAnaphaseTelophaseCytokinesisPhaseChromosome Appearance & LocationImportant EventsInterphaseProphaseMetaphaseAnaphaseTelophaseCytokinesisDNA replication, cell grows and replicates organellesNuclear envelope disappears, spindle fibers formDNA copies itself; chromatinChromosomes coil upChromosomes line up in the middleSpindle fibers connect to chromosomesChromosome copies divide and move apartSpindle fibers pull chromosome copies apart to opposite polesChromosomes uncoil back into chromatinNuclear envelopes reform, 2 new nuclei are formed, spindle fibers disappearDivision of the rest of the cell: cytoplasm and organellesChromatinCell Cycle43

Mitosis Animationhttp://www.youtube.com/watch?v=m73i1Zk8EA0&feature=youtube_gdata_playerhttp://www.youtube.com/watch?v=DD3IQknCEdc&feature=youtube_gdata_playerhttp://www.youtube.com/watch?v=XSKh-GLQn4E&feature=youtube_gdata_playerhttp://www.youtube.com/watch?v=eTvaGPcYNF8&feature=youtube_gdata_playerCOOL LINKS