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ANNOUNCEMENTSNo class next week fall breakMake sure to look at your class grade on SakaiIf you have C- or lower in the class, receive academic alertI highly suggest these students come see meMust get C- or better in this classDeadline to withdraw Oct. 31st Briefly discuss testput all materials away firstCell Division

Two Modes of Cellular ReproductionMitosis and MeiosisGerm Cells Vs. Somatic CellsIn humans, the body cells (somatic cells) reproduce by mitosis.

The germ cells in humans give rise to the gametes through meiosis. Two Modes of ReproductionMitosis and MeiosisAsexual reproduction (mitosis)

One cell makes an exact copy of itself. In eukaryotic organisms, this is accomplished through mode of cell division called mitosis.

Chromosome

Locus the position on a chromosome where a gene resides

Cell Cycle

Interphase vs. Mphase (mitosis or meiosis)

CytokinesisSee picture in lab manualMITOSISOnion Root Tip

Root CapZone of Cell DivisionZone of Cell Elongation

Onion Root TipYou also may want to watch the video link below on the bead simulation of mitosis.

http://www.youtube.com/watch?v=zGVBAHAsjJMP 75 bead activity5-2 onion root tip5-3 whitefish blastulaThese correspond to questions 5-1 to 5-4 in the lab exerciseWhen complete we will move onto meiosis Diploid vs. HaploidDiploid cells contain two sets of chromosomes. One set inherited from each parent.Haploid cells contain one set of chromosomes.

Two Modes of ReproductionMeiosisSexual reproduction (In Animals) Each parent contributes chromosomes.Number of chromosomes stay constant from generation to generation because the number of chromosomes in the gamete is one half that of the parent cell.In humans, gametes are formed through the process of meiosis.In meiosis, four new cells are produced and the number of chromosomes in each cell is cut in half.

Two Modes of ReproductionMitosis and MeiosisSexual reproduction (In Animals) Two organisms produce cells called gametes (egg and sperm)Gametes fuse during fertilization

Fig. 13-5KeyHaploid (n)Diploid (2n)Haploid gametes (n = 23)Egg (n)Sperm (n)MEIOSISFERTILIZATIONOvaryTestisDiploidzygote(2n = 46)Mitosis anddevelopmentMulticellular diploidadults (2n = 46)21

Fig. 13-6KeyHaploid (n)Diploid (2n)nnGametesnnnMitosisMEIOSISFERTILIZATIONMEIOSIS2n2nZygote2nMitosisDiploidmulticellularorganism(a) AnimalsSporesDiploidmulticellularorganism(sporophyte)(b) Plants and some algae2nMitosisGametesMitosisnnnZygoteFERTILIZATIONnnnMitosisZygote(c) Most fungi and some protistsMEIOSISFERTILIZATION2nGametesnnMitosisHaploid multi-cellular organism(gametophyte)Haploid unicellular ormulticellular organism22

Fig. 13-4KeyMaternal set ofchromosomes (n = 3)Paternal set ofchromosomes (n = 3)2n = 6CentromereTwo sister chromatidsof one replicatedchromosomeTwo nonsisterchromatids ina homologous pairPair of homologouschromosomes(one from each set)23

Fig. 13-7-1InterphaseHomologous pair of chromosomesin diploid parent cellChromosomesreplicateHomologous pair of replicated chromosomesSisterchromatidsDiploid cell withreplicated chromosomes27

Fig. 13-7-2InterphaseHomologous pair of chromosomesin diploid parent cellChromosomesreplicateHomologous pair of replicated chromosomesSisterchromatidsDiploid cell withreplicated chromosomesMeiosis IHomologouschromosomesseparate 1Haploid cells withreplicated chromosomes 28

Fig. 13-7-3InterphaseHomologous pair of chromosomesin diploid parent cellChromosomesreplicateHomologous pair of replicated chromosomesSisterchromatidsDiploid cell withreplicated chromosomesMeiosis IHomologouschromosomesseparate 1Haploid cells withreplicated chromosomes Meiosis II2Sister chromatidsseparate Haploid cells with unreplicated chromosomes 29

Fig. 13-12-5Prophase Iof meiosisPair ofhomologsNonsisterchromatidsheld togetherduring synapsisChiasmaCentromereAnaphase IAnaphase IIDaughtercellsRecombinant chromosomesTEM30

Fig. 13-11-3Possibility 1Possibility 2Two equally probablearrangements ofchromosomes atmetaphase IMetaphase IIDaughtercellsCombination 1Combination 2Combination 3Combination 431

Fig. 13-9aMITOSISMEIOSISMEIOSIS IProphase IChiasmaChromosomereplicationHomologouschromosomepairChromosomereplication2n = 6Parent cellProphaseReplicated chromosomeMetaphaseMetaphase IAnaphase ITelophase IHaploid n = 3Daughter cells ofmeiosis IMEIOSIS IIDaughter cells of meiosis IInnnn2n2nDaughter cellsof mitosisAnaphaseTelophase32

Can be a haploid cell as well!

Interphase ProphaseMetaphase Anaphase Mid-telophaseLate-telophase Daughter cellsP 78 meiosis bead activity ends p.81Corresponds to 5-5 to 5-8 in lab exerciseDo 5-9, using photos of meiosisAnswer 5-10info in lab manual and powerpointOnion Root Tip Mitosis Stages

Interphase

Early Prophase

Middle Prophase Late Prophase

Metaphase

Anaphase Telophase & Cytokinesis