Cell ReproductionCell Reproduction

Chapter 8Chapter 8

Cell Reproduction

8-2 Cell Division

8-1 Chromosomes

8-3 Meiosis

DNA: ChromosomesDNA: Chromosomes DNA: DNA:

NucleotidesNucleotides GenesGenes Forms In Eukaryotes:Forms In Eukaryotes:

1. Chromosome Coiled DNACoiled DNA

• Histone proteinsHistone proteins• Nonhistone proteinsNonhistone proteins• CentromereCentromere

1.1. Chromatin Chromatin DNA plus proteinDNA plus protein• Loose storageLoose storage

ProkaryotesProkaryotes Single circular moleculeSingle circular molecule

Copy C

hromatid

Chrom

atid

Chromosome

Centromere

****Revisiting DNA** StructureStructure

Nucleotide

Nucleic Acid

Chromosome Structure & NumbersChromosome Structure & Numbers

DIPLOID NUMBER

DNA StructureDNA Structure

EukaryoticEukaryotic ProkaryoticProkaryotic

Structure of DNA while not replicating chromatin

Types & Organization of ChromosomesTypes & Organization of Chromosomes Sex ChromosomesSex Chromosomes: :

2 chromosomes2 chromosomesDetermines genderDetermines gender

XX= female XX= female XY= maleXY= male

Carry genesCarry genes AutosomesAutosomes: :

44 chromosomes44 chromosomesAll other chromosomesAll other chromosomes

Homologous ChromosomesHomologous ChromosomesPairs carrying genes for same traitPairs carrying genes for same trait

KaryotypeKaryotype: : 22 pairs homologous autosomes22 pairs homologous autosomes2 sex chromosomes2 sex chromosomes

****Karyotype****

What type of organism is this?

What sex is this organism?

Does this organism have any chromosomal abnormalities?

Cells & ChromosomesCells & ChromosomesDiploidDiploid (2N) (2N)

Both chromosomes in homologous pairBoth chromosomes in homologous pairAll cells except reproductive cellsAll cells except reproductive cellsHuman: Human:

46 chrom.= 22 autosome pairs+2 sex chrom46 chrom.= 22 autosome pairs+2 sex chromHaploidHaploid (1N) (1N)

One set of chromosomes from pairOne set of chromosomes from pairReproductive Cells: sperm & egg= Reproductive Cells: sperm & egg= gametesgametes

Sperm + Egg = zygote (2N)Sperm + Egg = zygote (2N)HumanHuman

23 chrom= 22 autosomes + 1 sex chrom23 chrom= 22 autosomes + 1 sex chrom

# of Chromosomes in Various # of Chromosomes in Various OrganismsOrganisms

ee DiploidDiploid HaploidHaploid

Karyotype Analysis

1. Identify this organism?

2. Identify the gender?

3. Determine if this is a normal karyotype?

II. **II. **Cell Division: Prokaryotes **** Binary Fission: Binary Fission:

2 new genetically identical 2 new genetically identical offspringoffspring

3 stages3 stages

1.1. Chromosome copies Chromosome copies itselfitself

2.2. Cell wall forms between Cell wall forms between chromosomeschromosomes

3.3. Cell splitsCell splits

Cell Division: EukaryotesCell Division: Eukaryotes2 Types: 2 Types:

Mitosis: genetically identical, 2NMitosis: genetically identical, 2NMeiosis: genetically different gametes, 1NMeiosis: genetically different gametes, 1N

Cell CycleCell Cycle Interphase = prep!!!Interphase = prep!!!

GG11 (Gap 1) Phase (Gap 1) PhaseS Phase – SYNTHESIS OF DNAS Phase – SYNTHESIS OF DNAGG22 Phase Phase

Or GOr G00 Phase: after G Phase: after G11, exit cell cycle, no division, exit cell cycle, no divisionMitosis (M phase)Mitosis (M phase)Cytokinesis (C phase)Cytokinesis (C phase)

****Cell Cycle****

****Mitosis Phases***

1.1. Prophase Prophase Chromosomes formChromosomes form Nucleolus & nuclear envelope disappearNucleolus & nuclear envelope disappear Centrosomes (contain centrioles) separate to Centrosomes (contain centrioles) separate to

opposite poles of cellopposite poles of cell Spindle fibers make mitotic spindleSpindle fibers make mitotic spindle

Kinetochore fibers attach to kinetochore in Kinetochore fibers attach to kinetochore in chromosomechromosome

Polar fibersPolar fibers

Mitosis PhasesMitosis Phases2.2. MetaphaseMetaphase

Chromosomes line up on midlineChromosomes line up on midline

3.3. AnaphaseAnaphase Chromatids separateChromatids separate ““chromosomeschromosomes””

4.4. TelophaseTelophase Spindle fibers disappearSpindle fibers disappear ChromosomesChromosomes chromatin chromatin Nucleolus and nuclear envelope reformsNucleolus and nuclear envelope reforms

Cytokinesis: Cytokinesis: Cytoplasm divides in telophaseCytoplasm divides in telophase Cleavage furrow in cell membraneCleavage furrow in cell membrane Cell plate: plant cellsCell plate: plant cells

**Mitosis** Diagram**Mitosis** Diagramhttp://en.wikipedia.org/wiki/File:Mitosis_drosophilahttp://en.wikipedia.org/wiki/File:Mitosis_drosophila

_larva.ogv_larva.ogv

**Cytokinesis: Cleavage Furrow & Cell Plate**Cytokinesis: Cleavage Furrow & Cell Plate

**Meiosis**: Reproductive Cells Only**Meiosis**: Reproductive Cells Only Forms gametes (1N) from diploid cells (2N)Forms gametes (1N) from diploid cells (2N)

4 genetically different haploid cells4 genetically different haploid cells Meiosis IMeiosis I: haploid cells form by end: haploid cells form by end

Prophase IProphase ISynapsisSynapsis tetrad tetrad**Crossing over****Crossing over** genetic recombination genetic recombination

Metaphase IMetaphase IAnaphase IAnaphase I

Independent assortmentIndependent assortmentTelophase ITelophase I

Meiosis IIMeiosis II: : Prophase, Metaphase, Anaphase, Telophase IIProphase, Metaphase, Anaphase, Telophase II

http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter28/animation__how_meiosis_works.html 

**Meiosis I**

**Meiosis II (con)**

SpermatogenesisSpermatogenesis

In testesIn testesProduces 4 genetically Produces 4 genetically

different haploid different haploid spermatidsspermatids

Spermatids mature into Spermatids mature into spermsperm

OogenesisOogenesis

In ovariesIn ovariesProduces Produces

1 Egg1 Egg3 Polar Bodies3 Polar Bodies

UnequalCytoplasm

Division

Spermatogenesis vs Oogenesis

**Mitosis vs Meiosis**

Asexual & Sexual ReproductionAsexual & Sexual ReproductionAsexualAsexual

Offspring from 1 parentOffspring from 1 parentUnicellularUnicellular mitosis or budding mitosis or buddingMulticellularMulticellular budding budding

Always genetically identical to parentAlways genetically identical to parentSexualSexual

Offspring results from union of gametes= Offspring results from union of gametes= zygotezygote

Offspring genetically different from parents Offspring genetically different from parents due to meiosis recombining genesdue to meiosis recombining genes

Allows species to adapt more quicklyAllows species to adapt more quickly