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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