Chapter 8: Cell Chapter 8: Cell ReproductionReproduction
ReviewReviewOrganellesOrganelles
CentriolesCentriolesMade of microtubulesMade of microtubulesActs as anchors in cell divisionActs as anchors in cell division
Mitotic Spindle fibersMitotic Spindle fibersTwo Main typesTwo Main types
Kinetochore Fibers- Attach from centriole to Kinetochore Fibers- Attach from centriole to centromere of chromosomes and assists in centromere of chromosomes and assists in movement of chromosomesmovement of chromosomesPolar Fibers – Extend from pole to pole and keep Polar Fibers – Extend from pole to pole and keep the shape of the cell during cell divisionthe shape of the cell during cell division
Nuclear envelopeNuclear envelopeDouble Phospholipid bilayer surrounding nucleusDouble Phospholipid bilayer surrounding nucleusAllows selective passage of RNA and other Allows selective passage of RNA and other materialmaterial
NucleolusNucleolusDense area where DNA is concentrated in the Dense area where DNA is concentrated in the nucleusnucleus
Section 8.1Section 8.1ChromosomesChromosomes
Chromosome StructureChromosome StructureRod-shaped and made of DNA and proteins called Rod-shaped and made of DNA and proteins called histoneshistonesTwo full copies of DNATwo full copies of DNAForm it takes before cell divisionForm it takes before cell divisionHas two identical halves called chromatidHas two identical halves called chromatid
ChromatidChromatidHalf of the chromosomeHalf of the chromosomeOne full copy of DNAOne full copy of DNAAttached in the centerAttached in the center
CentromereCentromereCenter where chromatids areCenter where chromatids areheld togetherheld together
ChromaChromatintinLess tightly coiled DNA-protein complexLess tightly coiled DNA-protein complexTin = thin *Think spaghettiTin = thin *Think spaghettiForm taken during transcriptionForm taken during transcription
Section 8.1Section 8.1Sex ChromosomesSex Chromosomes
Determine gender of the organismDetermine gender of the organismMay carry genes for other characteristicsMay carry genes for other characteristicsEither X or YEither X or YFemale = XX Male = XYFemale = XX Male = XYOne pair (or two chromosomes)One pair (or two chromosomes)
AutosomesAutosomesRemaining chromosomesRemaining chromosomesContain genes for Contain genes for many many traitstraits22 pairs (or 44 chromosomes)22 pairs (or 44 chromosomes)
Section 8.1Section 8.1Homologous ChromosomesHomologous Chromosomes
Two copies of each autosomeTwo copies of each autosomeOne copy from each parentOne copy from each parentSame size and shapeSame size and shapeCarry genes for the same Carry genes for the same traittrait
KaryotypeKaryotypePhotomicrograph of Photomicrograph of chromosomeschromosomesNotice there are 22 pairs of Notice there are 22 pairs of autosomes and 1 pair of sex autosomes and 1 pair of sex chromosomeschromosomesWhat is the gender of this What is the gender of this organism?organism?
Section 8.1Section 8.1DiploidDiploid
Cells that are diploid contain two autosomes Cells that are diploid contain two autosomes from each homologous pair and two sex from each homologous pair and two sex chromosomeschromosomesAbbreviated as Abbreviated as 2n2n
Memory key * di = twoMemory key * di = two
Occurs in all cells except sperm and egg cells Occurs in all cells except sperm and egg cells
HaploidHaploidCells contain only one set of chromosomesCells contain only one set of chromosomesTherefore, half the number of chromosomes Therefore, half the number of chromosomes of a diploid cellof a diploid cellAbbreviated as Abbreviated as 1n1n
Memory key * hap = halfMemory key * hap = half
Sperm cell (Sperm cell (1n1n) and egg cell () and egg cell (1n1n) create a ) create a diploid cell (diploid cell (2n2n))
Section 8.1Section 8.1Notice high Notice high
number of number of chromosomechromosomes in fern s in fern compared to compared to humans!humans!
Section 8.1Section 8.1ActivityActivity
Create a karyotype!Create a karyotype!Arrange in pairs according to length, Arrange in pairs according to length, centromere position, and banding pattern centromere position, and banding pattern
QuestionsQuestions1.1. How many autosomes are there? How many How many autosomes are there? How many
sex chromosomes?sex chromosomes?
2.2. Is the organism a male or female?Is the organism a male or female?
3.3. Why are karyotypes important tools for Why are karyotypes important tools for geneticists?geneticists?
HomeworkHomeworkReview questions on p. 153 #1-5Review questions on p. 153 #1-5
Section 8.1 Review Section 8.1 Review AnswersAnswers
1.1. Name the proteins that DNA wraps around to Name the proteins that DNA wraps around to form a chromosome in eukaryotic cells.form a chromosome in eukaryotic cells.• Histones.Histones.
2.2. How do the structure and location of a How do the structure and location of a prokaryotic chromosome differ from that of a prokaryotic chromosome differ from that of a eukaryotic chromosome?eukaryotic chromosome?• A prokaryotic chromosome consists of a A prokaryotic chromosome consists of a
circular DNA molecule. Eukaryotic circular DNA molecule. Eukaryotic chromosomes are rod-shaped, associated with chromosomes are rod-shaped, associated with histone and nonhistone proteins, and found histone and nonhistone proteins, and found within the cell’s nucleus.within the cell’s nucleus.
3.3. Does chromosome number indicate whether Does chromosome number indicate whether an organism is a plant or animal? Explain.an organism is a plant or animal? Explain.• No. For example, chimpanzees have the same No. For example, chimpanzees have the same
number of chromosomes as potatoes or plums.number of chromosomes as potatoes or plums.
Section 8.1 Review Section 8.1 Review AnswersAnswers
4. Contrast sex chromosomes with autosomes.4. Contrast sex chromosomes with autosomes.• Sex chromosomes determine the gender of Sex chromosomes determine the gender of
an organism. Autosomes are all of the other an organism. Autosomes are all of the other chromosomes in an organism.chromosomes in an organism.
5. Using Table 8-1, list the haploid and diploid 5. Using Table 8-1, list the haploid and diploid number of chromosomes for each organism.number of chromosomes for each organism.
Section 8.1 Review Section 8.1 Review AnswersAnswers
Organism Diploid # Chromosomes Haploid # Chromosomes
Adder’s tongue fern 1262 631
Carrot 18 9
Cat 32 16
Chimpanzee 48 24
Dog 78 39
Earthworm 36 18
Fruit fly 8 4
Garden pea 20 10
Gorilla 48 24
Horse 64 32
Human 46 23
Lettuce 18 9
Orangutan 48 24
Sand dollar 52 26
Section 8.2Section 8.2Cell CycleCell Cycle
Repeating set of events in the life ofRepeating set of events in the life of
a cella cellInterphaseInterphase
Time between cell divisionsTime between cell divisions
Three phasesThree phases
G1 – Cell growthG1 – Cell growth
S – DNA is copiedS – DNA is copied
G2 – Growth and prep for cell divisionG2 – Growth and prep for cell division
Cell divisionCell divisionTwo phasesTwo phases
Mitosis – Nucleus of the cell dividesMitosis – Nucleus of the cell divides
Cytokinesis – Division of the cell’s Cytokinesis – Division of the cell’s cytoplasmcytoplasm
Section 8.2Section 8.2Cell DivisionCell Division
ProkaryotesProkaryotesRemember: Has cell wall, no nuclei, no Remember: Has cell wall, no nuclei, no membrane-bound organellesmembrane-bound organelles
Binary fissionBinary fissionDivision of prokaryotic cell into two offspring Division of prokaryotic cell into two offspring cellscells
Section 8.2Section 8.2Cell Division (cont’d)Cell Division (cont’d)
EukaryotesEukaryotesMitosisMitosis
Division of the nucleusDivision of the nucleus
Four stages (Prophase, Four stages (Prophase, Metaphase, Anaphase, Metaphase, Anaphase, Telophase)Telophase)
CytokinesisCytokinesisIn animal cells, pinching of cellIn animal cells, pinching of cell
membrane occursmembrane occurs
Cleavage furrowCleavage furrow
In plants, cell plate formation In plants, cell plate formation
Section 8.2Section 8.2Control of Cell Control of Cell DivisionDivision
Checkpoints = traffic Checkpoints = traffic signalsignal
Three main Three main checkpointscheckpoints
G1 checkpointG1 checkpoint
G2 checkpointG2 checkpoint
Mitosis checkpointMitosis checkpoint
Section 8.2Section 8.2ActivityActivity
Venn diagram:Venn diagram: Cell division in Prokaryotes Cell division in Prokaryotes vs Eukaryotesvs Eukaryotes
Karyotype Part 2Karyotype Part 2
HomeworkHomeworkCreate the cell cycleCreate the cell cycle
Section 8.2 Section 8.2 (cont’d)(cont’d)
MitosisMitosisProphaseProphase
Tight coiling of DNA into chromosomesTight coiling of DNA into chromosomes
Nucleolus and nuclear membrane break Nucleolus and nuclear membrane break downdown
Centrosomes appear and move to Centrosomes appear and move to opposite ends of the cellopposite ends of the cell
Kinetochore fibers extend from Kinetochore fibers extend from kinetochore from each chromatid to kinetochore from each chromatid to centrosomecentrosome
Metaphase = MiddleMetaphase = MiddleKinetochore fibers move chromosomes to Kinetochore fibers move chromosomes to center of cellcenter of cell
All chromosomes line up in a single file All chromosomes line up in a single file lineline
Section 8.2Section 8.2AnaphaseAnaphase
Chromosomes separate at the Chromosomes separate at the centromere and chromatids move to centromere and chromatids move to opposite polesopposite poles
Chromatids are now considered Chromatids are now considered individual chromosomesindividual chromosomes
TelophaseTelophase
Spindle fibers disassembleSpindle fibers disassemble
Chromosomes return to less tightly Chromosomes return to less tightly coiled chromatin statecoiled chromatin state
Nuclear envelope forms around each set Nuclear envelope forms around each set of chromosomesof chromosomes
Nucleolus forms in each of the newly Nucleolus forms in each of the newly forming cellsforming cells
Animation
Mitosis vs MeiosisMitosis vs MeiosisWhere do they occur?Where do they occur?
Mitosis – in the body cellsMitosis – in the body cellsMeiosis – in the germ cellsMeiosis – in the germ cells
Why does it occur?Why does it occur?MitosisMitosis
Asexual reproductionAsexual reproductionGrowth and developmentGrowth and developmentTo replace old cellsTo replace old cells
MeiosisMeiosisFormation of gametes (egg and sperm cells) Formation of gametes (egg and sperm cells) that will be used in sexual reproductionthat will be used in sexual reproduction
Mitosis vs MeiosisMitosis vs MeiosisEnd result?End result?
46
46 46
MITOSIS
46
23 23
23 23 23 23
MEIOSIS
MeiosisMeiosisAlso known as reduction divisionAlso known as reduction division
Occurs in germ cells found in the ovaries Occurs in germ cells found in the ovaries and testesand testes
Produces sex cells which are haploidProduces sex cells which are haploid
Occurs in two phasesOccurs in two phasesMeiosis IMeiosis I
Reduces the number of chromosomes from Reduces the number of chromosomes from diploid to haploiddiploid to haploid
Meiosis IIMeiosis IIProduces four haploid daughter cellsProduces four haploid daughter cells
Meiosis IMeiosis I
Meiosis IMeiosis IProphase IProphase I
DNA coils tightly into DNA coils tightly into chromosomeschromosomes
Spindle fibers appearSpindle fibers appear
Nucleolus and nuclear Nucleolus and nuclear envelope disassembleenvelope disassemble
Synapsis =Pairing of Synapsis =Pairing of homologous chromosomeshomologous chromosomes
Tetrad =Pair of homologous Tetrad =Pair of homologous chromosomes twisted around chromosomes twisted around each other each other
Crossing over may occurCrossing over may occur
Genetic recombinationGenetic recombination
Meiosis IMeiosis IMetaphase IMetaphase I
Spindle fibers attach to centromere of tetradsSpindle fibers attach to centromere of tetrads
Tetrads line up along midlineTetrads line up along midline
Anaphase IAnaphase IHomologous chromosome pairs are separated Homologous chromosome pairs are separated and move to opposite polesand move to opposite poles
Independent assortment occursIndependent assortment occurs
Telophase ITelophase IChromosomes reach opposite ends of cellChromosomes reach opposite ends of cell
Spindle Fibers disappearSpindle Fibers disappear
Cytokinesis beginsCytokinesis begins
Meiosis IIMeiosis II
Meiosis IIMeiosis IIProphase IIProphase II
Spindle fibers form and attach to the centromeres Spindle fibers form and attach to the centromeres of the double stranded chromosomesof the double stranded chromosomes
Metaphase IIMetaphase IIChromosomes are moved to the midline of the Chromosomes are moved to the midline of the dividing celldividing cell
Anaphase IIAnaphase IIChromatids separate and move toward opposite Chromatids separate and move toward opposite polespoles
Telophase IITelophase IINuclear membrane forms in each of the four new Nuclear membrane forms in each of the four new cellscells
Cytokinesis II occurs resulting in four new cells, Cytokinesis II occurs resulting in four new cells, each with half the original cell’s number of each with half the original cell’s number of chromosomes chromosomes
Section 8.3Section 8.3Results of mitosis vs. meiosisResults of mitosis vs. meiosis
Section 8.3Section 8.3Development Development of Gametesof Gametes
SpermatogenSpermatogenesisesis
OogenesisOogenesis
Polar bodiesPolar bodies
Sexual Sexual reproductionreproduction
Top Related