Cell ReproductionCell Reproduction

QSR #6??QSR #6?? 1. _________ is the process by which 1. _________ is the process by which

cells divide to make more cells.cells divide to make more cells. 2. Your _______ cells divide most 2. Your _______ cells divide most

often while your ______ cells almost often while your ______ cells almost never divide.never divide.

3. In eukaryotic cells, chromosomes 3. In eukaryotic cells, chromosomes are found in the _______, but in are found in the _______, but in prokaryotic cells they are found in prokaryotic cells they are found in the ____________.the ____________.

Cell ReproductionCell Reproduction

Cell division is the process by which Cell division is the process by which cells reproducecells reproduce

ChromosomesChromosomes: rod-shaped : rod-shaped structures made of DNA and proteinsstructures made of DNA and proteins

ChromatidsChromatids

One single strand One single strand of the chromosomeof the chromosome

Held together by a Held together by a centromerecentromere

Cell CycleCell Cycle

Sequence of growth and division of a Sequence of growth and division of a cell – the life cycle of a cellcell – the life cycle of a cell• Apoptosis: cellular deathApoptosis: cellular death

• Figure2.14 – In the embryo, fingers and Figure2.14 – In the embryo, fingers and toes are carved from webbed structures. toes are carved from webbed structures. In syndactyly, normal apoptosis, fails to In syndactyly, normal apoptosis, fails to carve the digits and webbing occurscarve the digits and webbing occurs

CELL CYCLE

A. InterphaseA. Interphase

1. Resting phase because it is not dividing 1. Resting phase because it is not dividing but it can be getting ready for divisionbut it can be getting ready for division

2. performing everyday, normal functions2. performing everyday, normal functions 3. Can be divided into 3 stages3. Can be divided into 3 stages

• G1G1• SS• G2G2

B. G1 phase (Gap 1)B. G1 phase (Gap 1)

1.Growth phase1.Growth phase 2.Grows rapidly2.Grows rapidly 3.Carries out routine functions3.Carries out routine functions

C. S phaseC. S phase

Synthesis of DNASynthesis of DNA DNA is copiedDNA is copied

D. G2 phase (Gap 2)D. G2 phase (Gap 2)

1.Growth and Prep for Mitosis1.Growth and Prep for Mitosis 2.organelles replicates2.organelles replicates (Doubling everything to prepare for (Doubling everything to prepare for

mitosis)mitosis)

Cells divide at different rates:Cells divide at different rates: Cell type Cell type Approximate life Approximate life

spanspan• Skin cellsSkin cells 2 weeks2 weeks• Red blood cellRed blood cell 4 months4 months• Liver cell Liver cell 300-500 days300-500 days• Intestinal cellsIntestinal cells 4-5 days4-5 days• Muscle/other cellsMuscle/other cells 16 years16 years• Brain cellsBrain cells maybe nevermaybe never• ++++++++++++++++++++++++++++++++++++++++++++++++

MitosisMitosis Process in which the nucleus of a cell Process in which the nucleus of a cell

divides into two nuclei, each with the divides into two nuclei, each with the same kind of chromosomessame kind of chromosomes

InterphaseInterphase

Chromosomes are replicatedChromosomes are replicated Chromosomes appear as threadlike Chromosomes appear as threadlike

coils (chromatin) at the start, but coils (chromatin) at the start, but each chromosome and its copy each chromosome and its copy (sister chromosome) change to sister (sister chromosome) change to sister chromatids at the end of this phasechromatids at the end of this phase• ***Remember: sister chromatids are ***Remember: sister chromatids are

held together by a held together by a centromere.centromere.

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The Stages of the cell cycle

ProphaseProphase

Mitosis begins in this phaseMitosis begins in this phase Centrioles (poles) appear and begin to Centrioles (poles) appear and begin to

move to opposite ends of cell.move to opposite ends of cell. Spindle fibers form between the polesSpindle fibers form between the poles CHROMATIN condenses (coils up) into CHROMATIN condenses (coils up) into

CHROMOSOMES CHROMOSOMES The nuclear envelope starts to break up The nuclear envelope starts to break up the Nucleolus disappearsthe Nucleolus disappears

MetaphaseMetaphase

Chromatids or pairs of chromosomes Chromatids or pairs of chromosomes attach to the spindle fibersattach to the spindle fibers

the Chromosomes line up at the the Chromosomes line up at the “Middle” of the cell“Middle” of the cell

AnaphaseAnaphase

Chromatids (or pairs of Chromatids (or pairs of chromosomes) separate and begin to chromosomes) separate and begin to move to opposite ends of the cell move to opposite ends of the cell 

Centromere divides Centromere divides

TelophaseTelophase

Two new nuclei formTwo new nuclei form Chromosomes appear as chromatin Chromosomes appear as chromatin

(threads rather than rods)(threads rather than rods) Nuclear envelope & nucleolus Nuclear envelope & nucleolus

reformsreforms

CytokinesisCytokinesis

Division of the cytoplasmDivision of the cytoplasm• Cell membrane moves inward to create Cell membrane moves inward to create

two two daughterdaughter cells cells – each with its own – each with its own nucleus, identical chromosomes, and a nucleus, identical chromosomes, and a total of 46 chromosomes eachtotal of 46 chromosomes each

• MicroscopeMicroscope: fish blastodisc (white fish) : fish blastodisc (white fish) mitosis, onion tip mitosis, ascaris mitosis mitosis, onion tip mitosis, ascaris mitosis (parasite – intestinal roundworm)(parasite – intestinal roundworm)

What phase and Why?What phase and Why?

What phase and Why?What phase and Why?

What phase and Why?What phase and Why?

What phase and Why?What phase and Why?

What phase and Why?What phase and Why?

Animated mitosis

Mitosis, Mitosis Mitosis, Mitosis Amelia ArellanoAmelia Arellano

Mitosis, Mitosis divided into four Mitosis, Mitosis divided into four stages. Prophase, Metaphase, stages. Prophase, Metaphase, Anaphase, and Telephase. Prophase Anaphase, and Telephase. Prophase Prophase, Nucleus breaks down Prophase, Nucleus breaks down Metaphase, Metaphase Chromosomes Metaphase, Metaphase Chromosomes line up in the center. Anaphase, line up in the center. Anaphase, Anaphase chromosomes moving to Anaphase chromosomes moving to the opposite poles. Telophase, the opposite poles. Telophase, Telophase envelop forms And the Telophase envelop forms And the spindle fiber begin to disappear spindle fiber begin to disappear

Results of MitosisResults of Mitosis

CellsCells TissuesTissues

• musclemuscle OrgansOrgans

• stomachstomach Organ systemOrgan system

• Digestive systemDigestive system OrganismOrganism

Stem cellsStem cells

Undifferentiated/ blank cellUndifferentiated/ blank cell Can be developed into a variety of Can be developed into a variety of

different cellsdifferent cells

Ex: embryonic stem cell can give rise to Ex: embryonic stem cell can give rise to almost any cellalmost any cell

Ex: Adult stem cells can give rise to Ex: Adult stem cells can give rise to related cellsrelated cells

Why is stem cell research so important? Why is stem cell research so important?

Cell DifferentiationCell Differentiation

Cells become specialized to perform Cells become specialized to perform specific functions…liver cells, skin specific functions…liver cells, skin cells, etc.cells, etc.

Is based on location in an embryoIs based on location in an embryo• Outer– skin, brain, spinal cordOuter– skin, brain, spinal cord• Middle– bones, muscles, kidneysMiddle– bones, muscles, kidneys• Inner– internal organs (pancreas, Inner– internal organs (pancreas,

stomach, etc.)stomach, etc.)

Asexual ReproductionAsexual Reproduction Creation of an offspring with only one parentCreation of an offspring with only one parent Ex: Binary Fission Ex: Binary Fission

• a form of mitosisa form of mitosis• – – division into 2 equal parts division into 2 equal parts

**** (done in prokaryotic cells) ******** (done in prokaryotic cells) **** Genetically identical to parentGenetically identical to parent Ex: bacteria, some plants (stem cutting), sea starEx: bacteria, some plants (stem cutting), sea star

How is this different from sexual reproduction? How is this different from sexual reproduction? ###################### ######################

QSR #8QSR #8 1. Fill in the blanks to make the correct order: 1. Fill in the blanks to make the correct order:

cells, ______, ______, cells, ______, ______, systems, _________.systems, _________. 2. _____ cells are undifferentiated meaning they 2. _____ cells are undifferentiated meaning they

____________ and can become other types of cells.____________ and can become other types of cells. 3. Cell differentiation depends on the location of 3. Cell differentiation depends on the location of

the cells inside the ______. If they are in the outer the cells inside the ______. If they are in the outer layer they can become ________, middle layer they can become ________, middle layer________, inner layer________.layer________, inner layer________.

4. How are embryonic stem cells different from 4. How are embryonic stem cells different from adult stem cells?adult stem cells?

CancerCancer

CancerCancer• Uncontrolled Mitosis/Cell DivisionUncontrolled Mitosis/Cell Division• Enzymes (proteins) monitor a cell’s Enzymes (proteins) monitor a cell’s

progress from phase to phaseprogress from phase to phase

CancerCancer

Caused by damaged genesCaused by damaged genes• Cancerous (malignant) cells form Cancerous (malignant) cells form

masses of tissuemasses of tissue TumorsTumors

• Deprive normal cells of nutrientsDeprive normal cells of nutrients• Spread throughout the body Spread throughout the body

Metastasis (cancer cells break away, get into Metastasis (cancer cells break away, get into blood stream, and spread)blood stream, and spread)

Cause of CancersCause of Cancers 1. Environmental factors (Carcinogens) – damage 1. Environmental factors (Carcinogens) – damage

genesgenes• Cigarette smoke, air pollutants, UV radiationCigarette smoke, air pollutants, UV radiation

2. Genetic2. Genetic 3. Viral Infections3. Viral Infections 4. Different types of cancers in different parts of 4. Different types of cancers in different parts of the worldthe world

• Breast cancerBreast cancer High USHigh US Low JapanLow Japan

• Stomach cancerStomach cancer High in ChinaHigh in China Low in USLow in US

Cancer PreventionCancer Prevention

DietDiet• Low in fat Low in fat • High in fiberHigh in fiber

Cancer PreventionCancer Prevention

Healthy Exercise and NO TOBACCO Healthy Exercise and NO TOBACCO products!!!!products!!!!

Vitamins and mineralVitamins and mineral• YellowYellow• Orange Orange • AA• CC• EE• CaCa