Chapter 9 Cellular Basis of Inheritance

Brief Overview of Chapter

• 9.1 All Cells from Cells• 9.2 The Cell Cycle• 9.3 Mitosis (asexual)

• 9.4 Cancer Cells• 9.5 Meiosis (sexual reproduction)

• 9.6 Genetic Variation

Our Learning Goal Today1. Unicellular Vs Multicellular Reproduction

2. Stages of the Cell Cycle

9.1 All Cells come 9.1 All Cells come from….from….CellsCells

• Organisms reproduce their own kind– No humans with zebra babies or tigerman…

• Cells are important for:– Repair, growth and reproduction

• Reproduction• Asexual or Sexual

– AsexualAsexual• Simple cell division with no genetic

variation– SexualSexual

• 2 parents involved, genetic material from each combine to produce genetically different offspring

• Union of egg and sperm

ReproductiReproductionon

• Unicellular Organism– Asexual usually; can sexually

• Multicellular Organism– Sexually usually; some can asexually

Which they “choosechoose” depends on

various reasons… anyone?anyone?

9.2 Cell 9.2 Cell CycleCycle

• Body makes 25 million new Body makes 25 million new cells per second!cells per second!– Most of time spent doing Most of time spent doing

cellular activities (not dividing)cellular activities (not dividing)

• 2 Phases of Cell Division2 Phases of Cell Division

– 1- Interphase•G1, S, G2

– 2- Mitotic Phase•Mitosis, Cytokinesis

But First…. Chromo But First…. Chromo WHATS?!WHATS?!

• Chromatin- fibers made up of DNA

• Chromatid- one “side” of chromosome

• Chromosome- condensed chromatin

• Centromere- where 2 chromatids join

Squiggly lines

inside

One half of the

chromosome

Forms a “X” like shapeWhere they join in the

center

The Cell Cycle

• How often a cell divides depends on the type of depends on the type of cellcell

• Eukaryotic cells that Eukaryotic cells that divide undergo divide undergo cell cyclecell cycle

• Prokaryotic cells go Prokaryotic cells go through binary fissionthrough binary fission

Binary Fission in

Prokaryotes!!

The Cell The Cell CycleCycle

• Phase 1: Phase 1: InterphaseInterphase

– 90% cell life90% cell life– Routine function– Metabolic functions

1.1. G1- First GrowthG1- First Growth– Is it healthy?

2.2. S- DNA copied S- DNA copied – Copied correctly?

3.3. G2- Second GrowthG2- Second Growth

The Cell CycleThe Cell Cycle

• Phase 2: Mitotic PhasePhase 2: Mitotic Phase– Cell divides

4. Mitosis:4. Mitosis:•Nucleus & duplicated chromosomes

dividedivide into 2 daughter nucleiinto 2 daughter nuclei

5. Cytokinesis5. Cytokinesis• Cytoplasm dividesCytoplasm divides

Process produces 2 genetically identical Process produces 2 genetically identical daughterdaughter cells each with a single cells each with a single nucleusnucleus

Mitosis unique to eukaryotes

So… Did you LEARN So… Did you LEARN Today?!Today?!

1. What are cells important for?2. Describe how unicellular and multicellular cells reproduce.

(how are they different)

3. Draw the Cell Cycle– Label each phase/step– Describe what’s happening in each

– QUIZ 9.1/9.2/9.3 Thurs- CP BIOLOGYGeneral Bio Cell Division (today’s notes) TOMORROW

MitosisMitosis• What’s happening?What’s happening?

– Cells make identical copiesCells make identical copies– 4 steps4 steps

• Why?Why?1.1. Prep for meiosisPrep for meiosis

2.2. Means of asexual Means of asexual

reproductionreproduction

R E M E M B E R E M E M B E R…R…

• Mitosis is PART of the Cell CycleMitosis is PART of the Cell Cycle– InterphaseInterphase

•G1, S, G2G1, S, G2– Mitotic PhaseMitotic Phase

•MitosisMitosis, Cytokinesis, Cytokinesis

These are the 4 steps to mitosis...These are the 4 steps to mitosis...

Step 1: Step 1: ProphaseProphase

• Chromatin condenses into chromosomesChromatin condenses into chromosomes• Nuclear envelope disappearsNuclear envelope disappears• Spindles form (with microtubules)Spindles form (with microtubules)

Step 2: Step 2: MetaphaseMetaphase

• Chromosomes gather across cell Chromosomes gather across cell “equator”“equator”

• Chromatids attaches to spindle Chromatids attaches to spindle microtubulesmicrotubules

Step 3: Step 3: AnaphaseAnaphase

• SisterSister chromatids pulled apart by chromatids pulled apart by microtubules toward polesmicrotubules toward poles

• As they are pulled cell gets As they are pulled cell gets pushed out fartherpushed out farther

Step Step 4:Telophase4:Telophase

• Spindles disappearSpindles disappear• Nuclear envelopes appear Nuclear envelopes appear

around each nucleiaround each nuclei• Chromosomes uncoil into Chromosomes uncoil into

chromatinchromatin

CytokinesisCytokinesis

• Division of cytoplasm

• Completes Cell Cycle– 2 genetically identical cells2 genetically identical cells

– Animals cytoplasm pinches– Plants cell plate forms

Do you Remember?Do you Remember?

1. What are the 2 phases of cell division?

2. What are the 5 steps to cell division and what phases are they found in?

3. What are the 4 steps of mitosis?4. What is the purpose of mitosis?5. How do prokaryotes reproduce?6. What happens in each step of

mitosis?7. What is a pneumonic device to

remember the steps of mitosis in order?

Reinforcement Activity

• Pages 186-187MITOSIS FLIP BOOK!!!

• Interphase• Prophase• Metaphase• Anaphase• Telophase

– Label each on opposite sides!!

9.4 Cancer • Normal cells have “control

system”– Malfunctions

•Tumors & Cancer

9.4 Cancer 9.4 Cancer • Out of control cell reproduction

– Tumor (mass)• Benign tumors mass of

normal cells• Malignant tumor mass of

cancer cells– Cancer (disease)

• Caused by severe disruption of mechanism that normally controls cell cycle

9.4 Cancer 9.4 Cancer

• Cancerous cells spread– Diseased cells replace normal ones (malignant)– If not killed, removed it spreads to other parts of

the body and can form new tumors• Metastasis spread of cancer cells beyond

their original site

Cures?

9.4 Cancer 9.4 Cancer TreatmentsTreatments

• Malignant Vs Benign

• Surgery?• Radiation Therapy (chemo)

– Try to stop cell division– Anti-mitotic drugs… do what?

• Side effects?

9.4 Cancer

• Video Clips

– Awake Tumor Removal– Angiogenisis

9.5 Meiosis9.5 Meiosis

• Each offspring in a sexually Each offspring in a sexually reproducing species reproducing species inherits a unique combination of genes from its two parents– Creates a unique combination of Creates a unique combination of

traitstraits

9.5 Meiosis9.5 Meiosis

• MeiosisMeiosis cell division that cell division that produces 4 cellsproduces 4 cells– Each with half the number of Each with half the number of

chromosomes as parent cellchromosomes as parent cell– Occurs in sex organsOccurs in sex organs

9.5 Role of Chromosomes in 9.5 Role of Chromosomes in MeiosisMeiosis

• Almost all cells have same number Almost all cells have same number and type of chromosome within an and type of chromosome within an organismorganism– Males and Females from same species Males and Females from same species

also have number and typealso have number and type

• Humans have 46 chromosomesHumans have 46 chromosomes– Each has a twin (23 pairs)Each has a twin (23 pairs)

• Homologous chromosomesHomologous chromosomes– Same sequencesSame sequences same inherited same inherited

characteristicscharacteristics

9.5 Chromosome Role in 9.5 Chromosome Role in MeiosisMeiosis

• Homologous chromosomes– Eye color gene

•Same locations•Slightly different versions

– (blue, brown, green)

– DIFFERENT from sister chromatids!

»Those are identical in every way

9.5 Chromosome Role in 9.5 Chromosome Role in MeiosisMeiosis

• 23 homologous pairs of chromosomes 23 homologous pairs of chromosomes (46 total)(46 total)

• PAGE 193 karyotypePAGE 193 karyotype – Chromosome “map”Chromosome “map”– FemalesFemales all 23 homologous pairs look all 23 homologous pairs look

alikealike– MalesMales only 22; 1 pair look different only 22; 1 pair look different

• SEX CHROMOSOMESSEX CHROMOSOMES– Female XXFemale XX– Male XYMale XY

9.5 Chromosome Role in 9.5 Chromosome Role in MeiosisMeiosis

• Sex chromosomesSex chromosomes– Determine if male or femaleDetermine if male or female– Most genes carried on “X”Most genes carried on “X”– X genes not on Y and vice X genes not on Y and vice

versaversa

9.5 Chromosome Role in 9.5 Chromosome Role in MeiosisMeiosis

• Have 2 sets of chromosomes (one Have 2 sets of chromosomes (one from each parent)…key to life cyclefrom each parent)…key to life cycle– Diploid (2n)Diploid (2n) contain 2 homologous sets contain 2 homologous sets

of chromosomesof chromosomes• Most cells are diploidMost cells are diploid• 2n=462n=46

– Haploid (n)Haploid (n) single set of homologous single set of homologous chromosomeschromosomes• Sex cells (sperm, eggs)Sex cells (sperm, eggs)• n=23n=23• Formed through meiosisFormed through meiosis

The birds and the The birds and the bees…bees…

• Human Life Cycle Human Life Cycle – Nucleus of sperm (n) cell fuses with Nucleus of sperm (n) cell fuses with

nucleus of egg (n) during fertilizationnucleus of egg (n) during fertilization– Egg & sperm = gametesEgg & sperm = gametes– Forms human zygote (2n)Forms human zygote (2n)

•2 sets of homologous chromosomes2 sets of homologous chromosomes•Meiosis is the formation of these (n) Meiosis is the formation of these (n)

Do You Remember?

• Draw a benign and malignant tumor.• Draw homologous chromosomes.• What are the male and female sex chromosomes?• How many pairs of chromosomes do humans

have?• What are the male and female gametes? • What is a zygote?• What symbol represents haploid? • Diploid?• What is a karyotype?

The Process of The Process of MeiosisMeiosis

• Alternating diploid/haploid stagesAlternating diploid/haploid stages• w/o meiosis chromosome number w/o meiosis chromosome number

would increase exponentially!would increase exponentially!• 2 Meiotic divisions2 Meiotic divisions

– Meiosis I Meiosis I • Prophase I, Metaphase I, Anaphase I, Prophase I, Metaphase I, Anaphase I,

Telophase ITelophase I– Meiosis IIMeiosis II

• Prophase II, Metaphase II, Anaphase Prophase II, Metaphase II, Anaphase II, Telophase IIII, Telophase II

The Process of Meiosis

• Meiosis IMeiosis I– Prophase I

• Homologous chromosomes stick lengthwiseHomologous chromosomes stick lengthwise• Chromosomes form tetradsChromosomes form tetrads• Crossing over between tetradsCrossing over between tetrads

One Big, One Little

From each parent

9.5 Meiosis

• Metaphase I– Tetrads move to middle of cell & line

up across spindle

9.5 Meiosis

• Anaphase I– Homologous chromosomes separate as they

migrate to opposite poles of spindle– Sister chromatids move together– Only 2 chromosomes (w/2 copies) moving to

each pole

9.5 Meiosis

• Telophase I & Cytokinesis– Poles have haploid daughter nucleus– Nuclear envelope forms, cell divides

9.5 Meiosis

• Prophase II– In each haploid daughter cell

• Spindle attaches to centromeres & moves chromosomes to middle

9.5 Meiosis

• Metaphase II– Chromosomes lined up in the middle

with microtubules attached to each sister chromatid

9.5 Meiosis

• Anaphase II– Sister chromatids separate & move to

poles

9.5 Meiosis

• Telophase II & Cytokinesis– Individual chromosomes at poles– Cytoplasm splits

Final Product = 4 haploid daughter cells

Review Game

• Meiosis Memory!!• 6pm Appointments!!• Play against each other

Meiosis

• Illustrate MeiosisProphase I: _____________________________________________________________________________________________

1.1. Draw cell- use colored pencilsDraw cell- use colored pencils

2.2. Label PicturesLabel Pictures

3.3. Write out step to the rightWrite out step to the right

4.4. Put in correct orderPut in correct order

Reflection Activity

• Complete Venn Diagram for Mitosis & Meiosis– How are they similar?– Different:

• What happens in mitosis but NOT in meiosis?

• What happens in meiosis but NOT in mitosis?

• What are the products