TopicTopic: Reproduction and : Reproduction and DevelopmentDevelopment

AimAim: How do cells divide? : How do cells divide?

Do NowDo Now: Explain the differences between sexual and : Explain the differences between sexual and asexual reproduction. What types of things reproduce asexual reproduction. What types of things reproduce

sexually? Asexually? sexually? Asexually?

HW: PAGE 96-97 10 MAIN POINTS & FINISH HANDOUTHW: PAGE 96-97 10 MAIN POINTS & FINISH HANDOUT

What are the two types of What are the two types of reproduction?reproduction?

• Asexual reproductionAsexual reproduction • Sexual reproductionSexual reproduction

MITOSISMITOSIS MEIOSISMEIOSIS

What is What is ASEXUALASEXUAL Reproduction?Reproduction?

•Requires one parent that Requires one parent that dividesdivides– AsexualAsexual “A”parent “A”parent

•Offspring are identical to Offspring are identical to parents parents

•Same # of chromosomesSame # of chromosomes

How does How does ASEXUALASEXUAL reproduction reproduction occur?occur?

•MITOSISMITOSIS – cell division – cell division•One cell divides into two One cell divides into two

identical daughter cells (same identical daughter cells (same # of chromosomes as parent)# of chromosomes as parent)

•Occurs in all body cells Occurs in all body cells EXCEPTEXCEPT sex cells sex cells

What are the steps of What are the steps of Mitosis?Mitosis?

• InterphaseInterphase• ProphaseProphase• MetaphaseMetaphase• AnaphaseAnaphase• TelophaseTelophase

– CytokinesisCytokinesis

InterphaseInterphase

The mass of DNA inside The mass of DNA inside the nucleus during the nucleus during interphase is known as interphase is known as CHROMATIN.CHROMATIN.

CHROMATINCHROMATIN

ProphaseProphase

MetaphaseMetaphase

AnaphaseAnaphase

TelophaseTelophase

What are the steps of What are the steps of Mitosis?Mitosis?

1.1. INTERPHASEINTERPHASE: cell grows to mature size and : cell grows to mature size and chromatin replicate (makes copy of DNA)chromatin replicate (makes copy of DNA)

2.2. PROPHASEPROPHASE: chromatin forms : chromatin forms chromosomes, nuclear membrane chromosomes, nuclear membrane disappears and spindle fibers formdisappears and spindle fibers form

3.3. MMETAPHASEETAPHASE: chromosomes line up in the : chromosomes line up in the MMiddleiddle of the cell of the cell

4.4. AANAPHASENAPHASE: chromosomes separate and : chromosomes separate and move move AAwayway from each other from each other

5.5. TELOPHASETELOPHASE: nuclear membrane starts to : nuclear membrane starts to formform

What is Cytokinesis?What is Cytokinesis?

• Part of telophasePart of telophase• Cell membrane pinches in Cell membrane pinches in

(cytoplasm separates) resulting in 2 (cytoplasm separates) resulting in 2 new cellsnew cells

CYTOKINESISCYTOKINESIS

How is mitosis different in plant How is mitosis different in plant cells?cells?

1.1. Cell membrane DOES NOT pinch in Cell membrane DOES NOT pinch in • Instead a Instead a CELL PLATECELL PLATE forms forms

between 2 new cellsbetween 2 new cells

2.2. Plant cells do not have centrioles Plant cells do not have centrioles (animal cells do)(animal cells do)

CELL PLATECELL PLATE

CytokinesisCytokinesis – Animal and – Animal and PlantPlant

What is Cancer?

• Abnormal and uncontrolled cell division

What are the different types of ASEXUAL Reproduction?

1. Binary Fission – one celled organism divides into two identical cells (mitosis)

• Binary Fission means “equal division”• Examples: ameba and paramecia

2. Budding – unequal division of organisms

• Examples: hydra, yeast

3. Sporulation – spores (specialized cells) develop into new organisms (mitosis)

• Examples: mold, mushrooms

What are the different types of ASEXUAL Reproduction?

4. Vegetative Propagation – Asexual reproduction used by plants

a. Runners (strawberries)

b. Buds (potatoes)

c. Grafting (roses)

d. Bulbs (onions)

Binary Fission & Budding

BINARY FISSION BUDDING

Sporulation

Vegetative Propagation

RUNNERS

BUDS

GRAFTING

BULBS

Topic: Reproduction and Development

Aim: What is sexual reproduction?

Do Now: Why does sexual reproduction require two parents?

What is sexual reproduction?

• Requires 2 parent cells, each with half the normal number of chromosomes

• Involves sex cells

• Human: sperm + egg → zygote

23 + 23 → 46

What is meiosis?

• Cell division occurs only in sex organs to produce sex cells (sperm and egg)

• Produces 4 daughter cells with half the number of chromosomes as parent cell (23 in humans)

• 2 divisions (1 → 2 → 4)

Meiosis

How does meiosis occur in males?

• Occurs in testes to produce sperm

• Produces 4 new sperm cells

How does meiosis occur in females?

• Occurs in ovaries

• Produces 1 egg cell and 3 polar bodies

What is fertilization?• Union of egg and sperm to form a zygote

• Two types:

• Internal fertilization: occurs inside the female (humans)

• External fertilization: occurs outside the female (frogs); can occur on land or in water

What happens to the zygote after fertilization?

• Zygote divides by MITOSIS to form 3 layers that will develop into different parts of the embryo

1. Outer layer: forms the skin and nerves

2. Middle layer: forms muscles

3. Inner layer: forms heart and stomachOuter layer

Middle layer

Inner layer