Cellular Reproductio

n

Cellular Reproductio

n

ChCh.. 99ChCh.. 99

I. Cellular GrowthI. Cellular Growth- Cells grow until they reach their

size limit, then they either stop growing or divide.

A. Cell Size Limitations A. Cell Size Limitations - Why are cells so small?

1. Ratio of Surface Area to Volume

1. Ratio of Surface Area to Volume - As a cell grows, its volume

increases faster than its surface area.

1. Ratio of Surface Area to Volume

1. Ratio of Surface Area to Volume - As a cell grows, its volume

increases faster than its surface area.

- Large cells don’t have enough surface area (cell membrane) to support the cell with food and oxygen by diffusion.

2. Transport of Substances 2. Transport of Substances - Most materials (O2, CO2, water,

wastes, etc.) enter and exit the cell by diffusion.

- Diffusion is efficient only over very short distances.

3. Cellular Communications 3. Cellular Communications - If the cell is too large, it cannot

make proteins fast enough to support itself.

B. The Cell Cycle B. The Cell Cycle - Cell reproduction enables an

organism to grow, heal injuries, or to reproduce.

Sea Sea Urchin Urchin EmbryoEmbryo

Sea Sea Urchin Urchin EmbryoEmbryo

B. The Cell Cycle B. The Cell Cycle - Cell reproduction enables an

organism to grow, heal injuries, or to reproduce.

Mitotic cell division &

Differentiation

Mitotic cell division &

Differentiation

Tissues

Fertilized egg

(zygote)

Fertilized egg

(zygote)

Multicell stage

(embryo)

Multicell stage

(embryo)

Asexual Reproduction by Mitosis

Asexual Reproduction by Mitosis

Binary Fission in Paramecium

Binary Fission in Paramecium

Asexual Reproduction by Mitosis

Asexual Reproduction by Mitosis

Budding in

Yeast

Budding in

Yeast

- The cell cycle is a continuous process consisting of 3 stages: Interphase, Mitosis, and Cytokinesis.

- Takes place in 12 – 24 hours.

1. Interphase 1. Interphase - Stage of normal cell activity, growth, and DNA replication.

- Occurs in 3 phases:

1. Interpase 1. Interpase - Stage of normal cell activity, growth, and DNA replication.

- Occurs in 3 phases:

a) G1: cell growth and normal activity

b) S: DNA replication

- Chromosomes: structure in nucleus that contain DNA

- Chromatin: active, extended form of chromosomes

c) G2: preparation for mitosis

DNA DNA Double Double HelixHelix

DNA DNA Double Double HelixHelix

ChromatiChromatinn

ChromatiChromatinn

ChromosomChromosomee

ChromosomChromosomee

Chromosome Structure

Chromosome Structure

DNA Packaging

1:44

DNA Packaging

1:44

2. Mitosis 2. Mitosis - Division of the nucleus

3. Cytokinesis 3. Cytokinesis - Division of the cell into

2 identical daughter cells

4. Prokaryotic Cell Division 4. Prokaryotic Cell Division - Binary fission: simple cell

division

E.E.

colicoliE.E.

colicoli

Binary Fission in Bacteria

Binary Fission in Bacteria

attachment site

cell wall

plasma membran

ecircular DNA

11

DNA ReplicatesDNA Replicates

22

33

Cell ElongatesCell Elongates

Binary Fission in Bacteria

Binary Fission in Bacteria

Fission OccursFission Occurs

55

Cell ConstrictsCell Constricts

44

II. Cell DivisionII. Cell Division- Mitosis and Cytokinesis A. Mitosis

- 4 stages (P, M, A, T)

ProphasProphaseeProphasProphasee

MetaphasMetaphaseeMetaphasMetaphasee

TelophasTelophaseeTelophasTelophasee

AnaphasAnaphaseeAnaphasAnaphasee

1. Prophase1. Prophase

- first and longest stagea. Chromatin condenses

to form chromosomes. - Each replicated

chromosome consists of 2 identical sister chromatids attached at the centromere.

DNA DNA Double Double HelixHelix

DNA DNA Double Double HelixHelix

ChromatiChromatinn

ChromatiChromatinn

ChromosomChromosomee

ChromosomChromosomee

Chromosome Structure

Chromosome Structure

ChromatidChromatidChromatidChromatid

Human ChromosomesHuman Chromosomes

b. Nuclear membrane and nucleoli disappear.

c. Spindle fibers form

- microtubule structures that aid in movement of chromosomes

d. Centrioles move to opposite ends of the cell (animal cells only).

ProphasProphaseeProphasProphasee

2. Metaphase 2. Metaphase - second and shortest stage

- Chromosomes line up along the middle of the cell.

MetaphasMetaphaseeMetaphasMetaphasee

3. Anaphase 3. Anaphase - Centromeres

split and chromosomes move apart to opposite sides of the cell.

AnaphaseAnaphase AnaphaseAnaphase

TelophasTelophaseeTelophasTelophasee

4. Telophase 4. Telophase - last stage

- "reverse" of prophase

a. Chromosomes revert to chromatin.

b. Spindle fibers disappear.

c. Nuclear membrane and nucleolus reform.

CytokinesCytokinesisisCytokinesCytokinesisis

B.Cytokinesis B.Cytokinesis 1.Animal Cells

- Cell membrane pinches in forming 2 daughter cells.

2. Plant Cells2. Plant Cells- Cell plate forms

between 2 daughter cells.

Cell plateCell plate

Which stage of the cell cycle?

Which stage of the cell cycle?

AnaphaseAnaphase

Which stage of the cell cycle?

Which stage of the cell cycle?

InterphaseInterphase

Which stage of the cell cycle?

Which stage of the cell cycle?

MetaphaseMetaphase

Which stage of the cell cycle?

Which stage of the cell cycle?

ProphaseProphase

Which stage of the cell cycle?

Which stage of the cell cycle?

TelophaseTelophase

Which stages of the cell cycle?

Which stages of the cell cycle?

ProphaseProphase

InterphaseInterphase

Which stage of the cell cycle?

Which stage of the cell cycle?

Early AnaphaseEarly Anaphase

Which stage of the cell cycle?

Which stage of the cell cycle?

MetaphaseMetaphase

Which stage of the cell cycle?

Which stage of the cell cycle?

ProphaseProphase

Which stage of the cell cycle?

Which stage of the cell cycle?

TelophaseTelophase

Onion Root Tip Cells

Onion Root Tip Cells

Mitosis Video

6:11

Mitosis Video

6:11

III. Cell Cycle Regulation III. Cell Cycle Regulation - The timing and rate of cell

division varies by cell type.

A. Normal Cell Cycle A. Normal Cell Cycle - Cell division is complex, crucial,

and highly regulated.1. Cyclins and Cyclin-

dependent Kinases (CDKs)- Various combinations trigger different stages of the cell

cycle.2. Quality Control Checkpoints

- Coordinate important events in the cell cycle.

B. Abnormal Cell Cycle: Cancer

B. Abnormal Cell Cycle: Cancer - disease in which cells have lost

the ability to control their own growth

Cervical Cancer Cell Dividing

Cervical Cancer Cell Dividing

1.Causes of Cancer 1.Causes of Cancer - due to changes in a gene

(mutations) that controls cell division

- Carcinogens: cancer causing agents (asbestos, tobacco smoke, dioxin, UV radiation, X rays)

2.Cancer Genetics 2.Cancer Genetics - More than 1 mutation is required

to produce a cancer cell.

- Some genes that lead to cancer (oncogenes) can be inherited.

3.Characteristics of Cancer Cells

3.Characteristics of Cancer Cells a)Rapid cell division

b)Undifferentiated cells

c) Metastasis:

- cells don't stick together and can move elsewhere

C. Apoptosis C. Apoptosis - programmed cell death

C. Apoptosis C. Apoptosis - programmed cell death- occurs in worn out cells and

during embryonic development

C. Apoptosis C. Apoptosis - programmed cell death- occurs in worn out cells and

during embryonic development

D.Stem Cells D.Stem Cells - unspecialized cells that can

differentiate into specialized cells

1.Embryonic Stem Cells 1.Embryonic Stem Cells - Cells from an early embryo can

differentiate into any cell type.

2.Adult Stem Cells 2.Adult Stem Cells - Stem cells found in various adult

tissues can give rise to several types of tissues where they are found.

The EndThe End

Zygote

Nervoussystem,outerskin, mus-culature

Musculature,gonads

Outer skin,nervous system

Germ line(futuregametes)

Musculature

First cell division

Tim

e af

ter

fert

iliza

tio

n (

ho

urs

)0

10Hatching

Intestine

Intestine

Eggs Vulva

ANTERIOR POSTERIOR1.2 mm

Fate Map of Cell

Lineage in C. elegans

Fate Map of Cell

Lineage in C. elegans

Caenorhabditis elegans Adult crawling

Caenorhabditis elegans Adult crawling

C. elegans Embryonic Development

C. elegans Embryonic Development