Cell CycleCell Cycle

Based on what you already know: What is Diffusion?Does Rate of Diffusion effect if a cell will grow?

• Remember, the cell membrane allows nutrients (ex. Glucose, oxygen, etc.) in and wastes out (diffusion)

• Diffusion is fast over short distances but slow over long distances

• So, b/c of slow rate of diffusion, cells can’t be giants b/c they would starve to death or be poisoned from the build up of wastes!!

So what must happen?

• Before the cells become to large it must divide into 2 “daughter cells”

• http://www.youtube.com/watch?v=Q6ucKWIIFmg

WHY DON’T CELLS GROW INDEFINENTLY?

The larger a cell becomes, the harder it gets to move nutrients & waste throughout the cell.

Cells abide by a certain volume to surface area ratio.

If the cell is too big in volume, then there is not enough surface area to meet the cell's requirements.

A certain surface area is needed so that materials can pass through the cells membrane and sustain the volume of the cell.

Types of cell division

• Prokaryotes

• Binary fission

• Eukaryotes

• Mitosis: (Asexual Reproduction)

• Growth, development & repair

• Asexual reproduction (yields genetically identical cells)

• Occurs in somatic (body) cells

• Meiosis: (Sexual Reproduction)

• Sexual reproduction (yields genetically different cells with half the # of chromosomes)

• Occurs in specific reproductive cells

• Yields gametes (e.g., eggs & sperm) or spores

Cells must divide for:• Growth

• Repair

• Reproduction

Why Do Cells Divide?

Important Facts to know before we begin…

• Completed in 2003, the Human Genome Project (HGP)

• 13-year project coordinated by the U.S. Department of Energy and the National Institutes of Health.

• To identify all the approximately 20,000-25,000 genes in human DNA,

• To determine the sequences of the 3 billion chemical base pairs that make up human DNA,

• To store this information in databases,

• To improve tools for data analysis,

• To transfer related technologies to the private sector, and

• To address the ethical, legal, and social issues (ELSI) that may arise from the project.

• Genome-the total complement of an organism’s genes

• Chromatin-network of DNA and fibrils in a nucleus that is NOT dividing

• Chromosome-structure of DNA that transmits genetic information to the next generation

• Chromatids-two copies of the same chromosome attached together

• Centromere-constriction where sister chromatids of a chromosome are held together.

• Sister chromatids

1.In body cells, chromosomes occur as pairs. 2.Each set of chromosomes is a homologous pair3.One member of each homologous pair is inherited from

the male parent, the other member from the female parent.

www.treachercollins.co.uk

Homologous Chromosomes

(Mader 2007)

What is the picture below?

• All living things grow and reproduce

• The cell cycle has two parts—growth (interphase) and reproduction (mitosis)

• B. Controlled by enzymes called CYCLINS

• 1. These enzymes, produced with instructions from the cell's DNA (genes), control when the cell undergoes mitosis.

• 2. When DNA (genes) are damaged, the enzymes controlling mitosis may not be produced,

• a. resulting in cell death.

•Apoptosis is programmed cell death

•Apoptosis and cell division are balancing processes that maintain the normal level of somatic (body) cells.

•Death by apoptosis prevents a tumor from developing.

Apoptosis

• b. Damaged DNA (genes) could also cause the enzymes that control mitosis to be produced in excess amounts, resulting in uncontrolled cell growth (cancer).

• Brain Tumor

includes

is divided into is divided into

Section 10-2

Cell Cycle

M phase (Mitosis)

Interphase

G1 phase S phase ProphaseG2 phase Metaphase TelophaseAnaphase

Go to Section:

17

Eukaryotic Cell Cycle

The eukaryotic cell cycle has 5 main phases: (cell cycle: Series of events a cell goes through as they grow and divide)

1. G1 (gap phase 1)

2. S (synthesis)

3. G2 (gap phase 2)

4. M (mitosis) (M) phase (mitosis and cytokinesis)

5. C (cytokinesis)

The length of a complete cell cycle varies greatly among cell types.

InterphaseCells spend 90% of their time in this phase

a. grows and develops

b. makes new proteins

G1 Phase

• Synthesis

• chromosomes replicate in the nucleus

• Chromosomes form an EXACT copy so daughter cell will have a the correct number of identical chromosomes

• When Chromatin have replicated, we call them Sister Chromatides

S Phase-Replication

20

G2 Phase• preparing for mitosis by making RNA and

proteins needed for cell division

• During G2 the chromosomes undergo condensation, becoming tightly coiled and are called chromosomes.

• Centrioles (microtubule-organizing centers) replicate and one centriole moves to each pole.

Interphase Diagram

Interphase

Animal Cell Plant Cell

Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

MitosisAsexual ReproductionProphase, Metaphase, Anaphase, Telophase

Which type of Cells Go Through Mitosis?

•Somatic Cells (Body Cells):• Skin, hair, muscle, etc.

•Each human body cell has 46 chromosomes

Prophase (1st stage of cell division)

The cell prepares for nuclear division

a.) Sister Chromatids condense and a.) Sister Chromatids condense and shorten, become distinguishableshorten, become distinguishable

b.) Nuclear membrane disintegrates, b.) Nuclear membrane disintegrates, nucleolus disappearsnucleolus disappears

c.) Centrioles separate, migrate to the c.) Centrioles separate, migrate to the polespoles

d.) Spindle fibers form between d.) Spindle fibers form between centrioles and attach to the centrioles and attach to the centromere on the sister centromere on the sister chromatidschromatids

e.)e.)

Prophase

Early prophase Late prophase

ProphaseProphase

Animal Cell Plant Cell

Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

Metaphase- 2nd stage (shortest)

a.) chromosomes line up in a.) chromosomes line up in pairs at equator (center of pairs at equator (center of cell)cell)

b.) centromere of each b.) centromere of each chromosome is attached chromosome is attached to a separate spindle fiberto a separate spindle fiber

MetaphaseThe cell prepares chromosomes for division

Sister Chromatids line up across the middle of the cell.

• Animal Cell

• Chromosomes line up at the center of the cell

• Spindle fibers attach from daughter cells to chromosomes at the centromere

• Plant Cell

• Chromosomes line up at the center of the cell

• Spindle fibers attach from daughter cells to chromosomes at the centromere

Metaphase

Animal Cell Plant Cell

Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

MMeettaapphhaassee ddiiaaggrraamm

Metaphase

Anaphase- 3Anaphase- 3rdrd stage stage

a.) Centromere of each a.) Centromere of each chromosome divides (separates)chromosome divides (separates)

b.) Separation of the chromatids in b.) Separation of the chromatids in each paireach pair

c.) Spindle fibers appear to shorten, c.) Spindle fibers appear to shorten, pulling the chromatids apart at pulling the chromatids apart at the centromere (now called the centromere (now called chromosomes)chromosomes)

d.) migration of the chromosomes d.) migration of the chromosomes ends with the arrival at the poles ends with the arrival at the poles and the formation of clustersand the formation of clusters

AAnnaapphhaassee ddiiaaggrraamm

Anaphase

AnaphaseThe chromosomes divide

• Animal Cell

• Spindle fibers pull chromosomes apart

• ½ of each chromosome (called chromotid) moves to each daughter cell

• Plant Cell

• Spindle fibers pull chromosomes apart

• ½ of each chromosome (called chromotid) moves to each daughter cell

Anaphase

Animal Cell Plant Cell

Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

Telophase – 4th stage

a.) Cleavage furrow forms b/w 2 cells and a.) Cleavage furrow forms b/w 2 cells and spindle fibers disappearspindle fibers disappear

b.) Nuclear membrane forms around each b.) Nuclear membrane forms around each set of chromosomes (forms 2 new set of chromosomes (forms 2 new nuclei)nuclei)

c.) Chromosomes uncoil to form c.) Chromosomes uncoil to form chromatin net (getting ready for chromatin net (getting ready for interphase)interphase)

d.) Nucleoli reorganizedd.) Nucleoli reorganized

TTeelloopphhaassee DDiiaaggrraamm

Telophase

TelophaseThe cytoplasm divides

• Animal Cell

• DNA spreads out

• 2 nuclei form

• Cell wall pinches in to form the 2 new daughter cells

• Plant Cell

• DNA spreads out

• 2 nuclei form

• New cell wall forms between to nuclei to form the 2 new daughter cells

Telophase

Animal Cell Plant Cell

Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

Last phase of Cell Cycle Cytokinesis

• Cytokinesis- division of the cytoplasm-tCytokinesis- division of the cytoplasm-the cytoplasm divides to form 2 new, identical cells.

• In animal cells- In animal cells- cell membrane pinchescell membrane pinches together, together, furrow formsfurrow forms along the equator. along the equator.

• In plant cells- In plant cells- cell platecell plate forms in the middle of forms in the middle of the dividing cellthe dividing cell

Picture of cytokinesis

*Image courtesy Indigo Instruments. Visit indigo.com for more original content like this. Reprint permission is

granted with this footer included.*

Mitosis Animation

http://www.cellsalive.com/mitosis.htm

Animal Mitosis -- Review

Interphase

                                                      

      

Prophase

                                                     

       

Metaphase

                                                      

      

Anaphase

                                                     

       

Telophase

                                                      

      

Interphase

                                                     

       

Plant Mitosis -- ReviewInterphase

                                                            

Prophase

                                                            

Metaphase

                                                            

Anaphase

                                                            

Telophase

                                                            

Interphase

                                                            

MITOSIS SUMMARY

46

46 46

•After Interphase, Mitosis, and Cytokinesis, 1 cell has become 2 new, identical cells – each containing the same genetic information.

•Mitosis is a form of asexual reproduction

•A single parent cell divides once to form 2 daughter cells identical to themselves and to the parent cell.

Figure 12.5x Mitosis

Figure 12.9 Mitosis in a plant cell

Figure 12-09x Mitosis in an onion root

Uncontrolled Cellular Division CausesCANCER…

Chemicals, radiation, and some viruses & bacteria can cause mutations to your cells that make mitosis uncontrollable!

How cancer forms in the body…

Abnormal Cell Growth

Abnormal Cell Growth

Cancer

• Occasionally, cells lose control of the cell cycle

• Cancer is a malignant growth resulting from uncontrolled cell division

• Malignant =dangerous to health; marked by uncontrolled growth

• This results from:

• failure to produce certain enzymes,

• the overproduction of enzymes

• Or the production of enzymes at the wrong time.

Tumors

• Tumors are abnormal growth of cells

• Benign tumors are non cancerous and and only grow locally

• Malignant tumors are cancerous and spread to other areas of the body

A Large Abdominal Tumor

Surgical Removal of Tumor

Body without Tumor

Number of deaths for leading causes of death according to the CDC

• Heart disease: 599,413

• Cancer: 567,628

• Chronic lower respiratory diseases: 137,353

• Stroke: 128,842

• Accidents (unintentional injuries): 118,021

• Alzheimer's disease: 79,003

• Diabetes: 68,705

• Influenza and Pneumonia: 53,692

• Nephritis, nephrotic syndrome, and nephrosis: 48,935

• Intentional self-harm (suicide): 36,909

• Cancer is the second leading cause of death in the U.S.

• Lung, colon, breast, and prostate cancers are the most prevalent types

• Genetics

Environmental Factors

• Cigarette smoke

• Air and water pollution

• Exposure to UV radiation

• Certain food products

• industrial chemicals

• viruses are some of the MANY substances implicated in DNA damage.

Cancer prevention

• Healthy Lifestyle

• Low fat, high fiber diet

• Exercise

• Not smoking

• Taking daily vitamins and minerals

• Carotenoids, Vitamins A, C, E, and calcium

Cancer

• Cancer is difficult to treat in later stages because the cancer may have spread to vital organs and damaged them beyond repair.

• Cancer staging is the process of finding out how advanced and widespread a cancer has become.

• http://www.youtube.com/watch?v=LEpTTolebqo