Cellular Reproduction

How Do Cells Receive Nutrients?• Cell Membrane

–The membrane allows in:

•Food

•Water

•Oxygen

The Cell Membrane

• Selectively permeable – allows only certain materials to pass through.

• Diffusion – the movement of molecules from areas of higher concentration to areas of lower concentration

• Osmosis – the movement of molecules from areas of higher to areas of lower concentration through the cell membrane.

The Cell Membrane

• Three types of solution

• Hypotonic

• Note: = Water = Concentration

The Cell Membrane

• Three types of solution

• Isotonic

• Note: = Water = Concentration

The Cell Membrane

• Three types of solution

• Hypertonic

• Note: = Water = Concentration

The Cell Membrane

• Three types of solutions

• Hypotonic Isotonic Hypertonic

• The concentration of water outside of the cell is:

• Higher Same Lower

The Cell Membrane

• Three types of solutions

• Hypotonic Isotonic Hypertonic

• The concentration of dissolved substance outside of the cell is:

• Lower Same Higher

The Cell Membrane

• Three types of solutions

• Hypotonic Isotonic Hypertonic

• The cell contents will:

• Swell Stay the same Shrink

The Cell Membrane

• The concentration (amount) of dissolved substance affects the movement of water into and out of the cell.

The Cell Membrane

• Homeostasis – the ability of an organism to maintain a constant internal balance even when the conditions around it change.

• Examples:

1.Turgor Pressure – the force of the cell contents pushing against the cell wall

The Cell Membrane

2. Passive Transport – the movement of substances through the cell membrane without using energy.

3. Active transport – the movement of molecules from areas of lower to higher concentration with the use of energy.

The Cell Membrane

• Protein Molecules Lipid Molecules

Surface Area to Volume Ratio

• Cell Diameter increases 10 times

• Surface Area increases 100 times

• Volume increases 1000 times

Surface Area to Volume Ratio

• Double the cell size (2 times)

–8 times more nutrients required

–8 times more waste to excrete

–Surface area increase only 4 times

• Cell starve to death or be poisoned

Why is it important to have many small cells

rather than one Larger cell?

• Larger cell has:

–Difficulty in receiving enough nutrients and oxygen

–Difficulty in removing wastes

–One copy of DNA

Cell DivisionCell divides into two daughter cells

Mitosis• Process by which

the nucleus of the cell is divided into two nuclei, each with the same number and kinds of chromosomes as the parent cell.

Interphase• G1 phase

– Cellular Growth – Development

• S phase – DNA Replication – Protein synthesis

• G2 phase – Synthesis of organelles – Materials for cell

division

Interphase

ChromosomesChromosomes• Contain the Contain the

genetic information genetic information (DNA) that is (DNA) that is passed from one passed from one generation of cells generation of cells to the next.to the next.

• DNA

• Proteins (histones)

ChromosomesChromosomes

Chromosome Chromosome StructureStructure

Sister Chromatid

Centromere

DNA

Number of Number of ChromosomesChromosomesOrganism Chromosome Number

AmoebaAmoeba 50

CarrotCarrot 18

CatCat 32

ChimpanzeeChimpanzee 48

DogDog 78

EarthwormEarthworm 36

GoldfishGoldfish 94

HUMANHUMAN 46

LettuceLettuce 18

Prophase

• Appearance of chromosomes• Nucleolus disappears• Nuclear membrane breaks down• Centrioles separate and migrate to

opposite poles of cell• Spindle fibers from the centrioles attach

to the centromeres• Chromatin coils up (shortens) into

chromosomes

Longest (50 - 60%)

Prophase

Metaphase

• Chromosomes line up across center (equator) of cell

• Spindle fibers from centromere to centrioles

Shortest

Metaphase

Chromosome

Centriole

Spindle Fiber

AnaphaseAnaphase• Sister Chromatids split at

Centromere• Individual Chromosomes

move toward poles• Chromatid pairs from each

chromosome separate from each other

• Chromatids are pulled apart by the shortening of the microtubules in the spindle fibers

AnaphaseAnaphase

TelophasTelophasee

• Spindle fibers breakdown• Chromosomes uncoil into Chromatin• Nuclear envelope (membrane) reforms• Nucleolus becomes visible• Chromosome reach the ends of the cell• The centrioles double• The cytoplasm is divided

Final Phase

TelophaseTelophase

Mitosis in Whitefish and OnionMitosis in Whitefish and Onion

CytokinesisCytokinesis• The process by which the cytoplasm

divides, forming two new cells.

CytokinesisCytokinesis• Animals

– Cell membrane – pinches inward

• Plants– Cell plate

Result of MitosisResult of MitosisTwo cells that are identical to each

other.

Cell Theory

• Developed by Robert Hooke

• Came up with the name cells

• Encouraged other scientists to look for cells in their research

• Cell theory is made up of three main ideas:

Cell Theory

1. All organisms are composed of one or more cells.

– Most organisms are multicellular

2. Cells are the basic units of structure and function in organisms

3. All cell arise from existing cells– Cell theory states that a cell divides to

form two identical cells

Cancer

Cancer

“When Cell Division Goes

Bad”

Cancer•Uncontrolled cell growth creating a malignant tumor

Tumor

• A growth from a single mutated cell that has repeatedly undergone cell division

Malignant

• A tumor that invades surrounding tissue and spreads to other parts of the body

Benign•A tumor that does not invade surrounding tissues and does not spread

Metastasize

• The spread of cancer from the place of origin throughout the body

–The cancer migrates and invades tissues

Causes of Cancer• Heredity -- Breast Cancer, Retinoblastoma

• Changes in enzymes production• Carcinogens -- environmental

agent– Tobacco (smoke and smokeless),

saccharin, pesticides, herbicides, asbestos, benzene, water polution

• Radiation -- UV light, X-rays, nuclear bombs

• Viruses -- papillomavirus

Types of Cancer

• Breast

• Lung

• Prostate

• Colon/Rectum

• Bladder

• Lymphoma

Types of Cancer• Uterus

• Skin (melanoma)

• Oral Cancer

• Leukemia

• Pancreas

• Ovary

• Testicular

Treatments for Cancer

• Surgery -- the actual removal of the tumor and other infected areas

• Chemotherapy -- the use of a drug to selectively kill off cancer cells

• Radiation -- mutating the dividing cells to stop them from dividing

Prevention• Low fat diet

• High fiber diet

• Vitamins and minerals

• Daily Exercise

• Not using tobacco