Cell Division

Cell Division: Cell must divide because

-They get too big due to cell growth

-Get injured and die -Get too old -to continue the species

Two ways cells divide:1. Cell replacement and body

growth are accomplished by mitosis and cytokinesis

2. Sex cell production is accomplished by meiosis.

Cell Cycle

The cell cycle is an ordered set of events, culminating in cell growth and division into two daughter cells of body (somatic) cells.

Non-dividing cells not considered to be in the cell cycle (nerve cells and muscle cells)

Cell cycle is under control of a special proteins called cyclins:

Cell CycleControl of the Cell Cycle

The stages are G1-S-G2-M.

The G1 "GAP 1". Cell growth occurs

The S stage "Synthesis". DNA replication occurs.

The G2 stage "GAP 2". Second cell growth occurs to accommodate replicated organelles from S stage

G1, S and G2 occur during Interphase, the longest stage of the cell cycle.

M stage stands for "mitosis", and is when nuclear (chromosomes separate)

Finally, Cytokinesis: cytoplasmic division occur. Mitosis is further divided into 4 phases.

Genetic Engineering

DNA Extraction LabRecombinant DNA

Restriction EnzymesGel Electrophoresis

Mitosis and Meiosis

Mitosis and Cytokinesis

Stages of MeiosisComparison of

Meiosis and MitosisUNIQUE FEATURES

OF MEIOSIS

P-MAT

Interphase

ProphaseMetaphase

Anaphase

telophase Cell plate

A

C

B

D

InterphaseE

PlantAnimal

Mitosis in Plants and AnimalStructure Plants AnimalsCell plate yes noCleavage furrow no yesMitotic spindles no yesDivision begins in Anaphase no yesDisision begins in Telophase yes no

Lab: Plant Cell Mitosis

Read each part carefullyStart focusing in low powerChange to medium power and focus using fine

adjustment knobFinally, change to high power and focus again

using the fine focus knobDraw one cell for each stage using pencilAnswer questions for each sectionDo analysis question; Remember, it’s the most

important part of the lab!

Cellular senescence

Cellular senescence is the phenomenon where cells lose the ability to divide and cells begin to age.

This is noticeable in our bodies as graying of hair,

wrinkling of skin, redistribution of body fat, etc…

Theories of Aging

Shortening of telomeres: Cells with critically short telomeres become senescent, unable to divide further, and eventually malfunction. Some even die

Shortening occurs because of repeated replication

Theories of Aging

Free Radicals:Free radicals are oxygen molecules with unpaired electrons.

Free radicals damage cells in an organism, causing aging.

Our bodies generate free radicals in the mitochondria during cellular respiration.

Anti oxidants can inhibit production of free radicals

Antioxidants

Can slow down aging and prevent Cancer

Antioxidants include: Vitamin C… Vitamin E… Selenium mineral

What about cloning human cells?

Federal Occupational Health 19

What Is Skin Cancer?

An abnormal overgrowth (a tumor) of certain types of skin cells in the epidermis that began as normal skin structures.

A tumor can be either benign (generally localized and not life-threatening) or malignant (invasive or spreading, and may be deadly).

Skin cancer is a malignant tumor, able to invade surrounding tissues and metastasize (or spread) to other parts of the body, BUT…..

Melanoma

A form of skin cancer that arises in melanocytes, the cells that produce pigment and also are found in the epidermis.

Melanomas usually begin in a mole, which is a benign cluster of melanocytes and other tissue.

Normal

moles:

Melanoma

Melanoma is the deadliest form of skin cancer, causing more than 75% of all skin cancer deaths.

About 53,600 people in the United States were diagnosed with a melanoma skin. cancer in 2002, and approximately 7,400 died from the disease.

Melanoma (the A-B-C and Ds)

Asymmetry -- The shape of one half does not match the other.

Melanoma (the A-B-C and Ds)

Border -- The edges are often ragged, notched, blurred, or irregular in outline; the pigment may spread into the surrounding skin.

Melanoma (the A-B-C and Ds)

Color -- The color is uneven. Shades of black, brown, and tan may be present. Areas of white, grey, red, pink, or blue also may be seen.

Melanoma (the A-B-C and Ds)

Diameter -- There is a change in size, usually an increase. Melanomas are usually larger than the eraser of a pencil (5 mm or 1/4 inch).

Melanoma

May be found when a pre-existing mole changes:Early changes

- forming a new black area

- newly formed fine scales

- itching in a mole

More advanced changes

- texture changes (becomes hard or lumpy)

- itch, ooze, or bleed

- usually do not cause pain

Who is at risk for skin cancer?

Light skin color, hair color, eye color. Family history of skin cancer. Personal history of skin cancer. Certain types and a large number of moles. Freckles, which indicate sun sensitivity and sun

damage. Chronic exposure to the sun. History of sunburns early in life.

Sunburns are common

The Behavior Risk Factor Surveillance System provided data showing nearly 32% of all adults in the US report having had a sunburn in 1999.

More than 57% of adults age 18 to 29 reported having had a sunburn.

Over 40% of children are reported to have had sunburns over the preceding year.

How is it found?

Mostly by self examination of the skin By observations by family members By skin examination during visits to the doctor

To catch it early, you have to LOOK for it!…

and then you have to DO something about it!

How is skin cancer treated?

The physician will: Determine what type it is (medical history,

examination, biopsy) Determine how localized or extensive it is Then treat it….

surgery (e.g., Moh’s, cryo, laser, curettage, grafts)

chemotherapy radiation