Cell Growth &

Reproduction short

Egg & sperm

Limit to cell size due to:

3. Surface area-to- volume ratio

• As size inc. volume inc. faster than surface area.

• If a cell becomes too big its surface area would be too small to allow enough food or oxygen to enter or waste products to leave.

• If cell size doubled, it would require 8 X the more nutrients and have 8 X more waste to secrete. It would starve or become poisoned by a build up of waste.

• Cells divide before this point is reached.

Mitosis cell reproduction

used for body growth & repair• All organism grow

and change• worn out tissues are

repaired or replaced• Healing/Age, etc.• The average human cell

has a cell cycle of 20 hours.

• Cell life span (avg)– Brain cells 30-50 yrs– Blood 120 days– Stomach 2 days– Skin- 20 days

Genetic Material- carry DNAComparing the different forms

• genes- units of heredity• Thousands on each

chromosome

• Chromatin • Long tangled strands of DNA

not visible during interphase• becomes chromosomes during

cell reproduction• Chromosomes • Chromatin that thickens and is

copied- used in cell reproduction

• carries code for inherited traits• to offspring

• Sister chromatids- the copied set of chromosomes during Mitosis, Prophase

• Tetrad-composed of two chromatids from each chromosome, forming a thick (4-strand) structure.

• ****************• Only one set of

chromosomes needed in new cells

• Duplicated chromosomes must be split to prevent too many copies.

The Cell Cycle composed of periods of growth &

division • Interphase -

growth

• Mitosis-division phase in a cell

• Prophase

• Metaphase

• Anaphase

• Telophase

Mitosis moviehttp://

www.biology.arizona.edu/cell_bio/tutorials/cell_cycle/cells3.html

javascript:movie() Mitosis javascript:movie() Mitosis movie http://www.biolo...

Mitosisanimation Movie

Stage Events

Prophase Replication has occurred and each chromosome is composed of 2 sister chromatids

Metaphase Duplicated chromosomes are at the equator of the cell

Anaphase Sister shromatids separate, and each is now termed a chromosome

Telophase At each pole, there is a diploid number of chromosomes, the same number and kinds of chromosomes as the mother cell

The life cycle of the cell is typically divided into 5 major phases.

Interphase. The cell is engaged in metabolic activity The DNA duplicates, Chromosomes are not clearly

visible. Prophase. Chromatin condenses and becomes visible,

nuclear membrane dissolves. Proteins attach to the centromeres

Metaphase. Spindle fibers align the chromosomes along the middle of the cell nucleus.

Anaphase. The paired chromosomes separate and move to opposite sides of the cell.

Telophase. New membranes form around the daughter nuclei while the chromosomes disperse and are no longer visible. Cytokinesis or the partitioning of the cell may also begin during this stage.

Prophase

• Chromatin coils into chromosomes

• Sister chromatids- chomosomes made up of 2 halves (exact copies of each other)

• Centromere- structure which holds sister chromatids together.

• spindle forms between centrioles- help separate the chromatids.

• Tetrads- composed of two chromatids from each chromosome, forming a thick (4-strand) structure.

Plant cell mitosis

Mitosis

Changes in rate of Mitosis

• As you get older, the rate at which cells are repaired slows down.

• Muscles do not undergo mitosis- leading to heart problems (old thought) We now know they can have limited repair

Cancer• Uncontrolled cell

division

• Results from failure to produce certain enzymes

• Env. Factors can trigger damaged genes into action.

• may be caused by

• Genes• env. Factors

– Cigarettes– Pollution– UV light– viruses.

• cancer- determined by where they live more than genetics

ASEXUAL REPRODUCTION

• New organisms from 1 parent

• Fission-splitting-into 2 parts

• spore production-plants• budding-cells pinch free• cloning- cell placed in

nutrient & exact duplicate is formed

• Regeneration- replacement of lost parts- repair damaged

Cancer• 2nd leading

cause of death in U.S.

• Can affect any tissue of the body

• U.S.-main ones-lung

• Colon• Breast• prostate

• - diet-

• low in fat • & high in fiber• Fruits, veggies,

grain, and some vitamins & minerals may prevent

• high fat linked to;• colon, breast,

prostate cancers

Cancer•Tumor-

Cancerous cells

• form masses of tissue

• deprive normal cells of nutrients.

Metastasis• Final stages of

cancer- • cancer cells enter

the circulatory system & spread throughout the body forming new tumors.

Melanoma• A malignant form

of skin cancer• most caused by

sun• develops on face

or neck• 4 Identifying traits

– Asymmetry – Border– Color– Diameter

Basal Cell Carcinoma

• carcinomas- • 2nd most

common type of skin cancer. Relatively harmless/removed easily

• can become squamous cell

• Grows rapidly & spreads

• chemotherapy & radiation therapy used

Cell Reproduction Video

• ASEXUAL REPRODUCTION Fission-splitting-into 2 parts – spore production-

plants– budding-cells

pinch free– cloning- cell

placed in nutrient & exact duplicate is formed

• Sexual Reproduction gametes- sex cells

• egg-female gamete

• sperm-male gamete

• Pollen- plants- male gamete

Sexual ReproductionMeiosis

• Sex cells from 2 parents combine

• Increases chances of adapting to survive a changing env.

• gametes- sex cells

• egg-female gamete

• sperm-male gamete

• Pollen- plants- male gamete

Sex Cells

• The union of egg and sperm add the # of chromosomes together

• sex cells have ½ the number of normal body cells

• During fertilization, a zygote is formed with 46 chromosomes (diploid)

•

If chromosome # don’t match

• A horse has 60 chromosomes in body cells. A donkey has 66. If they mate, the offspring is a sterile mule.

• Why do you think it is sterile?

• How many chromosomes would the mule have?

Meiosis• Prophase I-

chromosomes appear, pair, form tetrads

• Metaphase I• tetrads lineup at middle • Anaphase I- • chromatin do not

separate but move to opposite poles

• Telophase I- • division complete- • 2 haploid daughter cells

• Pro II-• chromosomes visible

& compact• Meta II• Chromosomes line up

at middle• Ana II• chromatids separate

& go to opposite poles• Telo II-• division complete, • 4 haploid daughter

cells

Meiosis

Spermatogenesis

• Production of sperm in males

• through meiosis

• results in 4 viable haploid sperm from each original cell

Oogenesis• Production of eggs

in females• through meiosis-

results in unequal cytoplasmic division

• produces only • 1 functional egg • & at least 2

nonfunctional polar bodies that later degenerate.

Compare

4 small sperm

1 large egg, & 3

polar bodies that die

Mitosis vs MeiosisProduces 2 identical cells Produces 4 different cells

Produces diploid cells46 chromosomes

Produces haploid cells23 chromosomes

PMAT PMAT I & II

Body cells Sex cells1 Egg, 4 sperm, ? pollen

Aging & growthregeneration

Only occurs in gonadsOvaries & testes

Asexual reproduction Sexual reproduction

Sister chromatids tetrads

Sexual Reproduction

• Production & fusion of haploid sex cells

• when a sperm fertilizes an egg, a zygote results (fertilized egg)

• Zygotes are diploid & develop by Mitosis into a multi-cellular organism

Mitosis & Meiosissimiliar

• Interphase- Growth

•Prophase- Nuclear membrane disappears & see chromosomes

•Metaphase- Chromosomes line up at equator

•Anaphase- Chromosomes separate

•Telophase- New cell wall

Genes – lined up on chromosomes-

a thousand or more on each chromosome

•Genes are located on chromosomes & exist in alternative forms called alleles.

• 2 Alleles- gene variations for each trait

• One from each parent-

• ex. Gene for tall & short

Chromosome number is not related to the complexity of the

organism• ex. • Indian

Fern = 1260People = 46

A B C D E

Put the following into the correct order

A B C D E

Correct order

Meiosis Phase II

• No replication- only a division of cytoplasm & separation of chromatids

• Each cell receives only 1 chromosome/ homologous pair

• Same as those of Mitosis- except 4 haploid cells are formed from the original diploid.

• Haploid cells form gametes

• Gametes – sex cells• Sperm and eggs (&

pollen) are produced-all have ½ # of chromosomes

• Puberty- life-stage where sex cells begin to form

• Testes make sperm-small• Ovaries make eggs-large• zygote (fertilized egg). a

diploid cell formed during fertilization when the 2 haploid cells unite