________________________ to help organisms: we grow because our cells divide fingernail growth slows...

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To help organisms:

We grow because our cells divide

Fingernail growth slows due to mitosis slowing down.

Skin Cells: 20 days

Red Blood Cells: 120 days

Stomach lining cells: 2 days

Brain cells: 30-50 years

Platelets: 10 days

Intestinal lining cells: 3 days

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• DNA plus proteins is called chromatin.• Strand of protein that attaches to

The chromosome is called a fiber.• One half of a duplicated

chromosome is a chromatid.• Sister chromatids – chromosome

after it has made an exact copy. Held together at the centromere.

• Telomeres protect DNA and do not include genes.

• Before the first step of Mitosis

chromosomes make exact copies

of themselves. Condensed, duplicated chromosomeCondensed, duplicated chromosome

chromatid

telomere

centromere

telomere

• The four stages of the cell cycle are gap 1, synthesis, gap 2, and mitosis.1) Gap 1 (G1): cell growth and

normal functions

• Mitosis occurs only if the cell is large enough and the DNA undamaged.

2) DNA synthesis (S): copies DNA

3) Gap 2 (G2): additional growth

4) Mitosis (M): includes division of the cell nucleus (mitosis) and division of the cell cytoplasm (cytokinesis)

Parent cell

centrioles

spindle fibers

centrosome

nucleus withDNA

• Mitosis- the process of making new body cells

• Interphase prepares the cell to divide.

Inter=G1-S-G2• During

interphase, the DNA is duplicated.

Mitosis and cytokinesis produce two genetically identical daughter cells.

•Prophase

•Metaphase

•Anaphase

•Telophase

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Sister Chromatids

Nuclear Membrane

Centrioles Fibers

Shorten and Thicken

Begins to break down

Move apart from one another

Form between centrioles

Sister Chromatids

Nuclear Membrane

Centrioles Fibers

Become attached to the

fibers. Are pulled to

middle of cell

Remains dissolved

Move to opposite ends

of cells

Are stretched between the

two ends of cell

Sister Chromatids

Nuclear Membrane

Centrioles Fibers

Pulled apart by fibers.

Each chromatid is

separate from its “sister”

Remains dissolved

Still at cell’s poles;

Pull each chromatid

toward opposite ends

of cell

Sister Chromatids

Nuclear Membrane

Cell Membrane

Fibers

Each end of cell has a complete

set of chromosomes.

Begins to reformBegins to pinch, forming two new

cells

Begin to disappear

• Cytokinesis differs in animal and plant cells.

– In animal cells, the membrane pinches closed.

– In plant cells, a cell plate forms.

The process is VERY SIMILAR in each type of cell.

There are only 2 differences:

1. Plant cells do not have centrioles

2. A cell wall is laid down at the end of the cell division.

Plant cell Animal Cell

Cell WallChloroplasts

Animal Cell

Plant cell

Prophase

Metaphase

Anaphase

Telophase

Plant cell

Animal Cell

Centrioles are not always found in plant cells.

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Life Cycle Animation

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Mitosis video - DS

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Signs of Aging:Loss of HairLoss of CalciumWrinkles

•Cancer cells form disorganized clumps called tumors. They cause problems by crowding normal cells.

•Benign tumors remain clustered and can be removed.•Malignant tumors metastasize, or break away, and can form more tumors.

cancer cellbloodstream

normal cell

Cell division is uncontrolled in cancer.

• Cancer cells do not carry out necessary functions and crowd out normal cells.

• Cancer cells come from normal cells with damage to genes involved in cell-cycle regulation.

• Carcinogens are substances known to promote cancer.

• Standard cancer treatments typically kill both cancerous and healthy cells.

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ORGANISM “GUESSTIMATE” ACTUAL CHROMOSOME #

CAT

DOG

CHIMPANZEE

EARTHWORM

GOLDFISH

CARROT

LETTUCE

ONION

CHICKEN

GUINEA PIG

HUMAN

MOSQUITO

PEA

PENICILLIN

CORN

FROG

327848

369418

1816

7864

466

14

1-42026

Stem cells are unique body cells.• Stem cells have the ability to

– divide and renew themselves– remain undifferentiated in form– develop into a variety of specialized cell types

Meaning: The cell could become a lung cell, or a skill cell;… it is NOT predetermined!

• Stem cells are classified into three types.– totipotent, or growing into any other cell type– pluripotent, or growing into any cell type but a totipotent

cell– multipotent, or growing into cells of a closely related cell

family

• Stem cells come from adults and embryos.– Adult stem cells can be hard to isolate and

grow.– The use of adult stem cells may prevent

transplant rejection.– The use of embryonic

stem cells raisesethical issues

– Embryonic stem cellsare pluripotent andcan be grown indefinitelyin culture. First, an egg is fertilized by a sperm cell in a petri

dish. The egg divides, forming an inner cell mass. These cells are then removed and grown with nutrients. Scientists try to control how the cells specialize by adding or removing certain molecules.

• The use of stem cells offers many currently realized and potential benefits.

– Stem cells are used to treat leukemia and lymphoma.– Stem cells may cure disease or replace damaged

organs.– Stem cells may revolutionize the drug development

process.

Stem cells Ethical issue