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