Ch. 8: The Cell Cycle
description
Transcript of Ch. 8: The Cell Cycle
![Page 1: Ch. 8: The Cell Cycle](https://reader036.fdocuments.in/reader036/viewer/2022070403/568139f9550346895da1ba30/html5/thumbnails/1.jpg)
Ch. 8: The Cell Cycle
![Page 2: Ch. 8: The Cell Cycle](https://reader036.fdocuments.in/reader036/viewer/2022070403/568139f9550346895da1ba30/html5/thumbnails/2.jpg)
Why does a cell divide?
-As a cell absorbs nutrients and gets larger, the volume of the cell increases faster than the surface area.
-Therefore, the demands of the cell (the volume) exceed the ability of the cell to bring in nutrients and export wastes. Solution? Divide into two smaller cells
![Page 3: Ch. 8: The Cell Cycle](https://reader036.fdocuments.in/reader036/viewer/2022070403/568139f9550346895da1ba30/html5/thumbnails/3.jpg)
When is cell division occurring?
GROWTH -increase number of cellsREPAIR -replace lost cells due to injury, diseaseCANCER – Abnormally high rates of cell division due to mutation
Different kinds of cells divide at different rates:E. coli – 20 minutes (What domain?)
Yeast cell – 2 hours (What domain? What kingdom?)
Amoeba – a few days (What domain? What kingdom?)
Human embryo cell – 15-20 minutesHuman adult cell – 8 hours to 100 days
![Page 4: Ch. 8: The Cell Cycle](https://reader036.fdocuments.in/reader036/viewer/2022070403/568139f9550346895da1ba30/html5/thumbnails/4.jpg)
AgingAll cells die after a certain number of divisions (programmed cell death-”apoptosis”). At any given time some cells are dividing and some cells are dying.
Childhood Cell division > cell death
Adulthood Cell division = cell death
Aging Cell division < cell death
![Page 5: Ch. 8: The Cell Cycle](https://reader036.fdocuments.in/reader036/viewer/2022070403/568139f9550346895da1ba30/html5/thumbnails/5.jpg)
Control of the Cell Cycle Cell proliferation
![Page 6: Ch. 8: The Cell Cycle](https://reader036.fdocuments.in/reader036/viewer/2022070403/568139f9550346895da1ba30/html5/thumbnails/6.jpg)
Interphase
Interphase ~ 90% of the time.
G1: Little new cell absorbs nutrients and grows larger. Does protein synthesis, its job.
S phase: Synthesis of new DNA (DNA replication) for daughter cells in preparation for mitosis.
G2: Cell continues to grow, do protein synthesis, do its job. Gets too large, needs to divide.
![Page 7: Ch. 8: The Cell Cycle](https://reader036.fdocuments.in/reader036/viewer/2022070403/568139f9550346895da1ba30/html5/thumbnails/7.jpg)
Chromosomes exist in 2 different states, before and after they replicate their DNA.
Before replication chromosomes = 1 chromatid.
After replicationchromosomes = 2 sister
chromatids, held together at the centromere. Each chromatid is one piece of DNA with its supporting proteins.
![Page 8: Ch. 8: The Cell Cycle](https://reader036.fdocuments.in/reader036/viewer/2022070403/568139f9550346895da1ba30/html5/thumbnails/8.jpg)
Structure of a eukaryotic chromosome
• unreplicated chromosome
arm armcentromere
![Page 9: Ch. 8: The Cell Cycle](https://reader036.fdocuments.in/reader036/viewer/2022070403/568139f9550346895da1ba30/html5/thumbnails/9.jpg)
Prior to cell division:• chromosomes (DNA) are replicated (duplicated)
duplicatedchromosome
• duplicated chromosome – attached at their centromeres – as long as attached, known as sister chromatids
![Page 10: Ch. 8: The Cell Cycle](https://reader036.fdocuments.in/reader036/viewer/2022070403/568139f9550346895da1ba30/html5/thumbnails/10.jpg)
daughterchromosomes
sisterchromatids
![Page 11: Ch. 8: The Cell Cycle](https://reader036.fdocuments.in/reader036/viewer/2022070403/568139f9550346895da1ba30/html5/thumbnails/11.jpg)
• Division of somatic cells (body cells)(non reproductive cells) ineukaryotic organisms
What is Mitotic Cell Division?
• A single cell divides into two identical daughter cells (cellular reproduction)
=> Maintains chromosome ploidy of cell
![Page 12: Ch. 8: The Cell Cycle](https://reader036.fdocuments.in/reader036/viewer/2022070403/568139f9550346895da1ba30/html5/thumbnails/12.jpg)
MITOSISEqual distribution of the 2 sets of DNA amongst the 2 daughter cells.
4 Stages: “PMAT”
1. Prophase
2. Metaphase
3. Anaphase
4. Telophase
How the Cell Cycle Works
Mitosis Animation
Cell Cycle
![Page 13: Ch. 8: The Cell Cycle](https://reader036.fdocuments.in/reader036/viewer/2022070403/568139f9550346895da1ba30/html5/thumbnails/13.jpg)
As a cell enters mitosis from interphase it has 2 complete sets of chromosomes because of replication in the S phase.
Each set must be re-arranged and distributed into the 2 new daughter nuclei. This is mitosis.
![Page 14: Ch. 8: The Cell Cycle](https://reader036.fdocuments.in/reader036/viewer/2022070403/568139f9550346895da1ba30/html5/thumbnails/14.jpg)
• Chromatin condenses (coils) into chromosomes. (Sister chromatids joined by centromere)
• Nuclear membrane dissolves.
• Nucleolus disappears.• Centrioles divide and
move to opposite poles forming spindle b/w them.
Prophase…
![Page 15: Ch. 8: The Cell Cycle](https://reader036.fdocuments.in/reader036/viewer/2022070403/568139f9550346895da1ba30/html5/thumbnails/15.jpg)
chromatin
nucleolus
nucleus
centrioles
condensingchromosomes
![Page 16: Ch. 8: The Cell Cycle](https://reader036.fdocuments.in/reader036/viewer/2022070403/568139f9550346895da1ba30/html5/thumbnails/16.jpg)
Metaphase
-Sister chromatids line up on metaphase plate.
-Centromeres lock on to spindle fibers
![Page 17: Ch. 8: The Cell Cycle](https://reader036.fdocuments.in/reader036/viewer/2022070403/568139f9550346895da1ba30/html5/thumbnails/17.jpg)
Anaphase• Centromeres divide.• Spindle fibers
contract pulling sister chromatids apart to poles.
![Page 18: Ch. 8: The Cell Cycle](https://reader036.fdocuments.in/reader036/viewer/2022070403/568139f9550346895da1ba30/html5/thumbnails/18.jpg)
•Telophase:New nuclear membranes form around new nuclei
Mitosis Movie
![Page 19: Ch. 8: The Cell Cycle](https://reader036.fdocuments.in/reader036/viewer/2022070403/568139f9550346895da1ba30/html5/thumbnails/19.jpg)
CYTOKINESIS – Cytoplasm splits into 2 cells.Animal cells: Cleavage furrow forms from outside in.
Plant cells: Division/cell plate forms from inside out.
![Page 20: Ch. 8: The Cell Cycle](https://reader036.fdocuments.in/reader036/viewer/2022070403/568139f9550346895da1ba30/html5/thumbnails/20.jpg)
Cell now returns to interphase . The chromosomes uncoil back into chromatin. The whole cell cycle starts over again…..
http://www.cellsalive.com/mitosis.htm
![Page 21: Ch. 8: The Cell Cycle](https://reader036.fdocuments.in/reader036/viewer/2022070403/568139f9550346895da1ba30/html5/thumbnails/21.jpg)
At any point in time the cells in a tissue will be at different stages in the cell cycle.
![Page 22: Ch. 8: The Cell Cycle](https://reader036.fdocuments.in/reader036/viewer/2022070403/568139f9550346895da1ba30/html5/thumbnails/22.jpg)
![Page 23: Ch. 8: The Cell Cycle](https://reader036.fdocuments.in/reader036/viewer/2022070403/568139f9550346895da1ba30/html5/thumbnails/23.jpg)
Mitosis Stages
Put these in the correct order..
![Page 24: Ch. 8: The Cell Cycle](https://reader036.fdocuments.in/reader036/viewer/2022070403/568139f9550346895da1ba30/html5/thumbnails/24.jpg)
The Guarantee of Mitosis…The 2 daughter cells formed are identical to each other and identical to the mother cell. Why is this so important?
![Page 25: Ch. 8: The Cell Cycle](https://reader036.fdocuments.in/reader036/viewer/2022070403/568139f9550346895da1ba30/html5/thumbnails/25.jpg)
Mitosis
![Page 26: Ch. 8: The Cell Cycle](https://reader036.fdocuments.in/reader036/viewer/2022070403/568139f9550346895da1ba30/html5/thumbnails/26.jpg)
Whitefish Blastula
![Page 27: Ch. 8: The Cell Cycle](https://reader036.fdocuments.in/reader036/viewer/2022070403/568139f9550346895da1ba30/html5/thumbnails/27.jpg)
Mitosis in Plant Cells
![Page 28: Ch. 8: The Cell Cycle](https://reader036.fdocuments.in/reader036/viewer/2022070403/568139f9550346895da1ba30/html5/thumbnails/28.jpg)
Onion Root Tip
![Page 29: Ch. 8: The Cell Cycle](https://reader036.fdocuments.in/reader036/viewer/2022070403/568139f9550346895da1ba30/html5/thumbnails/29.jpg)
Ch. 8: The Cell Cycle
![Page 30: Ch. 8: The Cell Cycle](https://reader036.fdocuments.in/reader036/viewer/2022070403/568139f9550346895da1ba30/html5/thumbnails/30.jpg)
Mitosis
![Page 31: Ch. 8: The Cell Cycle](https://reader036.fdocuments.in/reader036/viewer/2022070403/568139f9550346895da1ba30/html5/thumbnails/31.jpg)
Whitefish Blastula
![Page 32: Ch. 8: The Cell Cycle](https://reader036.fdocuments.in/reader036/viewer/2022070403/568139f9550346895da1ba30/html5/thumbnails/32.jpg)
Mitosis in Plant Cells
![Page 33: Ch. 8: The Cell Cycle](https://reader036.fdocuments.in/reader036/viewer/2022070403/568139f9550346895da1ba30/html5/thumbnails/33.jpg)
Onion Root Tip
![Page 34: Ch. 8: The Cell Cycle](https://reader036.fdocuments.in/reader036/viewer/2022070403/568139f9550346895da1ba30/html5/thumbnails/34.jpg)
Controls on the Cell Cycle:1. Cell Type: Some cells stop dividing
when mature (stay in G0) Ex: neurons & muscle cells2.Growth factors – protein that stimulates cell division3.Density-dependent inhibition (cell to cell contact) Cells stop growing when they touch other cells4.Anchorage (cells may required contact with a surface for cell division)
![Page 35: Ch. 8: The Cell Cycle](https://reader036.fdocuments.in/reader036/viewer/2022070403/568139f9550346895da1ba30/html5/thumbnails/35.jpg)
Cell Cycle Regulators:Intracellular factors:
1. Checkpoints & Cyclins: All chromosomes are replicated? All spindles are attached? Are there enough mitochondria, etc.. If cells “pass” these checkpoints, the next stage of cell cycle begins.
Cyclins = that start/stop cell cycle progression based on checkpoints
Extra-cellular factors: - Binding of growth factors- Cell to cell contact
![Page 36: Ch. 8: The Cell Cycle](https://reader036.fdocuments.in/reader036/viewer/2022070403/568139f9550346895da1ba30/html5/thumbnails/36.jpg)
Cell Cycle Regulators: Cyclins operate at
checkpoints
![Page 37: Ch. 8: The Cell Cycle](https://reader036.fdocuments.in/reader036/viewer/2022070403/568139f9550346895da1ba30/html5/thumbnails/37.jpg)
Cell Cycle Controls: External to Cell
![Page 38: Ch. 8: The Cell Cycle](https://reader036.fdocuments.in/reader036/viewer/2022070403/568139f9550346895da1ba30/html5/thumbnails/38.jpg)
Growing Out of Control: Cancer
• Cancer is a disease of the cell cycle• Cells do not respond normally to controls of the
cell cycle system• Tumor: abnormally growing mass of body
cells– Benign: abnormal cells remain at original sight
forming a lump; although can cause problems, normally can be fully removed by surgery
– Malignant: “cancerous” spread, displacing normal tissue and disrupting organ function
– Metastasis: spread of cancer cells via circulatory system transport (traveling cancer cells)
http://www.cancer.gov/cancertopics/understandingcancer/cancer/page2
![Page 39: Ch. 8: The Cell Cycle](https://reader036.fdocuments.in/reader036/viewer/2022070403/568139f9550346895da1ba30/html5/thumbnails/39.jpg)
Molecular Basis of Cancer:
• Tumor Suppressor Genes: - genes that normally halt the cell cycle
- problem if stuck “OFF” (cells keep dividing)
• Oncogenes: - genes that tell cells to divide
- problem if stuck “ON” (cells keep dividing)
![Page 40: Ch. 8: The Cell Cycle](https://reader036.fdocuments.in/reader036/viewer/2022070403/568139f9550346895da1ba30/html5/thumbnails/40.jpg)
Cancer categorized based on site of origin: (Not on
quiz)• Carcinoma: originate in internal or external
coverings of the body (skin or lining of intestine)
• Sarcoma: Arise in support tissue (bone or muscle)
• Leukemia: Arise in blood or bone marrow (abnormal number of white blood cells)
• Lymphoma: Arise in lymphatic cells of the immune system (lymph nodes or spleen)
![Page 41: Ch. 8: The Cell Cycle](https://reader036.fdocuments.in/reader036/viewer/2022070403/568139f9550346895da1ba30/html5/thumbnails/41.jpg)
Treating Cancer• Surgical removal of tumor
• Radiation: – Damages DNA in cancer cells more than normal
cell– Cancer cells do not have the ability to repair– Cancer cells die without dividing/reproducing
• Chemotherapy: (For widespread or metastatic tumors) – Chemicals that disrupt specific steps in the cell
cycle• freezes the mitotic spindle• prevents formation of spindle• Damage DNA or RNA involved in making growth factors
![Page 42: Ch. 8: The Cell Cycle](https://reader036.fdocuments.in/reader036/viewer/2022070403/568139f9550346895da1ba30/html5/thumbnails/42.jpg)
Controls on the Cell Cycle:
Some cells stop dividing when mature (stay in G0)
ex) many neurons (nerve) & muscle cells Others divide for growth & repair Influences of cell division:
Growth factors – protein that stimulates cell division Density-dependent inhibition (cell to cell contact)
![Page 43: Ch. 8: The Cell Cycle](https://reader036.fdocuments.in/reader036/viewer/2022070403/568139f9550346895da1ba30/html5/thumbnails/43.jpg)
Cell Cycle Regulators:• Proteins called cyclins start/stop the
cell cycle.• The cycle is regulate by various factors:
1. Intracellular factors (Checkpoints)- All chromosomes are replicated- All spindles are attached
2. Extra-cellular factors: - Binding of growth factors- Cell to cell contact
![Page 44: Ch. 8: The Cell Cycle](https://reader036.fdocuments.in/reader036/viewer/2022070403/568139f9550346895da1ba30/html5/thumbnails/44.jpg)
Growing Out of Control: Cancer
• a disease of the cell cycle• Cells do not respond normally to controls of the
cell cycle system• Tumor: abnormally growing mass of body
cells– Benign: abnormal cells remain at original sight
forming a lump; although can cause problems, normally can be fully removed by surgery
– Malignant: spread, displacing normal tissue and disrupting organ function
– Metastasis: spread of cancer cells via circulatory system transport
See slide show http://www.cancer.gov/cancertopics/understandingcancer/cancer/page2
![Page 45: Ch. 8: The Cell Cycle](https://reader036.fdocuments.in/reader036/viewer/2022070403/568139f9550346895da1ba30/html5/thumbnails/45.jpg)
Molecular Basis of Cancer:
• Tumor Suppressor Genes: - genes that normally halt the cell cycle
- problem if stuck “OFF” (cells keep dividing)
• Oncogenes: - genes that tell cells to divide
- problem if stuck “ON” (cells keep dividing)
![Page 46: Ch. 8: The Cell Cycle](https://reader036.fdocuments.in/reader036/viewer/2022070403/568139f9550346895da1ba30/html5/thumbnails/46.jpg)
Treating Cancer• Surgical removal of tumor
• Radiation: – Damages DNA in cancer cells more than normal
cell– Cancer cells do not have the ability to repair– Cancer cells die without dividing/reproducing
• Chemotherapy: (For widespread or metastatic tumors) – Chemicals that disrupt specific steps in the cell
cycle• freezes the mitotic spindle• prevents formation of spindle• Damage DNA or RNA involved in making growth factors