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All organisms, including humans, have the ability to regenerate something in the body. Cells must divide and specialize to replace a lost limb. Chapter 10 Mystery. How many cells are in a typical adult human?.
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All organisms, including humans, have the ability to regenerate something in the body. Cells must divide and specialize to replace a lost limb. Chapter 10 Mystery
How many cells are in a typical adult human? • What process makes those cells different or unique (special) from one another? 2 terms
Why do cells divide? • The nucleus is not big enough to control a bigger cell. • The cell membrane’s surface area is not large enough to get food and expel waste for a bigger cell • growth • repair/replacement of injured or worn-out parts SURFACE-TO-VOLUME RATIO - Do the quick lab on page 275.
cell division liver cell undergoing cell division splits into two daughter cells
What very important step must occur prior to cell division? • cell replicates, or copies, all of its DNA so that each daughter cell will get one complete set of genetic information
http://www.ncbi.nlm.nih.gov/science96/ http://www.ncbi.nlm.nih.gov/projects/genome/genemap99/
chromosome number • species specific • fruit flies - 8 • human cells - 46 • carrot cells - 18
cell division • when a cell forms 2 “daughter” cells
essay question • How do all cells get a copy of the genetic code?
Mitosis vs. Meiosis http://www.pbs.org/wgbh/nova/miracle/divide.html
asexual reproduction • In 1-celled organisms, cell division is also reproduction called binary fission.
sexual reproduction • fertilization • pollination
Why can bacterial infections spread so rapidly? • genetically identical offspring are made by cell division • one parent
slower able to adapt in a changing environment genetically unique offspring two parents must find one another to mate • faster • take full advantage of a good environment • genetically identical offspring • only one parent
chromosomes are neat packages of DNA that make it easier to divide up
bacterial chromosomes and plasmids Plasmids carry between 2 and 30 genes. Some seem to have the ability to move in and out of the bacterial chromosome.
Describe the life cycle of a typical cell. What are the phases of the cycle, and what is happening in each phase? What happens when the cell cycle is out of control?
The Cell Cycle
http://www.biology.arizona.edu/cell_bio/activities/cell_cycle/cell_cycle.htmlhttp://www.biology.arizona.edu/cell_bio/activities/cell_cycle/cell_cycle.html
centrioles – centrosomeasters, polar fibers, kinetochore fibers
http://biog-101-104.bio.cornell.edu/biog101_104/tutorials/cell_division.htmlhttp://biog-101-104.bio.cornell.edu/biog101_104/tutorials/cell_division.html
Not all cells go through the cell cycle at the same rate. • heart cells – typically don’t divide • brain cells – typically don’t divide • bone marrow cells – divide rapidly
cyclins - proteins that regulate the cell cyclea protein that when injected into a non-dividing cell, would cause a mitotic spindle to form • internal regulators – respond to factors inside the cell • won’t begin mitosis until chromosomes replicate • won’t begin anaphase until chromosomes attached to spindle • external regulators – respond to factors outside the cell • growth factors - initiate cell division embryonic development and wound healing - stop cell division
contact inhibition • most cells grow and divide until they touch another cell • controls on cell growth and cell division can be turned on and off
apoptosis - programmed cell death two different reasons. • needed for proper development Examples: • The resorption of the tadpole tail • The formation of the fingers and toes of the fetus requires the removal of the tissue between them. • The sloughing off of the inner lining of the uterus at the start of menstruation • The formation of the proper connections between neurons in the brain 2. to destroy cells that represent a threat Examples: • Cells infected with viruses • Cells with DNA damage • Cancer cells
tumor - neoplasm • mass or growth of cells 1. benign • encapsulated • slow-growing • compacted (noninvasive) • seldom kill • malignant – cancerous • spreads to surrounding tissues and uses nutrients • prevents proper functioning
Explain how the DNA is your code. What does it code for? How does the code work? What happens if there is a mistake in the code?
What Is Cancer? • actually refers to many diseases • there are more than 100 types of diseases known collectively as cancer • overgrowth of cells • also known as malignancy • doctors who specialize in treating people with cancer are called oncologists
CARCINOGENS – GENERATE CANCER • tobacco, radiation exposure, and even viral infection mutagens – generate mutations Spit tobacco contains 28 known carcinogens. These include formaldehyde, arsenic, cyanide, nickel, and polonium-210.