chapter 11 Flashcards
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adult stem cells
undifferentiated cells found in tissues or organs that can give rise to a limited number of cells (ex: brain, bone marrow, blood, blood vessels, skeletal muscle,skin, liver)
some of these cells have been induced to grow into other types of tissues and organs (multipotent) - cells are prepared to become different kinds of cells
problems with adult stem cells
- more difficult to obtain and grow in culture than embryonic stem cells
- do not tend to survive as long as embryonic stem cells (don’t continue to reproduce for as many generations as embryonic stem cells)
advantages of adult stem cells
- few ethical issues
- the person’s body will not tend to reject new the tissue, if the orginal tissue came from his or her body (whereas people will often reject things that come from different people)
amniotic epithelial cells
some stem cells extracted from the placenta are called amniotic epithlial cells
thought to retain the ability of form any type of cell (pluripotent)
Have been used to make artificial heart valves, working tracheas, as well as muscle, fat, bone, heart, neural and liver cells
advantages of amniotic epithelial cells
- since the placenta is commonly discarded after birth, they could be an easy source of non-controversial stem cells
- pluripotent
- few ethical concerns
problems of amniotic epithelial cells
may not be as potent as embryonic cells
cloning
stimulating one cell to replicate and differentiate into a whole multicellular organism, identical to the orginal organism
Dolly
the first animal that was cloned - sheep
ethical concerns with cloning
- many attempts before it worked in sheep and other animals
- many attempts produce deformed organisms
- health of clone? Dolly died prematurely
cancer
considered a genetic disease because it results from changes in the DNA; these changes are caused by mutations (base substitutions and deletions; mutations caused by chemicals, radiation, and sometimes viruses)
cancer as a genetic disease
these changes occur only in the genes that reulate cell division and cell growth (not just any genes)
genes that ____ may experiences changes
- stimulate cell division - turn on cell division (proto-oncogene)
- suppress cell division - turn off cell division (tumor suppressor genes)
proto-oncogenes
normal and necessary genes that regulate cell division and cell growth; “on” switches; these are good and necessary genes because they keep up going and continue replications… they are our friends
oncogene
proto-oncogenes that have had a mutation in some part of their DNA causing them to always be turned “on”
stimulating the cell which means it keeps dividing; these are not good
tumor suppressor genes
regulatorygenes that normally turn “off” cell division; “off” swithces; mutations in their gene sequences can make them code for nonfunctional proteins; 3d shape is incorrect so they don’t signal the cell to stop dividing
cancer cell development
multiple mutations needed to change a normal cell to a malignant cell - cancer cell (usually 3-4 changes in the DNA of a cell will cause it, on and off switches) - one oncogene activated and three tumor suppressor genes must be inactivated
what causes multiple mutations
cancer cells divide very rapidly and sometimes pass (or skips)checkpoints that are looking for errors in DNA replication (gap 1 and gap 2 during interphase are in charging of checking DNA to make sure nothing got messed up)
cancer prevalence as a result of age
the rate of cancer deaths clibs steeply after 40 an even more after 60 because the older a person gets, the more they have been exposed to agents that can cause mutatinos (more opportunities for changes to occur in DNA) and becuase immune systems becomes less effective with age
carcinogens
agents that cause cancer
mutagens
cause mutations; most mutagens are carcinogens
