Sheet 10-Test 4 Flashcards
How did Hammerling show that heredity information is probably stored in the nucleus?
- -Used Acetobularia (unicellular marine algae; grows up to 5cm)
- one cell differentiated into foot, stalk and cap
- -could regenerate parts of nucleus was present
- -nucleus determines cap shape
.How did Briggs, King, and Gurdon prove that hereditary information is stored in the nucleus?
.–removed nucleus from frog egg; no development until a nucleus from an embryo was added
– gurdon transplanted nuclei from tadpole cells
How did steward prove that (nearly) every cell in a plant is totipotent?
–threw carrots in a blender
–every cell gave rise to new individual
toti poten– each cell has full set of hereditary instructions; can generate adult individual
how did Ian Wilmut clone a sheep and what did cloning a sheep teach us about animal cells?
- -close is genetically idnetical to DNA donor (dolly is the name of the clone)
- Dolly was the first sucessful clone from a differentiated animal cell
Cloning Sheep showed that:
transplanted nucleus could direct the developent of a new individual (totipotent)
*paper
what are some practical problems and what are some ethical problems created by cloning humans?
Pratical
1) susceptibility to disease
2) low success rate
3) clone as old as donor of DNA
Ethica:
1) bad for child
2) low success rate
3) slows evoultionc
what are some alternatives to cloning humans for organ transplants?
Therapeutic Cloning– use DNA of patient needing transplant to produce stem cells in an embryo
- -stem cells used to produce organ
- less liklihood of rejection
what are stem cells, and why are they useful
Stem cells are undifferentiated, yet continue to divde (havent been told their job yet)
–cells can be isolated from cell mass of blastocyst ad gown in culture as embyronic stem cells
- -stem cells may be:
1) totipotent- can become any cell type
2) pluripotent- can become multiple different cell types ex. bone marrow cells
what is genetic transformation
.a change in the genome of an indivdual
ex. making E. coli ampicillin resistant + able to glow green
how did griffith discover genetic transformation
mouse injected with non pathogen: lives
mouse injected with virulent bacterium: dies
mouse injectd with dead pathogenic bacerteria: lives
mouse injected with dead virulent and live non pathogenic: dies
pathogen is streptococcus pneumoniae virulent strain has polysaccharied coat
- -virulent bacteria were recovered
- -live bacteria had been transformed
- -genetic information specifying polysaccharide coat had been passed from dead bacteria to living bacteria
- -howeveer, griffith didnt know wht had transformed cells
why did Avery, MacLeod, and McCarty conclude that DNA is the transforming principle?
digested extract of dead coated bacteria with DNA ase, RNA ase, or protease
–activity was affected by DNA ase, not RNA ase or protease
–concluded DNA is transforming principle (hereditary material)
why did very few people believe in them
didnt provide a mechanism, believed protein was hereitary material
why did Hershey and chase decide that DNA is the hereditary material in T2 bacteriophage?
–used bacteriophase: T2
–bacteriophage is a virus that infects bacteria
t–they labeled viral DNA with radioactive phosphorus
–they labeled viral protein with readioacctive sulfur
–know that viruses inject genetic material into has cell
found infected cell contained 32^P
SO: DNA stores hereditary material
what is the primary structure of DNA?
Ladder
why do we say that nucleic acids run 5’ to 3’
any strand of DNA (or RNA) will have a free 5’ phosphase group at one end and a free 3- hydroxy group at the other end
-* write base sequences 5’ to 3’
5’ Aug 3’
what are chargaffs rules
Amount of A = Amount of T
Amount of C= G
