(on slides from How Gene’s Work) He took two strains of Streptococcus (which causes pneumonia in mammals) and had 2 strains. R (harmless, nonpathogenic) and S (pathogenic).
First, starts with injecting living S cells that have a protective capsule, the mouse dies because capsule protects the S strain from the mouse’s defenses. It is pathogenic.
Then, injects living R cells with no protective capsule. Mouse lives because mouse’s defenses aren’t stopped by a capsule.
Next, he injected heat killed S cells which are harmless so mouse lives.
Finally, he mixes heat-killed S cells with living R cells that don’t have a protective capsule and the mouse dies because the mixture becomes pathogenic.
When he took a blood sample from the mixture of the heat killed S cells and living R cells, living S sells are found.
Why do DNA base-pairing rules explain Chargaff’s Rule? (How Gene’s Work)
Chargaff’s Rule stats A and T always go together and C and G always go together. The width of the pairings has to be 2 nm wide. If A & G (2 purines) are paired together they are too wide. If C and T (2 pyrimidines) are paired together they are too narrow. The perfect length when pairs is A-T and C-G.
Explain the Central Dogma of biology, (You may use an arrow diagram to help illustrate your answer). (How Gene’s Work)
DNA RNA Protein. You can’t get protein without first going through RNA.
What is the difference between an organism’s genotype and its phenotype? (How Gene’s Work)
The genotype is determined by the sequence of bases in the DNA and the phenotype is determined by the resulting proteins produced.
Explain “redundancy” and “ambiguity” as these terms relate to the genetic code. (How Gene’s Work)
Describe Modern Synthesis (Microevolution)
Apply Mendelian genetics to Darwinian evolution. (early 1940’s: Theodorus Dobzhansky, Ernst Mary, George Gaykird Simpson, G. Ledyard Stebbins were key architects. It emphasized the importance of populations as the units of evolution
Populations evolve—individuals DO NOT evolve
Central role of natural selection as the mechanism of evolution
Gradualism-accumulation of many small changes to larger changes
No paradigm remains unchallenged: modern synthesis is constantly being questioned, tested, refine
What does the Hardy-Weinberg Principle state? (Microevolution) a theorem to describe allele and genotype frequencies in sexually reproducing non-evolving populations.
Hardy-Weinberg Principle: frequencies of alleles and genotypes in a population remain constant over generations unless acted on by agents other than sexual recombination
Considered not simply alleles of parental pairs, but of entire populationgene pool
Describes a non-evolving population and provides a method for:
Calculating allele frequencies in a population
Calculating genotype frequencies in a population
List the assumptions of the Hardy-Weinberg Principle. (Microevolution)
Very large population
No natural selection
No gene flow (isolated from other populations (no migrations)
No genetic drift (random changes in allele frequencies due to chance events
What is the difference between microevolution and macroevolution?
Compare a bottle-necking event and a founder event. (Microevolution)
Bottle Neck Effect: event that reduces population size dramatically and unselectively no particular genotype has a better chance than any other of surviving the bottlenecking event-which genotypes survive is due to random change
Genetic makeup of survivors is unlikely to be representative of the original population’s genetic variability
Decrease genetic variation among survivors
Fixed genes are common
Example: bottle with white, blue, green, yellow, and red marbles. Bottle necking event happens and only blue and 1 white marble survive.
Examples of species: Cheetah (twice, 10,000ybp and early