Transcript APPLYING MENDEL`S PRINCIPLES

APPLYING MENDEL’S PRINCIPLES
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It took 20 yrs. After his death for his work to be recognized.
GENES AND PROBABILITY
Probability: The likelihood that a particular event will occur
The # of times a particular event occurs
The # of opportunities for the event to occur (# of trials)
Examples: The flipping of a coin or tossing of a die
Couple of important rules/considerations:
You only get expected ratio w/large a number of trials
The previous events don’t affect future outcomes
So, when doing pea plants you need a large number of plants.
PUNNETT SQUARES
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Handy for analyzing results of experimental crosses
ONE-FACTOR CROSS
Test Cross: Cross of unknown genotype w/homozygous
recessive. In pea plants (T) is dominant and (t) is recessive.
If any offspring shows the recessive phenotype, then the
unknown parent must be heterozygous.
TWO-FACTOR CROSS
(G) green are dominant over (g) yellow pods
(N) smooth are dominant over (n) constricted pods
So, when a heterozygous (GgNn) is crossed with a (ggnn)
what happens?
GENOTYPE RATIO- 4:4:4:4 = 1:1:1:1
PHENOTYPE RATIO- 4:4:4:4 = 1:1:1:1