Transcript Introduction to probability

Genetics and probability
Science of Heredity
Heredity
Chemical instructions passed from parent
to offspring at fertilization (one time only)
Chemical instructions are chromosomes,
genes, and DNA
Genotype
Phenotype
Observable traits
Variation (differences)
among species members
Sexual reproduction, Gene Recombination,
Crossing over, etc.
Genotypes
A gene picture for a trait
Alphabet used to symbolize gene picture
Examples
Dominant gene is symbolized in upper case
most abundant variation in a population
• RR – dominant trait shown
Recessive gene is symbolized in lower case
Can be hidden if with a dominant gene
• rr – recessive trait shown
Phenotypes
The physical appearance for a trait
What is visible
Examples - Mendel’s Peas
Dominant gene is a smooth pea
most abundant variation in a population
Recessive gene is a wrinkled pea
Can be hidden if with a dominant gene
Probability: The science of chance
Not an exact science, but will predict the
chances that an event may or should
occur
Expressed as a fraction: ½, ¾, etc.
Read as 1 chance out of 2 chances
Probability Laws
 Probability Law #1
The more data that is observed means that the percent
deviation will get smaller and the validity or reliability of
the data will get better
 Probablity Law #2
The results of one trial of a chance event does not affect
the results of later trials of the same event
 Probablity Law #3
The chance that two independent events will occur
together is the multiplication product of their chances of
occurring separately