11-1 Gregor Mendel What he did

Genetics Genetics = the scientific study of heredity Mendel understood the basic idea of fertilization = when the male and female reproductive cells join to make new cells, and grow to become new organisms.

Who is Gregor Mendel? Known as the “Father of Genetics” Worked with pea plants Looked at traits and how they are passed on

Genes and dominance Trait = a specific characteristic (tall, short, green, yellow) Hybrid = having parents with different traits Genes = The chemical factors that determine traits, found in DNA Allele = The different forms of a gene Being tall or short

What Mendel Did Mendel started with two pure strain plants (he knew exact parent traits) Mendel crossed two plants with pure opposite traits, one pure tall plant with one pure short plant Only one of the traits appeared in the next generation, all the offspring were tall Mendel called this the F1 generation

Mendel concluded that Tall is the dominant allele Short is the recessive allele Dominant trait is the trait that is seen Recessive trait is the trait that is not seen (hidden)

Law of Dominance States that some alleles are dominant and others are recessive

Explaining the F1 Cross During gamete formation, alleles segregate from each other so each gamete carries only a single copy of each gene Gamete = sex cell Segregation = separation of the alleles

Genetics and Probability 11-2 Probability is the likelihood of a particular event happening Flipping a coin – what is the chance of getting a head? Tail? Probability can be used to predict the outcomes of genetic crosses

Punnett Squares Punnett Square = a diagram used to show the gene combinations that might result from a genetic cross

Tall (TT) x Short (tt)

Tall (TT) x Short (tt)

Tall (TT) x Short (tt)

Homozygous = when an organism has two identical genes Example TT or tt Heterozygous = having two different genes Example Tt Phenotype = physical characteristics; what is seen Example = tall or short Genotype = the genetic make up; what the genes are Example = TT, tt and Tt

Probability Predicts Averages Probabilities predict the average outcome of a large number of events Probability cannot predict the precise or actual outcomes