Gregor Mendel = Father of Genetics Studied Pea Plants and determined the Laws of Modern Genetics To understand the Laws remember that humans are diploid (2n) organisms that make haploid (1n) gametes (sex cells) Diploid = 2 of each type of chromosome Humans have 46 total chromosome or 23 pairs Haploid = 1 of each type of chromosomes Sperm and egg only have 23 individual chromosome

Mendel’s Results Law of Segregation- the 46 chromosomes separate during the formation of egg & sperm (Meiosis) putting only 23 chromosomes into each gamete Law of Independent Assortment- different characteristics (genes) are distributed to the egg and sperm randomly Recessive & Dominant Traits Dominant- the factor that dominates/ masks the other Represented by a Capital Letter Recessive- the factor that is masked Represented by a lowercase letter

Genetic Crosses - predicting the probable genetic make-up of offspring - interpret information to determine the appearance of offspring Genotype- genetic make-up, type of genes Phenotype- physical appearance, what the organism looks like Ex Brown Eyes - Dominant Blue Eyes - Recessive BB bb P1 Genotype- Bb F1 Phenotype- Brown eyes

Homozygous- both alleles of a pair are the same for a characteristic Homozygous- both alleles of a pair are the same for a characteristic BB – Dominant bb – Recessive Heterozygous- alleles are not the same: Bb Make predictions using a Punnett Square

Modes of inheritance Codominance ( THINK COW!!!) Incomplete dominance Heterozygous genotype that equally expresses the traits from both alleles Ex. Red flower(RR) x White flower(rr) = Rr red AND white flower Incomplete dominance Heterozygous phenotype that is a blend of the two homozygous phenotypes Ex. Red flower (RR) x White flower(rr) = Rr pink flower

Multiple alleles When there are three or more forms of a gene for a trait. That doesn't mean that a person can have all three of them. The person still only gets two ... it's just that there are three or more of the alleles in the gene pool that are available. Examples: Blood types (A, B and O) and Eye color

XAXa x XaY Sex-linked inheritance Polygenic inheritance Sex linked inheritance involves genes located on either the X or the Y chromosome XAXa x XaY Polygenic inheritance When a single trait is controlled by many alleles (2 or more sets of alleles.) Most human traits are polygenically inherited. Examples would be skin and eye color

What organism did Gregor Mendel work with that helped him to formulate his Laws of Genetics? A. Fruitflies B. Rats C. Pea plants D. Bacteria

Solve this Monohybrid In mice, black fur is dominant over brown fur. A heterozygous black mouse mates with a brown mouse. What percentage of the offspring will be brown? A. 0% B. 25% C. 50% D. 100%

Sex-Linked Example Colorblindness is a recessive, sex-linked trait located on the X chromosome. Gaspar is a colorblind man, and his wife Stephanie is a carrier for colorblindness. If they have a male child, what is the probability that their son will be colorblind? A. 0% B. 25% C. 50% D. 100%

Four major blood phenotypes (A, B, AB, and O) are determined by three alleles: A, B, and O. A person with type A has a certain protein on their blood cells' membranes. A person with type B has a different protein appearing on their cells' membranes. Cells from type AB have both proteins, but cells from type O, which is recessive, has neither protein. This example illustrates which of the following phenomena? A. codominance B. complete dominance C. partial dominance D. polygenic inheritance

Blood Type is controlled by 3 alleles: A, B, O Blood Type is controlled by 3 alleles: A, B, O. A & B are codominant, O is recessive. Solve the following: A woman with type A blood (genotype AO) is married to a type B person (genotype BO). What proportion of their children will have: A blood? _______ B blood? ______ O blood _____ AB blood ________

If a red snapdragon flower is crossed with a white snapdragon flower and the offspring are pink, explain how this happened. A. codominance B. complete dominance C. incomplete dominance D. polygenic inheritance

A man has six fingers on each hand and six toes on each foot A man has six fingers on each hand and six toes on each foot. His wife and their daughter have the normal number of digits (5). Extra digits is a dominant trait. What fraction of this couple's children would be expected to have extra digits?

The genotype of F1 individuals in a tetrahybrid cross is AaBbCcDd The genotype of F1 individuals in a tetrahybrid cross is AaBbCcDd. Assuming independent assortment of these four genes, what are the probabilities that F2 offspring would have the following genotypes? aabbccdd AaBbCcDd AABBCCDD AaBBccDd AaBBCCdd

The pedigree below traces the inheritance of a vary rare biochemical disorder in humans. Affected individuals are indicated by filled-in circles and squares. Is the allele for this disorder dominant or recessive? What genotypes are possible for the individuals marked 1, 2, and 3.