1 Mendelian Genetics

2 Gregor Mendel The Father of Genetics

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Gene A gene is a discrete unit of heredity, which transmits a set of specifications from one generation to the next; consisting of a specific nucleotide sequence in DNA (or RNA in some viruses) that codes for a specific product Ex: a gene for blood typ e. 4

5 Alleles Different or alternate forms or expressions of the same gene. Example: Blood type A, B, and O. Tall or short. Round seed or smooth seed. Every trait has 2 alleles one from each parent The location of an allele on a chromosome is known as the locus (loci)

6 Genotype The letters that represent the trait being investigated. Examples: Bb, BB, bb

7 Phenotype The actual representation of the genes as a physical trait. Examples: brown eyes, blond hair, freckles

8 Dominant allele An allele that is fully expressed in the phenotype of a heterozygous organism. Represented by capital letters.

9 Recessive allele An allele that is not fully expressed in the phenotype of a heterozygous organism. Represented by lower case letters.

10 Homozygous When both genes (letters) are the same. BB = Homozygous Dominant bb = Homozygous recessive

11 Heterozygous Having two different alleles for a given gene. One upper case letter and one that is lower case. Bb = Heterozygous

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Hybrid Another name for individuals that are heterozygous for a trait. 13

14 Example Problem Round = R wrinkled = r If a plant has round seeds, do we know what its genotype is? It could be RR or Rr If a plant has wrinkled seed, do we know what its genotype is? Yes, it is rr.

15 Punnett Square A method for finding predicted outcomes and probabilities for offspring from any cross. A chart for predicting the traits of offspring.

Example Problem 16 b b Bb Bb bbBb bb B = Brown b = blue