Introduction to Genetics Objectives: 6F - predict possible outcomes of various genetic combinations such as monohybrid crosses, dihybrid crosses and non-Mendelian inheritance 6D - recognize that gene expression is a regulated process  Genetics = the study of heredity

Gregor Mendel The Father of Genetics carried out important studies of heredity Heredity—the passing on of traits from parents to offspring Born in 1822 Austrian monk Used garden peas in his experiments

Trait- a specific characteristic that is controlled by genes Exp. Eye color, hair color, height

Sections of DNA that control your traits Chromosomes Tightly coiled DNA where your genes are carried Genes Sections of DNA that control your traits The original parents, the true-breeding plants, are known as the P1 generation. The offspring of the parent plants are known as the F1 generation. When you cross two F1 plants with each other, their offspring are the F2 generation.

Homologous Chromosomes Chromosomes that are the same size and shape and carry the same genes. You get one from your mother and one from your father that match up. P1 Short pea plant Tall pea plant F1 An organism’s two alleles are located on different copies of a chromosome—one inherited from the female parent and one from the male parent. All tall pea plants F2 3 tall: 1 short

The different forms a gene can take. (Letters) Alleles The different forms a gene can take. (Letters) 2 Types of Alleles: 1. Dominant - Represented by a capital letter (Exp. A) 2. Recessive - Represented by a lower-case letter (Exp. a) When recording the results of crosses, it is customary to use the same letter for different alleles of the same gene. An uppercase letter is used for the dominant allele and a lowercase letter for the recessive allele. The dominant allele is always written first.

Genotype The combination of two alleles (letters) that represent the genetic make-up of an individual. (AA, Aa, aa) Phenotype The observable physical characteristic of an individual that are the result of its genotype. (Long eyelashes, Blue or Brown eyes)

3 Types of Genotypes: 1. Homozygous Dominant 2. Heterozygous 2 identical alleles that are capitalized (AA, TT) 2. Heterozygous 2 different alleles (Aa, Tt) 3. Homozygous Recessive 2 identical alleles that are lower-case (aa, tt)

Principle of Dominance An organism with a recessive allele for a particular trait will exhibit that form only when the dominant allele for the trait is not present. Organisms with a heterozygous genotype (Aa) will never exhibit the recessive trait because it is hidden (masked) by a dominant allele. Punnett Squares: Are used to predict and compare the genetic variations that will result from a cross. The types of gametes go on the top and left sides of the square The possible gene combinations appear in the four boxes If you know the genotypes of the parents, you can use a Punnett square to predict the possible genotypes of their offspring.

You try this one: A a

Etymology Homozygous: homo- (same) + -zygous (joined) Heterozygous: hetero- (other) + -zygous (joined)

Question 1 The passing on of characteristics from parents to offspring is __________. A. genetics B. heredity C. pollination D. allelic frequency Section 1 Check

Question 2 Answer What are traits? A specific characteristic that is controlled by genes. Height, hair color and eye color are examples of traits in humans. Section 1 Check

Question 3 Gametes are __________. A. male sex cells B. female sex cells C. both male and female sex cells D. fertilized cells that develop into adult organisms Section 1 Check

Question 4 Which of the following genotypes represents a animal that is homozygous dominant for a trait? a. KK b. Kk c. kk Section 1 Check

Question 5 Which of the following genotypes represents a plant that is homozygous recessive for height? A. TT B. Tt C. tt Section 1 Check