Genetics
What is Genetics? The study of heredity Heredity: passing of traits from parent to offspring
Study of Genetics Children inherit traits Need to study many generations
Genes Section of DNA on chromosomes Carry instructions to make living things Paired: 1 from mom & 1 from dad
Gregor Mendel (1857) “Father of Genetics” Discovered patterns of inheritance by breeding pea plants
Flower Anatomy
What We Know Different forms of a gene are alleles Represented by letters Ex. flower color alleles P (purple) or p (white)
Alleles Capital letter = dominant allele Ex. P (purple) Lower case = recessive allele Ex. p (white)
Important Vocabulary Genotype = alleles (letters) that make up that trait Ex. PP Phenotype = physical appearance of trait Ex. Purple
Important Vocabulary (Cont.) Homozygous: two of the same alleles Ex. PP or pp Heterozygous: two different alleles (Aka Hybrid) Ex. Pp
Inheritance Of Traits If you inherit one dominant allele the recessive allele will not be expressed
Predicting Our Traits Punnett squares show possible genotypes
Setting up a Punnett Square Alleles from Father g Alleles from Mother g G = Green g = White
Interpreting Punnett Squares Gg Offspring
Interpreting Punnett Squares (Cont.) Offspring are: 100 % Heterozygous Their genotypes are Gg Their phenotype are green
Probability Measure of how likely something will occur Ex. What is the probability of getting heads when you flip a coin? Ans. 50%
Probability (cont.) What is the probability of flipping a coin and getting heads 3 times in a row? ½ x ½ x ½ = 1/8
Incomplete Dominance Dominant & recessive traits appear to "blend" Ex. snapdragon flowers red x white = pink RR rr Rr
Codominance Two traits are both fully seen Ex. Roan Horses have both red & white hairs
Codominance Black (B) White (W) BB = Black WW = White BW = Spotted
Multiple Alleles Two or more alleles control the phenotype Ex. Human ABO blood groups
Polygenic Traits Traits that are controlled by multiple genes Ex. height, weight, hair color, skin color
Sex-Linked Traits Carried on sex chromosomes Most are recessive & on X chromosome Color blindness, hemophilia
Sex-Linked Traits (cont.) Affect men more than women Men have only one X chromosome Women can be carriers or affected