Genetics History

The Lottery Directions: I am going to roll 6 dice…one at a time. In order, write the numbers you think I will roll.

What were the odds of you winning? Pretend these were the numbers you guessed. What are the odds the 1st number is 5? 2nd number is 2? 3rd number is 6? 4th number is 5? 5th number is 1? 6th number is 3? How do you calculate the overall odds? 1 6 1 6 1 6 1 6 1 6 1 6 X X X X X 1 46,656 = .00002%

What is Genetics? Genetics: Study of heredity Heredity: passing of traits from parent to child Gregor Mendel Austrian monk Uncovered pattern for how traits can be passed from generation to generation

Mendel’s 7 traits studied

Mendel’s Experiment P Generation: F1 Generation: Male: purple flowers Female: Purple flowers F1 Generation: 100% purple Learned? Traits are inherited from parents male female F1 Generation

Mendel’s Experiment P Generation: F1 Generation: Male: white flowers Female: white flowers F1 Generation: 100% white male female F1 Generation

Mendel’s Experiment P Generation: F1 Generation: Learned? Male: purple flowers Female: White flowers F1 Generation: 100% purple Learned? Some traits are dominant Some traits are recessive P Generation male female F1 Generation

Mendel’s Experiment F1 Generation: F2 Generation: Learned? Male: purple flowers Female: Purple flowers F2 Generation: 75% purple 25% white Learned? Offspring won’t always resemble the parents Traits can skip generations male female Remember… these had a white parent F2 Generation F1 Generation

Mendel’s 7 traits studied

Each trait had a 3:1 ratio. No way that can be a coincidence!

Chromosomes and Genes Genes are sections of DNA that create proteins: located on chromosomes inherited from parents come in dominant & recessive forms known as alleles Defined: Alternative form of a gene Ex: Flower color Purple allele (dominant) White (recessive) Letters used to abbreviate alleles Dominant Allele = Capital letter Recessive Allele = Lowercase letter

Common Vocabulary Genotype: genetic make-up of an organism (combination of two alleles) Homozygous Dominant (purebred): combination of 2 dominant alleles Gene for dominant purple flowers Gene for dominant purple flowers P P Homozygous dominant allele

Common Vocabulary p p Genotype: combination of two alleles Gene for recessive white flowers Gene for recessive white flowers Genotype: combination of two alleles Homozygous Dominant (purebred): combination of 2 dominant alleles Homozygous Recessive (purebred): combination of 2 recessive alleles p p Homozygous recessive allele

Common Vocabulary P p Genotype: combination of two alleles Gene for dominant purple flowers Gene for recessive white flowers Genotype: combination of two alleles Homozygous Dominant (purebred): combination of 2 dominant alleles Homozygous Recessive (purebred): combination of 2 recessive alleles Heterozygous (hybrid): Combination of 1 dominant, 1 recessive allele P p Heterozygous allele

pp Common Vocabulary PP Pp Genotype: combination of two alleles Homozygous Dominant (purebred): combination of 2 dominant alleles Homozygous Recessive (purebred): combination of 2 recessive alleles Heterozygous (hybrid): Combination of 1 dominant, 1 recessive allele Phenotype: Physical expression of the gene PP Phenotype: PURPLE Pp Phenotype: pp white

30 Seconds: Discuss with your neighbor: Choices: YY Tall Yy SS yY gg Smooth Green TT Dwarf Which choice(s) are examples genotypes?

30 Seconds: Discuss with your neighbor: Choices: YY Tall Yy SS yY gg Smooth Green TT Dwarf Which choice(s) are examples heterozygous genotypes?

30 Seconds: Discuss with your neighbor: Choices: YY Tall Yy SS yY gg Smooth Green TT Dwarf Which choice(s) are examples phenotypes?

30 Seconds: Discuss with your neighbor: Choices: YY Tall Yy SS yY gg Smooth Green TT Dwarf Which choice(s) are examples of hybrid genotypes ?

30 Seconds: Discuss with your neighbor: Choices: YY Tall Yy SS yY gg Smooth Green TT Dwarf Which choice(s) are examples of purebred genotypes?

Punnett Squares p p P P P P P P 100% p p p p Homozygous dominant Homozygous recessive Defined: Genetics tools used to predict offspring probability Setting Up Punnett Squares: 1) Parent genotypes on outside of the squares 2) Simply fill in each square 3) Inside squares represent the possible offspring genotypes Probability of growing purple flowers? p p P P P p P p P p P p 100%

P p P P P P p P p p p p 1) List the genotypes. 1 PP, 2Pp, 1pp 1 minute: Cross a heterozygous purple (Pp) plant with another heterozygous purple (Pp) plant P 1) List the genotypes. 2) List the phenotypes. 3) What is the probability of having a white plant? p 1 PP, 2Pp, 1pp P P P P p 3 purple, 1 white P p p p p 25%

Autosomal Recessive Inheritance Hh Hh Autosome: Non-sex chromosome Autosomal disorders are caused by genes found on the non-sex chromosomes ex: Sickle cell = chromosome #11 ex: Cystic fibrosis = chromosome #7 Sufferers must inherit 2 recessive alleles to have the disease H = healthy h = disease H H h H h h healthy Healthy (carrier) disease

1 Minute: Maria is a heterozygous healthy (Hh) female and Jeff suffers from recessive cystic fibrosis (hh). h h Key H = healthy h = cystic fibrosis H H h H h h h h h h 1) Probability of having a healthy child? _________ 2) Probability of having a homozygous dominant child? ________ 50% 0%

Review 1) How are dominant alleles expressed? Recessive? 2) Which of the following are genotypes? Phenotypes? Heterozygous genotypes? Hybrid? TT Green yY Pp Purple gg Smooth 3) Genes may often be found in two forms (dominant and recessive). What are these alternate forms of a gene called? 4) Genes are segments of DNA found on _______________. 5) If item A is found in a 1:2 ratio compared to item B, what percentage is item A? 6) Cross a heterozygous tall with a homozygous recessive short pea plant. List the genotypes in a Punnett square. What’s the probability of growing a tall plant? What’s the probability of growing a homozygous dominant plant? What’s the probability of growing a homozygous recessive plant?