Do Now Put modeling meiosis in bin. 2. Explain difference between heterozygous and homozygous. 3. Explain difference between dominant and recessive. 4. Explain difference between phenotype and genotype.

Portion of DNA (nitrogen bases) that codes for a trait Review: Gene Portion of DNA (nitrogen bases) that codes for a trait

Two different forms of a gene: Dominant and Recessive Review: Allele Two different forms of a gene: Dominant and Recessive

Key: D = no dimples and d = dimples AND H = Unibrow and h = Two eyebrows Identify the Genes: Identify the Alleles: Alleles Phenotype Genotype dd HhDd DD Ddhh

Tool used to predict the genotypes and phenotypes of offspring Punnett Square Tool used to predict the genotypes and phenotypes of offspring

What is Monohybrid Cross? Punnett square using only one trait.

Monohybrid Cross and Mendel If purple is dominant and white is recessive, cross a purebred (homozygous dominant) purple flower with a white flower. Which allele is dominant? Purple X PP pp

PP x pp p p P Pp Pp P Pp Pp

1st generation Self Pollinates Pp x Pp P p P PP Pp p Pp pp

What do Punnett Squares represent? MEIOSIS Possible eggs from Mom A Possible sperm from Dad a Each square represents the possible combinations of alleles inherited by offspring MEIOSIS A A A A a A a A a a a a

How to do a Punnett square problem 1. List the symbols & alleles T = Tall t = Short

How to do a Punnett square problem 2. List the Parental Cross T = Tall t = Short Tt x Tt

How to do a Punnett square problem 3. Do the Punnett square T = Tall t = Short T t Tt x Tt T T T T t t T t t t

How to do a Punnett square problem 4. List the genotypic ratio T = Tall t = Short T t Tt x Tt T T T T t G = 1TT : 2Tt : 1tt t T t t t

How to do a Punnett square problem 5. List the phenotypic ratio T = Tall t = Short T t Tt x Tt T T T T t G = 1TT : 2Tt : 1tt t T t t t P = 3 Tall:1 Short

How to do a Punnett square problem 6. Answer any questions associated with the problem. T t T = Tall t = Short T T T T t Tt x Tt G = 1:2:1 t T t t t P = 3:1

Example #1 A male that is heterozygous for purple hair is crossed with a orange haired woman. What chance to they have in producing a purple haired child? Orange haired child? (Purple hair = P and orange hair = p)

Example #2 If a man that is a purebred with big ears marries a heterozygous woman for this trait, what is the chance that their first child might express the dominant trait? Big ears = B and Little ears = b

Example #3 A couple is heterozygous for the gene for big nose. They are about to have a child and hope that it has a small nose. Do they have a chance? How much of a chance? B = Big nose and b = small nose