Essential Question: How does genotype determine phenotype?
A. Law of Segregation 1. During meiosis, the genes that control each trait separate. 2. One gene from each pair is passed to the offspring. Haploids have only 1 of each gene. 3. These genes randomly unite (combine) at fertilization.
1. The inheritance of one trait is unaffected by the inheritance of another trait. 2. You may get your eye color from mom but hair color from dad.
Phenotype: physical characteristics or traits Genotype: genes
Dominant Allele A VERSION OF THE TRAIT THAT IS ALWAYS EXPRESSED. Represented by CAPITAL LETTER R, T, D
Recessive Allele A VERSION OF THE TRAIT THAT IS ALWAYS MASKED IF PAIRED WITH A DOMINANT ALLELE. Represented by LOWERCASE LETTERs r, t, d
GENOTYPES: 1. Homozygous dominant (ex: RR, TT, EE) 2. Homozygous recessive (ex: rr, tt, ee) 3. Heterozygous (ex: Rr, Tt, Ee) Heterozygous genotypes always express the dominant trait!
Brown eyes (B) are dominant over blue eyes(b). What are the 3 possible genotypes? BB, Bb, bb What are the phenotypes? BB-brownBb-brownbb-blue
1.Decide on all possible genotypes/phenotypes. 2.Find the genotype of the parents. 3.Do a “Punnett” square to show the possible combinations of genes in the offspring.
Straight thumb (T) is dominant to hitchhiker’s thumb. If Brenda, who is heterozygous for this trait had children with Jason who is homozygous recessive, what is the chance that their children will be able to hitchhike correctly?
1.What are all possible genotypes/ phenotypes? TT- Straight thumb Tt- Straight thumb tt- hitchhiker’s thumb
2. Find the genotype of the parents. Brenda Tt Jason tt
3. Do a Punnett square to show the possible combinations of genes in the offspring. Tt t t TtTtTtTt tttttttt TtTtTtTt tttttttt Mother Tt Fathertt
TtttTttt Tt- straight thumb Tt- hitchhiker’s thumb 2/4= 50%
Having freckles (F) is dominant over not having freckles (f). A woman is heterozygous marries a man who is homozygous recessive. What are the chances of their children having freckles?
Find the genotype of the parents. Woman Ff Man ff
Do a Punnett square to show the possible combinations of genes in the offspring. Ff f f FfFfFfFf ffffffff FfFfFfFf ffffffff Mother Ff Fatherff
FfffFfff Ff- freckles ff- no freckles 2/4= 50%
3: In three complete sentences, write three things you learned about in today’s lesson. 2: List two things you found interesting. 1: Draw an Emoji that best describes how comfortable you feel with the material OR write one question you still have.