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Week 16 Journal Question. Thursday Q: Explain how a person get’s their full set of chromosomes. . Table of Contents . Notes: Genetics. Mendel’s Laws A. Law of Segregation- 1. During meiosis, the genes that control each trait separate .
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Week 16 Journal Question Thursday Q: Explain how a person get’s their full set of chromosomes.
Mendel’s Laws 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.
B. Law of Independent Assortment 1. The inheritance of one trait is unaffected by the inheritance of another trait. 2. You may get your eye color from mombut hair color from dad.
Important Vocabulary Terms Phenotype: physical characteristics or traits Genotype: genes
Important Vocabulary Terms Dominant Allele • A VERSION OF THE TRAIT THAT IS ALWAYS EXPRESSED. • Represented by CAPITAL LETTER • R, T, D
Important Vocabulary Terms Recessive Allele • A VERSION OF THE TRAIT THAT IS ALWAYS MASKED IF PAIRED WITH A DOMINANT ALLELE. • Represented by LOWERCASE LETTERs • r, t, d
Possible combination of alleles GENOTYPES: • Homozygousdominant (ex: RR, TT, EE) • Homozygousrecessive (ex: rr, tt, ee) • Heterozygous (ex: Rr, Tt, Ee) Heterozygous genotypes always express the dominant trait!
Example 1 Brown eyes (B) are dominant over blue eyes(b) . What are the 3 possible genotypes? BB, Bb, bb What are the phenotypes? BB-brown Bb-brown bb-blue
How to Do a Punnett Square Problem • Decide on all possible genotypes/phenotypes. • Find the genotype of the parents. • Do a “Punnett” square to show the possible combinations of genes in the offspring.
Example Genetic Problem 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?
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? • What are all possible genotypes/ phenotypes? • TT- Straight thumb • Tt- Straight thumb • tt- hitchhiker’s thumb
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? 2. Find the genotype of the parents. BrendaTt Jason tt
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? 3. Do a Punnett square to show the possible combinations of genes in the offspring. Mother Tt T t t Father tt Tt tt tt Tt t
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? Tt- straight thumb Tt- hitchhiker’s thumb 2/4= 50%
Having freckles (F) is dominant over not having freckles (f). A woman who is heterozygous marries a man who is homozygous recessive. What are the chances of their children having freckles? 1. 2. 3.