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Genetics Gregor Mendel • “father of genetics” • studied pea plants – genes carry inherited traits – predicted how traits were inherited Genetics Vocabulary • Allele – a section of DNA; you have 2 for every trait, one from mom and one from dad • DOMINANT – trait/allele that shows up; represented by CAPITAL letters • recessive – trait/allele that is hidden; represented by lowercase letter alleles Genetics Vocabulary If A stands for axial flowers and a stands for terminal flowers • genotype – what your DNA says your traits are; represented by 2 letters (b/c you have 2 alleles for each trait) or or • phenotype – what you see because of the DNA you have phenotype= Axial flowers phenotype= Axial flowers phenotype= terminal flowers Practice: Are these genotypes or phenotypes? • • • • • • • Tt round black BB smooth rr tall Genetics Vocabulary • homozygous – 2 letters of the same size, same alleles (pure) Homozygous dominant Homozygous recessive • heterozygous – 2 letter of the different sizes, different alleles (hybrid) Practice: Are these genotypes homozygous or heterozygous? If they are homozygous, are they dominant or recessive? • • • • • • AA Gg hh Oo MM ss In pea plants, green pods are completely dominant over yellow. What letter will we use? What are the genotypes? • Homozygous yellow • Heterozygous green gg Gg • Pure dominant • Hybrid GG Gg Punnett Squares • Punnett Squares: used to predict the possible genotypes and phenotypes of offspring. Parent 1 Parent 2 offspring offspring offspring offspring Genetic Crosses • There are 4 genetic crosses we will discuss. – Simple Dominance – Incomplete Dominance – Codominance – Sex-linked Traits Genetic Crosses • There are 4 genetic crosses we will discuss. – Simple Dominance – one trait • Use 1 letter and capital or lowercase letters Ex: In pea plants axial flowers are dominant to terminal flowers. What would be the result of a cross between a homozygous dominant pea plant and a homozygous recessive pea plant? Ex: In pea plants axial flowers are dominant to terminal flowers. What would be the result of a cross between a homozygous dominant pea plant and a homozygous recessive pea plant? What letter are we using? What genotypes for the parents? Parent 1: Parent 2: Parent 1 Parent 2 Ex: In pea plants axial flowers are dominant to terminal flowers. What would be the result of a cross between a homozygous dominant pea plant and a homozygous recessive pea plant? What letter are we using? A What genotypes for the parents? Parent 1: Parent 2: Parent 1 Parent 2 Ex: In pea plants axial flowers are dominant to terminal flowers. What would be the result of a cross between a homozygous dominant pea plant and a homozygous recessive pea plant? What letter are we using? A What genotypes for the parents? Parent 1: AA Parent 2: aa Parent 1 Parent 2 Ex: In pea plants axial flowers are dominant to terminal flowers. What would be the result of a cross between a homozygous dominant pea plant and a homozygous recessive pea plant? What letter are we using? A What genotypes for the parents? Parent 1: AA Parent 2: aa A A a a Ex: In pea plants axial flowers are dominant to terminal flowers. What would be the result of a cross between a homozygous dominant pea plant and a homozygous recessive pea plant? What letter are we using? A What genotypes for the parents? Parent 1: AA Parent 2: aa A A a Aa a ***Bring the letters down and over Ex: In pea plants axial flowers are dominant to terminal flowers. What would be the result of a cross between a homozygous dominant pea plant and a homozygous recessive pea plant? What letter are we using? A What genotypes for the parents? Parent 1: AA Parent 2: aa A A a Aa a Aa ***Bring the letters down and over Ex: In pea plants axial flowers are dominant to terminal flowers. What would be the result of a cross between a homozygous dominant pea plant and a homozygous recessive pea plant? What letter are we using? A What genotypes for the parents? Parent 1: AA Parent 2: aa A Aa A a Aa a Aa ***Bring the letters down and over Ex: In pea plants axial flowers are dominant to terminal flowers. What would be the result of a cross between a homozygous dominant pea plant and a homozygous recessive pea plant? What letter are we using? A What genotypes for the parents? Parent 1: AA Parent 2: aa A a Aa Aa A a Aa Aa ***Bring the letters down and over Ex: In pea plants axial flowers are dominant to terminal flowers. What would be the result of a cross between a homozygous dominant pea plant and a homozygous recessive pea plant? What letter are we using? A What genotypes for the parents? Parent 1: AA Parent 2: aa Genotypes: A a Aa Aa A a Aa Aa Ex: In pea plants axial flowers are dominant to terminal flowers. What would be the result of a cross between a homozygous dominant pea plant and a homozygous recessive pea plant? What letter are we using? A What genotypes for the parents? Parent 1: AA Parent 2: aa Genotypes: Aa 4:0 100% A a Aa Aa A a Aa Aa Ex: In pea plants axial flowers are dominant to terminal flowers. What would be the result of a cross between a homozygous dominant pea plant and a homozygous recessive pea plant? What letter are we using? A What genotypes for the parents? Parent 1: AA Parent 2: aa Genotypes: Aa 4:0 100% A a Aa Aa A a Aa Aa Phenotypes: Ex: In pea plants axial flowers are dominant to terminal flowers. What would be the result of a cross between a homozygous dominant pea plant and a homozygous recessive pea plant? What letter are we using? A What genotypes for the parents? Parent 1: AA Parent 2: aa Genotypes: Aa 4:0 100% A a Aa Aa A Phenotypes: Axial 4:0 100% a Aa Aa Genetic Crosses • There are 4 genetic crosses we will discuss. – Simple Dominance – Incomplete Dominance – Codominance – Sex-linked Traits Genetic Crosses • There are 4 genetic crosses we will discuss. – Incomplete Dominance: neither allele is completely dominant over the other, so the phenotypes BLEND together. Ex. Red X = PINK Ex: Snapdragons are flowers controlled by incomplete dominance. When you cross a red snapdragon with a white snapdragon the results are pink snapdragons. What would be the cross of 2 pink snapdragons? What are the genotypes of red, white, and pink snapdragons? Red: White: Pink: What genotypes for the parents? Genotypes: Parent 1: Parent 2: Phenotypes: Ex: Snapdragons are flowers controlled by incomplete dominance. When you cross a red snapdragon with a white snapdragon the results are pink snapdragons. What would be the cross of 2 pink snapdragons? What are the genotypes of red, white, and pink snapdragons? Red: RR White: WW Pink: RW What genotypes for the parents? Genotypes: Parent 1: Parent 2: Phenotypes: Ex: Snapdragons are flowers controlled by incomplete dominance. When you cross a red snapdragon with a white snapdragon the results are pink snapdragons. What would be the cross of 2 pink snapdragons? What are the genotypes of red, white, and pink snapdragons? Red: RR White: WW Pink: RW What genotypes for the parents? Genotypes: Parent 1: RW R W Parent 2: RW R Phenotypes: W Ex: Snapdragons are flowers controlled by incomplete dominance. When you cross a red snapdragon with a white snapdragon the results are pink snapdragons. What would be the cross of 2 pink snapdragons? What are the genotypes of red, white, and pink snapdragons? Red: RR White: WW Pink: RW What genotypes for the parents? Genotypes: Parent 1: RW R W Parent 2: RW R RR Phenotypes: W Ex: Snapdragons are flowers controlled by incomplete dominance. When you cross a red snapdragon with a white snapdragon the results are pink snapdragons. What would be the cross of 2 pink snapdragons? What are the genotypes of red, white, and pink snapdragons? Red: RR White: WW Pink: RW What genotypes for the parents? Genotypes: Parent 1: RW R W Parent 2: RW R RR RW Phenotypes: W Ex: Snapdragons are flowers controlled by incomplete dominance. When you cross a red snapdragon with a white snapdragon the results are pink snapdragons. What would be the cross of 2 pink snapdragons? What are the genotypes of red, white, and pink snapdragons? Red: RR White: WW Pink: RW What genotypes for the parents? Genotypes: Parent 1: RW R W Parent 2: RW RR RW Phenotypes: W RW Ex: Snapdragons are flowers controlled by incomplete dominance. When you cross a red snapdragon with a white snapdragon the results are pink snapdragons. What would be the cross of 2 pink snapdragons? What are the genotypes of red, white, and pink snapdragons? Red: RR White: WW Pink: RW What genotypes for the parents? Genotypes: Parent 1: RW R W Parent 2: RW R RR RW Phenotypes: W RW WW Ex: Snapdragons are flowers controlled by incomplete dominance. When you cross a red snapdragon with a white snapdragon the results are pink snapdragons. What would be the cross of 2 pink snapdragons? What are the genotypes of red, white, and pink snapdragons? Red: RR White: WW Pink: RW What genotypes for the parents? Genotypes: Parent 1: RW RR; RW; WW R W Parent 2: RW 1:2:1 25%:50%:25% R RR RW Phenotypes: W RW WW Ex: Snapdragons are flowers controlled by incomplete dominance. When you cross a red snapdragon with a white snapdragon the results are pink snapdragons. What would be the cross of 2 pink snapdragons? What are the genotypes of red, white, and pink snapdragons? Red: RR White: WW Pink: RW What genotypes for the parents? Genotypes: Parent 1: RW RR; RW; WW R W Parent 2: RW 1:2:1 25%:50%:25% R W RR RW RW WW Phenotypes: Red; Pink; White 1:2:1 25%:50%:25% Genetic Crosses • There are 4 genetic crosses we will discuss. – Simple Dominance – Incomplete Dominance – Codominance – Sex-linked Traits Genetic Crosses • There are 4 genetic crosses we will discuss. – Codominance – Both alleles are dominant. Both alleles show up. Black X = C e k r d Codominance Codominance Ex: In chickens, feather color is controlled by codominant alleles. When black chickens are crossed with white chickens, black and white checkered chickens appear. What is the cross between two checkered chickens? What are the genotypes of black, white, and checkered chickens? Black: White: Checkered: What genotypes for the parents? Parent 1: Genotypes: Parent 2: Phenotypes: Ex: In chickens, feather color is controlled by codominant alleles. When black chickens are crossed with white chickens, black and white checkered chickens appear. What is the cross between two checkered chickens? What are the genotypes of black, white, and checkered chickens? Black: BB White: WW Checkered: BW What genotypes for the parents? Parent 1: Genotypes: Parent 2: Phenotypes: Ex: In chickens, feather color is controlled by codominant alleles. When black chickens are crossed with white chickens, black and white checkered chickens appear. What is the cross between two checkered chickens? What are the genotypes of black, white, and checkered chickens? Black: BB White: WW Checkered: BW What genotypes for the parents? Parent 1: BW Genotypes: Parent 2: BW B W B Phenotypes: Ex: In chickens, feather color is controlled by codominant alleles. When black chickens are crossed with white chickens, black and white checkered chickens appear. What is the cross between two checkered chickens? What are the genotypes of black, white, and checkered chickens? Black: BB White: WW Checkered: BW What genotypes for the parents? Parent 1: BW Genotypes: Parent 2: BW B W B BB Phenotypes: W Ex: In chickens, feather color is controlled by codominant alleles. When black chickens are crossed with white chickens, black and white checkered chickens appear. What is the cross between two checkered chickens? What are the genotypes of black, white, and checkered chickens? Black: BB White: WW Checkered: BW What genotypes for the parents? Genotypes: Parent 1: BW B W Parent 2: BW B BB BW Phenotypes: W Ex: In chickens, feather color is controlled by codominant alleles. When black chickens are crossed with white chickens, black and white checkered chickens appear. What is the cross between two checkered chickens? What are the genotypes of black, white, and checkered chickens? Black: BB White: WW Checkered: BW What genotypes for the parents? Parent 1: BW Genotypes: Parent 2: BW B W B BB BW Phenotypes: W BW Ex: In chickens, feather color is controlled by codominant alleles. When black chickens are crossed with white chickens, black and white checkered chickens appear. What is the cross between two checkered chickens? What are the genotypes of black, white, and checkered chickens? Black: BB White: WW Checkered: BW What genotypes for the parents? Genotypes: Parent 1: BW B W Parent 2: BW B BB BW Phenotypes: W BW WW Ex: In chickens, feather color is controlled by codominant alleles. When black chickens are crossed with white chickens, black and white checkered chickens appear. What is the cross between two checkered chickens? What are the genotypes of black, white, and checkered chickens? Black: BB White: WW Checkered: BW What genotypes for the parents? Genotypes: Parent 1: BW BB; BW; WW B W Parent 2: BW 1:2:1 25%:50%:25% B BB BW Phenotypes: W BW WW Ex: In chickens, feather color is controlled by codominant alleles. When black chickens are crossed with white chickens, black and white checkered chickens appear. What is the cross between two checkered chickens? What are the genotypes of black, white, and checkered chickens? Black: BB White: WW Checkered: BW What genotypes for the parents? Genotypes: Parent 1: BW BB; BW; WW B W Parent 2: BW 1:2:1 25%:50%:25% B W BB BW BW WW Phenotypes: Black; Checkered; White 1:2:1 25%:50%:25% Incomplete or Codominance? • Red cow crossed with white cow results in roan cattle. Roan cattle have both red and white hairs. • A blue blahblah bird and a white blahblah bird produce offspring that are silver. • A certain species of mouse with black fur is crossed with a mouse with white fur and all of the offspring have grey fur. Incomplete or Codominance? • White chicken x black chicken = black and white checkered chicken • A red flower and a white flower produce pink flowers. • A black cat and a tan cat produce tabby cats, cats where black and tan fur is seen together. • A woman with blood type A and a man with blood type B have a child with blood type AB Genetic Crosses • There are 4 genetic crosses we will discuss. – Codominance – Both alleles are dominant. Both alleles show up. – Blood Types There are 4 blood types: A, B, AB, and O AB blood type is codominant Blood Types Genotype Genotype Phenotype IAIA or IAi AA or AO A IBIB or IBi BB or BO B IAIB AB AB ii OO O EOC way Ms. Edmonds way (easier) ***this problem is not specific so we have to do multiple punnett squares Ex: What would be the expected outcomes of children between a man with A blood and a woman with B blood? What genotypes for the parents? Parent 1: Parent 2: Genetic Crosses • There are 4 genetic crosses we will discuss. – Simple Dominance – Incomplete Dominance – Codominance – Sex-linked Traits Genetic Crosses • There are 4 genetic crosses we will discuss. – Sex-linked Traits – traits that are determined by sex (gender). On the X chromosome. • Males XY • Females XX – Examples of sex-linked traits • Colorblindness • Hemophilia Sex-Linked Traits: •Some genes are found on the sex chromosomes •Some are found on the X sex chrom. but not the Y Ex – the color vision gene is on the X chromosome - NOT FOUND ON THE “Y” Sex-linked traits are RECESSIVE (mostly) traits that are found on the ‘x’ sex chromosome Colorblindness Self Test Can you see the hidden numbers? Colorblindness Self Test: NUMBERS: 5 | 8 | 9 | 5 | 3 | 5 | 9 | 10 | Hidden Shapes: SHAPES: Plate 1 - Circle and arch Plate 2 - Circle, star and square Hemophilia Pedigree of Queen Victoria Hypertrichosis – Human Werewolf Syndrome: Congenital generalized hypertrichosis (CGH) Rare, X-linked dominant trait Found in a single multigenerational Mexican family Why do males go bald??? •Females have 2 X chromosomes so they can be “carriers” for the sex-linked trait but their phenotype is the normal condition •One of the chromosomes can “mask” the sexlinked trait •Males have only 1X chromosome so if they get the recessive trait that is a sex-linked trait, then they will show it. Sex-Linked Genotypes/Phenotypes Phenotype Male Female Genotype Genotype Normal XH Y X HX H Affected XhY X hXh Carrier None X HX h Ex: If a man with hemophilia marries a woman whose father was a hemophiliac, what are the possible genotypes and phenotypes of their children? Man: Woman: What genotypes for the parents? Man: Woman: Genotypes: Phenotypes: Ex: If a man with hemophilia marries a woman whose father was hemophiliac, what are the possible genotypes and phenotypes of their children? Man: hemophilia Woman: father was hemophiliac which makes her a carrier What genotypes for the parents? Man: Woman: Genotypes: Phenotypes: Ex: If a man with hemophilia marries a woman whose father was hemophiliac, what are the possible genotypes and phenotypes of their children? Man: hemophilia Woman: father was hemophiliac which makes her a carrier What genotypes for the parents? h Man: X Y H h Woman: X X Genotypes: Phenotypes: Ex: If a man with hemophilia marries a woman whose father was hemophiliac, what are the possible genotypes and phenotypes of their children? Man: hemophilia Woman: father was hemophiliac which makes her a carrier What genotypes for the parents? h Man: X Y H h Woman: X X h X X X H h Genotypes: Y Phenotypes: Ex: If a man with hemophilia marries a woman whose father was hemophiliac, what are the possible genotypes and phenotypes of their children? Man: hemophilia Woman: father was hemophiliac which makes her a carrier What genotypes for the parents? h Man: X Y H h Woman: X X h X Y H X HX h X HY h XhXh XhY X X Genotypes: Phenotypes: Ex: If a man with hemophilia marries a woman whose father was hemophiliac, what are the possible genotypes and phenotypes of their children? Man: hemophilia Woman: father was hemophiliac which makes her a carrier What genotypes for the parents? h Man: X Y H h Woman: X X h X Y XHXh; XhXh; XHY; XhY Phenotypes: H X HX h X HY h XhXh XhY X X Genotypes: 1:1:1:1 25%: 25%: 25%: 25% Ex: If a man with hemophilia marries a woman whose father was hemophiliac, what are the possible genotypes and phenotypes of their children? Man: hemophilia Woman: father was hemophiliac which makes her a carrier What genotypes for the parents? h Man: X Y H h Woman: X X h X Y H X HX h X HY h XhXh XhY X X Genotypes: XHXh; XhXh; XHY; XhY 1:1:1:1 25%: 25%: 25%: 25% Phenotypes: Carrier girl hemophiliac girl Normal boy hemophiliac boy 1:1:1:1 25%: 25%: 25%: 25% Pedigrees • Shows a pattern of inheritance in a family for a specific trait (phenotype) • Genotypes can usually be determined • Why would we want to use a pedigree in genetics? • Track the occurrence of diseases such as: – – – – Huntington’s – simple dominant – lethal allele – causes breakdown of the brain Cystic fibrosis – 1/2500 – mucus accumulates (white North Amer.) Tay-Sachs disease – lipids accumulate in CNS (Jewish) Phenylketonuria – missing enzyme causes problems in CNS (Nordic/Swedish) Pedigree of Queen Victoria Pedigree Analysis Have you ever seen a family tree… do you have one?? Graphic representation of family inheritance. The Symbols used: Sample pedigree: •generations are numbered with Roman Numerals •oldest offspring are on the left • How many males are present? How many females? • How many females show the trait being studied? • What is the sex of offspring III-9? • How many offspring did the generation I parents have? • What is the difference between the II-3 & 4 and IV-2 & 3? Inheritance patterns: • Autosomal dominant: The disease is passed from the father (II-3) to the son (III-5), this never happens with X-linked traits. The disease occurs in three consecutive generations, this never happens with recessive traits. Males and females are affected, with roughly the same probability. –Examples: Polydactyly –Huntington’s disease Inheritance patterns: • Autosomal recessive Males and females are equally likely to be affected. The recurrence risk to the unborn sibling of an affected individual is 1/4. The trait is characteristically found in siblings, not parents of affected or the offspring of affected. Parents of affected children may be related. The rarer the trait in the general population, the more likely a consanguineous mating is involved. –Cystic fibrosis –Tay-Sach’s disease Inheritance patterns: • Sex-linked recessive conditions The disease is never passed from father to son. Males are much more likely to be affected than females. •All affected males in a family are related through their mothers. –Examples: Trait or disease is typically passed from an affected grandfather, through his carrier daughters, to half of his grandsons. –Color-blindness –Hemophilia –Duchenne Muscular Dystrophy The Ultimate Pedigree Challenge • https://migrc.org/Library/UltimatePedigreeCh allengeResources.html • Take out a sheet of paper/or sketch this in your notes. • Listen to the song and make a pedigree of the singer and his family. Use the lyrics to help you. Making Your Own Pedigree! • Sketch out on notebook paper your own family pedigree • Must include at least 3 generations or 15 people [grandparents, parents (with aunts, uncles, etc.) and you (brothers, sisters, cousins)] • Choose one trait that you have and track that trait with as many members of your family as you can (label the genotypes that you know) – Keep your trait simple. EXAMPLES, MORE EXAMPLES • Your final pedigree must be on computer or construction paper! Pedigree Project Rubric (25 points) 5 4-3 2-1 0 Correctness /5 Neatness /5 Presentation /5 Title and Key /5 Labeled Genotypes /5 Total = To get a 5: Correctness – All aspects of the pedigree are correct. Symbols used appropriately. Pedigree is numbered appropriately. Neatness – Pedigree is neat and colorful. Presentation – Pedigree is on final paper. Title and Key – Title and Key are present and located on the front of the paper next to the pedigree Labeled Genotypes – You, any siblings, and biological parents possible genotypes are listed next to individual or in the key. /25