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Unit 12 - Heredity Unit 12 - Heredity father of genetics Gregor Mendel was born in 1822 in Heinzendorf, Austria, to a peasant farming family. Austria Poland Italy Germany Czech Republic Austria When he was 21, one of Mendel’s teachers took note of his exceptionally bright mind and persuaded him to join the Augustinian monks. St.Thomas Church, (now Brno, Czechoslovakia) Mendel conducted numerous experiments on plants. Mendel narrowed his focus to one particular type of garden pea. For 8 years, Mendel experimented with over 28,000 peas in the large gardens attached to the monastery. Rather than study every characteristic of the garden pea, Mendel narrowed his observations to 7 traits Garden Pea Traits Observed Seed shape smooth wrinkled Seed color yellow green Pod shape smooth Pod color green Flower color purple Flower location Along stem Plant size tall bumpy yellow white at tip short In 1866 when Mendel was 44, his experimental results were published . . . and ignored long after he died. In 1900, 3 scientists Carl Correns, Hugo de Vries, and Erich von Tschermak all independently rediscovered and verified Mendel's principles, marking the beginning of modern genetics. He is now considered the father of genetics. Genetics & Heredity Heredity-The passing of characteristics from parents to offspring Genetics -The branch of biology that focuses on heredity Are these inherited traits? Your eye color Your hair color and texture Your height Are these inherited traits? Your personality Your musical, athletic, and artistic abilities Think about this…. •My parents have brown eyes, why are mine blue?” •“My brother is tall. Why am I short?” •“Why does my sister have blonde hair while mine is brown?” Mendel’s studies led to… •Alleles- the different versions of a gene (an individual receives one allele from each parent) Mendel’s studies led to… •Dominant- the expressed form of the trait ex. H •Recessive- the trait that is not expressed if a dominant allele is present ex. h Mendel’s studies led to… •Genotype- the genetic makeup of an organism (the set of alleles an individual has) ex: Ff or FF •Phenotype- the physical appearance of an organism ex. has freckles Mendel’s studies led to… •Homozygous- the two alleles present for a characteristic are the same Ex: hh or HH •Heterozygous- the two alleles present for a characteristic are different Ex: Hh Tongue Roller R = Tongue Roller r = Unable to Roll Tongue Widow’s Peak W = Widows Peak w = Lack of Widow’s Peak Free Ear Lobe Attached Ear Lobe E = Free Ear Lobe e = Attached Ear Lobe Hitchhiker’s Thumb H = Straight Thumb h = Hitchhiker’s Thumb Bent Little Finger B = Bent Little Finger b = Straight Little Finger Mid-digital Hair M = Mid-Digital Hair m = Absence of Mid-Digital Hair Dimples D = Dimples d = Absence of Dimples Short Hallux H = Short Hallux h = Long Hallux Short Index Finger S = Short Index Finger s = Long Index Finger The Theory of Heredity Inherited allele for purple P Inherited allele for purple P HOMOZYGOUS purple flower (PP) The Theory of Heredity Inherited allele for purple P Inherited allele for pink flower (p) HETEROZYGOUS purple flower (Pp) The Theory of Heredity Inherited allele for pink flower (p) Inherited allele for pink flower (p) HOMOZYGOUS pink flower (pp) PREDICTING HEREDITY Probability • The likelihood that a specific event will occur • Probability = # of 1 kind of possible outcome Total number of possible outcomes • Example: What is the probability that a tossed coin will be heads? • ½ or 50% Probability • What is the probability that a couple will have four boys? ½ x ½ x ½ x ½ = 1/16 • What is the probability you will win the lottery? 6/50 x 5/49 x 4/48 x 3/47 x 2/46 x 1/45… Monohybrid Cross: a cross that shows the possible offspring for one trait A a A AA Aa a Aa aa Aa x Aa A: White fur a: Brown fur Genotypic Ratio: 1:2:1 Phenotype: 3 white:1 brown Dragons have either smooth or wrinkled noses. Wrinkled is dominant over smooth. If a smooth-nosed female dragon is crossed with a heterozygous wrinkle-nosed male, how many of their offspring are likely to have smooth noses? _ _ *genotypic ratio: *phenotypic ratio: *What is the probability of having smooth-nosed offspring? *What is the probability of having two smooth-nosed offspring? _ _ Dihybrid Cross: a cross that shows the possible offspring for two traits Fur Color: B: Black b: White Coat Texture: R: Rough r: Smooth BbRr x BbRr Dihybrid Cross: BbRr x BbRr First, you must find ALL possible gametes that can be made from each parent. Remember, each gamete must have one B and one R. Dihybrid Crosses: a cross that shows the possible offspring for two traits Fur Color: B: Black b: White Coat Texture: R: Rough r: Smooth BbRr x BbRr Phenotypic Ratio: 9:3:3:1 BR Br bR br BR BBRR BBRr BbRR BbRr Br BBRr BBrr BbRr Bbrr bR BbRR BbRr bbRR bbRr br BbRr Bbrr bbRr bbrr Dihybrid Crosses: a cross that shows the possible offspring for two traits •How many of the offspring would have black, rough coat? •How many of the offspring would have a white, smooth coat? BR Br bR br BR BBRR BBRr BbRR BbRr Br BBRr BBrr BbRr Bbrr bR BbRR BbRr bbRR bbRr 1 16 •How many of the offspring would have a white, rough coat? br BbRr Bbrr bbRr bbrr More Complex Patterns of Heredity 1 –Codominance –Multiple Alleles –Sex-Linked Traits 16 Codominance: two dominant alleles are expressed at the same time 1 CRCR CWCW 16 CRCW Codominance • Sickle-Cell Anemia is another codominant trait. NS 1 NA NA NSNA NSNA NA=Normal RBC 16 NS=Sickle Cell RBC NA NANA NANA Pedigree Analysis Pedigree Used to show genetic inheritance over generations in a family Pedigree Example male Marriage female Female Carrier Offspring Royal Family Hemophilia People who are “carriers” for People affected the disease, butbydothe notdisease have symptoms—can pass on to children