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CH 11 Catalyst • What are the chances of flipping a penny and having it land on head? Catalyst • What are the chances of flipping a penny and having it land on head? – There are two possible outcomes for this action: Heads or Tails – Answer: Head Head or Tail = 1 2 Catalyst • What are the chances of flipping a penny and having it land on head? Heads Tails Catalyst • What are the chances of flipping two pennies and having them both land on head? Catalyst • What are the chances of flipping two pennies and having them both land on head? – There are four possible outcomes for this action: Heads/Heads, Heads/Tails, Tails/Heads or Tails/Tails – Answer: Heads/Heads Heads/Heads, Heads/Tails, Tails/Heads or Tails/Tails = 1 4 Catalyst • What are the chances of flipping two pennies and having them both land on head? Heads Tails Heads Tails • Genetics- study of heredity • Gregor Mendel – Austrian monk who performed cross fertilization experiments in 1822 • Genetics- study of heredity • Gregor Mendel – Austrian monk who performed cross fertilization experiments in 1822 – Result: • 1. inheritance is determined by factors passed from one generation to the next – Gene- section of DNA that codes for a protein remember: DNA RNA protein trait • 2. principal of dominance – Some traits appear whenever the gene is present (dominant) – Some traits appear when only that gene is present (recessive) – Some traits are intermediate during meiosis Possible combinations during Fertilization Vocab • Trait- characteristic of an organism – Ex) • Phenotype- physical appearance of a trait – Ex) • Genotype- alleles for a trait – Ex) • Allele- version of a gene – Ex) Vocab • Homozygous genotype- two of the same alleles for a trait • AKA “pure-breeding” or “true-breeding” • Ex) BB or bb • Heterozygous genotype- two different alleles for a trait – AKA hybrid • Ex) Bb Smiley Questions • 1. Explain why were two people flipping pennies to create one Smiley. • 2. List any examples of the offspring’s genotype that is homozygous. List any examples of the offspring’s genotype that is heterozygous. • 3. For which traits does your offspring have the same genotype as it’s mother? • 4. For which traits does your offspring have the same phenotype as it’s father? • 5. Compare the phenotype of your Smiley to another groups Smiley. Explain why the offspring have different traits if the parents have the same genes. Vocab Matching 1. ___ Father of Genetics 2. ___ What it looks like, physical trait 3. ___ 2 different alleles for the same trait 4. ___ 2 of the same alleles for the trait 5. ___ the genetic make-up 6. ___ will exhibit the trait only if there are no dominant traits present 7. ___ sequence of DNA that codes for a protein and this determines a trait 8. ___ one of a number of different forms of a gene 9. ___ organism with an allele for a particular form of a trait will always exhibit that form of the trait A. B. C. D. E. F. G. H. I. Gene Dominant Heterozygous Homozygous Genotype Allele Recessive Gregor Mendel Phenotype Remember meiosis Vocab • Monohybrid Cross- Punnet Square to predict the results of a trait determined by one gene • Create a Punnet Square to show the possible offspring for two parents heterozygous for tongue-rolling. Tt Tt In genetics, what do the T and t represent? • The T and t are both alleles (different versions of a trait). – The alleles that an individual inherits are the genotype, the combination of genes that was inherited. • For example, for the trait tongue-curling, there are different variations. – The trait that is dominant is represented with the capital letter: H (or T) • Tongue curling is dominant – The trait that is recessive is represented with the lower case letter: h (or t) • Not curling is recessive Tt T T Tt t Segregation during meiosis t alleles in gametes for one parent T T alleles in gametes for second parent t t Tt T T Tt t Segregation during meiosis t possible combinations during fertilization T T t t possible combinations during fertilization T T t TT t possible combinations during fertilization T T t TT t possible combinations during fertilization T T t TT t Tt possible combinations during fertilization T T t TT t Tt possible combinations during fertilization T T TT t Tt t Tt possible combinations during fertilization T T TT t Tt t Tt possible combinations during fertilization T T TT t Tt t Tt possible combinations during fertilization T t T TT Tt t Tt tt possible combinations during fertilization Which genotype combinations are homozygous? heterozygous? TT, Tt, tt • Homozygous: TT or tt • Heterozygous: Tt Ratios, Percentages and Fractions • 1. Which of the following represent 50% a. 1:1 b. 1:3 c. 1 d. 1:2:1 • 2. Which ratio is equal to 3/4 a. 1:1 b. 3:1 c. 1 d. 1:2:1 • 3. Which represents 100% a. 1:1 b. 3:1 c. 1 d. 1:2:1 T t T TT Tt t Tt tt What is the probability the offspring will have a heterozygous genotype? T t T TT Tt t Tt tt What is the probability the offspring will have a heterozygous genotype? 2/4 = 1/2 1:1 ratio or 50% T t T TT Tt t Tt tt What is the probability the offspring will have a homozygous genotype? T t T TT Tt t Tt tt What is the probability the offspring will have a homozygous genotype? 2/4 = 1/2 1:1 ratio or 50% T t T TT Tt t Tt tt What is the probability the offspring will have a homozygous dominant genotype? T t T TT Tt t Tt tt What is the probability the offspring will have a homozygous dominant genotype? 1/4 1:3 ratio or 25% T t T TT Tt t Tt tt What is the probability the offspring will have a homozygous recessive genotype? T t T TT Tt t Tt tt What is the probability the offspring will have a homozygous recessive genotype? 1/4 1:3 ratio or 25% T t T TT Tt t Tt tt What is the probability the offspring will have a recessive phenotype? T t T TT Tt t Tt tt What is the probability the offspring will have a recessive phenotype? 1/4 1:3 ratio or 25% T t T TT Tt t Tt tt What is the probability the offspring will have a dominant phenotype? T t T TT Tt t Tt tt What is the probability the offspring will have a dominant phenotype? 3/4 3:1 ratio or 75% Pedigrees • How do you show traits in families? Pedigrees Affected female Affected Male Unaffected female Unaffected Male Carrier Carrier Vocab • P Generation- parent generation • F1 Generation- first filial generation • F2 Generation- second filial genration Pedigree • Number each generation starting at top: I, II, III, etc • Number each person starting in generation I: 1, 2, 3, etc • Married couples are connected by a horizontal line. • Children are shown connected to their parents by a vertical line. • • • • 1. Identify a married couple. 2. How many children did they have? 3. Identify the genotypes of all individuals. 4. Create a Punnet square and show the probability of the unknown (?) inherit the trait. • 5. Predict if this is a dominant or recessive trait. Explain why. Dominant Trait Hints • Usually in every generation • If a child has the trait, at least one parent must show the trait Recessive Trait Hints • Can skip generation • A child can have the trait but the parents not show the trait (carriers) Catalyst: make a pedigree • Lisa and Ashton got married and had three girls, Cari, Mary, and Terry. It was discovered that Lisa had muscular dystrophy. Terry married Perry and had two boys, Pike and Tike. It was discovered that Terry and Pike had muscular dystrophy. Catalyst • An alien species has been found. Genetists visiting their home planet have observed the following: • Most aliens on the planet have three eyes, however, when an alien from a family of three eyes mates with an alien from a family that just have one eye, all the offspring have one eye. • Which is the dominant phenotype? Dominant and Recessive Traits • Dominant alleles are able to “mask” recessive alleles • Dominant traits are expressed when an individual is homozygous or heterozygous – EX) RR or Rr • Recessive traits are only expressed when an organism is homozygous – EX) rr • If a pea plant with yellow pods and a pea plant with green pea pods are crossed, all the offspring are yellow. Intermediate Traits • Not all traits are dominant or recessive, sometimes a blend or mix of traits appears in the heterozygote. – Ex) True breeding red flower and true breeding white flowers are crossed and all the offspring are pink. – Ex) True breeding white horses are crossed with true breeding red horses and all the offspring are red and white (roan). Codominant Traits • The heterozygote shows a mix (BOTH) of traits – “Co” = both – Ex) True breeding white horses are crossed with true breeding red horses and all the offspring are red and white (roan). R R • R = red • R’ = white R’ R’ Codominant Traits • The heterozygote shows a mix (BOTH) of traits – “Co” = both – Ex) True breeding white horses are crossed with true breeding red horses and all the offspring are red and white (roan). R R • R = red • R’ = white R’ RR’ RR’ RR’ RR’ R’ Incomplete Dominance Traits • The heterozygote shows a blend (combination) of traits – Ex) True breeding red flower and true breeding white flowers are crossed and all the offspring are pink. • R = red • R’ = white R R’ R’ R Incomplete Dominance Traits • The heterozygote shows a blend (combination) of traits – Ex) True breeding red flower and true breeding white flowers are crossed and all the offspring are pink. • R = red • R’ = white R’ R R RR’ RR’ RR’ RR’ R’ Catalyst • An alien species has been found. Genetists visiting their home planet have observed the following. Six finger aliens that mate with eight fingered aliens have eight fingered offspring. Aliens with blue skin that mate with aliens with red skin have purple skin offspring. Aliens with straight antennae that mate with aliens with curly antennae have offspring that have both straight and curly antennae. Match the trait to the pattern of inheritance: • ___ 1. Finger Number a. Codominant • ___ 2. Skin Color b. Incomplete Dominance • ___ 3. Antennae Type c. Dominant and Recessive Multiple Alleles • Some genes have more than two alleles that can be inherited. – Ex) Blood type • Type A and B are codominant and O is recessive – Alleles: » IA – A allele » IB- B allele » i- O allele Phenotypes (Blood Type) Genotypes Type A IAIA or IAi Type B IBIB or IBi Type AB I AI B Type O ii Catalyst • Jane has type O blood. Her brother John has type B blood and her sister Jordan has type A blood. What are the genotypes of their parents? Sex-linked traits • Genes that are on sex chromosomes (X or Y) are inherited differently that traits not on sex chromosomes (autosomes). • Review – XX = female – XY= male • Recessive x-linked traits are more common in males than females. – Sample – Examples in humans = hemophilia and color blindness female male XHXH= normal female XHY= normal male XHXh= carrier female XhY = male with hemophilia Xh Xh = female with hemophilia • Hemophilia is an X-linked trait. A normal male person has children with a normal female who carries the hemophilia allele. What is the probability their offspring will have hemophilia? What is the probability their daughters will have hemophilia? What is the probability their sons will have hemophilia? • Color-blindness is an X-linked trait. A male who is colorblind mates with a normal female. What is the probability their offspring will have color-blindness? What is the probability their daughters will have color-blindness? What is the probability their sons will have color-blindness? X-link Pedigree hints • Skips generations • More common in males • Males must have carrier mothers OR mothers with trait – Ie. Sons inherit this trait from their moms Catalyst • A normal vision pregnant mother is concerned about having a colorblind son because her husband is colorblind. No one in the mothers family has the colorblindness trait. What would you tell her? Polygenic Traits • Traits that are due to interaction of more than one gene – Variety of phenotypes – Human examples: • Hair color • Eye color • Skin color Inheritance Chart Test Cross • Cross of homozygous recessive (rr) individual with a individual with a individual with a dominant trait (RR or Rr) • Used to identify the genotype of a individual with a dominant trait Karyotype • Picture of chromosome – Used to identify sex of unborn child – Used to identify genetic disorders caused by nondisjunction Making a karyotype – Amniocentesis • Fetal cells removed from amniotic fluid of pregnant mother – Cells stained, picture taken and chromosomes arranged from largest to smallest • Identifying sex using karyotype – Male: X and Y chromosome – Female: XX chromosomes • Identifying genetic disorders caused by nondisjunction – Ex) Down’s Syndrome • Trisomy 21 (3 chromosome 21’s) Klinefelter's Syndrome (XXY) Turner Syndrome (XO) O = missing chromosome Down Syndrome: Trisomy 21 Cri-du-chat: “meow” when laugh (deletion mutation chromosome 5) • Monosomy X (Turner's syndrome): XO individuals are genetically female, however, they do not mature sexually during puberty and are sterile. Short stature and normal intelligence. (98% of these fetuses die before birth) • 47, XYY males: Individuals are somewhat taller than average and often have below normal intelligence. • Klinefelter syndrome: 47, XXY males. Male sex organs; unusually small testes, sterile. Breast enlargement and other feminine body characteristics. Normal intelligence. • Edward's syndrome (trisomy 18): almost every organ system affected 1:10,000 live births. Children with full Trisomy 18 generally do not live more than a few months. • Patau syndrome (trisomy 13): serious eye, brain, circulatory defects as well as cleft palate. 1:5000 live births. Children rarely live more than a few months. • Down syndrome (trisomy 21): The result of an extra copy of chromosome 21. Down syndrome affects 1:700 children and alters the child's phenotype either moderately or severely: characteristic facial features, short stature; heart defects, susceptibility to respiratory disease, shorter lifespan , prone to developing early Alzheimer's and leukemia , often sexually underdeveloped and sterile, usually some degree of mental retardation. Nondisjunction • When a homologous pair (tetrad) does NOT separate during anaphase of meiosis • Result: 1 cell has extra Chromosome (trysomy), other cell has 1 less chromosome (monosomy)