Topic XIII: Heredity: Mendelian Genetics

Day 1: Lesson Objectives Explain the principles of segregation and independent assortment Identify and explain Dominant and Recessive inheritance

Review Our DNA is our genetic __________________ Our DNA is distributed between ___________ chromosomes We have two copies of every ______________ Genes are specific segments of DNA that determine an organism’s _________________ We have two copies of each ______________

Allele The different __________ of a gene -we have _________ copies of every gene

Principle of Segregation During reproduction, sexually reproducing organisms only pass on ________ of their genetic material  ONLY PASS ON ___________OF YOUR ____________COPIES OF EACH GENE The Principle of Segregation states that _____________separate during gamete (sperm and egg) formation so ONLY ONE GENE IS ______________________ON

Dominant Recessive Trait _____________ or seen -TT- Tall -Tt – Tall -Must have a __________________ __________to be dominant Trait _________________ or not seen if ________________allele is present also – Tt – tall – tt- short

Principle of Dominance The Principle of ______________________ states that some alleles are dominant while others are ________________________

Homozygous Heterozygous ____________alleles are the same -TT- homozygous ________________ -tt – homozygous recessive Each allele is __________________ – Tt – heterozygous

Genotype Phenotype The ________________ make-up of an organism – Homozygous or heterozygous The _______________ appearance of an organism

Weird Genetics Terminology ______: generation: these are the parents ______: these are the offspring of the P generation – The “kids” of the P generation ______: these are the offspring of the F1, – The “grandchildren” of the P generation

Dominant vs Recessive T t ___ t TT Tt ___ Tt Genotype TT =25% or 1 Tt= 50% or 2 tt- 25% or 1 Results: 1:2:1 Phenotype tall = 75 % short = 25% 3:1 tall to short T- tall t – short Cross - Tt (MOM) x Tt (DAD)

Let’s Practice Together Round seeds are dominant to wrinkled seeds. A homozygous dominant plant is crossed with a homozygous recessive plant. What is the probability of the F1 plants having wrinkled seeds?

Genotype of Parent 1: ___________________ Genotype of Parent 2: ___________________ Cross of P generation: ___________________

Punnett Square R- Round r – wrinkled Cross - _______ (MOM) X ______ (DAD) What is the probability of having a wrinkled seed? __________________

What is the probability of a wrinkled seed in the F2?

Punnett Square R- Round r – wrinkled Cross - ______ (MOM) X ________ (DAD) What is the probability of having a wrinkled seed? __________________

Day 2: Lesson Objectives Identify and explain various patterns of inheritance: Incomplete Dominance, Codominance, polygenic inheritance, and multiple alleles

Trait mixed C R C R = Red C R C W = Pink C W C W = White Incomplete Dominance

Definitions ___________________Dominance: When an organism has ______________different alleles, the phenotype is intermediate to the two alleles – ____________________________has phenotype intermediate to parental phenotypes _______________________: When an organism has two different alleles, the phenotype expresses _______________________alleles – Both phenotypes of the parents are expressed

Incomplete Dominance CRCRCRCR CRCRCRCR CWCWCWCW C R C W C R C W CRCWCRCWCRCWCRCW CWCWCWCW CRCWCRCWCRCWCRCW CRCWCRCWCRCWCRCW “ INC” === “PINK” NOTE: we now use two letters for each gene in place of one. The capitol letter represents the gene (in this case the color gene) while the superscript letter represents the different alleles (Red or White here)

Codominance CRCRCRCR CRCRCRCR CWCWCWCW C R C W C R C W CRCWCRCWCRCWCRCW CWCWCWCW CRCWCRCWCRCWCRCW CRCWCRCWCRCWCRCW _____________types are a great example of codominance: Type A: homozygous A or A and O Type B: homozygous B or B and O Type AB: heterozygous A B Type O: homozygous O NOTE: we now use two letters for each gene in place of one. The capitol letter represents the gene (in this case the color gene) while the superscript letter represents the different alleles (Red or White here)

1)A heterozygous black mouse breeds with a homozygous white mouse. What is the probability of their offspring being white? Black? What kind of inheritance is this? ________________________________ ______________________________

2) A homozygous black guinea pig is crossed with a heterozygous gray guinea pig. What kind of inheritance is this? __________________________________________ What is the probability of having black offspring? __________________________________________ What percent of the offspring are expressing incomplete dominance? ___________________________________________

3) There is a family of guinea pigs where one offspring is gray, three offspring are black, and two are white. What are the genotypes of the mother and father? _____________________________________ _____________________________________ _____________________________________

4) A green and orange striped flower is being crossed with a solid orange flower. What are the phenotypes and genotypes of their offspring? ________________________________________ What kind of inheritance is this? _______________________________________ What percent of the offspring are expressing codomiance? _________________________________________

Definitions ___________________Inheritance: Many genes affecting one phenotypic trait – __________________and skin color in human – Not just one gene controlling a trait ___________________Alleles: Occurs when there are more than two alleles in a gene pool. – Remember, each individual can only have 2 alleles – _________________________in humans – there are three alleles: A, B, and O

Day 3: Lesson Objectives Identify and explain sex-linked inheritance Analyze a pedigree chart to determine the pattern of inheritance

Sex-Linked Inheritance ____________linked inheritance deals with chromosome number _______________ Males have one ________ chromosome and one _________ chromosome: _________ Females have two _____ chromosomes: ____ We will be talking about traits on the _________ chromosome

Sex-Linked Inheritance Remember that to show a recessive trait, _____of your alleles must be the ____________ trait – Example: to be a short tree, you must be _______ ____________ are more likely to show sex- linked recessive traits. Why? – Because males only have ________ X chromosome so one copy of the recessive ___________will cause the recessive __________

Sex-Linked Inheritance It is possible for a _____________to be a carrier of an _______________ recessive trait. It is not possible for a ____________to be a carrier

B » B----- ______ » b----- ______ ______

Let’s Practice Together!!! Hemophilia is a sex-linked, recessive trait. What is the probability of hemophilia in the offspring of a man who does not have hemophilia and a woman who is a heterozygous carrier? ___________________ What is the probability of males having hemophilia? __________________________ What about females? ___________________

Sex-Linked Inheritance XYXY XXhXhXXhXh XX XY XX h XhYXhYXhYXhY

Your turn Color-blindness is a sex-linked recessive trait. What is the probability of an affected male and a carrier female producing an affected offspring? _____________________________ An affected male? ______________________ An affected female? _____________________

Pedigree Chart- is a chart which tells you all of the known _________________and ______________________for an organism and its ancestors, most commonly humans.

Steps to Interpreting a Pedigree Chart 1. Determine if the pedigree chart shows an _______________or X linked disease. – Autosomal---non-sex genes (Chromosome # __________) – Sex Genes (X or Y)---Chromosome # ____________ – If most of the males are affected, then the disorder is _____________________. – If it is a 50/50 ratio between men and women, then the disorder is ________________________.

Steps to Interpreting a Pedigree Chart 2. Determine whether the disorder is _______________or _________________. – If the disorder is dominant, _____________of the parents must have the disorder. – If the disorder is recessive, ________________of the parents could have the disorder because their parents’ genotype could be _______________________.

Rules of Inheritance Autosomal Recessive – Appears in ____________ sexes with equal frequency – Trait tends to ____________ generations – Affected _____________________ are usually born to unaffected parents – When both parents are heterozygous, ______________ of their offspring will be affected. Autosomal Dominant – _______________sexes transmit the trait to their offspring – __________________ skip generations – When one parent is affected (hetero), and the other parent is not, approximately _______________ of the offspring will be affected. – _________________parents do not transfer the trait. So, affected offsprings must have an _________________parent.

Pedigree Charts

Example 1

Example 2

Example 3

Example 4

Rules of Inheritance X-Linked Dominant – ____________males and females are affected. – Mostly ____________________are affected. – Does not skip generations – Affected ________must have an affected mother. – Affected daughters must have an affected mother or father. – Affected father will pass the trait to all of his daughters. – Affected mothers if heterozygous will pass the trait to _____________ of their sons and ____________ of their daughters. X-Linked Recessive – _____________males than females are affected – ______________ generations – Affected sons are usually born from unaffected mothers – Approximately ________________ of carrier’s mothers’ sons are affected – It is never passed from father to son – _____________daughters of affected fathers are carriers.

Let’s Practice- Explain how the last generation acquired their genotypes?