Mendel and Genetics. Mr. Nagel Meade High School

Mendel and Genetics Mr. Nagel Meade High School

Warm Up Meiosis Review Consider the following about Meiosis: How many daughter cells are created? How many chromosomes are in each daughter? What words could be used to describe the daughter cells? What events in Meiosis lead to nearly infinite possibilities in genetic variation?

IB Syllabus Statements 4.1.1 4.1.2 4.3.1 4.3.2 State that eukaryote chromosomes are made of DNA and proteins. Define gene, allele and genome. Define genotype, phenotype, dominant allele, recessive allele, codominant alleles, locus, homozygous, heterozygous, carrier and test cross. Determine the genotypes and phenotypes of the offspring of a monohybrid cross using a Punnett grid. 10.1.4 State Mendel s law of independent assortment. 10.1.5 Explain the relationship between Mendel s law of independent assortment and meiosis. http://click4biology.info/c4b/4/gene4.1.htm

What is inheritance? Question? Inheritance: Passing on traits by transmitting them from parents to offspring How does it relate to you personally? Why does it matter to you and your future family members?

Once Upon a Time Gregor Mendel (1865) Austrian Monk A PAIR of factors control the expression of each inherited trait in an organism Sutton (1900) These factors are on chromosomes Modern Thought These factors are called GENES and are segments of DNA

Give Peas A Chance Why use pea plants? What physical features could you monitor?

Factors Observed by Mendel

Mendel s First Experiment What are the genotypes for each seed? Which trait is dominant? Which trait is recessive? Is the parental Spherical seed homozygous or heterozygous?

Down With the Lingo? Gene Allele Genome Dominant Recessive Homozygous Heterozygous Self-Pollination Cross-Pollination Parental Generation Filial Generation Independent Assortment Segregation Genotype Phenotype

Down With the Lingo? Gene segment of DNA on a chromosome that controls a particular trait Allele equivalent of Mendel s factor - several alternative forms of a gene {one from each parent} Genome entire genetic makeup of an organism Dominant dominates the other factor of the trait Recessive masked in the presence of a dominant factor Homozygous when both alleles of a pair are the same Heterozygous when both alleles of a pair are NOT the same Self-Pollination mating with self (same plant) Cross-Pollination mating with a different plant Parental original generation Filial children (generation of offspring) Independent Assortment there is no connection AT ALL between any given inherited trait (color and height, etc.) Segregation two factors (alleles) that a parent possess for a trait are separated during egg/sperm formation Genotype genetic makeup of an organism Phenotype external appearance of an organism

Mendel and Meiosis Discuss with a partner: What does independent assortment mean in terms of what is observed in Meiosis? Hint: Linkage is when two traits are known to commonly exist together. What does segregation mean in terms of what is observed in Meiosis? Hint: Disjunction is when the chromosomes separate, sending one trait to each sex cell.

Punnett Grids Graphical representation of possible offspring Each parent occupies one side Each parental gene occupies one side of a box Based on ideas of Probability In Meiosis, there is a 50/50 possibility that each trait is passed on. (Think coin flip) Parental Genes Mom 1 Mom 2 Dad 1 Kid 1 Kid 2 Dad 2 Kid 3 Kid 4

Punnett Grids

Punnett Grids What are the two parental genotypes? What are the two parental phenotypes? What are the offspring s genotypes? Ratio? What are the offspring s phenotypes? Ratio?

Homozygous Dominant (YY) x Homozygous Recessive (yy) What are the two parental genotypes? What are the two parental phenotypes? What are the offspring s genotypes? Ratio? What are the offspring s phenotypes? Ratio? Parental Genes Dad 1 Dad 2 Mom 1 Kid 1 Kid 2 Mom 2 Kid 3 Kid 4

Homozygous Dominant (YY) x Heterozygous (Yy) What are the two parental genotypes? What are the two parental phenotypes? What are the offspring s genotypes? Ratio? What are the offspring s phenotypes? Ratio? Parental Genes Dad 1 Dad 2 Mom 1 Kid 1 Kid 2 Mom 2 Kid 3 Kid 4

Heterozygous (Yy) x Heterozygous (Yy) What are the two parental genotypes? What are the two parental phenotypes? What are the offspring s genotypes? Ratio? What are the offspring s phenotypes? Ratio? Parental Genes Dad 1 Dad 2 Mom 1 Kid 1 Kid 2 Mom 2 Kid 3 Kid 4

Warm Up Intro to Genetics Review How are Mendel s laws associated with our understanding of Meiosis? Independent Assortment? Segregation? Consider the trait for silliness. S (silliness) is dominant over s (serious). Create a Punnett Grid of a mating of two parents that are silly but produce a serious child.

IB Syllabus Statements 4.3.2 Determine the genotypes and phenotypes of the offspring of a monohybrid cross using a Punnett grid. 10.2.1 Calculate and predict the genotypic and phenotypic ratio of offspring of dihybrid crosses involving unlinked autosomal genes. 4.3.3 State that some genes have more than two alleles (multiple alleles). 4.3.4 Describe ABO blood groups as an example of codominance and multiple alleles. 4.3.5 Explain how the sex chromosomes control gender by referring to the inheritance of X and Y chromosomes in humans. 4.3.6 State that some genes are present on the X chromosome and absent from the shorter Y chromosome in humans. 4.3.7 Define sex linkage. 4.3.8 Describe the inheritance of colour blindness and hemophilia as examples of sex linkage. 4.3.9 State that a human female can be homozygous or heterozygous with respect to sex-linked genes. 4.3.10 Explain that female carriers are heterozygous for X-linked recessive alleles. 4.3.11 Predict the genotypic and phenotypic ratios of offspring of monohybrid crosses involving any of the above patterns of inheritance. http://click4biology.info/c4b/4/gene4.3.htm

Dihybrid Cross Parental Genes Dad 1 Dad 2 Dad 3 Dad 4 Mom 1 Kid 1 Kid 2 Kid 3 Kid 4 Mom 2 Kid 5 Kid 6 Kid 7 Kid 8 Mom 3 Kid 9 Kid 10 Kid 11 Kid 12 Mom 4 Kid 13 Kid 14 Kid 15 Kid 16

Parental Genes Homozygous Dominant (TTYY) x Homozygous Recessive (ttyy) Dad 1 Dad 2 Dad 3 Dad 4 Mom 1 Kid 1 Kid 2 Kid 3 Kid 4 Mom 2 Kid 5 Kid 6 Kid 7 Kid 8 Mom 3 Kid 9 Kid 10 Kid 11 Kid 12 Mom 4 Kid 13 Kid 14 Kid 15 Kid 16

Parental Genes Heterozygous (TtYy) x Heterozygous (TtYy) Dad 1 Dad 2 Dad 3 Dad 4 Mom 1 Kid 1 Kid 2 Kid 3 Kid 4 Mom 2 Kid 5 Kid 6 Kid 7 Kid 8 Mom 3 Kid 9 Kid 10 Kid 11 Kid 12 Mom 4 Kid 13 Kid 14 Kid 15 Kid 16

Codominant I Imagine a cat that is black, and another that is white. What if all the offspring were gray? What if half the offspring were gray and half were white? Parental Genes Dad 1 Dad 2 Mom 1 Kid 1 Kid 2 Mom 2 Kid 3 Kid 4

Codominant II Consider two parents, one with type A blood and one with type B. How could a child of this mating have type O blood? Parental Genes Dad 1 Dad 2 Mom 1 Kid 1 Kid 2 Mom 2 Kid 3 Kid 4

Sex-Linked I Imagine a colorblind mom mating with a noncolorblind dad. What predictions could you make about the offspring? What do you notice about the boys? Parental Genes Dad 1 Dad 2 Mom 1 Kid 1 Kid 2 Mom 2 Kid 3 Kid 4

Sex-Linked II Imagine a hemophilic dad mating with a nonhemophilic mom. What predictions could you make about the offspring? Parental Genes Dad 1 Dad 2 Mom 1 Kid 1 Kid 2 Mom 2 Kid 3 Kid 4

Testcross What if we know the offspring phenotypes and/or genotypes, but don t know one of the parents? Breed with a homozygous recessive! Parental Genes Dad 1 Dad 2 Mom 1 Kid 1 Kid 2 Mom 2 Kid 3 Kid 4

Fun With Traits Pick a few traits from the list below: Dominant Widow s peak Dimples Bent little finger Mid-digital hair Dwarfism L-over-R Thumb folding Detached Earlobes Tongue Rolling Recessive Hitch-hiker s Thumb (90 ) Chin cleft Sex-Linked Hemophilia Red-green Colorblindness Male Pattern Baldness Co-Dominant Blood type Flower Color (Red/White) Map out a Punnett Square based on the trait you selected, where mom and dad are both heterozygous for the condition or trait.

Where are Genes Located? http://www.ncbi.nl m.nih.gov/books/n BK22266/

Assessment Imagine a parent that is blue and another that is red. Construct a Punnett Square for each that demonstrates this mating if: ALL the offspring are Blue. ALL the offspring are Purple. HALF of the offspring are Red. (2) Parental Genes Dad 1 Dad 2 Mom 1 Kid 1 Kid 2 Mom 2 Kid 3 Kid 4

Warm Up Genetics Review Consider a parent with type A blood. What type of parental mating would determine the parent s genotype? What is called? The parent is found to have the genotype Ao. List the possible offspring with a parent with genotype AB. What was the probability of having a child with the type blood: AB A

Gizmo Observe outcomes predicted in Punnett Grids for: Single Trait Two traits Aliens Codominance

Warm Up Genetics Review Consider the following situation. Two parents, one possessing Nagel s Disease and one perfectly healthy, mate. Describe the mode of inheritance and construct a Punnett Grid if: None of the children are visibly affected. (2 possible) Half of the children are visibly affected. Only the male offspring have the disorder.

IB Syllabus Statements 4.3.12 Deduce the genotypes and phenotypes of individuals in pedigree charts. http://click4biology.info/c4b/4/gene4.3.htm

Pedigrees http://www.sciencecases.org/hemo/hemo.asp

Let s take a look at Queen Victoria s son Leopold s family. His daughter, Alice of Athlone, had one hemophilic son (Rupert) and two other children a boy and a girl whose status is unknown. What is the probability that her other son was hemophilic? What is the probability that her daughter was a carrier? Hemophilic? What is the probability that both children were normal? Pedigrees

Now for the Spanish connection: Victoria s youngest child, Beatrice, gave birth to one daughter, one normal son, and two hemophilic sons. Looking at the pedigree of the royal family, identify which of Beatrice s children received the hemophilic gene; why can you make this conclusion? Notice that Beatrice s daughter, Eugenie, married King Alfonso XIII of Spain and had six children, one of whom was the father of Juan Carlos, the current King of Spain. Would you predict that Juan Carlos was normal, a carrier, or a hemophilic? What is the probability that her unnamed son was hemophilic? Pedigrees

Lastly, the royal line of Russia. What are the probabilities that all four of the girls were carriers of the allele hemophilia? Supposing Alexis had lived and married a normal woman, what are the chances that his daughter would be a hemophiliac? What are the chances his daughters would be carriers? What are the chances that his sons would be hemophiliacs? Pedigrees

Pedigree Practice Use the worksheets in small groups to determine the genotypes and phenotypes of the given subjects.

Warm Up Chi Square Test for Dihybrid Cross Chi Square Problem: An ear of corn has a total of 381 grains, including 216 Purple & Smooth, 79 Purple & Shrunken, 65 Yellow & Smooth, and 21 Yellow & Shrunken. Hypothesis: This ear of corn was produced by a dihybrid cross (PpSs x PpSs) involving two pairs of heterozygous genes resulting in a theoretical (expected) ratio of 9:3:3:1. Objective: Test the hypothesis using chi square and probability values. In order to test your hypothesis you must fill in the columns in the following Table. http://waynesword.palomar.edu/lmexer4.htm

Warm Up Chi Square Test for Dihybrid Cross Chi Square Problem: An ear of corn has a total of 381 grains, including 216 Purple & Smooth, 79 Purple & Shrunken, 65 Yellow & Smooth, and 21 Yellow & Shrunken. Hypothesis: This ear of corn was produced by a dihybrid cross (PpSs x PpSs) involving two pairs of heterozygous genes resulting in a theoretical (expected) ratio of 9:3:3:1. Objective: Test the hypothesis using chi square and probability values. In order to test your hypothesis you must compare your value to that on the chart. Degrees of Freedom =??? http://waynesword.palomar.edu/lmexer4.htm

Probability Lab Using pennies, we will model births to determine population statistics Then we will use math to make similar predictions Lastly, we will use pedigrees to illustrate why inbreeding allows recessive traits to become expressed frequently!

Warm Up Inheritance Given the parents AaBbCcDd and aabbccdd: What are the chances of a child aabbccdd? What are the chances of a child AaBbCcDd? What are the chances of a child AABBCCDD? What are the chances of a child aabbccdd?

IB Syllabus Statements 10.3.1 Define polygenic inheritance. 10.3.2 Explain that polygenic inheritance can contribute to continuous variation using two examples, one of which must be human skin colour. http://click4biology.info/c4b/10/gene10.3.htm

Polygenes Polygenes have an additive effect the more dominants you have, the more intense the feature: Fingerprint Ridge Count Eye Color Skin Color

Warm Up Meiosis What event in Meiosis I accounts for the shuffling of traits amongst non-sister chromatids? Given a parent AaBb, what is the probability that AB will be passed on? Which of Gregor Mendel s laws dictates this? Could this rule ever be broken?

IB Syllabus Statements 10.2.1 Calculate and predict the genotypic and phenotypic ratio of offspring of dihybrid crosses involving unlinked autosomal genes. 10.2.3 Explain how crossing over between non-sister chromatids of a homologous pair in prophase I can result in an exchange of alleles. 10.2.4 Define linkage group. 10.2.5 Explain an example of a cross between two linked genes. 10.2.6 Identify which of the offspring are recombinants in a dihybrid cross involving linked genes. http://click4biology.info/c4b/10/gene10.2.htm

What would you do? William Bateson & R.C. Punnett (early 1900s) Sweet pea plants PpLl x PpLl P = purple eyes p = red eyes L = long pollen l = round pollen Phenotype Expected (9:3:3:1) Observed Purple, Long 3911 4831 Purple, Round 1303 390 Red, Long 1303 393 Red, Round 435 1338 TOTAL 6952 6952

Plant height tall-dwarf Le-le 4 http://users.rcn.com/jkimball.ma.ultranet/biologypages/l/linkage.html Why does this happen? Genes located on the same chromosome exhibit this behavior if they are close to each other, but Genes on far ends of the same chromosome act nearly independent thus Gregor Mendel got really lucky! Trait Phenotype Alleles Chromosome A A a a Seed form round-wrinkled R-r 7 Seed color yellow-green I-i 1 B B b b Pod color green-yellow Gp-gp 5 Pod texture smooth-wrinkled V-v 4 Flower color purple-white A-a 1 Flower location axial-terminal Fa-fa 4

Read about it! http://biology.clc.uc.edu/courses/bio105/s ex-link.htm

So what? Genes can be mapped based on their distance apart Closer = less likely crossing over occurs A map unit is 1 cm, or centimorgan, and represents a 1% cross over rate Shout out to Morgan s work with flies and discovering crossing over

Gene Maps In The Modern Age http://www.ncbi.nlm.nih.gov/books/nbk22 266/

Recombinants Recombinants Products of meiosis with allelic combinations different from those of the haploid cells that formed the meiotic diploid. RESULT OF CROSSING OVER! Re-combined DNA These appear as the lower than expected values in the observed matings