Inheritance and Genetics

1. Inheritance and Genetics BI30-GB1 Explore classical (i.e. Mendelian) and current (i.e. chromosomal) understandings of biological inheritance.

2. Indicators • (a) Pose questions about why and how offspring only inherit some traits from their parents. ((S, A) • (b) Explore patterns of inheritance by interpreting pedigrees, including your own family tree. ((K, A, S) • (c) Discuss the historical development of Mendelian genetics, including why Gregor Mendel is considered the "father of genetics". ((STSE, K) • (d) Discuss the importance of probability in predicting the likelihood of inheriting particular traits. ((K) • (e) Distinguish among patterns of inheritance (e.g., dominant and recessive alleles, sex-linked traits, codominance, incomplete dominance, multiple alleles and polygenic inheritance) of heritable traits. ((K) • (f) Determine an organism's phenotype from its genotype, and where possible, its genotype from its phenotype. ((S, K) • (g) Construct Punnett squares for monohybrid crosses using P1 genotypes (i.e., homozygous and heterozygous) to determine genotypic and phenotypic frequencies for F1 and F2 generations. ((S) • (h) Describe how gene flow, genetic drift and natural selection influence the frequency of alleles within a population. ((K) • (i) Recognize that scientists now understand chromosomes to be the mechanism of Mendel's laws (i.e., law of segregation, law of independent assortment and law of dominance). ((STSE, A, K) • (j) Investigate the importance of meiosis, including crossing-over, in creating genetic variation in gametes and non-disjunction in creating chromosomal abnormalities. ((K) • (k) Identify, using karyotypes, chromosomal abnormalities and how these abnormalities may lead to chromosomal disorders such as Klinefelter syndrome, Down syndrome and Turner syndrome. ((K, S)

3. InheritancePose questions about why and how offspring only inherit some traits from their parents. ((S, A) Questions about Petlak’s family (dad side) • What is inheritance? • Why do we only get some traits from our parents? • How does genetic information get passed from parents to offspring? • How does this connect to evolution?

4. InheritancePose questions about why and how offspring only inherit some traits from their parents. ((S, A) • What is inheritance? Transfer of genetic information • Why do we only get some traits from our parents? Mutation, dominant/recessive traits • How does genetic information get passed from parents to offspring? Combination of gametes in sexual reproduction • How does this connect to evolution? Those most able to survive, reproduce and pass on their genetics – in theory they should be even better as offspring is a combination of two “successful” individuals.

5. Importance of Inheritance • Why is it important to know about inheritance? • Why might knowing about dominant and recessive genes be important when considering offspring? • We’ll hopefully discuss my 23andMe.ca results – but why would I get that done?

6. Importance of Inheritance • Why is it important to know about inheritance? • To get an understanding of potential health problems you have to deal with (some conditions are inherited). • Could increase sense of self – better understanding your genes/family’s genes • Why might knowing about dominant and recessive genes be important when considering offspring? • Knowing about your partner’s genetic make-up could help you avoid the occurrence of genetic conditions that may be recessive or problematic. • We’ll hopefully discuss my 23andMe.ca results – but why would I get that done?

7. Patterns of InheritanceExplore patterns of inheritance by interpreting pedigrees, including your own family tree. ((K, A, S) • When determining inheritance we need to look at the __________’s of organisms in addition to their _____________ and ____________. • Many traits that we look at we need to determine whether they are found on _______________ (X,Y) or __________ (the other 22 pairs). • How does a particular trait look in our __________ (record of descent of an organism)?

8. Patterns of InheritanceExplore patterns of inheritance by interpreting pedigrees, including your own family tree. ((K, A, S) • When determining inheritance we need to look at the genome’s of organisms in addition to their genotypes and phenotypes. • Many traits that we look at we need to determine whether they are found on sex chromosomes (X,Y) or autosomes (the other 22 pairs). • How does a particular trait look in our pedigrees (record of descent of an organism)?

9. PedigreesExplore patterns of inheritance by interpreting pedigrees, including your own family tree. ((K, A, S) • Pedigrees help us establish ______________ and determine ____________________________________________ . • They are useful in identifying __________________ that children hold and whether or not they may be ______________ . • Functions as a ____________________________ . Can be animal-breed specific, or characteristic specific.

10. PedigreesExplore patterns of inheritance by interpreting pedigrees, including your own family tree. ((K, A, S) • Pedigrees help us establish family trees and determine potentialphenotypes/genotypes of offspring. • They are useful in identifying characteristics (good or bad) that children hold and whether or not they may be genetically linked. • Functions as a record of descent. Can be animal-breed specific, or characteristic specific.

12. This assumes one partner mating. What if a male/female has offspring with another partner?

13. Creating a PedigreeExplore patterns of inheritance by interpreting pedigrees, including your own family tree. ((K, A, S) • Pick a trait that you think is a dominant/recessive trait in your family (baldness, hair colour, etc). Feel free to google search background information on a trait if you wish. • Create a three-generation pedigree of your lineage (from yourselves to your grandparents) to see if the pedigree created actually represents this. • We will draw an example on the next page.

14. Example Pedigree: Petlak’s Family • Pick a trait – start creating symbols for family members. • Drawing a Pedigree:

15. Example Pedigree: Petlak’s Family • Pick a trait – start creating symbols for family members. • Drawing a Pedigree:

16. Example Pedigree: Petlak’s Family • Pick a trait – start creating symbols for family members. • Drawing a Pedigree:

17. Pedigree ReflectionDiscussion following creation of family tree/pedigree. • Do certain people having certain traits agree with the inheritance you expected? • Why might you not have a trait that your father has? • This emphasizes the ____________________ in genetics.

18. Pedigree Reflection • Do certain people having certain traits agree with the inheritance you expected? Not all of them should. There may be confused questions of: “Why don’t I have this?” “Why am I different from both mom and dad?” • Why might you not have a trait that your father has? Might have been a recessive trait, mom may have a dominant trait that “masks” it? Maybe other genes are influencing the activation of that gene? Maybe environmental factors your father was exposed to you haven’t been? Maybe there was mutations that occurred in your sperm that has brought about new subtle changes? • This emphasizes the role of probabilityin genetics.

19. Gregor Mendel • Who is he?

20. Gregor Mendel • Who is he? Austrian Monk Lived a couple hundred years ago (1800s). Observed characteristics of peas.

21. Mendel’s Process

22. Mendel’s Laws – Chromosomes and Meiosis • _______________________- states that allele pairs separate or segregate during gamete formation, and randomly unite at fertilization. • _______________________- when two or more characteristics are inherited, individual hereditary factors assort independently during gamete production, giving different traits an equal opportunity of occurring together. • ______________________- one of the factors for a pair of inherited traits will be dominant and the other recessive, unless both factors are recessive. **These ideas arose then, but then as we learned more about chromosomes and DNA these scientific laws became reinforced/fine-tuned.

23. Mendel’s Laws – Chromosomes and Meiosis • Law of segregation - states that allele pairs separate or segregate during gamete formation, and randomly unite at fertilization. • Law of independent assortment - when two or more characteristics are inherited, individual hereditary factors assort independently during gamete production, giving different traits an equal opportunity of occurring together. • Law of dominance** - one of the factors for a pair of inherited traits will be dominant and the other recessive, unless both factors are recessive. **These ideas arose then, but then as we learned more about chromosomes and DNA these scientific laws became reinforced/fine-tuned.

24. Mendelian Genetics: Probability and Statistical Analysis • _______________ is the fundamental idea behind this. Possibility and chance abound and account for genetic diversity. • Analyzing the statistics leads to an overlap of math and science! We use math and likelihood of events to occur to make inferences about organisms’ offspring! • However, why might this not always be accurate?

25. Mendelian Genetics: Probability and Statistical Analysis • Probability is the fundamental idea behind this (what Mendel did). Possibility and chance abound and account for genetic diversity. • Analyzing the statistics leads to an overlap of math and science! We use math and likelihood of events to occur to make inferences about organisms’ offspring! • However, why might this not always be accurate?Genetics isn’t just “one gene codes for one trait”, multiple genes can code for one trait.

26. Mendelian Genetics - Vocabulary In order to observe/understand inheritance, there is certain terminology that must be understood. • ______________ = has a genotype composed of two different alleles. • ______________ = has a genotype composed of two of the same allele. • __________ = a copy of coding for a particular trait at a specific gene loci (one letter). A = capital letter means dominant. a = lower case letter means recessive. • __________ = location of coding for an organism’s genetics (DNA), typically for a specific characteristic – however, some phenotypes are coded by multiple loci. • ________ = basic unit of heredity. Ex. At a particular gene, you will have two alleles. • ________ = combination of alleles an individual possesses (Aa). • ________ = the visible expression of the genotype (the code means we see ________) (Aa = brown hair).

27. Mendelian Genetics - Vocabulary In order to observe/understand inheritance, there is certain terminology that must be understood. • Heterozygous = has a genotype composed of two different alleles. • Homozygous = has a genotype composed of two of the same allele. • Allele = a copy of coding for a particular trait at a specific gene loci (one letter). A = capital letter means dominant. a = lower case letter means recessive. • Gene loci = location of coding for an organism’s genetics (DNA), typically for a specific characteristic – however, some phenotypes are coded by multiple loci. • Gene = basic unit of heredity. Ex. At a particular gene, you will have two alleles. • Genotype = combination of alleles an individual possesses (Aa). • Phenotype = the visible expression of the genotype (the code means we see ________) (Aa = brown hair).

28. Mendelian Genetics - Vocabulary • Monohybrid Crosses – • Dihybrid Crosses – • Codominance – • Sex-linked – • Autosomes – • P, F1, F2 generations –

29. Mendelian Genetics - Vocabulary • Monohybrid Crosses (A monohybrid cross is a mating between two individuals with different alleles at one genetic locus of interest.) AA x aa • Dihybrid Crosses (A dihybrid cross is a mating between two individuals with different alleles at two genetic loci of interest.) AaBB x aaBB • Codominance – when two alleles are both represented in a phenotype. • Sex-linked – chromosomes/genes that are located on X or Y chromosome. • Autosomes – non-sex-linked chromosomes. • P, F1, F2 generations – parent, first gen of offspring, second gen of offspring

30. Monohybrid/Dihybrid Crosses - Punnett’s SquaresIf a male who was heterozygous for a trait mated with a female who was also heterozygous for the same trait… • Include potential combinations of parental genotypes to determine probability of offspring.P = parental generationF1 = first generation of offspringF2 = second generation of offspring (using offspring from F1)

31. Monohybrid/Dihybrid Crosses - Punnett’s SquaresIf a male who was heterozygous for a trait mated with a female who was also heterozygous for a trait… Phenotypic Ratio = 75% (or ¾) will express the dominant A allele; 25% (or ¼) will express the recessive a allele. Genotypic Ratio = ¼ AA; ½ Aa; ¼ aa OR 25% AA; 50% Aa; 25% aa • Include potential combinations of parental genotypes to determine probability of offspring.P = parental generationF1 = first generation of offspringF2 = second generation of offspring (using offspring from F1) • We can use the genotype to determine phenotype (if a represented hair colour and A = brown, a = blonde, we could predict likelihood of offspring).

32. Sample Dihybrid • White hair colour in horses is recessive (w), and brown hair is dominant (W). Long mane length is a dominant trait (M), and short mane length is a recessive trait (m). If a heterozygous male (for both traits), mates with a heterozygous brown-haired, homozygous long maned female, what is the phenotypic and genotypic ratios of offspring? What is the percent chance for the different phenotypes of offspring?

33. Test Cross QuestionPerforming a test cross and looking at offspring can help us determine genotypes, how? • Using a male, test cross horse (homozygous recessive for both traits = wwmm), we are trying to determine the genetic make-up of a brown, long-maned female. The offspring ratio for the phenotype was:100% brown and long-maned.What is the genotype of the unknown female? • If we use a full-recessive organism, if the organism they mate with has a dominant trait, it will show us and give us an idea of their genotype.

34. Mendelian Genetics - Vocabulary As we’ve established, certain phenotypes don’t fall into the binary-view of every trait having a dominant or recessive allele. A gene loci can have many different types of alleles. Or several genes can code or influence one particular trait. • Incomplete dominance – • Multiple alleles – • Polygenic inheritance -

35. Mendelian Genetics - Vocabulary As we’ve established, certain phenotypes don’t fall into the binary-view of every trait having a dominant or recessive allele. A gene loci can have many different types of alleles. Or several genes can code or influence one particular trait. • Incomplete dominance – one trait isn’t completely dominant over the other so you get a mixed phenotype. • Multiple alleles - we end up with two alleles for every trait in our phenotype (that doesn’t mean there aren’t more than two alleles for a trait). • Polygenic inheritance - occurs when one characteristic is controlled by two or more genes.

36. Genes and Natural SelectionExplore the factors (e.g., gene flow, genetic drift and natural selection) which influence the prevalence (i.e., expression and frequency) of genes and alleles within a population. (K) • What is natural selection and how might this connect to genetics? • If we reproduce, we contribute to the gene pool. What is the gene pool? • What is genetic drift again?

37. Genes and Natural SelectionExplore the factors (e.g., gene flow, genetic drift and natural selection) which influence the prevalence (i.e., expression and frequency) of genes and alleles within a population. (K) • What is natural selection and how might this connect to genetics? Only organisms with the phenotypes best suited to the environment survive and pass on their genetics. • If we reproduce, we contribute to the gene pool. What is the gene pool?Sum total of all genes available in a population. • What is genetic drift again?Random things can occur that affect the genetic makeup of a population. So certain genes and their associated phenotypes can disappear in evolutionary history.

38. Genes and Natural SelectionExplore the factors (e.g., gene flow, genetic drift and natural selection) which influence the prevalence (i.e., expression and frequency) of genes and alleles within a population. (K) • How does expression/frequency of alleles connect to natural selection? • How does genetic drift/gene flow connect? • In class – let’s pick a trait we can all observe, make-up a hypothetical selective pressure – and observe a change in allele frequency in the population as a result.

39. Genes and Natural SelectionExplore the factors (e.g., gene flow, genetic drift and natural selection) which influence the prevalence (i.e., expression and frequency) of genes and alleles within a population. (K) • How does expression/frequency of alleles connect to natural selection? A dominant or recessive allele that is beneficial is more likely to be passed on – when certain alleles equate to certain phenotypes that are beneficial, the presence of these alleles increases while others decrease in the gene pool. • How does genetic drift/gene flow connect?Random events can lead to the disappearance or decline of certain alleles in a population. • In class – let’s pick a trait we can all observe, make-up a hypothetical selective pressure – and observe a change in allele frequency in the population as a result.

40. This is something you’d get into more in AP Biology and University Biology Hardy-Weinberg and Evolutionp + q = 1 (p = dominant allele, q = recessive allele)p2 + 2pq + q2 = 1 (p2 = AA, pq = Aa, q2 = aa • We can actually use analysis of genes in a population to determine if evolution/change occurs using math. • If we observe an allele exists in the population with a frequency of 80% of members having it in a specific point in time, then after generations (time) we see it decline to 30%, we may infer that evolution is taking place because the frequency of that allele declines – it likely declined due to a change. • If we saw blonde hair increase in allele frequency in humans, despite being recessive, we may infer that a new selective pressure or influence on our evolution is that blondes may have a reproductive advantage or be more attractive.