FUNDAMENTALS OF GENETICS USEFUL MATERIALS Video- Garden of Inheritance Guinea Pig Work sheet Text pages Worksheet and word search

Vocabulary 90. Independent assortment Monohybrid cross True breeding Cross pollination Self pollination Alleles Homozygous dominant Heterozygous Homozygous recessive Genotype Phenotype 101. Test cross Read:

Remember this about chromosomes? X = shorthand for chromosomes 46 total – 23 from mom and 23 from dad (23 pairs) centromere Chromatids (2)

Types of Chromosomes Autosomes – do not determine sex (1-22) Sex Chromosomes – determine sex (X and Y) = 23 rd –XY – male –XX - female

Hereditary Terms Trait – genetic characteristic of an organism Gene – DNA sequence that codes for a protein (may lead to a trait) Allele – different forms of a gene

I. Principles of Heredity There are two factors which determine what and who you are, or what an organism looks like and how it behaves. –HEREDITY - the genetic make-up –ENVIRONMENT- conditions during development Is it “NATURE OR NURTURE” that determines the ultimate product? –Studies on TWINS are inconclusive

II. PARADOX OF HEREDITY A paradox is a seeming contradiction. –“Success is measured sweetest by those who never succeed.” – Dickens –“We are most lonely at times when we are among many men” H. D. Thoreau –Consider a situation in which a father and his son are driving down the road. The car collides with a tree and the father is killed. The boy is rushed to the nearest hospital where he is prepared for emergency surgery. On entering the surgery suite, the surgeon says, "I can't operate on this boy. He's my son."

So what is the paradox of heredity? Why are some characteristics inherited exactly and others are variable? –Species Characteristics: 5 fingers, walk erect, nervous system, appendix, 2 eyes –Individual Characteristics: height, hair color, skin color, hair line

Diagram 2 homologous pairs of chromosomes with alleles on each pair X

Useful Terms Do you remember these? Trait: characteristic of an organism. Gene: piece of DNA that codes for a protein. Allele: different forms of a gene. Phenotype- observable feature 9eye color, hair color, blood type) Genotype- arrangement of alleles (Aa, Tt, Bb Gg)

Useful Terms Do you remember these? P generation (parental): true breeding F 1 (first filial) offspring of P generation F 2 (second filial) offspring from F 1 cross

III. History Gregor Mendel: Austrian Monk ( ) –Published the results of scientific research on Garden Peas (Pisium sativum) in Why study peas? –Great natural variation- stem length, seed color, pod shape,pod color, small, edible, easy to grow, many offspring, easy to cross fertilize, grow well in tne climate

Floral Anatomy pollination fertilization

Floral Anatomy

IV. EXPERIMENTAL CROSSES FOR INDIVIDUAL TRAITS Must begin with PURE BREEDING parents: HYBRID offspring F1 First Filia Generation Cross Pollination P yellow X green tall X short wrinkled X round F1 yellow tall round these are TEST CROSSES to determine dominance and recessiveness

allowed to Self Pollination F1 yellow X yellow Tall X Tall Round X Round F2 3 yellow 1 green 3 tall 1 short 3 round 1 wrinkled **Large sample sizes are needed to get an accurate picture of the frequency P red X white F1 red (self) F2 705 red 224 white P yellow X green F1 yellow

V. PUNNETT SQUARE Method for determining possible allele combination for the offspring Gametes outside Offspring Inside

Who was Punnett? REGINALD CRUNDALL PUNNETT ( ) was among the first English geneticists. He created the “Punnett Square” – a diagram to work out the possible allele combinations of the offspring of two parents.

How are gametes produced? Meiosis! –Where does this process happen in a flower? If a person is a tongue roller with the genotype Tt, what happens to the alleles during meiosis? Draw the process.

Draw summary and short hand of meiosis with 1 pair of chromosomes

Tongue Rolling

Chromosomes with alleles Gene: tongue rolling Alleles: T- can roll t – unable to roll X

VI. TEST CROSSES Monohybrid (one feature ) Dihybrid (two features)

Some more terms… Homozygous Dominant – TT – given two dominant alleles from parents Homozygous Recessive – rr – given two recessive alleles from parents Heterozygous – Gg – given one dominant allele and one recessive allele from parents

Tall P Dwarfx F1 All Tall Phenotype One Example of Mendel’s Work Clearly Tall is Inherited… What happened to Dwarf? F1 x F1 = F2 F2 3 / 4 Tall 1 / 4 Dwarf Dwarf is not missing…just masked as “recessive” in a diploid state… there IS a female contribution. 1.Tall is dominant to Dwarf 2.Use D/d rather than T/t for symbolic logic DDdd Dd Genotype Homozygous Dominant Homozygous Recessive Heterozygous Dwarf dd Tall Dd d Tall Dd Tall DD D dD Punnett Square: possible gametes

Unknown TallDwarfx Mendel as a Scientist dd Tall Dd Tall Dd D Tall Dd Tall Dd D dd possible gametes F1 x F1 = F2 F2 Dwarf dd Tall Dd d Tall Dd Tall DD D dD Punnett Square: possible gametes Test Cross: If Unknown is DD: Dwarf dd Dwarf dd d Tall Dd Tall Dd D dd possible gametes If Unknown is Dd: Test Progeny All Tall Test Progeny Half Tall Half Dwarf 1 / 3 of F2 Tall are DD 2 / 3 of F2 Tall are Dd

Unknown YellowGreenx Mendel as a Scientist gg Yellow Gg Yellow Gg G Yellow Gg Yellow Gg G gg possible gametes Test Cross: If Unknown is GG: Green gg Green gg g Yellow Gg Yellow Gg G gg possible gametes If Unknown is Gg: Actual ResultsDecision 3 Yellow 2 GreenGg 2 Yellow 3 Green Gg 1 Yellow 4 GreenGg 0 Yellow 5 GreenGg 4 Yellow 1 Green Gg 5 Yellow 0 Green GG <5% chance unknown is Gg 1 / 2 1 / 2 1 / 2 1 / 2 1 / 2 = 1 / 32 It only takes 1 green to be sure the unknown is Gg! Small families do not follow expected ratios perfectly! You could be wrong (rarely)! Rare, but it can happen!

Setting up a Punnett Square BB b b Bb Brown eyes (B) are dominant to blue eyes (b) Cross a homozygous brown-eyed person with a blue-eyed person BB vs. bb What is the probability of having an offspring with heterozygous brown eyes? 4/4 or 100%

Another Example Tongue rolling(T) is dominant to non- tongue rolling (t) Cross a homozygous tongue roller with a heterozygous tongue roller TT vs. Tt TT T t TT Tt What are the genotype possibilities? 2/4 or 50% TT and 2/4 or 50% Tt

Practice Problems Pea Plants: green – Gyellow – g GG x gg GG x Gg Gg x gg Gg x Gg Genotypic/phenotypic ratios:

GG x Gg

Gg x gg

Gg x Gg

A normal pigmented male (who has an albino mom) and an albino female get married and have two children. What are the phenotypic ratios and genotypic ratios? What alleles will you use? Genotypic Ratio: Phenotypic Ratio:

Some more practice problems: Two “normal” heighted but heterozygous people have a child who is a midget. The wife is pregnant. What is the chance that their second child will be of normal height? What alleles will you use? Genotypic Ratio: Phenotypic Ratio:

Dimples is a dominant trait. A heterozygous mom and a homozygous recessive dad have a child. What is the phenotypic ratio and genotypic ratio of the possible offspring? What is the genotype and phenotype of the parents?

Finding phenotypes and genotypes for 2 traits. Read lab Observed ratio- a record of the results of an event that has occurred Expected ratio- mathematically calculated results of an event prior to it occurring

Finding phenotypes and genotypes for 2 traits. Chance- not planned, accidental, not expected Sample Size- number of events recorded large sample side is needed to reduce the influence of chance and allow the true patterns to emerge.

Dihybrid Cross Cross 2 pea plants that are both heterozygous purple flowered and heterozygous for smooth seeds. P= purplep= white N= non-wrinkled (smooth)n= wrinkled Step 1: Figure out the different gametes for each parent Step 2: Set-up the cross and complete Step 3: Calculate the genotypic and phenotypic ratios

VII. Mendel’s Laws Mendel was a patient and keen observer. Some characteristics mask others yet reappear. –Principle of Dominance and Recessiveness Features can skip a generation. Theorized there were 2 factors for each trait. –Principle of Segregation of Alleles Pairs of factors separate into gametes without influenceing each other. –Principle of Independent Assortment

PTC tasting

Reality Show? Do you recognize this family? *Hint: They are from a TV show

They are the Roloff family from TLC’s show Little People Big World How are the members of this family the same? How are they different?

Great! You probably noticed that the family members share facial features, hair color etc. They are different because of their height Some family members (including the parents) exhibit the characteristic short stature of Achondriplasia, a dominant genetic disorder that results in a form of dwarfism.

How is it possible for Matt and Amy (the parents) to have a child like Zach with Achondriplasia and three children who do not have the disease?

The key is understanding dominant and recessive genes and the concept of segregation

Zach and Jeremy are Fraternal Twins – what does that tell us about their genes? Fraternal twins have genes that are different - genetically, they are no more similar than any other set of siblings. If Zach and Jeremy were Identical Twins, how would this picture change? Both boys would either display the short stature of Achondriplasia or be of normal height – Identical twins have identical genes! Zach Jeremy

Quiz Topics –FRIDAY 3/5 Read: Vocab Worksheets (pg 127 and pg 129) Mendel and his laws Terminology (P, F1, F2, heterozygous, homozygous dom, homozygous rec, phenotype, genotype, trait, gene, allele) Monohybrid vs Dihybrid crosses Doing monohybrid problems

Review Questions RRTT RrTt RRtt Rrtt List gametes possible from these parents

(T) is the allele for tall humans and is dominant over the allele (t) for short humans. The allele for widows peak (W) is dominant over (w) non-widows peak hairlines. What are the phenotypes for the following parents? TtWw - _________________ TTww - _________________ What are the possible gametes formed by the parents listed above? AND

1. A woman with free ear lobes marries a man with attached ear lobes. Two of their children have attached ear lobes and two have free ear lobes. The alleles are (E) - free (e) - attached A. what is the genotypes of the woman? B. what is the genotype of the man? C. What are the chances of the 5th child having free ear lobes?

(F) striped fur is dominant over (f) white fur in Australian cats. What is the result of a cross between a homozygous recessive parent and a heterozygous parent? Give phenotypic ratios and genotypic ratios. Genotypic Ratio: Phenotypic Ratio: