Heredity: The passing of characteristics from parents to offspring

Genetics: The science of heredity and the process by which traits are passed from parents to offspring

P generation: The 1st two individuals that are crossed (parental generation) F1 generation : The offspring of the P generation (offspring of the parents) F2 generation: The offspring of the F1 generation (offspring of the F1 generation)

Mendel’s Hypotheses 1.) For each inherited character ( red, freckles, etc.), an individual has 2 copies of the gene – 1 from each parent

2.) There are alternative versions of the gene known as alleles Brown Hair Blonde Hair Red Hair Black Hair 2.) There are alternative versions of the gene known as alleles

Mother: Brown Hair Father: Blonde Hair Child: Brown Hair 2.) Two different alleles occur together, one of them may be completely expressed while the other shows no observable appearance

R = dominant allele For example R = red hair Rr or RR The expressed form a characteristic as: Dominant R = dominant allele For example R = red hair Rr or RR If R is dominant for red hair… then is it true that all of the Weasley children have either the Rr combination or the RR combination?

r = recessive trait = brown hair Rr Trait NOT expressed while the dominant form is present is known as the: recessive allele r = recessive trait = brown hair Rr If the allele combination is rr is the recessive trait expressed? _____________ Why or why not?

Homozygous - IF 2 alleles of a certain gene are the same, the individual is said to be: homozygous (** true regardless of if the two are dominant OR recessive**) - Write using promethium board..

Heterozygous If the alleles of a gene in an individual are different, the individual is: heterozygous Write using promethium board

Genotype: set of alleles an individual has for a characteristic Example: Rr is the genotype for red hair

Phenotype: the physical appearance of a characteristic So … if the genotype is Rr then the phenotype is ____________________.

Questions: T = tan colored feathers t = white color feathers Is t the dominant allele or the recessive allele? _________________ An owl has white colored feathers ( tt ) , this physical appearance of having white feathers is known as the owl’s ________________ ? If an owl’s genotype is Tt, what color feathers will it have? ____________

Law of Segregation - states that the two alleles for a characteristic are segregate or SEPARATE when gametes are formed

Law of Independent Assortment: --Alleles of different genes separate independently of one another during gamete formation -- The inheritance of one characteristic did not influence the inheritance of any other characteristic

Law of Independent Assortment/Segregation Lab B – brown hair b – blonde hair F – freckles f– no freckles C – curly hair c – straight hair G – gap in between front teeth g – no gap in between front teeth

Punnett Square: --predicts the outcome of a genetic cross -- the basic 4 chambered Punnett Square can predict the outcome of a monohybrid cross Monohybrid cross – a cross that considers one pair of contrasting traits between two individuals

Do example problem: Ask students to name two different traits and have them decide which is dominant and which is recessive. Have them make up the genotype for both the father and the mother. Then have other students complete the crosses on the board. Have them come up and complete them on the board as well.

How could you find the genotype of an individual if it was not known? Test Cross Is performed when an individual shows a dominant phenotype but we are not sure whether they are heterozygous or homozygous. These individuals are crossed with a homozygous recessive individual

Have students come up with an organism that has a dominant phenotype Have students come up with an organism that has a dominant phenotype. Establish what letter the dominant will be and which is the recessive. Then have students choose the recessive homologous phenotype as well. Have a student or students come up to the board and do the test cross. Ask them why they filled in the blocks the way they did. Ask students what they can determine from the results.

If half of the offspring express the dominant trait and half express the recessive trait, then the unknown individual’s genotype is? ______________________________________

IF all of the offspring express the dominant phenotype which genotype is the unknown individual? _____________________________________

Discuss percents when performing crosses. Break each block into 25% Discuss percents when performing crosses. Break each block into 25%. Discuss how by genotype you would see that depending on the parental crosses you could get 100% with all the same genotype or with a different parental cross you could get 75% with one genotype and 25% with another. Mention fractions as well/ratios for example 1:2:1 or 3:1 Ask them to answer about the percents to make sure they understand the concept Make sure to mention that even though you have 75% and 25% the phenotype ( the physical appearance that you see may not be those exact percentages.

Section 4: Complex Patterns and Heredity Polygenic Inheritance: when several genes influence a character

Incomplete dominance: an individual that displays a phenotype that is intermediate between the two parents Remember that in Mendel’s pea-plant crosses, one allele was completely dominant over another. In some organisms, however, an individual displays a phenotype that is intermediate between the two parents. This condition is known as incomplete dominance. Straight hair + Curly Hair = Wavy hair why? Wavy hair is heterozygous and is the intermediate between straight and curly hair

red x white ---> red & white spotted Codominance: With codominance, a cross between organisms with two different phenotypes produces offspring with a third phenotype in which both of the parental traits appear together.  red x white ---> red & white spotted

Roan Fur in Cattle WW = all white hairs RR = all red hairs RW = red & white hairs together

Sex-linked gene’s allele is located ONLY on the X or Y chromosome Carried on the X chromosome and are recessive Males: only have one X chromosome (XY) Male who carries a recessive allele on the X chromosome will express the sex-linked condition

Female: if she is a carrier of the recessive allele on one X chromosome, she will NOT exhibit the allele if her other X chromosome exhibits the dominant allele Thus her chances of inheriting AND expressing a sex-linked condition are significantly less than a males

Dihybrid Crosses - A genetic cross that consists of two different traits instead of one

Dihybrid Crosses Instead of Rr x rr R= round, r = wrinkled You are now including another trait into the cross: Y= yellow, y = green RRYY x rryy

RRYY x rryy Parent 2 Parent 1

Parent 2 Parent 1 RRYY RRYy RrYy RrYY In the breeding season, male Anole lizards court females by bobbing their heads up and down while displaying a colorful throat patch. Assume for this question that both males and females bob their heads and have throat patches. Assume also, that both traits are controlled by single locus genes on separate chromosomes. Now, suppose that anoles prefer to mate with lizards who bob their heads fast (F) and have red throat patches (R) and that these two alleles are dominant to their counterparts, slow bobbing and yellow throats. A male lizard heterozygous for head bobbing and homozygous dominant for the red throat patch mates with a female that is also heterozygous for head bobbing but is homozygous recessive for yellow throat patches.

Parent 2 Parent 1

Pedigree --- A family history that shows how a trait is inherited over several generations

Albinism is a genetic disorder transmitted by a recessive allele. The light purple symbols represent affected individuals

Determining Information From a Pedigree 1.) Autosomal or sex-linked? Autosomal: the gene will appear in both sexes equally - Autosomes are all the other chromosomes other than the X or Y sex chromosome

Epidermodysplasia verruciformis (EV)

Determining Information From a Pedigree 2. ) Dominant or Recessive Autosomal Dominant: EVERY individual with the condition will have a parent with that condition hypercholesterolemia

If the condition is recessive: -- an individual that expresses the condition can have one, two or neither parent express the condition

Erythropoietic porphyria (Günther disease)

Determining Information From a Pedigree 3.) Homozygous or Heterozygous - if individuals with autosomal traits are homozygous dominant or heterozygous, - their phenotype will show the dominant allele Polydactyly (extra fingers or toes): PP or Pp = extra digits, aa = 5 digits. 98% of all people in the world are homozygous recessive (pp).

Individual is homozygous recessive, their phenotype will show the recessive allele

Two people who are heterozygous carriers of a recessive mutation Will not show the mutation, but can produce children who are homozygous for the recessive allele

Characters Influenced by Environment An individual’s phenotype often depends on the condition of the environment Identical twins are used in these types of studies

Human Genetic Disorders

Sickle Cell Anemia - Recessive Genetic Disorder Cause: Mutated allele that produces a defective form of the protein hemoglobin 1 in 500 African Americans have sickle cell anemia

Heterozygous Superiority - Individuals that are heterozygous for sickle cell have what is considered “heterozygous superiority” The recessive allele that causes the sickle cell shape protects the individual from malaria * Also do not have sickle cell anemia because they are heterozygous*

Cystic Fibrosis (CF) - Airways of the lungs become clogged with thick mucus, and the ducts of the liver and pancreas become blocked - Most common, fatal, hereditary recessive disorders among Caucasians ( 1 in 25 have at least one copy of the defective gene )

- Caused by a mutated protein that does not allow chloride to be moved into or out of cells - Then…causes mucus to dehydrate and become thick and sticky in the lungs

Hemophilia - Sex- linked Trait - Recessive genetic disorder that impairs the blood’s ability to clot - Sex- linked Trait

Huntington’s Disease (HD) - Caused by a dominant allele located on an autosome - Symptoms: Mild forgetfulness and irritability appear in people in their thirties and forties

- HD causes loss of muscle control, uncontrollable physical spasms, severe mental illness, and eventually death Brain wastes away…