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 1 st two individuals that are crossed (parental generation) F 1 generation : The offspring of the P generation (offspring of the parents) F 2 generation: The offspring of the F 1 generation (offspring of the F 1 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 Black Hair Red Hair

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

The expressed form a characteristic as: Dominant R = dominant allele For example R = red hair Rr or 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**)

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

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

How could you find the genotype of an individual if it was not known?

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? _____________________________________

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

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.

Roan Fur in Cattle RR = all red hairs WW = all white 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

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

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

1.) Number all of the letters in the cross RRYY X rrYY and 2 can never be paired together 3 and 4 can never be paired together You would pair 1 with 3 and 4 You would then pair 2 with 3 and 4 ( these pairings would occur for both genotypes RY, RY, RY, RY rY, rY, rY, rY ( these two letter pairings are now the possible gametes from the female and the male)

ry RYRrYy RYRrYy RYRrYy RYRrYy RRYY x rryy

RRYYRRYyRrYy RrYYRrYy

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

2. ) Dominant or Recessive Autosomal Dominant: EVERY individual with the condition will have a parent with that condition

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

3.) Homozygous or Heterozygous - if individuals with autosomal traits are homozygous dominant or heterozygous, - their phenotype will show the dominant allele

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