Do Now 3/9/17 How does this all work?!?! Can two parents with brown hair, have a child with blond hair? (yes/no) Can two parents with blue eyes have a child with brown eyes? (yes/no) Can parents, one with brown eyes and one with blue eyes have a child with green eyes? (yes/no) How does this all work?!?! Homework: Trait Wheel packet due Monday

Genetics!

Terms Review Heredity Trait Genetics Passing of physical characteristics from parent to offspring Trait Different forms of characteristics (eye color etc…) Genetics The scientific study of heredity and traits

Reproduction Sexual reproduction – requires sex cells, happens when the two sex cells (egg and sperm) join together Process of joining is called fertilization Asexual reproduction – does not require sex cells for reproduction

Gregor Mendel Experimented with thousands of pea plants back in the 1800’s He used controlled fertilization of plants to see what happens to traits through the generations Fertilization The process of an egg and sperm cell joining to form a new organism

Gregor Mendel He crossed (forced reproduction of) plants with different traits Tall with short Pink flowers with white flowers He always started with purebred organisms Purebred Means they have the same allele twice (DD, rr)

Gregor Mendel - Plants First generation of plants he called the “P” generation (parent). Crossed one tall (TT) and one short (tt). Each was purebred. Notice the traits of the offspring in the “F1” generation (offspring) All tall

Gregor Mendel - Plants He then took plants from the F1 generation and crossed two of them. Notice the traits of the second (F2) generation Three are tall, one is short

Gregor Mendel - terms By crossing plants, he learned about dominant and recessive alleles Alleles – differing forms of a gene Gene – located on a chromosome, controls traits Chromosome – compressed form of DNA Dominant Allele – trait will always show up, even with only one present Recessive Allele – trait needs two alleles present to show up. Hidden by one dominant allele

Mendel’s Plants Parent Generation – (TT) X (tt) Possible outcomes for F1? Tt F1 Generation – (Tt) X (Tt) Possible outcomes for F2? TT, Tt, tt When an organism has two different alleles for a trait (Tt) it is called a hybrid

Do Now 3/10/17 What determines which allele your parent pass on to you? Homework: trait wheel packet due Monday

Probability and Heredity Probability – number that describes how likely an event is Coin flipping 2 options – heads, tails Probability of heads is ½ or 50% Probability of tails is ½ or 50%

Probability and Heredity When you toss a coin and it lands heads, what is the probability of heads on the next flip? Still ½ or 50% Probability deals with each flip individually. What would be the results of flipping a coin 10 times? Not always 50% heads 50% tails

Probability and Heredity Which alleles you get from your parents are all based on probability and statistics You have 50% chance of getting either allele for each trait (T or t)

Probability and Mendel Mendel crossed the F1 generation (Tt) ¾ or 75% of the offspring were tall ¼ or 25% were short First scientist to see that probability applied to heredity

Punnett Squares Punnett square – chart that shows all the possible combinations of alleles from a genetic cross

Punnett Squares Take both alleles from each parent and place them outside the square Parents are (Rr) X (Rr) R is dominant for red r is recessive for white What color are the parents? Both red

Punnett Squares Carry the alleles across or down the table to place them in the correct place.

Punnett Squares You can count the small squares at the end to see probability Outcomes are RR – 1/4 Rr – 2/4 rr – 1/4 If R is the dominant allele for red color and r is the recessive allele for white color, what is the probability of having a white offspring? ¼ or 25%

Punnett Squares 0/4 or 0% Try another one! B B b B b B b B b b B b Guinea pigs have the dominant allele (B) for black fur and recessive allele (b) for white fur If we crossed one black (BB) and one white (bb), what is the probability of having a white offspring? B B 0/4 or 0% b B b B b B b b B b

3/13/17 DO NOW Homework Have out homework One parent is (Rr) and another parent is (rr). Complete the Punnett square for this cross to state what the percent change of having purebred, recessive offspring would be. Homework Bikini Bottom Genetics (first page) due tomorrow

“Types” Phenotype – physical appearance based on its genes Genotype – genetic makeup or combination of alleles

“Zygous” Purebreds have 2 of the same allele (TT) or (tt) Another name for this is homozygous Hybrids have 1 of each allele (Tt) Another name for this is heterozygous A heterozygoat!

Weird Crosses Incomplete dominance Happens when both alleles are expressed by blending together in hybrids (heterozygous) Plant has alleles for red and white, a mix produces a pink flower No “dominant” or “recessive” in these types of problems.

Weird Crosses Co-dominance Cows When both alleles are equally expressed in the hybrid (heterozygous) offspring Cows RR – brown rr – white Rr – “Roan”

Weird Crosses Sex-Linked traits Happens only with genes that are found on the “X” chromosome Expressed differently by gender. Why?? Because females have two “X” chromosomes and males have one “X” chromosome

Carriers A carrier refers to someone who has an allele for a trait, but does not display the trait Someone with brown eyes who has the alleles (Bb) is a “carrier” for blue eyes