Quiz Wednesday probability of cards, dice, coins, spinner, tree diagrams

4.4 Probability & Genetics

Probability If you roll one die, what’s the probability of rolling a 6? If you pull one card from the deck, what’s the probability of getting the ace of hearts? If you flip a coin, what’s the probability of landing on heads? 1/6 (1 out of 6) 1/52 (1 out of 52) 1/2 (1 out of 2)

A Genetic Cross Gregor Mendel (1865) discovered that probability could be used to predict the results of a genetic cross (mating) If you know parent genotypes, you can predict offspring genotypes

Genotype ( 유전형 ) A genotype is an individual's collection of genes. The word 'genotype' is usually used when talking about the genetics of a particular trait (like eye color).

Examples of genotype are the genes responsible for: eye color hair color height how your voice sounds certain diseases certain behaviors a person’s shoe size

Phenotype ( 표현형 ) Phenotype is the observable physical or biochemical characteristics of an individual organism, determined by both genetic make-up and environmental influences, for example, height, weight and skin color.

Phenotypes are the actual visible characteristcs including: Eye color Hair color Height Sound of your voice Certain types of disease Certain behaviors An individual’s shoe size

Definitions Homozygous – means both parts (alleles) of the genes are the same. Heterozygous - means both parts (alleles) of the genes are the different. 두벌이 다 다르면 이형접합자, 같으면 동형접합자, 한벌만 있으면 반접합자, 다 없으면 무접합자이다

More Definitions Alleles can be either DOMINANT ( 우성유전자 ) or Recessive ( 열성유전자 ) When the two alleles are different, the dominant one determines the traits.

Shape of faceOval dominant, square recessive Cleft in chinNo cleft dominant, cleft recessive HairlineWidow peak dominant, straight hairline recessive Eyebrow sizeBroad dominant, slender recessive Eyebrow shapeSeparated dominant, joined recessive Eyelash lengthLong dominant, short recessive DimplesDimples dominant, no dimples recessive EarlobesFree lobe dominant, attached recessive Eye shape Almond dominant, round recessive Freckles Freckles dominant, no freckles recessive Tongue rolling Roller dominant, nonroller recessive Tongue folding Inability dominant, ability recessive Bent little fingerBent dominant, straight recessive Hair on back of handHair dominant, no hair recessive

A Genetic Cross If you know parent genotypes, you can predict offspring genotypes Example:  Brown hair (B) is dominant to blond hair (b).  What are the possible genotypes for their offspring? bb Bb ♀ Bb x ♂ bb Bb, Bb, bb, bb

A Genetic Cross If you know parent genotypes, you can predict offspring genotypes Example:  Brown hair (B) is dominant to blond hair (b).  What is the probability that the Incredibles’ next child will have brown hair? bb Bb ♀ Bb x ♂ bb Bb, Bb, bb, bb 2/4 (50%) chance of brown hair

A Genetic Cross If you know offspring genotypes, you can predict parent genotypes Example:  Brown eyes (B) are dominant to blue eyes (b).  If Dash’s genotype is bb, what are his parents’ genotypes? bb ?? Bb

Practice In pea plants, smooth peas (S) are dominant to wrinkled peas (s). A homozygous smooth pea is crossed with a wrinkled pea. ♀ _____ x ♂ _____

Practice In pea plants, smooth peas (S) are dominant to wrinkled peas (s). A homozygous smooth pea is crossed with a wrinkled pea. Determine the possible offspring genotypes & phenotypes. ♀ SS x ♂ ss Ss, Ss, Ss, Ss 100% chance of smooth peas

Punnett Squares Created by Reginald Punnett (1900) to make predicting the outcome of genetic crosses easier show all the possible outcomes of a genetic cross show the probability of each outcome 25%

Punnett Squares show all the possible outcomes of a genetic cross show the probability of each outcome Example:  In dogs, short hair (S) is dominant to long hair (s).  Determine the possible offspring phenotypes. 25% ♀ Ss ♂ SS SsSs S 100% chance of short hair S SsSs S SsSs

Why Use a Punnett Square? Most scientists study MANY traits at one time It gets VERY confusing without a Punnett Square!

Practice In humans, straight toes (S) is dominant to curled toes (s). Determine the possible results for a cross between a recessive male & heterozygous female. 25% ♀ Ss ♂ ss 50% chance of straight toes 50% chance of curled toes SsSs s s SsSsSsSs

Practice In pea plants, yellow color (Y) is dominant to green (y). Determine the possible results for a cross of 2 heterozygous plants. 25% ♀ Ss ♂ Ss S s SsSs S SsSs SsSss 75% chance of yellow peas 25% chance of green peas

Bikini Bottom Genetics 1) Heterozygous(hybrid) (He) – capital and small letter Homozygous(purebred) (Ho) – both capital or both small 2) Dominant gene is capital – if there is one capital – the phenotype is the dominant trait. 3) What mixtures of letters are possible 4-8) Make a Punnett square and answer the questions

Homework Spongebob Genetics Worksheet