Genetics and Heredity

Are these inherited traits? Eye Color Hair Texture & Color Height Musical, athletic, And artistic ability Personality

These are questions that Gregor Mendel *Think About This*… “My parents have brown eyes, why do I have blue?” “My brother is tall, why am I short?” “Why does my sister have blonde hair while mine is brown?” These are questions that Gregor Mendel tried to answer…

Mendel’s Studies Studied Garden Pea plant in three generations: P Generation- The parental generation F1 Generation- The offspring of the parental generation Mendel studied the garden pea plant in three generations: P generation: parental generation F1 generation- the offspring of the parental generation F2 generation- the offspring of the F1 generation from self-pollination F2 Generation- The offspring of the F1 generation from self-pollination

Phenotype: Physical Appearance An individual is determined by the alleles that code for a specific trait: Eyes Phenotype is the physical appearance of an organism. Hair Skin Color

Genotype: the set of alleles you contain (genes or genetic makeup) Mendel concluded that an individual contains 2 genes (1 from each parent) for each trait. Letters of the alphabet are used to represent alleles of a genotype Capital letters are for dominant alleles Lowercase letters are for recessive alleles For example, the gene for brown eyes is dominant over the gene for blue eyes. If you have blue eyes, your genotype is bb. Genotype: the set of alleles you have and they determine your genetic makeup. Mendel concluded that an individual contains 2 genes (1 from each parent) for each trait. Letters of the alphabet are used to represent alleles of a genotype. Capital letters are for dominant alleles Lowercase letters are for recessive alleles For example, the gene for brown eyes is dominant over the gene for blue eyes. If you have blue eyes, your genotype is bb. Brown eyes can be BB or Bb. BB= brown eyes Bb= brown eyes bb= blue eyes

Mendel’s studies led to: Recessive (h) Dominant (H) - Homozygous- same (HH or hh) - Heterozygous- different (Hh) Phenotype (blonde, red, brown) Genotype (HH, Hh or hh) - Purebred (HH or hh) Hybrid (Hh) -

Theory of Heredity Inherited allele for purple P HOMOZYGOUS purple flower PP

Theory of Heredity Inherited allele for pink flower p HOMOZYGOUS pink flower pp

Theory of Heredity Inherited allele for purple P Inherited allele for pink flower p HETEROZYGOUS purple flower Pp

Predicting Heredity Probability

Probability The likelihood that a specific event will occur. Probability = # of times event occurs # of possible outcomes Ex: What is the probability that a coin will be heads? ? OR ? 50% 1/2

Genotypic Ratio: compares all possible allele combinations Homozygous dominant : Heterozygous Phenotypic Ratio: compares all possible physical characteristics # showing dominant trait : # showing recessive trait

Monohybrid Cross a cross that shows the possible offspring for ONE trait A a Aa X Aa Mom Dad Aa A AA A: White Fur a: Brown Fur Aa aa a Genotypic Ratio: 1:2:1 Phenotypic Ratio: 3 white : 1 brown

Practice!! Cross a HOMOZYGOUS dominant female with a HETEROZYGOUS male using the same trait. A A What is the genotypic ratio? AA A AA 2:2 or 1:1 AA:Aa What is the phenotypic ratio Aa Aa a 4:0 white fur: brown