Bell Ringer  Look at your classmates. Note how they vary in the shape of the front hairline, the space between the two upper front teeth, and the way in which the earlobes are attached.  Make a list of the different forms of these traits that you have observed in the class or among other people you know. 1.Could these traits be inherited? From whom could they be inherited? 2.How is it possible that these traits could be found in a person and his or her biological grandparents but not in the biological parents?

Bell Ringer 1.Could these traits be inherited? From whom could they be inherited? 2.How is it possible that these traits could be found in a person and his or her biological grandparents but not in the biological parents?

Bell Ringer 1.Could these traits be inherited? From whom could they be inherited?  Yes; from parents. 2.How is it possible that these traits could be found in a person and his or her biological grandparents but not in the biological parents?  Genes are passed from generation to generation, but are not necessarily expressed in every generation. 3. Every living thing – plant or animal, microbe or human being – has a set of characteristics inherited from its parents.

Gregor Mendel  In 1865, Gregor Mendel published studies of inheritance in pea plants.  During sexual reproduction, male and female gametes join to form a zygote in the process known as fertilization.  Genetics= the scientific study of heredity.

Heredity is… the passing on of traits from parents to offspring. 1.Controlled by “factors.” 2.Passed from generation to generation. 3.Probability 4.Traits – characteristics that are inherited.

1902 – Chromosome Theory of Heredity  Genes (Mendels “factors”) are located on chromosomes.  The different forms of a gene are called Alleles.  This is the basis for the modern science of Genetics.

Genetic Principles 1. Alleles – gene form, Y or y, for each variation of a trait of an organism. 2. Dominance and Recessiveness D= visible, observable trait of an organism that masks a recessive form of a trait. R = a hidden trait of an organism that is masked by a dominant gene. 3.Separation, or Segregation 4.Independent Assortment

Other Terms  Phenotype – the way an organism looks and behaves. Physical characteristics of an organism.  Genotype – the gene combination of an organism.  Homozygous – when an organisms two alleles for a trait are the same.  Heterozygous – when an organisms two alleles for a trait are not the same.

Genes VS Alleles Gene Allele

Genes VS Alleles GenePlant HeightFlower Color Allele Tall PlantPurple Flowers Short PlantWhite Flowers

R.C. Punnett  In 1905, R.C. Punnett introduced the Punnett square.  Punnett squares can be used to predict and compare the genetic variations that will result from a cross

Using Punnett Squares Yellow pea seed (Y) is DOMINANT to green (y). Genotype:YY x yy Phenotype: Yellowx green Parents (P)YY y y

Using Punnett Squares Yellow pea seed (Y) is DOMINANT to green (y). Genotype:YY x yy Phenotype: Yellowx green Parents (P)YY y y

Using Punnett Squares Yellow pea seed (Y) is DOMINANT to green (y). Genotype:YY x yy Phenotype: Yellowx green Parents (P)YY yYy y

Using Punnett Squares Yellow pea seed (Y) is DOMINANT to green (y). Genotype:YY x yy Phenotype: Yellowx green Parents (P)YY yYy y

Using Punnett Squares Yellow pea seed (Y) is DOMINANT to green (y). Genotype:YY x yy Phenotype: Yellowx green Parents (P)YY yYy y

Using Punnett Squares Yellow pea seed (Y) is DOMINANT to green (y). Genotype:YY x yy Phenotype: Yellowx green Parents (P)YY yYy y

Using Punnett Squares Yellow pea seed (Y) is DOMINANT to green (y). Genotype:YY x yy Phenotype: Yellowx green Parents (P)YY yYy y

Using Punnett Squares Yellow pea seed (Y) is DOMINANT to green (y). Genotype:YY x yy Phenotype: Yellowx green Parents (P)YY yYy y

Using Punnett Squares Yellow pea seed (Y) is DOMINANT to green (y). Genotype:YY x yy Phenotype: Yellowx green Parents (P)YY yYy y

Using Punnett Squares Yellow pea seed (Y) is DOMINANT to green (y). Genotype:YY x yy Phenotype: Yellowx green All (100%) offspring in F 1 Generation are Yellow hybrids. Parents (P)YY yYy y

Monohybrid Cross Yyx Yy Yellow xYellow F 1 GenerationYy

Monohybrid Cross Genotype: Yyx Yy Phenotype: Yellow x Yellow F 1 GenerationYy Y y

Monohybrid Cross Genotype: Yyx Yy Phenotype: Yellow x Yellow F 1 GenerationYy Y y

Monohybrid Cross Genotype: Yyx Yy Phenotype: Yellow x Yellow F 1 GenerationYy YYY y

Monohybrid Cross Genotype: Yyx Yy Phenotype: Yellow x Yellow F 1 GenerationYy YYY y

Monohybrid Cross Genotype: Yyx Yy Phenotype: Yellow x Yellow F 1 GenerationYy YYY yYy

Monohybrid Cross Genotype: Yyx Yy Phenotype: Yellow x Yellow F 1 GenerationYy YYY yYy

Monohybrid Cross Genotype: Yyx Yy Phenotype: Yellow x Yellow F 1 GenerationYy YYYYy y

Monohybrid Cross Genotype: Yyx Yy Phenotype: Yellow x Yellow F 1 GenerationYy YYYYy y

Monohybrid Cross Genotype: Yyx Yy Phenotype: Yellow x Yellow F 1 GenerationYy YYYYy y yy

Monohybrid Cross Genotype: Yyx Yy Phenotype: Yellow x Yellow Phenotypic Ratio: 75% (3/4) offspring are Yellow; Ratio is 3:4 (Yellow : total) 25% (1/4) offspring are green; Ratio is 1:4 (green : total) F 1 GenerationYy YYYYy y yy

Dihybrid Cross  Round pea seed (R) is dominant to wrinkled pea seed (r).  FOIL: YyRr  YR, Yr, yR, yr  (These are the possible genotypic combinations)

Dihybrid Cross Round pea seed (R) is dominant to wrinkled pea seed (r). Possible Combinations YRYryRyr YR Yr yR yr

Dihybrid Cross Round pea seed (R) is dominant to wrinkled pea seed (r). Possible Combinations YRYryRyr YRYYRRYYRrYyRRYyRr YrYYRrYYrrYyRrYyrr yRYyRRYyRryyRRyyRr yrYyRrYyrryyRryyrr

What is the probability that the plant will produce: Yellow, Round Peas: Yellow, Wrinkled Peas: Green, Round Peas: Green, Wrinkled Peas: Possible Combos YRYryRyr YR YYRR Yellow, Round YYRr Yellow, Round YyRR Yellow, Round YyRr Yellow, Round Yr YYRr Yellow, Round Yyrr Yellow, wrinkled YyRr Yellow, Round Yyrr Yellow, wrinkled yR YyRR Yellow, Round YyRr Yellow, Round yyRR green, Round yyRr green, Round yr YyRr Yellow, Round Yyrr Yellow, wrinkled yyRr green, Round Yyrr green, wrinkled

What is the probability that the plant will produce: Yellow, Round Peas: 9/16 Yellow, Wrinkled Peas:3/16 Green, Round Peas:3/16 Green, Wrinkled Peas:1/16 Possible Combos YRYryRyr YR YYRR Yellow, Round YYRr Yellow, Round YyRR Yellow, Round YyRr Yellow, Round Yr YYRr Yellow, Round Yyrr Yellow, wrinkled YyRr Yellow, Round Yyrr Yellow, wrinkled yR YyRR Yellow, Round YyRr Yellow, Round yyRR green, Round yyRr green, Round yr YyRr Yellow, Round Yyrr Yellow, wrinkled yyRr green, Round Yyrr green, wrinkled

 Incomplete Dominance – When one allele is not completely dominant over another and the heterozygous genotype becomes the phenotype Example: Red flowers (RR) crosses with white flowers (WW) shows incomplete dominance for pink flowers (RW)

 Codominance – when both alleles contribute to the phenotype. Example – black feathers codominant with white feathers in chickens, both white and black feathers are present separately. Also blood types and a cholesterol enzyme in humans.

 Multiple alleles-genes that have more than 2 alleles This means that there are more than 2 possible alleles in a population Example: rabbit fur colors  Polygenic traits – traits controlled by more than 2 genes Example: human skin color is controlled by more than 4 different genes