Who was Gregor Mendel?

Mendel’s Principles of Inheritance

Gene-Chromosome Theory
(not really Mendel’s) / Law of Dominance (complete dominance) / Law of Segregation
(of alleles) / Law of Independent Assortment
Hereditary information is transmitted from parents to offspring as ______found on chromosomes. These genes determine an individual’s traits. / In cases in which two or more forms (______) of a gene for a single ______exist, some forms of the gene may be ______and cover up others that are ______. / In most ______reproducing organisms, each adult has ______copies of each ______: one from each parent. These genes are ______from each other when gametes are formed. / The alleles for different genes usually segregate ______of one another.

Dominant Alleles vs. Recessive Alleles

The dominant allele always ______or ______the recessive allele. It is the one that is ______and is what we see.

  • Dominant alleles are represented with ______letters.
  • The recessive allele is “weaker” and gets ______up by the dominant allele. It is not expressed unless an individual inherits ______copies of the alleles.
  • Recessive alleles are represented with l______letters .

Dominant Traits: tall stems, green pods, yellow seeds, round seeds

Recessive Traits: short stems, yellow pods, green seeds, wrinkled seeds

Mendelian Genetics Guided Practice

1)What is a gene? ______

2)What does a gene code for? ______

3)What is a phenotype? ______

4)What is an allele? ______

5)How many alleles does a person have that makes up his or her genotype? ______

For the chart below, use the information provided to practice assigning letters to represent alleles. Remember that it is good practice to use the letter of the dominant for of the trait.

Dominant Traits: tall stems, green pods, yellow seeds, round seeds

Recessive Traits: short stems, yellow pods, green seeds, wrinkled seeds

Trait / Height / Pod Color / Seed Color / Seed Shape
Dominant
Recessive

1)For each genotype below, indicate whether it is heterozygous (He) or Homozygous (Ho).

  1. TT ______b. Bb ______c. Dd ______d. LL ______e. gg ______
  2. Circle the genotypes above that would be considered purebred.
  3. Draw a square around the genotypes above that would be hybrids.

2)Determine the phenotype for each genotype using the information provided.

  1. Brown hair is dominant to blonde hair. e. Brown eyes are dominant to blueeyes.
  2. BB ______i. BB ______
  3. Bb ______ii. Bb ______
  4. bb ______iii. bb ______
  5. Which genotype is homozygous brown? _____f. Which genotype is heterozygous? ____
  6. Which genotype is homozygous blonde? _____g. Which genotype is homozygous blue?
  7. Which genotype is heterozygous? _____h. Which genotype is homozygous brown? _____

3)For each phenotype, give the genotypes that are possible.

  1. Tall plants (T) are dominant to short plants (t).b. Purple (P) flowers are dominant to white flowers (p).
  2. Tall = ______i. Purple = ______
  3. Short = ______ii. White = ______

4)For the next 3 problems, identify the genotype of each parent.

  1. Round seeds are dominant to wrinkled seeds. [Round = RR or ____, wrinkled = _____] Plant A is a wrinkle-seed plant, and it is crossed with Plant B which is homozygous for round seeds.
  2. Genotype of Plant A: ______
  3. Genotype of Plant B: ______
  4. Attached earlobes are dominant to detached earlobes. Sharon has detached earlobes. Bob is heterozygous for attached earlobes. [Attached = ____ or ____, Detached = ____]
  5. Genotype of Sharon: ______
  6. Genotype of Bob: ______
  7. Green seeds are dominant to yellow seeds. Two plants that are heterozygous for green seeds are crossed. [Green = ____ or ____, Yellow = ____]
  8. Genotype of 1st plant: ______
  9. Genotype of 2nd plant: ______

What will be the genotype of the offspring? ______