Ch 11 Genetics

Essential Vocab• True Breeding• Traits• Hybrids• P

• F1

• F2

• Genes

• Alleles

• Genotype

• Phenotype

• Dominant

• Recessive

• Homozygous

• Heterozygous

Gregor Mendel’s Contribution

• “Father of Genetics”

• Worked with pea plants because they are small, easy to grow, and produced large quantities of offspring.

• 7 characteristics are observable on pea plants

• Traits-characteristics like color, height, etc.

What did Mendel do?

• He fertilized the plants (P1) to observe what traits were present in the offspring (F1)

• And….F2

• Self Fertilization• Pea plants self

fertilize

• Cross Fertilization• Two different pea

plants fertilized

Fertilization

Mendelian Inheritance

• Individual’s characteristics are determined by factors that are passed from one parental generation to the next.

• Dominant- masks• What are the dominant

phenotypes?

• Recessive- is masked• What are the recessive

phenotypes?

Annotate and Predict F1

Mendelian Inheritance and Making Predicting

• Allele: A form of a gene. Humans have 2 for each trait.S=Normal Skin (dominant)s=Albanism (recessive)

The combination of them determines what trait we will have.

Genotype Phenotype

Recall: Dominant

• An organism with at least 1 dominant allele will exhibit the dominant trait.

• Shown by CAPITAL LETTERS (S)SS and Ss will have normal skin.

Recall: Recessive

• In order for a recessive trait to be expressed, two copies of that allele must be present.

• Shown by lower case letters (s)

• ss will have albanism

What does it mean? Heterozygous or Homozygous

(Word dissection)• Heterozygous

Ss

• Homozygous

SS and ss

SS homozygous dominant

ss homozygous recessive

Heterozygous or Homozygous Genotypes

Example: skin disorders…

Albanism or Normal Skin?

• S=normal skin

• s=albanismPredicting

expected

genotypes and

phenotypes

• What are the genotypes?

• • •

• What are the corresponding phenotypes?

• • •

What if you wanted to make a prediction for 20 offspring?