FERTILIZATIONFERTILIZATION& &

Intro to Mendelian GeneticsIntro to Mendelian Genetics

FERTILIZATION

http://www.youtube.com/watch?v=OToaX2A1Tgs

In vitro Fertilization

http://www.youtube.com/watch?v=FXeGivCzdDs

EMBRYO DEVELOPMENT

TWINS

Mendel and His Peas

Results

Tall x Tall

F1 offspring #3 X F1 offspring # 3 Tall Tall

Conclusion?

Short x Short

Tall x Short

Conclusion?

Conclusions• Every characteristic or trait (e.g. height) is

determined by two factors (alleles). • There are variations in alleles (e.g. height= tall

(T) or short (t))• Genotype: What combination of alleles an

individual has (TT, Tt, tt)• Homozygous: individual has two of the same

alleles (TT, tt)• Heterozygous: individuals have two different

alleles (Tt)

• Phenotype: What the individual physically looks like (determined by genotype)

• Dominant allele: The allele that shows up physically in the heterozygous form

• Recessive allele: The allele that is not displayed physically in the heterozygous form

Is Dominant the most common allele in the population?

Genotype Phenotype

Homozygous Tall TT Tall

Heterozygous Tall

Tt Tall

Homozygous Short

tt Short

Mendel’s Law of Segregation

• Each allele separates into different gametes during meiosis therefore only one allele is passed down to the offspring

T

t

T t T Tt t T

t

meiosis

DNA replication

Explaining Mendel’s Observations