Genetics - Lecture 2: Mendelian Genetics, Chromosomes, Mitosis, and Meiosis

Preformation

the entire organism was in a miniaturized version within a sperm or egg

Blended inheritance

offspring merge information from both parents,

resulting in a unique blend

Why were pea plants a good choice?

- short generation time

- small and easy to grow

- mating produces many seeds

- can self-fertilize or corss-fertilize

Pea flowers have both male and female parts called:

anthers(male) and ovules(female)

Mendel allowed his original 34 strains of pea plants to...

self-fertilize for many generations to ensure genetic purity meaning they were heavily inbred

Inbred pea plants

every member of the inbred strain is genetically identical

True-breeding

Organisms that, when reproducing, create offspring of all the same variety.

Qualitative traits

traits that differ from one another by discrete qualities

Quantitative traits

traits that show continuous variation (most traits, i.e.: height, intelligence, athleticism)

Which traits did Mendel work with?

Qualitative traits

Mendel's 7 traits

seed color (Yellow/green)

seed shape (Round/wrinkled)

seed coat (Gray/white)

pod color (Green/yellow)

pod shape (Smooth/constricted)

flower position (Axial/terminal)

plant height (Tall/short)

Why did Mendel succeed?

He chose his model system wisely and quantified his results

Mendel's imaginative and creative model

1. There is a gene responsible for each trait

2. Each gene comes in version - "alleles"

3. Each individual has 2 alleles, one from each parent

4. Some alleles can mask (dominant) other recessive alleles

Mendel's Law of Segregation

two alleles for each trait separate during meiosis

Mendel's Law of Independent Assortment

the inheritance of one character has no effect on the inheritance of another

Nucleoprotein complex

makes up eukaryotic chromosomes