Gregor Mendelthe father of genetics

1822-1884- studied botany & math- became a monk- studies pea plants and inheritance of traits

• Genetics—the scientific study of heredity

• Heredity—the passing of traits from parents to offspring

Why Peas?- many traits that exist in only 2 forms such as

Ex: tall vs short plants, no medium

- produce a large number of offspring

(kids) in each generation

- they can self-pollinate

or be cross pollinated

What is self-pollination?

• pollen from the stamen of a plant enters the pistil of the same plant.

What is Cross-Pollination?

• Mendel took pollen from a plant and rubbed it on the pistil of a different plant (with no stamens)

Cross Pollination diagram

• Purebred—always produces offspring with the same form of a trait as the parent.

• Ex. Purebred dogs. Like Cocker spaniels, golden retrievers, Poodles.

The opposite is hybrid.This would be a pound puppy

Mendel’s ExperimentsIn his first experiment Mendel crossed purebred tall plants (they only have tall genes) withpurebred short plants (that onlyhave short genes).

Filial (F1) generation—name given to the offspring of the firstcross.

Mendel’s Experiments

?Mendel cross-pollinated purebred tall plants with purebred short plants and got….

Tall plant (breed) short plants

P generation (think “parents”)

F1 generation

What he found...All TALL pea plants in the F1 generation….

P generation (think “parents”) F1 generation

11

He concluded

• Tall plants must DOMINATE over short plants

• He repeated the experiment switching which plant donated the POLLEN

• Same results• He repeated the experiment with several

other traits

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Traits Mendel studied in Pea Plants• Mendel also studied _7_ traits of pea plants: They were :

Seed shape, seed color, seed coat color, pod shape, flower position, flower color, and stem height.

Dominant and Recessive Alleles

• Alleles—the different forms of a gene (such as tall or short, wrinkled or smooth).

• Dominant allele—one whose trait always shows up when the allele is present.

• Recessive allele—is masked (or covered up) when the dominant allele is present. Recessive alleles only show up if a dominant allele is not present.

EXAMPLESrecessive dominant

Recessive is the green box and dominant is the black box. Each of your parents has a pair of alleles that they can share. If they only give one… answer the following questions.

?

?

?

dominant dominant

recessive recessive

recessive dominant

EXAMPLESrecessive dominant

Recessive is the green box and dominant is the black box. Each of your parents has a pair of alleles that they can share. If they only give one… answer the following questions.

dominant dominant

recessive recessive

recessive dominant

?

?

?

dominant

EXAMPLESrecessive dominant

Recessive is the green box and dominant is the black box. Each of your parents has a pair of alleles that they can share. If they only give one… answer the following questions.

dominant dominant

recessive recessive

recessive dominant

?

?

?

dominant

dominant

EXAMPLESrecessive dominant

Recessive is the green box and dominant is the black box. Each of your parents has a pair of alleles that they can share. If they only give one… answer the following questions.

dominant dominant

recessive recessive

recessive dominant

?

?

?

dominant

dominant

recessive

Notice

• The only time the green box (or recessive allele) could show up is when a black box (or dominant allele) was not present.

• This will lead us into punnett squares.

recessive recessive recessive

Activities for them

• Pea Soup• Animated Cross

• Princess and Wrinkled Pea, Biologica• Dragon Genetics, Biologica• Mendel’s Peas, Biologica• Cloning, Brain Pop• DNA, Brain Pop (digestion, avian flu too)

Future activities

Resources for me

• Serendipity Labs• Holy moly animations