Mendel and Natural Selection

Mendel and Natural SelectionWhat do you think Natural Selection

is?Who is Gregor Mendel?What is Asexual Reproduction?What is Sexual Reproduction?

Mendel and His Peas

Gregor MendelGregor Mendel, born in

1822, is named the “Father of Genetics”.

Mendel and His PeasGregor Mendel

Mendel began doing experiments with garden peas. He studied the shape of the seeds, how tall the plants grew to be, as well as the color of the flowers produced.

Mendel and His PeasGregor Mendel

Mendel crossed flowers that were true-breeding for each characteristic.

He crossed a purple flowered plant with a white flowered plant.

Mendel and His Peas

Gregor MendelHe created a

first-generation of plants that all had purple flowers.

Where did the white color go??

   

   

Purple Parent

White Parent

Mendel and His Peas

Gregor MendelMendel noticed in the first

generation, all of the white flowers seemed to disappear. He called this a recessive trait. The white color faded into the background at first. It then showed back up as he pollinated the flowers again.

Mendel and His Peas Mendel took two of

his four first generation purple flowered plants and crossed them together.

He then got three purple plants, and one white flowered plant.

   

   

Purple ParentPurple Parent

Mendel and His Peas

Gregor MendelThe color (purple) that seemed

to mask over the recessive color was named the dominant trait.

Mendel and His PeasGregor Mendel

Mendel was responsible for figuring out that each plant carried two sets of instructions for each characteristic (one from the “mom” and one from the “dad”).

Like many scientists, his work was not accepted until after his death.

Let’s Review

- 1 -1. If you crossed a true-breeding black rabbit with a true-breeding white rabbit, all of the offspring would be black. Which trait is dominant in rabbits: black fur or white fur?2. Which trait is recessive?

Answer

The trait for black fur is dominant over the trait for white fur. The white fur trait is recessive.

   

   

Black RabbitWhite Rabbit

Mendel and His Peas

What is the difference between sexual reproduction and asexual reproduction?

What Do You Think?

Mendel and His Peas

Sexual Reproduction Asexual Reproduction

Two parents needed One parent needed

New organism shares traits of both parents.

New organism is an exact copy of parent.

Most multi-celled organism reproduce

this way.

Most single-celled organism reproduce

this way.

Let’s Review!- 1 -

Which kind of reproduction results in offspring that are different from the parents-

sexual or asexual reproduction? Explain why.

Answer

Sexual reproduction results in offspring that are different from the parents. In sexual reproduction, two parent cells join together to form a new individual who has his or her own combination of genes.

Mendel and Natural SelectionVocabulary Heredity- the passing of traits from

parent to offspring. Self-pollinate- A plant is often able to

pollinate by itself because it contains both the male and female reproductive structures. This only requires 1 parent.

True-breeding- all of the offspring will have the same trait as the parent when self-pollinated.

Mendel and Natural SelectionVocabularyFirst-generation- the very first set of

offspring from two parents.Dominant trait- the trait observed

when at least one dominant allele for a characteristic is inherited.

Recessive trait- a trait that is apparent only when two recessive alleles for the same characteristic are inherited.

Mendel and Natural SelectionVocabularyGenes- a segment of DNA that

carries hereditary instructions and is passed from parent to offspring.

Alleles- multiple forms of the same gene.

Genotype- an organisms inherited combination of alleles.

Phenotype- an organisms inherited appearance.

Mendel and Natural Selection

Websites!http://www.globalchange.umich.edu/globalchange1/current/lectures/selection/selection.htmlhttp://science.discovery.com/interactives/literacy/darwin/darwin.htmlhttp://www.nysci.org/charlieandkiwi_finches/html