HeredityInherited Traits

• Have you ever wondered…..

Why do people have babies? Why do dogs have puppies?

Why do birds have baby birds?

Why do seals have pups?

We inherit our traits from our parents!

Click here to see an interactive about traits.

What is a trait?

• A trait is any notable feature or quality in a person or organism.

• Physical traits• Behavioral traits• Some traits can be influenced by our environment or the

things we do.• For example:

hair color skin color predisposition for certain medical conditions

What defines our traits?

• Our Genes determine our traits.

• NO, NOT YOUR BLUE JEANS!• The genes located on the chromosomes that

are found in the nucleus of our cells…• We inherited these from our parents • Click here to learn more about chromosomes.

Let’s look at some of the dominant traits listed below.

• Free earlobes• Cannot fold

tongue up• Clockwise hair

whorl• Bushy, thick

eyebrows• Brown Eyes

• Dark Hair • Dimples• Curly Hair • Freckles • Dark

eyebrows • Turned up

nose

• Widow’s peak• Straight little

finger• Can roll

tongue• Straight little

finger

Which ones do you have?

If you have a dominant trait, that means you inherited the trait from at

least one of your parents.

For instance Ff or FF for freckles.F + f = frecklesF + F = freckles

Alleles for dominant traits are usually represented with a capital letter.

If you have a recessive trait, that means you had to inherit the trait

from both of your parents.

For instance ff for no freckles.f + f = no freckles

Alleles for recessive traits are usually represented with a lower case letter.

The Mask

• Dominant genes mask, hide, or overpower the trait of the recessive gene. The recessive gene is still present, but it is not expressed…..

It does not show up in the form of a trait that can be seen or noticed by others.

• There are other traits that occur in degrees such as the color of carnation flowers. A white flower and a red flower can produce a pink flower.

Gregor MendelThe Father of Genetics

Click the picture to linkto Mendel’s biography.

Click here to learn more about Mendel and other scientists.

Gregor Mendel, 1863The Father of Genetics

• While studying pea plants, a monk named Gregor Mendel discovered that traits are passed from parent to offspring, that traits can be hidden for a generation, and that hidden traits can reappear in later generations.

• He theorized that the plant received an allele from each parent. The allele was the form of a gene and produced the trait.

• He created the Punnett Square, a mathematical square to predict the possible traits of offspring from certain parents. Click here to learn about Punnett Squares. Click here to use a Punnett Square.

Punnett Square

• Let’s work one on the board together for the freckles.

• If mom has FF and dad has ff, what happens?• F mom is Ff and dad is Ff, what happens?

Homozygous vs. Heterozygous

Homozygous means the alleles for the trait are

the same:

• FF or ff

Heterozygous means the alleles for the trait are

different:

• Ff

Where do the alleles come from?• Alleles come from the genes that are located on the

chromosomes inside the nucleus.

• Chromosomes are made of long molecules of DNA representing thousands of genes

• Build a DNA molecule.

• Click here to learn more about DNA, genes, and proteins.

• Francis Crick and James Watson figured out how a DNA molecule fit together. Click on the underlined names to meet them!

How are genes passed from parent to child?

• Through reproduction. • The child receives a set of chromosomes from

the mom and a set of chromosomes from the dad.

• Humans have 46 chromosomes or 23 pairs of chromosomes.

• Other organisms have different numbers of chromosomes.

• Click here to see the differences.

Each organism received its genes from its parents.

• Let’s use a critter to explore….• This critter has 8 chromosomes.• Let’s see if you can determine the traits a critter

would have if it had the chromosomes and alleles in your bag.

• Yellow chromosome BLUE green eye color• Pink chromosome BROWN orange spots or not• Orange chromosome PURPLE yellow skin color• Purple chromosome RED lt blue curly tongue

Now lets watch meiosis

• Demonstration by Mrs. Putnam.

Mrs. Putnam

4 Daughter Cells from One Parent Cell

HALF THE CHROMOSOME NUMBER FOR EACH CELL!!!!

4 Daughter Cells from One Parent Cell

HALF THE CHROMOSOME NUMBER FOR EACH CELL!!!!

Sex Cells are Haploid or Half

• The gametes are the sex cells of the parents. When formed they undergo meiosis. In the process, the chromosomes are duplicated, then separated and packaged as separate sets in the sex cells.

• If this were not the case, the number of chromosomes would double every time a new organism was created.

• Click here to see diagram of mitosis and meiosis.

Meiosis

More meiosis

Click here to see entire PowerPoint of mitosis and meiosis examples.

Cells dividing in meiosis

Mrs. Putnam’s Critters underwent Meiosis

• Duplicate, split, make 4 new cells• Now 4 daughter cells or 4 sex cells

• Does each daughter cell have the same alleles for the traits?????

YOUR TURN!

• You will not duplicate yours, just separate them so you have 2 sets of half.

• The left side of the table will pick one half to simulate meiosis.

• The right side of the table will pick one half to simulate meiosis.

• Now put the two chosen cells together. Do not plan, put them together randomly.

Congratulations!

• CONGRATULATIONS…..you have a new critter!

• Draw a baby picture of your critter.

• Yellow chromosome BLUE green eye color• Pink chromosome BROWN orange spots or not• Orange chromosome PURPLE yellow skin color• Purple chromosome RED lt blue curly tongue

Quiz

• How did you know which traits to draw?• Where are chromosomes located?• Do all organisms have the same number of

chromosomes?• Is there only one gene on a chromosome or

many?• Explain dominant and recessive.• Explain heredity.

Homework

• Ask your family to show you their traits.• Can they roll their tongues?• Do they have dimples?• What other traits will you notice?

• Whether through sexual or asexual reproduction, traits are passed from the parent to the offspring on the genes that are inherited.

Whose Genes Did they Get?

• Click here to learn more genetic terminology.

Click here to link Mrs. Putnam’s Heredity sites.