Why we look somewhat like our parents, but not exactly.

Think about the picture matching activity.

Everyone in the class is alike, but different.

How are we alike?

How are we different?

Click here and then on “Find out more about Heredity!

”

• The code for traits is contained in the nucleus of each cell of our body.

• Inside the nucleus are chromosomes which are made of DNA. This is the code to make you you.

Cell

Nucleus

Chromosome

DNA: One section of DNA is a gene

• Click here for an animation showing the relationship between cells, nuclei, chromosomes and DNA. – Then click on “What is DNA?”– Then “Cellular Journey”– Then Nucleus and – Then “DNA Basics”

======================================

• Put the following items in order from largest to smallest: chromosomes, DNA, cell, nucleus

• Chromosomes are very small.

• Here is what they look like when you see them through a microscope.

Chromosome smear

• Click here to see more about chromosomes. Then click on “What are Chromosomes?

List three words that describe a chromosome.

a.

b.

c.

• A karyotype is when chromosomes are grouped from largest to smallest.

• They are also grouped by the centromere position and the banding patterns.

• List at least 3 chromosomes characteristics that are used to make a karyotype. (What features of the chromosomes do people look at to help them put the chromosomes in the proper order?)

a.

b.

c.• Why do you think researchers and doctors would

rather look at a karyotype than at the chromosomes smear as they appear through a microscope?

• Compare the karyotypes for a male and a female.

A male karyotype

A female karyotype

Compare the male and female karyotypes.

1. How are they alike?

2. How are they different?

3. How can you tell a female karyotype from a male karyotype?

Body Cells

Body cells are all cells in the body, except the egg and sperm

• Lung cells• Liver cells• Bone cells• Nerve cells• Skin cells• Muscle cells, etc., etc., etc.

Where do we get new body cells?

• Write where you think that we get new cells.

• What do you think happens to the number of chromosomes in these new cells?

1. Before a body cell divides it copies every one of the chromosomes.

2. When the body cell divides, each new body cell gets a copy of each chromosomes.

3. The new body cell is exactly like the original cell!! They have the same number and same type of chromosomes.

Click here to see an animation of this.

1. Look at this body cell. How many chromosomes does it contain? _____

2. How many pairs of chromosomes? __

3. Sketch the body cells that will result after this one divides. Draw the new cell

here:

One section of DNA is a gene

Scientists are finding out more about DNA each day.

Human Genome Project:

• found the gene (code) for each chromosome in our body

• don’t know exactly how each gene (code) works.