Student Exploration: Human Karyotyping Vocabulary : autosome, chromosomal disorder, chromosome, genome, karyotype, sex chromosome
Prior Knowledge Question (Do this BEFORE using the Gizmo .)
A chromosome is a rod-shaped structure made of coils of DNA. Most human cells have 23 pairs of chromosomes.
1. Why do you think humans have two sets of 23 chromosomes? (Hint: Where did each set come from?)
2. How do you think different people’s chromosomes would compare?
Gizmo Warm-up Scientists use karyotypes to study the chromosomes in a cell. A karyotype is a picture showing a cell’s chromosomes grouped together in pairs. In the Human Karyotyping Gizmo™, you will make karyotypes for five individuals. Take a look at the SIMULATION pane. Use the arrows to click through the numbered list of chromosomes at the bottom right of the pane.
1. How does the appearance of the chromosomes change as you move through the list?
2. Examine the chromosomes labeled x and y . How do these two chromosomes compare?
Question: How are male karyotypes different from female karyotypes? 1. Compare : In the SIMULATION pane, make sure Subject A is selected. Click on and drag one of subject A’s chromosomes to the area labeled Identify . Use the arrows to compare the chromosome you picked with chromosomes 1 through 22 and also with X and Y.
Which chromosome did you select?
2. Create : Drag the chromosome to the appropriate position on the KARYOTYPING pane. Then select another chromosome, identify it, and place it on the karyotype. When you have identified and placed all of the chromosomes, click the camera ( ) to take a snapshot of the karyotype. Paste the snapshot into a document, and label it “Subject A.”
3. Count : Chromosomes 1 through 22 are called autosomes . Examine the karyotype you have created. How many total autosomes do human cells have?
4. Draw conclusions : Look at chromosome pair 23. These chromosomes are known as sex chromosomes because they determine the sex of an individual. Females have two copies of the X chromosome. Males have one X chromosome and one Y chromosome. Examine the karyotype. Is subject A a male or female?
How do you know?
Click the DIAGNOSIS tab to check your answer.
5. Analyze : Select Subject B from the SIMULATION pane. Complete subject B’s karyotype. Take a snapshot of the completed karyotype, paste it into your document, and label it.
Examine the karyotype. Is Subject B a male or female?