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Agenda Spring 2001

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Paper Karyotyping Lab

from HEREDITY: CHROMOSOMES AND PEDIGREES

Click here for a printable version

Prelab Questions

(Write answers in your lab notebook.)
  1. Imagine a city with about 100,000 separate home addresses. These locations where people live are arranged into 46 buildings of various sizes. Each building has more than one floor, but the number of floors varies from building to building. Large buildings may have as many as 3000 residents, while the smallest building has about 1000 residents. On the back of this sheet, draw an area of this city that has several buildings. Label your drawing with street names and specific addresses. Imagine yourself in one of the apartments. What is your address? Explain how you created your address.
  2. Assume that the buildings could be distinguished from each other by their size and distinctive exterior design. Design a directory or map that identifies three or four locations where friends live. It may be easiest to draw your answer.
  3. Below is a picture of a metaphase spread. Metaphase is a stage in the cell division cycle prior to division. Do the small dark objects resemble a bunch of miniature socks scattered on the floor, or do they resemble miniature buildings full of individual apartments? Think of both analogies and create an address system for these structures, called chromosomes, in which a specific location can be identified.

Lab Worksheet

MATERIALS

  • Human Chromosomes-Metaphase Spread Sheet
  • Fact Sheet
  • Human Karyotype Form

PROCEDURE
  • The chromosomes on the Metaphase SpreadSheet are from one human diploid cell and are treated with a giesma stain (G-banded) to give them a specific banding pattern.
  • Your task is to create a karyotype from these chromosomes by cutting them out and arranging them on the Human Karyotype Form.
  • The chromosomes are numbered to make it easier to identify them, but realize that in actual studies of chromosomes, these numbers are not attached to the chromosome but must be deduced by looking at the characteristics of the chromosome.
  • Carefully cut out your chromosomes, making sure not to lose any. Be especially careful not to sneeze on or otherwise disrupt your chromosomes before you glue them down. Arrange the chromosomes so that the short arm (the area above the constriction) is on top.
  • Arrange the chromosomes in order of size, from large too small.
  • Use a glue stick or tape to attach each individual chromosome above the appropriate number on the Human Karyotype Form.
  • Study the autosomes carefully and. on the back of this sheet, list ways to determine whether chromosomes really make a matched pair. How does the banding pattern help verify the match between two chromosomes?
 

HUMAN CHROMOSOMES

METAPHASE SPREAD SHEET 1:

 

HUMAN CHROMOSOMES

METAPHASE SPREAD SHEET 2:

Name

Human Karyotype Form

___________
___________
___________
___________
___________
1
2
3
4
5
___________
___________
___________
___________
___________
___________
___________
6
7
8
9
10
11
12
___________
___________
___________
___________
___________
___________
___________
13
14
15
16
17
18
___________
___________
___________
___________
___________
___________
___________
19
20
21
22
X
Y

 

 

POSTLAB WORKSHEET

You have prepared a karyotype from a picture of human chromosomes called a metaphase spread. Look carefully at your karyotype, and recall the metaphase spread as you answer the following questions.
  1. Summarize the relationship between the size of the chromosome and the number assigned to it.
  2. What are the exceptions to the pattern noted in question 1?
  3. In what ways are the female and male karyotypes alike, and in what ways are they different? You may need to look at a classmate's karyotype.
  4. Describe the general structure of a chromosome and the kinds of structural variation that exist among different chromosomes.
  5. Describe the patterns of light and dark areas (banding) found on the chromosomes.
  6. What advantage might chromosomal banding patterns have in the analysis and diagnosis of chromosomal problems or abnormalities