Lab 4 Chromosomes and Karyotyping PDF

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Lab #4 Chromosomes and Karyotyping Chromosomes are located in the nucleus of your cells. In body cells there are 46 chromosomes. The cell has two sets of each chromosome, one of the pair came from the mother, the other from the father. The maternal and paternal chromosomes in a homologous (homo = same) pair have the same genes at the same location. Simply put, chromosomes contain your genetic information. They are numbered based on their size, with pair number 1’s being the largest and pair number 22’s being the smallest. The first 22 pairs are called autosomes, and the 23 rd pair are the sex chromosomes. In a female, the sex chromosomes are XX and in a male they are Xy. Abnormalities can occur in the number of chromosomes, there could be one more than normal, one less, or even a piece of a chromosome could be missing. The most common syndrome with an extra chromosome is Down’s Syndrome which is when a fetus has an extra #21. Any of these differences can lead to health issues. A karyotype is a map of the chromosomes. Cells of the developing fetus are collected from the fluid surrounding the fetus (amniotic fluid) called an amniocentesis or from the developing placenta (chorionic villi sampling), treated and then mapped to see if there are any abnormalities. Current research is showing that there may even be some fetal cells in the mothers’ blood, which means in the future a karyotype may be completed with just a blood sample from the mother. This would be a good thing because the two other methods mentioned increase the risk of a miscarriage.

In this lab, you will gain experience in constructing and interpreting karyotypes. Unlike “old-fashioned” karyotypes that were generated from black-and-white photos, these karyotypes were prepared using a technique called FISH (fluorescence in situ hybridization). In FISH, fluorescently-labeled DNA molecules are allowed bind to specific chromosomes. These “probes” allow you to identify homologous pairs and to distinguish between pairs by looking at their patterns of colors. An example of a FISH karyotype is shown in Fig. 1. Note the banding patterns of the chromosomes, usually several per chromosome. Each band represents regions covering several hundred genes.

Activity 1. Constructing normal human karyotypes

Located below is one copy of each chromosome. On the following page is the second pair of each chromosome. Print out the next three pages, cut out the chromosomes from both pictures, pair them up and glue or tape them on the chart provided. You will then need to answer the questions on the bottom of the chart, take a picture or scan chart of completed project and insert into provided space in this document. You will also need to take a picture of you doing the assignment so half-way through taping or gluing, take a selfie with the partially completed assignment and insert into this document.

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Is this the karyotype of a human female or human male? _________________________ Why? ___________________

Chart 1

Glue the homologous pairs on the chart

Insert picture of completed Karyotype here:

Insert “selfie” picture here:

Activity 2: Go to the following website and answer the questions below. There is also a link in the lab 4 folder. http://www.biology.arizona.edu/human_bio/activities/karyotyping/karyotyping.html

Web Karyotyping Questions Patient A Notation: 47 XY +21 Diagnosis: Down Syndrome Describes characteristics of a person with this karyotype. Should be one paragraph long with a reference. There are many different characteristics for a person with down syndrome. One of those would be a short neck with excess skin at the back of the neck. Another characteristic would be a small head along with ears and mouth. Another would be upward slanting eyes. What are common symptoms of down syndrome? (2017, January 01). Retrieved February 28, 2021, from https://www.nichd.nih.gov/health/topics/down/conditioninfo/symptoms

Patient B

Notation: 47xxy+23 Diagnosis: Klinefelter Syndrome Describes characteristics of a person with this karyotype. Should be one paragraph long with a reference. Some characteristics of Klinefelter syndrome include sparse armpit and facial hair. It also includes a tall stature and abnormal body proportions such as long legs and a short trunk. Another characteristic of Klinefelter syndrome is enlarged breasts called gynecomastia. About klinefelter syndrome. (n.d.). Retrieved February 28, 2021, from https://www.genome.gov/Genetic-Disorders/Klinefelter-Syndrome#:~:text=Males%20who %20have%20Klinefelter%20syndrome,long%20legs%2C%20short%20trunk).

Patient C Notation: 47xy+13 Diagnosis: Trisomy 13 syndrome Describes characteristics of a person with this karyotype. Should be one paragraph long with a reference. Individuals with these defects tend to have heart defects. Another characteristic of Trisomy 13 syndrome is brain or spinal cord abnormalities. They also have very small or poorly developed eyes. Another characteristic is extra fingers or toes or a cleft lip. Trisomy 13: MedlinePlus Genetics. (2021, February 16). Retrieved February 28, 2021, from https://medlineplus.gov/genetics/condition/trisomy-13/#:~:text=Individuals%20with %20trisomy%2013%20often,weak%20muscle%20tone%20(hypotonia)....