SBI3U Karyotypes

The diagram below shows the karyotype of a normal human. Homologous pairs of chromosomes areidentified by their general shape, length, and tha pattern of banding produced by a special staining technique.Humans have 46 chromosomes (23 pairs; n=23).

The male karyotype has 44 autosomes, a single X chromosome, and a Y chromosome (written as 44 + XY),whereas the female karyotype shows two X chromosomes (written as 44 + XX).

Questions

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1. Explain what a karyotype is and comment on the information it provides.2. Distinguish between autosomes and sex chromosomes.

SBI3U: Genetic Continuity - Human Diseases Name: _

Karyotyping and Genetic Disorders

You are a team of highly skilled geneticists, working for the "Nationcl Centre ofGenetic Disorders" or the NCGD. Your team's expertise is needed to process arecent DNA sample and to determine what disorder the patient is suffering from.The NCGD has developed a process of karyotyping that is so powerful, that it notonly detects non-disjunction disorders (when a set of gametes has too many or notenough chromosomes), but it can also detect pathological alleles that cause otherdiseases as well.

Karyotyping involves exposing cell samples to drugs that suspend cell division;essentially, freezing genes in time. Cells are then stained to make theirchromosomes more readily seen, and to expose genetic banding that uniquelyidentifies each pair. If we arrange the chromosomal pairs by length in descendingorder, we can assign each pair a number. The longest pair is assigned the number 1and the smallest 22. Number 23 is reserved for the sex chromosomes.,--Task

Working in groups, your job is to process the alleles included with this lab brief. Thispatient is suffering from one of five possible disorders:

DownIS SyndromeKlinefelter SyndromeTurner SyndromeTay 5achsPhenylketonuria (PKU)

You are looking for two possible problems:1. The wrong number of chromosomes.2. Chromosomes whose banding does not quite match up.

Ciu&s+ions1) What set of chromosomes did you get? (A,B,C,D,E)2) What disease does your patient have?3) How many rows of chromosomes are in a human karyotype chart?4) What is the total number of chromosomes that your test patient has?

~~ 5) How many chromosome pairs are shown?6) What characteristics helped you to identify a chromosome pair?7) What is the sex of your patient?8) What point in the life cycle of a cell would be best for photographing

a karyotype?