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Karyotype Lab
The Role of DNA and
Chromosomes
1. During cell division, DNA condenses
and coils to form chromosomes.
2. Each chromosome contains millions of
nitrogen base pairs which serve as
genes.
3. Each gene controls the production of a
protein in the organism which creates
a trait (characteristic).
Chromosomes
4.The chromosomes in a diploid cell
can be organized into
Homologous pair = matched sets
of chromosomes.
Pairs are matched on the basis of:
*Overall length of the chromosomes
*Banding pattern on the chromosomes
*Location of the centromere
Homologous Chromosomes
Human Chromosomes
5.The 46 chromosomes in a diploid
human cell create 23 homologous
pairs of chromosomes.
*Pairs 1-22 are referred to as
AUTOSOMES
6. Pair #23 = the Gender Determining
Chromosomes (Sex Chromosomes)
*may or may not match exactly.
*referred to as the X sex
chromosome and the Y sex
chromosome.
*The Y sex chromosome carries the Sex
Determining Gene (SRY gene) which is
the master switch to the male gender.
7. If the 23rd pair of chromosomes
matches exactly, then the
combination is referred to as
XX = Female
23rd pair of
chromosomes
match =
female
8.If the 23rd pair of chromosomes
does not match, then the
. combination is referred to as
XY = Male
23rd pair of
chromosomes
do not match
= male
Karyotype
9. A Karyotype is a technique used
to identify and evaluate the size,
shape, and number of
chromosomes in a sample of body
cells.
*Extra, missing, or abnormal positions
of chromosome pieces can be
determined.
*The gender of the organism can also
be determined.
Example: Normal Human Karyotype:
Example: Abnormal Human Karyotype:
Example: Abnormal Human Karyotype: