Transcript KARYOTYPES & THE HUMAN GENOME

KARYOTYPES &
THE HUMAN GENOME
KARYOTYPES &
THE HUMAN GENOME


To analyze chromosomes, scientists
photograph cells while they are
undergoing mitosis when the
chromosomes are fully condensed &
easy to see.
They then cut out the chromosomes
from the photographs & arrange them
together in homologous pairs.
KARYOTYPES &
THE HUMAN GENOME

A picture of
chromosomes
arranged in this
way is called a
karyotype, like
the picture at left.
KARYOTYPES &
THE HUMAN GENOME



To review, humans have 46 chromosomes
in each of our body cells & 23 in each of
our sex cells.
Recall that the 23rd pair of chromosomes
are called sex chromosomes & they
determine a person’s gender.
Mutations can occur on any of our 23 pairs
of chromosomes.
KARYOTYPES &
THE HUMAN GENOME

Karyotypes play an
important role in identifying
genetic disorders, as they
can give doctors a preview
to the genome of an
unborn child & help
diagnose a disorder in
someone who has physical
or mental signs that there is
something wrong with
them.
GENETICISTS


A geneticist is a scientist that
works in the laboratory doing
molecular research or collecting
and analyzing family histories
and counseling families on
genetic diseases & disorders.
They have the opportunity to
discover new genes & can
possibly help cure genetic
disorders.
SEX-LINKED TRAITS


There is a special pattern of inheritance
for genes located on the X and Y
chromosomes.
Because their chromosomes determine
one’s gender, genes located on these
chromosomes are called sex-linked
genes.
SEX-LINKED TRAITS
SEX-LINKED TRAITS


More than 100 sex-linked genetic disorders
have now been mapped to the X chromosome.
The Y chromosome is much smaller than the X
chromosome & appears to contain only a few
genes.
SEX-LINKED TRAITS


Males have only one X
chromosome, therefore
all X-linked alleles are
expressed in males,
even if they are
recessive traits.
Colorblindness,
hemophilia and
muscular dystrophy are
considered sex-linked
traits.
DNA ANALYSIS

Due to the great diversity of the human
genome (all of the genes in a human’s
body), we can be sure that no two
individuals are exactly the same (except
identical twins).
DNA ANALYSIS


DNA Fingerprinting is a specific form of genetic
testing that analyzes sections of hair, blood,
sperm or skin tissue to locate patterns of
bands in the DNA that distinguishes one
person from any other person in the world.
This often helps solve criminal cases or free
someone who has been wrongfully accused
and convicted of a crime.
DNA ANALYSIS
HUMAN GENOME PROJECT

This project is an ongoing effort to
analyze the human genome in order to
map genes & determine what causes
certain diseases, to give us clues to
some of the properties of life and to
find information that may be useful in
developing drugs & treatments for
disease.
ETHICAL ISSUES


Many ethical issues exist in the advancement
of genetics.
Scientists have determined that some cells
(stem cells) can be manipulated with the
hopes of one day curing diseases & disorders,
however many people fear that cloning,
harvesting stem cells from fertilized cells and
other such genetic manipulations will result in
a self-engineered society.
ETHICAL ISSUES