Download The Human Genome

The Human
Genome
The Human Genome Project
The Human Genome Project is an ongoing
effort to analyze the human DNA sequence.
 A genome is the entirety of an organism's
hereditary information. It is encoded either
in DNA or, for many types of virus, in RNA.
 The human genome has over 6 million
base pairs.

Cont. HGP
Completed in 2003 and still being analyzed
 Project goals were to

identify all the approximately 20,000-25,000
genes in human DNA,
 determine the sequences of the 3 billion chemical
base pairs that make up human DNA,
 store this information in databases,
 transfer related technologies to the private sector,
and
 address the ethical, legal, and social issues
(ELSI) that may arise from the project.

How did they do it?

Started w/ DNA Fingerprinting
Analysis of sections of DNA that have little or no
known function, but vary widely from one
individual or another.
 Gel electrophoresis

A closer look………

Karyotypes

A picture of chromosomes.
We know this is a human
karyotype because there
are 46 chromosomes.
 Which 2 chromosomes are
the sex chromosomes?
 The rest are called
autosomes.

Chromosomal Disorders



Get too many or too few copies of a chromosome
Caused by non-disjunction during meiosis
Examples:


Down’s Syndrome: Trisomy 21
Turner’s Syndrome: X_
• Effects 1 in 2500 Females and symptoms include short stature,
sterile, "webbed" neck, a low hairline, drooping of the eyelids,
differently shaped ears that are set lower on the sides of the
head than usual, abnormal bone development (especially the
bones of the hands and elbows)

Klinefelter’s Syndrome : XXY
• Symptoms: Infertility, language and neurological impairment,
gynecomastia, lanky, youthful build.
Chromosomal Disorders

More Examples

Patau syndrome-extra 13
• Many don’t survive, but those who do have the following
symptoms: mental & motor challenged, polydactyl (extra digits),
low-set ears, holoprosencephaly (failure of the forebrain to
divide properly), heart defects, structural eye defects, cleft
palate, spinal defects, omphalocele (abdominal defect),
abnormal genitalia, overlap of fingers over thumb

Edward syndrome-extra 18
• Symptoms: Mental retardation, Low set ears, Rocker
bottom feet, Flexion deformities on the fingers,
Congenital heart disease, Low birth weight, Small
lower jaw, Recessed chin, Prominent back of skull
The passing on of traits….
In order to ensure that a trait is actually
inherited and not the result of environmental
influences, you have to study how the trait is
passed on from one generation to the next.
 A pedigree chart, shows the relationship of
traits in a family, can be used to help with this
task.

Pedigree Chart
Cleopatra’s Pedigree
Russian Royal Family
Another special pattern

Sex-linked inheritance
Many sex-linked genes are found on the X
chromosome.
 More than 100 sex-linked genetic disorders
have now been mapped to the X
chromosome.
 Males have just one X chromosome. Thus,
all X-linked alleles are expressed in males,
even if they are recessive.

Colorblind Test
Practice Punnett Square
Common Examples:
Colorblindness
Baldness
Hemophilia
Pedigree showing X vs. Y