Download The Human Genome

The Human Genome
Ch. 14
The Genome
• A genome is the base
sequence of all the
DNA in an organism.
• A karyotype is a
photograph of all of an
organisms
chromosomes that are
froze and stained
during metaphase.
• There are 23 different
genes that are donated
from each parent to
make you..46.
Karyotypes
• Can be used to find
certain chromosomal
abnormalities such as
down syndrome.
Types of Chromosomes
• Sex Chromosomes
determine whether
offspring will be male or
female.
XX- female
XY-male
Which sex determines the
sex of the baby if mom
and dad each give one?
Sex determination
• Autosomes- non-sex
chromosomes (traits)
Predictions and People
• Pedigrees are used to show how a trait and the
genes that control it are inherited within a
family.
• Let’s work a couple and let me explain how
they work.
Overview of Genetic Disorders
• How many have you heard of?
Recessive Disorders
• Tay Sachs Diseasepeople are not able to
metabolize a particular
lipid, it accumulates in
the brain and results in
blindness and brain
damage.
• 1/3600 people
• 1/30 carriers
• Die by age 5
• Cystic fibrosis results
in an excessive
secretion of mucus
that accumulates in the
digestive tract and
lungs.
• 1/2500 newborns, 1/25
carriers (Caucasian)
• ½ live to age of 31
More Recessive
• Albinism don’t have
skin pigment.
• PKU
(Phenylketonuria)accumulation of
phenylalanine in tissues;
lack of normal skin
pigment, mental
retardation.
• Sickle Cell Anemiablood cells sickle
shaped and can’t travel
through blood vessels
well.
• 1/10 Africans are
carriers
• Co-dominant disorder
Dominant Disorders
• In many cases, a
person who has
inherited a dominant
disorder dies before
they can pass it on to
offspring.
• 1/500 people
• 4,400 known
dominant disorders
• Huntington disease
results in the
deterioration of the
nervous system.
• Homozygous
dominant-Fatal
• Hh- live to be 40
More Dominant Disorders
• Acondroplasiadwarfism
• Homozygous
dominant-Lethal
• Aa- dwarf
• Marfan’s- can’t make
connective tissueTALL
• Abraham Lincoln
• Polydactlyty- extra
fingers and toes
• 98% of people are
recessive
Blood Types
•
•
•
•
•
Phenotypes
A
B
AB
O
Who can give to whom?
Give a blood transfusion
•
•
•
•
•
Genotypes
IAIA or IAi
IBIB or IBi
I AI B
ii
Environmental Effects
• 1.1b Different parts of
the genetic
instructions are used
in the different kinds
of cells and are
influenced by the
cell’s environment and
past history.
• Himalayan rabbits fur color
is affected by temperature.
• Western white butterfly
wing coloration is affected
by temp.
• Japanese goby fish can
change its sex back and
forth in response to
changes in its social
environment.
Let’s read about these on page 150-151.
Human Genes and Chromosomes
• Only 2% of DNA in your chromosomes
function as genes, those that are transcribed
into RNA.
• The average human genes consists of about
3,000 base pairs.
• Chromosomes 21 and 22 are the smallest
human autosomes.
1.29a The action of genes, patterns of inheritance,
and the reproduction of cells and organisms account
for the continuity of life.
1.29b What are ways that inherited characteristics
can be observed at the molecular and wholeorganism levels, in structure, chemistry, and
behavior?
Sex-Linked Traits
• Morgan studied
Drosophila and found
sex linked genes for
eye color.
• Human sex-linked
traits.
– Color Blindness is Xlinked recessive. XcXc,
XcY
– Hemophilia- blood
doesn’t clot.
– Duchenne MD
Why would males be
more likely to have
these disorders?
X-Chromosome Inactivation
• Barr Bodies are formed in females because one X
is all that is needed in some cells and the other is
switched off randomly and forms a dense region in
the nucleus.
• Cats
– You can tell if male or female by spots because genes
that controls spots is located on X chromosome. Males
will have one color of spot and females will have 2
colors if Barr Bodies are expressed at different times.
Why?
Nondisjunction
• Nondisjuntion is the
failure of
chromosomes to
separate correctly
during mitosis or
meiosis.
• Monosomy- the zygote has
only one copy of a
particular chromosome.
• Trisomy- the zygote has 3
copies a chromosome.
• Most of the times it is
disruptive and kills the
embryo, but if it survives
there can be developmental
difficulties.
Examples
• Monosomy
– Turners Syndrome XO
• Affects only girls
• Infertility
• Minimal physical
abnormalities
• Trisomy
– Trisomy 18 (Edwards
Syndrome)
– Trisomy 13 (Patau
Syndrome)
– XXY (Kleinfelters)
– XYY
– XXX (Triplo X)
Sex Limited Traits
• Sex limited traits are
only expressed in the
presence of sex
hormones and are only
observed in one sex or
the other.
• Autosomal
• Different colored
plumage in male and
female animals.
• Can you think of any?
Sex Influenced Traits
• Sex Influenced traits
are expressed in both
sexes, but they are
expressed differently.
• Male Pattern Baldness
1.27 Humans, along with every other species has a
unique DNA sequence. Everyone has a similar cell
chemistry and anatomy, but are still different.
Human DNA Analysis
• There are roughly 6 billion bp in your DNA.
• Labeled DNA probes are used to detect
complementary base sequences found in
disease causing alleles such as CF or Tay
Sachs.
DNA Fingerprinting
•
1)
2)
3)
4)
Used to determine whether blood, sperm or other
material left at a crime scene matches DNA.
DNA is cut with restriction enzyme
Small fragments separated by Gel Electrophoresis.
Fragments with variable regions are detected with
probe resulting in DNA bands of various sizes.
Look for pattern.
See page 356.
The Human Genome Project
• It’s goal is to sequence
all of the DNA on
each gene in the
human body.
• 90,000 genes…..6
billion bases
Rapid Sequencing aka. Shotgun
Sequencing
• Cutting DNA into random fragments and
then determining sequence of bases in each
fragment.
• Computers put together
Gene Therapy
• An absent or faulty gene is replaced by a normal,
working gene.
• Viruses are used because they can enter a cells
DNA. They are modified so they can’t cause a
disease.
• The DNA fragment containing the replacement gene
is spliced to viral DNA and the patient is infected
with the modified virus particles, that carry the gene
into the cells to correct genetic defects.
1.15 In biological systems, STRUCTURE
DETERMINES FUNCTION.
1.16 Specific interactions and complexing of
smaller levels or organization determine higher
levels. This requires a constant input of energy and
new material.
Human Genome Review
• Click on the following link, choose your
textbook and review the material and take
self-test for Ch. 14.
• Ch. 14 Review