Download Chromosome

Inherited Diseases and
Chromosomes
Genetic diseases passed from
parents to child before birth.
Autosome
Chromosome
Telomere
Centromere
Allele
Exon
Contagious
Metaphase
Intron
Gene
Zygote
Transposon
Genetic Material
Tay-Sachs
Heredity
Hemophilia
Karyotype
Cystic Fibrosis
Mutation
Huntingdon’s
Disease
Sex
Chromosome
Polycystic
Kidney Disease
Sickle Cell Anemia
• Autosomal Recessive
– Males = 42
– Females = 48
– Oldest = 85
World Distribution
• One of the common
misconceptions is that only
black people get sickle cell,
but this is not the case.
• There are many different
ethnicities that can have sickle
cell.
Who Can Get Sickle Cell?
•
• Disease.
Disease.
ANYONE can get Sickle Cell
ANYONE can get Sickle Cell
• It is most common in the following ancestries:
• oIt African
is most common in the following ancestries:
Africanor South American
ooCentral
Central or South American
ooCuban
Cuban
ooIndian
IndianArabian
ooSaudi
Saudi Arabian
ooMediterranean
Mediterranean
ooHispanics
o Hispanics
Prevalence
o It is estimated the up to 80,000 people in
America have Sickle Cell Disease
o 1/500 African Americans have Sickle Cell
Disease
o 1/1000 -4000 Hispanics have Sickle Cell
o 1/12 African Americans are carriers for
Sickle Cell
o 1/50 Asians are carriers for Sickle Cell
o 1/100 Greeks are carriers for Sickle Cell
It is Unknown why people with the Sickle Cell
Trait are resistant to Malaria, but there are
several theories…
1.
2.
The carriers of Sickle Cell have some
abnormal Hemoglobin, and when they come in
contact with the Malaria parasite they become
sickled. Then those cells go through the
spleen, which eliminates the cells because of
their sickle shape, so the Malaria would be
eliminated as well.
The Sickle Cell trait causes the malaria to stay
in the body for an extended period of time, so it
is able to build up a defense to it.
3. Because oxygen concentration is low in the spleen, and
because infected
cells often get trapped in the spleen, it is possible that they are
destroyed in the spleen
4. The Malaria parasite produces an acid when it is inside of the
red blood cells. This causes the red blood cells to polymerize,
and the cells will sickle. These sickled cells are then destroyed
when the blood cells go through the spleen.
Testing and Treatment
• Tests
– Physical Exam
– Blood Test
– Pedigree
– Electrophoresis
• Treatment
– Bone Marrow Transplant
– Stem Cell
– Drug Therapy
– Gene Therapy
Examples of Inherited Diseases
•
•
•
•
•
•
•
Tay Sachs
Hemophilia
Cystic Fibrosis
Huntington’s Disease
Polycystic Kidney Disease
Hemachromatosis
Sickle Cell Disease
Tay Sachs
What is it?
A metabolic disease caused by the
lack of an enzyme to efficiently
breakdown fatty acid. 2:1 ratio of
females to males.
What is the Severe neurological disorders with
outcome?
death usually occurring before age 4.
What are
•Loss of motor skills.
the
•Loss of muscle tone.
symptoms? •Listlessness and Irritability.
Hemophilia
What is it?
A metabolic disease caused by the
lack of a protein necessary to
efficiently clot blood.
What is the Prone to excessive bleeding, but
outcome?
modern drug therapy can lessen
effect.
What are
•Bruise easily.
the
•Blood slow to clot.
symptoms?
Cystic Fibrosis
What is it?
What is the
outcome?
A disease caused by the production
of abnormal, thick, sticky mucus.
Death caused by lung infections
usually before age 35.
What are
•Coughing and wheezing.
the
•Diarrhea.
symptoms? •Chronic lung infections.
Huntington’s Disease
What is it?
A progressive disease caused by the
deterioration of nerve cells in the
brain.
What is the Continual decline in mental and
outcome?
physical ability; death usually occurs
15 to 20 years after onset.
What are
•Difficulty walking.
the
•Uncontrollable body movements.
symptoms? •Memory and cognitive impairment.
Polycystic Kidney Disease
What is it?
A disease caused by the
development of fluid-filled growths
called cysts inside the kidney.
What is the Dialysis or a kidney transplant may
outcome?
eventually be required.
What are
•Blood in urine.
the
•Lower back pain.
symptoms? •Kidney stones.
Hemachromatosis
What is it?
What is the
outcome?
A metabolic disease caused by the
over absorption of iron.
Damage to multiple organs due to
excess iron.
What are
•Joint pain.
the
•Fatigue.
symptoms? •Heart problems.
Sickle Cell Disease
What is it?
A metabolic disease caused by the
production of deformed hemoglobin.
What is the Death in middle age due to increased
outcome?
risk of stroke, heart attack, and
infection.
What are
•Fatigue.
the
•Yellow colored skin—Jaundiced.
symptoms? •Increased number of infections.
How Are Diseases Inherited?
Passed from parent to child in the genetic
material in the same way that all traits are
passed to the next generation.
What Is Genetic Material?
• Genetic material refers to the chemical
molecules that encode all the instructions
cells need to function.
• These instructions are passed on to the
next generation when cells reproduce.
• Reproductive cells carry the genetic
material to create a new organism.
Human Reproductive Cells
•Egg: Produced by females in the ovary.
•Sperm: Produced by males in the testis.
Both types of cells carry the genetic material
needed to form a new human.
Egg Cell
Used with permission Scott Kaplan, Pacific Fertility Center
http://www.infertilitydoctor.com/lab/lab_embryo_devel.htm
Sperm Cells
Used with permission of Sandra Caudle, Calhoun Community College
http://webnt.calhoun.edu/distance/Internet/Natural/anatomy/EndoRepro/spermcells.html
What Causes Inherited Diseases?
• Genetic material of a cell is changed
causing a change in the cell’s and
ultimately the body’s function which lead to
a disease.
• The changed genetic material is passed
from parents to child.
Reproductive Cells and
Chromosomes
• Chromosomes contain the genetic
material.
• Each reproductive cell contains one copy
of each of the 23 human chromosomes.
Fertilization
• Sperm cell fuses with egg cell.
• The nucleus of the sperm cell is
injected into the egg cell.
• After the sperm fertilizes the egg, a
zygote containing 23 pairs of
chromosomes is formed.
Early Zygote
Nuclei
from egg
and
sperm
fusing
Used with the permission of Richard Sherbahn, MD. Advanced Fertility Center of Chicago
http://www.advancedfertility.com/embryos.htm
What Are Chromosomes?
• Complex structures found in the nucleus of
cells.
• Different types of organisms have different
numbers of chromosomes.
• Number of chromosomes does not
indicate complexity of the organism.
Number of Chromosomes in Cells
from Different Animals
Human
46
Dog
78
Cat
38
Horse
64
Cow
60
Sheep
54
Microsoft Office Clip Art www.microsoft.com
How Do Chromosomes Carry
Information?
Image courtesy of Dr. Sinnamon, Dean College of Arts and
Sciences, Southern Wesleyan University
Chromosomes—What We Know
• Located in the cell’s nucleus.
• Humans have 23 pairs.
• Inherit one of each of the 23 types of
chromosomes from each parent.
• Passed to new generation in sperm and
egg cells.
• Inherited diseases are passed to new
generation on chromosomes.
Chromosome Structure
• Each chromosome consists of a long
single molecule of deoxyribonucleic acid
(DNA).
• Basic chromosomal structure the same in
all cells that contain a nucleus.
– Including the cells that form plants, animals,
and fungi
Chromosome Structure
• Exons
– Specific nucleotide base sequence
– Involved in producing proteins
– DNA bases transcribed into mRNA and then
amino acids
• Introns
– DNA bases found between exons
– Are not transcribed
Chromosome Structure
• Centromere
– The constricted region of two sister chromatids.
• Teleomere
– The end of the chromosome
– Made of a reoccurring 6 nucleotide bases
• TTAGGG
Chromosome Function
• Contains the code or instructions for how
to make specific proteins which then
determine the organism’s traits.
• The specific instructions for a protein are
on sections of the chromosome called
genes.
What is a gene?
• A section of DNA that corresponds to a
discreet unit of heredity (traits such as hair
color).
– Generally a gene is the information needed to
make a specific polypeptide (chain of amino
acids).
– Proteins that are a single polypeptide are
usually associated with a single gene.
– Proteins that consist of multiple polypeptides
are associated with multiple genes.
Jumping Genes?
• Transposons are called jumping genes.
• Sequence of DNA that jumps around
within the chromosome.
• Can move, multiply, and mutate to alter
the genome and DNA.
Which are more, genes or transposons?
• Genes
– 28
• Transposons
– 500
DNA structure?
• 8 histone protein subunits attach to DNA
to form a NUCLEOSOME
• 6 nucleosomes stack on top of each other.
• This creates a chromatin.
• 6 feet of DNA will fit into a nucleus.
U.S. Department of Energy Human Genome Program,
http://www.ornl.gov/sci/techresources/Human_Genome/education/images.shtml
What is the relationship?
• A gene is a segment of the chromosome
that codes for a single protein.
• A gene is a sequence in a DNA strand.
• A chromosome is composed of a single
piece of DNA that contains genes.
Question
• What percentage of the human genome is
identical between individuals?
– 99.9%
How are you different from your
friends?
• Single nucleotide polymorphism (or SNP)
– Sites along the genome where individuals
differ by a single base pair.
– Multiple SNPs found throughout the three
million DNA base sequence.
Sex Linked Traits
• Genes on the X chromosome are called “sex-linked”, because they
expressed more often in males than in females
• There are very few genes on the Y chromosome.
• Since males only have one X chromosome, all genes on it, whether
dominant or recessive, are expressed.
• In contrast, a mutant gene on an X chromosome in a female is
usually covered up by the normal allele on the other X. Most
mutations are recessive. So, most people with sex-linked genetic
conditions are male.
• Another fact about sex-linked genes. Males produce ½ their sperm
with their X chromosome, and half with their Y chromosome. The Xbearing sperm lead to daughters and the Y-bearing sperm lead to
sons. So, sons get their only X from their mothers, and the father’s
X goes only to daughters.
• The Y chromosome is passed from father to son.
X-linked Inheritance – When Men and W
Behind the 8-ball? Colorblindness is an X-linked recessive trait.
A Boy with Cri-du-Chat Syndrome
– a Debilitating Disorder Caused by
Chromosome Deletion
Translocations Lead to a
Number of Human Cancers
In Burkitt’s lymphoma, a chromosome
translocation causes a cell cycle-promoting
gene to always be active.
Searching for Chromosomal Defects Amniocentesis and Chorionic Villus
Sampling
Many new
techniques for
learning about
individual
genes rather
than whole
chromosomes
are available or
Searching for Chromosome and
Gene Defects – Pre-Implantation
Removing a cell for
from a human
Genetic Diagnosisdiagnosis
(PGD)
embryo.
The diagnosis:
trisomy 21 (Down
syndrome).
Chromosomes and Sickle Cell
• Chromosome 11 carries the instructions
(genes) to make the hemoglobin protein.
• There are different versions of these
genes:
– Normal--healthy
– Mutated or changed--Sickle cell or other
hemoglobin disorder.
Activity 4.2.1
• Create chromosome spreads using human
cells taken from a cancerous tumor.
• Observe the number and shapes of
chromosomes in the spreads.
• Calculate the average number of
chromosomes per cell.
Autosome
A chromosome that is not directly involved in
determining sex, as opposed to a sex chromosome.
Chromosome
Any of the usually linear bodies in the cell nucleus that
contain the genetic material.
Contagious
Capable of being transmitted from person to person,
animal to animal, animal to human, or human to animal
by contact.
A discrete unit of hereditary information.
Gene
Genetic Material Molecules responsible for heredity and variation of
organisms.
Heredity
The transmission of traits from ancestor to descendant.
Karyotype
A display of the chromosome pairs of a cell arranged
by size and shape.
Mutation
A rare change in the genetic material, ultimately
creating genetic diversity.
Sex
Chromosome
One of the pair of chromosomes responsible for
determining the sex of an individual.