Download Karyotype and Genetic Disorders

Topic:
Karyotype and
Genetic Disorders
Name: ____________________________
Date:_________________________
Objective: SWBAT understand the process of karyotyping and become familiar
with possible genetic disorders.
Questions/Main Ideas:
What is the Human
Genome Project?
What is a karyotype?
What is a chromosome
map?
What are some examples
of recessive genetic
disorders?
Human Genome Project=
- 13 year project to identify all 20,000 genes for a human (completed in
2003)
- know the sequence of 3 billion base pairs (bp)
- store the information in a database
- may be useful in detection, prevention, and treatment of many genetic
diseases
- address the ethical questions of gene identification and gene therapy
Karyotype= Picture of arranged
chromosomes
- Humans have 23 pairs of
homologous chromosomes (22
autosomal pairs)
- Homologous= each similar in
size and shape
- Process= Scientists take a
picture of cells during mitosis,
cut out chromosomes, and
group in pairs according to size
and centromere location
- Uses= See the number of
chromosomes and identify
genetic disorders
Chromosome Map
- the picture of a chromosome with genes labeled
- Loci= the location of a gene on a particular chromosome
Genetic Disorders
Gene for Huntington Disease
Recessive disorders:
1. PKU= Phenylketonuria
- People with PKU lack the enzyme needed to break down
phenylalanine (amino acid found in milk), so it builds up in tissues
- May cause mental retardation
2. Tay Sachs
- Buildup of lipids in brain cells
- Causes a breakdown of the nervous system and blindness
- Leads to death in early childhood
3. CF= Cystic Fibrosis
- Caused by deletion of 3 bases in DNA
- Results in digestive problems and mucus buildup in lungs
4. Sickle Cell
- More common in African Americans
- Results in bent and twisted red blood cells,
causing them to get stuck in the capillaries (tiny
blood vessels)
- Physical weakness; damage to brain, heart, and
other organs
- Heterozygous are healthy and resistant to malaria
- One DNA base is substituted resulting in the
hemoglobin having a different sequence of amino acids
What are some dominant
genetic disorders?
Dominant disorders:
1. Huntington disease
- Loss of muscle control and mental function
- Symptoms appear middle age (30+)
What causes a
chromosomal disorder?
Chromosomal Disorders
Nondisjunction= homologous chromosomes fail to separate during meiosis
- Can occur with autosomal and sex chromosomes
- Causing abnormal number of chromosomes
- Risk of conceiving child with chromosomal disorder increases with the
mother’s age.
- Can cause disorders, such as:
What are some examples
of chromosomal disorders
caused by nondisjunction?
Summary:
1. Down Syndrome
- 3 copies of chromosome 21 (trisomy)
- People with Down Syndrome share common physical traits, such as flat
facial profile, small ears, and an upward slant in the eyes
- Causes mild to moderate mental retardation and developmental delays
- Affects 1 out of every 800 babies
2. Edward’s Syndrome
- 3 copies of chromosome 18 (trisomy)
- Results in developmental problems before birth and most do not survive
through pregnancy
- Affects 1 out of every 5,000 babies born
3. Turner’s Syndrome
- Only one X chromosome= X or XO
- Sterile female
4. Klinefelter’s Syndrome
- XXY= male
- No documented cases of person born without an X chromosome because
it is needed for normal development.