Download DNA Structure and Function

Genetic Disorders – Gene Disorders
What is a gene?
Gene – Sequence of DNA bases
that code for a trait
(blueprint)
Where are genes stored?
Genes are found on
chromosomes.
Each chromosome has
its own set of genes.
Notable genes on Chromosome 18:
Parkinson Disease
Some types of cancer
Some forms of obesity
Notable genes on Chromosome 20:
Breast Cancer
Diabetes
Epilepsy
Notable genes on Chromosome Y:
Infertility
Night blindness
Inability to make testes
How does DNA sequence lead to a trait?
In order to make a trait, a cell uses the
gene information to build a protein.
GENE
PROTEIN
What are some examples of proteins?
-Hair
-Fingernails, horns, antlers
- Hemoglobin
- Enzymes to digest food
- Antibodies to fight disease
What happens if the gene is
changed?
As with a blueprint, if you change the
directions you change the product.
What happens if the gene is
changed?
Mutation – Change in a DNA sequence
– missing base
– extra base
ACTATGG
ACTTGG
ACTATGG
ACTAGTGG
– substitute a base ACTATGG
ACTCTGG
Mutations Part 2
Everyone has a complete set of genes
(eye color, blood type, tongue rolling,
etc.) but which version you inherited
makes a big difference.
In reality there is no “cancer gene”.
Instead, there are versions of
checkpoint protein genes that don’t
control cell cycle properly.
Notable genes on Chromosome 18:
How food is
Some forms of obesity
absorbed
X
Notable genes on Chromosome 20:
X
Diabetes
Insulin to control
blood sugar
Basic Gene Disorder Questions
1. What type of genetics is it? (Dominant,
recessive, sex-linked, etc.?)
2. What gene is involved?
3. On what chromosome is this gene?
Basic Gene Disorder Questions
4. What protein does this gene make?
5. What is this protein supposed to do?
6. Since this protein isn’t working right,
how does this lead to the symptoms?
Gene Disorder Example
Tay Sachs
1. What type of genetics is it? (Dominant,
recessive, sex-linked, etc.?)
recessive
2. What gene is involved?
HexA gene
Gene Disorder Example
Tay Sachs
3. On what chromosome is this gene?
Chromosome 15
P’s and Q’s?
- Different ends
of chromosome
- #’s show
distance from
centromere
Gene Disorder Example
Tay Sachs
4. What protein does this gene make?
Part of hexosaminidase
Gene Disorder Example
Tay Sachs
5. What is this protein supposed to do?
A. Found in lysosomes of brain and
spinal cord cells
B. Digests fats called gangliosides
Gene Disorder Example
Tay Sachs
6. Since this protein isn’t working right,
how does this lead to the symptoms?
A. Hexosaminidase can’t break down gangliosides.
B. Gangliosides build up to toxic levels.
C. Nerve cells die.