5.2 Human Genetic Disorders
POINT > Define a gene in simple terms
POINT > Define and describe genetic mutations
POINT > Distinguish between gene and
chromosomal mutations
POINT > Describe examples of genetic diseases
caused by single gene mutations
POINT > Identify human diseases caused by
chromosomal mutations
POINT > Explain Pedigree analysis
POINT > Define a gene in simple terms
One gene is a sequence of DNA that codes for one protein
There are 1000’s of different proteins in a cell
Each protein has an important function in the cell
The DNA sequence in a gene determines the amino acid
sequence in a protein
The amino acid sequence of the protein has to be correct!
If not...
Werewolf
POINT > Define and describe genetic mutations
A mutation is a change to the DNA sequence of an
organism
A gene mutation affects only one gene/one protein
A chromosomal mutation affects the number of
chromosomes in the cell. This affects many genes
POINT > Define and describe genetic mutations
If the DNA is altered, the mutation is passed to
daughter cells through mitosis
If the mutation occurs in an egg cell or sperm cell,
the changes are passed to offspring
CHECK:
What is a mutation?
What is a gene mutation?
What is a chromosomal mutation?
The Mummy
POINT > Describe human diseases caused by
single gene mutations
1.Cystic fibrosis: a recessive allele carries a
mutation that causes mucus to fill the lungs
Difficulty breathing and death are the results of
this disease
POINT > Describe human diseases caused by
single gene mutations
2. Sickle cell anemia: A codominant allele causes
some red blood cells to be misshaped
Blood doesn’t carry oxygen as well
POINT > Describe human diseases caused by single
gene mutations
3.Hemophilia: A sex-linked (X chromosome)
recessive allele causes blood to not clot
Patients have excessive bleeding
CHECK:
What kind of allele causes cystic fibrosis?
What kind of allele causes sickle cell anemia?
What kind of allele causes hemophilia ?
Frankenstein monster
POINT > Identify human diseases
caused by chromosomal mutations
Down’s syndrome:
1 extra chromosome (#21)
Varying degrees of
mental retardation
Many distinct physical
characteristics
POINT > Identify human diseases caused by
chromosomal mutations
Edward’s syndrome
1 extra chromosome (#18)
Major physical
abnormalities & mental
retardation
~3% of cases result in live
birth, median lifespan is 515 days
CHECK:
What causes Down’s syndrome?
What causes Edwards syndrome?
Dracula
POINT > Explain pedigree analysis
POINT > Explain pedigree analysis
Pedigree analysis is used to trace a disease or trait
in a family history
POINT > Explain pedigree analysis
Examples of symbols:
Female:
Male:
POINT > Explain pedigree analysis
Examples of symbols:
Married Couple:
Offspring:
POINT > Explain pedigree analysis
Empty shape = unaffected
 Carrier. Has allele, but not the disease/trait
 Has the disease/trait
Color Blindness
About 1 in 10 men
have some form of
color blindness.
Sex-linked recessive
disorder
Homework:
Read pages 151-155
S.A. #1-3 page 155
GRAS pages 72-73
Pedigree analysis Worksheet