Chapter 11 Human Heredity
Developed by Nancy Manikas (8-06-97)
I. The Human Organism
________ chromosomes contain ______ billion nucleotide pairs of DNA.
Gametes (reproductive cells) contain a _____________ ____________ of each gene.
When a sperm (________ chromosomes) and an egg (_________ chromosomes)
combine, the fertilized egg is called a _____________.
Human Traits:
You must take __________________ influences into account.
For example: Humans are taller in countries where nutrition is good.
II. The Inheritance of Human Traits
- More than __________ human genes have been described and studied.
A. Human Blood Groups
Click here for more information about blood groups.
- Multiple Alleles - some genes have ______ or more alleles.
1. ABO Blood Groups
- In 1900 Karl ___________________ classified blood into four groups
- blood cells can carry 2 different _______________ which he called A and B.
- antigens are:
- the four blood types are ______, ________, _______, and ______.
- blood types are important in transfusions because giving the wrong type of blood will make the blood clot and clog the arteries - can be fatal.
- people with type _________ can receive blood from any other type because they will not fight off either A or B antigens.
- people with type ________ can only get blood from type _______ donors.
2. Rh Blood Groups
- the Rh factor is another ______________ found on red blood cells. If you have it, you are Rh positive; if you don't, you're Rh negative.
- Rh factor is determined by __________ common alleles and many other rare ones.
- ________ is dominant over _________.
B. Huntington Disease
For more information on genetic diseases, click here.
- genetic disease
- produced by a ______________ allele
- shows up between ages _______ and _________
- gradual damage to _______________ system
- painful progressive loss of _____________ control and ___________ function until death occurs.
- the gene is on chromosome #_________
- the normal gene is _________ base pairs long and the Huntingtons Disease allele is _________ bases long.
C. Sickle Cell Anemia
- discovered in 1904 by Dr. James Herrick
- blood cells are sickle shaped
1. Cause:
- Caused by a change in one of the ______________ found in hemoglobin (the protein that carries oxygen in red blood cells).
- When low in oxygen (like when ______________) hemoglobin molecules stick together to make fibers; fibers change the shape of the red blood cell.
- The sickle-shaped red blood cells stick together and get caught in the capallaries. This _________ and sometimes _________ the blood flow. Causes tissue damage and maybe even death.
2. The Genetics:
The allele for normal hemoglobin is _____________ with the allele for sickle cell.
Heterozygous =
Homozygous =
3. Molecular Basis:
There is only one ___________________ different between regular and sickle-cell protein.
Only one ____________ _____________ is different in the protein.
This difference makes the defective hemoglobin _______ ______________ in the blood.
When the body is stressed, the defective hemoglobin _____________ __________; cells get sickle-shaped and clog small blood vessels.
4. Distribution of Sickle Cell Anemia
Found primarily in __________ ______________, _____________, and ______________ (tropical).
People heterozygous for sickle cell are partially resistant to _____________.
D. Polygenic Traits
- traits controlled by:
- examples:__________, _______________, ________________
III. Sex-Linked Inheritance
1. Sex Determination
A. Sex Determination
The human XY system:
Errors can occur (usually nondisjunction); the gametes end up with 2 sex chromosomes or no sex chromosomes. If this gamete is part of the fertilized egg (either the egg or the sperm), then the resulting individual will have too many or too few sex chromosomes.
B. Nondisjunction Disorders
- _________ birth in ___________ involves an abnormality as the result of non disjunction of the sex chromosomes.
- ______________ in appearance
- ______________ sex organs don't develop
- ______________
- 45X or 45XO = missing the sexond sex chromosome.
2. Klinefelter Syndrome
- ______________ in appearance
- ______________
- 47XXY
For more information on Klinefelter Syndrome, click here.
What nondisjunction disorders have shown us:
1. The X chromosome:
2. Sex is determined by:
2. Sex-Linked Genetic Disorders
A. Colorblindness
- most types caused by a ________________ allele carried on the _____ chromosome.
- some eye pigments necessary for color vision are ____________.
- ___________________ colorblindness is the most common.
- about _________ of males and ________ female caucasions are colorblind
- ___________ denotes a colorblind female
- ___________ denotes a carrier female
B. Hemophilia = "Bleeder's Disease"
For more information on hemophilia, click here.
- due to a ________________ gene carried on the _______ chromosome.
- missing __________________ (AHF) factor necessary for normal blood clotting.
- females: 1 in ______________
- males: 1 in ________________
- treated by _________________ of AHF taken from donor blood.
- can use a pedigree to determine the risks of getting a genetic disease (see below).
C. Muscular Dystrophy
- progressive wasting away of the ____________ muscle.
- most common type results from a defective muscle protein called ________________.
- the gene is carried on the ________ chromosome.
3. Sex-Influenced Traits
- some traits manifest differently in males in females with the same alleles.
-example: the gene for _______________ is on an autosomal chromosome, but is expressed differently in males and females:
BB = normal hair
bb = baldness
Bb = males tend to bald; females tend to have hair
IV. Diagnosis of Genetic Disorders
- caused by nondisjunction of autosomes (___________ 21)
- mental retardation, more susceptable to diseases
- 1 baby out of ___________ has this genetic disorder.
B. Prenatal Diagnosis
1. Amniocentesis:
2. Chorionic Villus Biopsy:
It is now possible to detect over 300 genetic disorders.
C. Ethical Considerations
What do you do if you find out your fetus is abnormal?
