5.7 Genetic Disorders and Chromosome Changes
Notes
Some disorders come from single genes; others come from changes in whole chromosomes.
- Cystic fibrosis and sickle cell disease are autosomal recessive. Huntington's disease is autosomal dominant.
- Nondisjunction is when chromosomes fail to separate in meiosis, giving gametes with too many or too few chromosomes.
- Down syndrome (trisomy 21) results from three copies of chromosome 21.
- A karyotype is a picture of a person's chromosomes arranged in pairs; it can show extra or missing chromosomes.
Practice
Down syndrome is caused by:
Trisomy 21 means three copies of chromosome 21.
Which tool would a doctor use to check if a person has an extra chromosome?
A karyotype shows the number and shape of chromosomes.
The failure of chromosomes to separate properly during meiosis is called:
Nondisjunction produces gametes with the wrong number of chromosomes.
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