Download I. Down Syndrome - Plain Local Schools

BIOLOGY
Chapter 12: Human Genetics
Name:________________________
Section Goal: The student will relate Down’s syndrome and non-separation of chromosomes, describe how
chromosomes can be damaged and explain how a “jumping gene” can affect other genes.
Vocabulary:
1. Trisomy 21
2. Down’s syndrome
3. Nondisjunction
4. Duplication
5. Deletion
6. Inversion
7. Translocation
8. Transposon
Concept 12.2: Accidents affecting chromosomes can cause disorders.
I. Down Syndrome
A. Trisomy 21 results in having three number 21 chromosomes
B. In most cases, a human embryo with an abnormal number of chromosomes results in a miscarriage
C. People with trisomy 21 have Down syndrome, named after John Langdon Down
II. Non-separation of Chromosomes
A. Nondisjunction is when homologous fail to separate
B. A woman’s age will have an effect on the possibility of nondisjunction occurring
C. This is due to the time line of egg cell development
III. Damaged Chromosomes
A. Duplication is when part of a chromosome is repeated
B. Deletion is when a fragment of a chromosome is lost
C. Inversion involves reversing a fragment of the original chromosome
D. Translocation occurs when a fragment of one chromosome attaches to a non-homologous
chromosome
IV. Jumping Genes
A. Single genes may move from one location to another in a chromosome or to a different
chromosome
B. This was discovered by Barbara McClintock in the 1940’s
C. These genes can land in the middle of other genes and disrupt them
D. These genes are called transposons
Lesson Reflection:
- On page 252 of your textbook, color the pictures of the damaged chromosomes.
Lesson Assessment:
1. List and define four types of damage to chromosome structure that can cause disorders.
2. What is a “jumping gene,” or transposon?
Summary of Key concepts: Summary of Key Concepts for 12.2
Technology/Application/Connection to real-world: