10.4 Flashcards
What is nondisjunction?
When a tetrad or chromosome fails to separate during meiosis.
What is a trisomy?
It is a result of nondisjunction; it causes someone to have three sex chromosomes, usually XXY or XXX.
What is a monosomy?
It is a result of nondisjunction, it causes someone to have only one sex chromosome, XO or OY.
OY is nonviable for life, XO causes complications with protein production.
What is an autosome?
Any chromosome that is not a sex chromosome.
What are sex chromosomes?
Chromosomes that determine what kind of reproductive system a person will grow.
What is a Barr body?
Extra X chromosomes (i.e. XXX. XX, XXY) turn into these, they are round lumps that sit at the bottom of the cell.
What are deletion, duplication, inversion, and translocation?
Deletion is when part of the gene code is mistakenly removed. Duplication is when part of the gene code is accidentally repeated twice on the same chromosome. Inversion is when part of the gene code is reversed, for example: A B C turning into C B A. Translocation is when two unrelated chromosomes swap genetic information.
How does nondisjunction lead to an incorrect number of chromosomes?
Some cells will end up with too many chromosomes or too free when they fail to split apart during anaphase.
What determines a human’s biological sex at birth?
The sex chromosomes they have determines their biological sex.
What happens to a zygote when the chromosomes are abnormal?
Abnormal chromosomes can cause problems for growth and development, and can make some zygotes completely nonviable, since there are not enough proteins being made.
