Chapter 11.5.2 (Exam 2) Meiosis Flashcards
Meiosis Leads to the Formation of Gametes
What happens to homologous chromosomes in meiosis? In mitosis?
In meiosis they pair up
In mitosis they don’t pair up
What lines up in metaphase during meiosis? During mitosis?
Homologous chromosomes line up during meiosis
All chromosomes line up during mitosis
Who separates during meiosis? During mitosis?
Homologous chromosomes separate during meiosis
Sister chromatids separate during mitosis
What is the ploidy of the daughter cells in meiosis? In mitosis?
Haploid daughter cells in meiosis
Diploid daughter cells in mitosis
What happens in meiosis II?
Not preceded by DNA replication
Sister chromatids are separated
Chance assortment of the chromatids contributes to genetic diversity
Final products are four haploid daughter cells (n)
What is one error that can occur in meiosis?
Nondisjunction
Describe nondisjunction.
Homologous pairs may fail to separate at anaphase I
In meiosis II, sister chromatids may fail to separate
Results in aneuploidy
What is aneuploidy?
Chromosomes are either lacking or present in excess
What is one example of aneuploidy in humans?
In humans, Down syndrome results from a gamete with two copies of chromosome 21, and three copies after fertilization (trisomic)
A fertilized egg that did not receive a copy of chromosome 21 will be monosomic, which is lethal
What is a polyploid?
An organism with complete extra sets of chromosomes
Triploid (3 n), tetraploid (4 n), and higher levels are possible
What can be caused by nondisjunction of all chromosomes during meiosis I?
Diploid gametes will form, leading to autopolyploidy after fertilization
What is a karyotype?
Karyotype is the number, shapes, and sizes of all chromosomes of a cell
What can karyotypes be used for? What is the branch of medicine they are under called?
Karyotypes can be used to diagnose abnormalities such as trisomies
Branch of medicine called cytogenetics
