Meiosis Etc Flashcards
(20 cards)
What is the primary function of meiosis?
To produce gametes with half the number of chromosomes (haploid) for sexual reproduction.
How many divisions occur in meiosis?
Two divisions: Meiosis I and Meiosis II.
What are the products of meiosis?
Four non-identical haploid gametes.
What are the phases of meiosis I?
Prophase I, Metaphase I, Anaphase I, Telophase I.
What occurs during Prophase I?
Chromosomes condense, synapsis occurs, and crossing over happens between homologous chromosomes.
What is crossing over?
Exchange of genetic material between nonsister chromatids at chiasmata.
What is independent assortment?
Random orientation of homologous pairs during metaphase I leading to genetic variation.
What are the sources of genetic variation in meiosis?
Crossing over, independent assortment, and random fertilization.
What happens in Anaphase I?
Homologous chromosomes separate and move to opposite poles.
What is nondisjunction?
Failure of chromosomes to separate properly during meiosis.
What can nondisjunction cause?
Trisomy or monosomy in the resulting zygote.
What is trisomy?
A condition where a zygote has an extra chromosome (e.g., Down syndrome = trisomy 21).
What is monosomy?
A condition where a zygote is missing a chromosome (e.g., Turner syndrome = only one X chromosome).
What is a karyotype?
A picture of someone’s chromosomes used to detect abnormal numbers or structure.
What are the stages of mitosis?
Prophase, Metaphase, Anaphase, Telophase.
What is the role of spindle fibers during mitosis?
They attach to chromosomes and help separate them during cell division.
What is interphase?
The longest phase where the cell grows, replicates DNA, and prepares for mitosis.
What are the sub-phases of interphase?
G1 (growth), S (DNA synthesis), G2 (preparation for division).
What happens during metaphase?
Chromosomes align at the cell’s equator and attach to spindle fibers.
What is cytokinesis?
The final pinching of the cell into two separate daughter cells.
