Meiosis and Nondisjunction Disorders Flashcards
What is diploid?
Two complete sets of chromosomes, one from each parent.
What is a haploid?
One of each chromosome.
What is a gamete?
Sperm or egg cell, gametes are haploid.
What is fertilization?
The process of one male (sperm) gamete and one female (egg) gamete coming together.
What is a zygote?
A cell formed when two gametes come together.
How many divisions and DNA are in meiosis?
Two divisions, 1/2 DNA in each of the four cells, are four the cells are genetically different.
What is a somatic cell?
Any other cell other than reproductive cells.
What happens during prophase I?
- Mitosis begins. Chromatin is condensed into chromosomes.
- Centrioles form spindle fibers and begin to move to opposite ends of the cell.
- Nuclear membrane breaks down and disappears.
- Crossing over occurs.
What is crossing over?
Homologous Chromosomes exchange genetic information to create genetic diversity in gametes.
What are homologous chromosomes?
Homologous chromosomes are chromosome pairs (same number and length).
What happens during metaphase I?
- Homologous Chromosomes attach themselves to spindle fibers.
- Homologous Chromosomes align randomly at the equator as pairs.
- Results in new genetic combinations/variations in gametes and therefore, offspring; greater genetic diversity.
What happens during anaphase I?
- Homologous Chromosomes move apart to opposite poles once attached to spindle fibers (in metaphase).
What happens as an end result of telophase I?
- The end result after cytokinesis is two cells with sister chromatids remaining to be separated.
Does DNA replicate again before meiosis II?
No, DNA doesn’t replicate itself a second time.
What happens during prophase II?
- Chromatin is recondensed into chromosomes.
- Centrioles form spindle fibers and begin to move to opposite ends of the cell.
- Nuclear membrane breaks down and disappears.
What happens during metaphase II?
- Chromosomes attach to the spindle fibers.
2. Sister chromatids randomly line up along the metaphase plate like regular mitosis.
What happens during anaphase II?
- During Anaphase II, centromeres break and each sister chromatid is pulled to opposite sides of the cell.
What happens during Telophase II?
- The two cells split off, end result is 4 gamete cells that are genetically different from each other.
What are inherited mutations?
Inherited mutations are when mutations are passed from a parent onto an offspring. All of the offspring’s cells will carry the mutation.
What are new mutations in the germline?
New Mutations in Germline are when a mutation associated with a disease occurs during gamete production. The offspring can inherit the mutation from an unaffected parent.
What are somatic cell mutations in development?
The development of specific tissues and organs in the body can be affected by somatic cell mutations that occur early in life. Are inherited by a parent.
What are somatic cell mutations later in life?
Cancer can result from somatic cell mutations that occur later in life. Are inherited by a parent.
What are proto-oncogenes?
Proto-oncogenes normally function to accelerate cell growth/division.
What happens when proto-oncogenes are mutated?
If they’re mutated, they become oncogenes and accelerate cell division and growth way too quickly out of control.
