Flashcards in Meiosis Deck (19)
What is sexual reproduction?
When one organism is produced by two organisms with sex cells. It requires sperm and egg, which creates a zygote.
What are sex cells?
Egg: female reproductive cell
Sperm: male reproductive cell
What is fertilization?
The joining of an egg and a sperm.
What is a zygote?
The first cell of a new organism. The zygote is a diploid.
What are Haploid Cells?
A cell with half the number of chromosomes. Sex cells have 23 chromosomes in humans. Offspring inherit these chromosomes from both parent sex cells, resulting, most of the time, in 46 chromosomes.
What is Meiosis?
A process of producing four haploid cells.
What happens during Interphase I?
This is the growth and development stage.
What occurs in Prophase I?
The nuclear membrane disintegrates. Crossing over occurs and chromosomes are visible. Spindle fibers appear.
When the homologous chromosomes partner.
What is Metaphase I?
Partner chromosomes line up across the center of the cell. (METAphase = middle)
What happens during Anaphase I?
Similar chromosomes are pulled apart. (ANAphase = AWAY)
What goes on during Telophase I?
The cytoplasm divides and two new cells are formed. This is the last stage of Meiosis I.
In Meiosis II, what happens during Prophase II?
The spindle fibers reappear.
Metaphase II is when...
The chromosomes move to the center of each cells. (METAphase = MIDDLE)
What happens in Anaphase II is...
The spindle fibers separate the chromatids. Each chromatid moves to the opposite of ends of the cell. (ANAphase = AWAY)
In the last stage of Meiosis II, Telophase II is when...
The spindle fibers disappear, the nuclear membrane appears, and the cytoplasm divides.
Summary of Meiosis.
At the end of Meiosis I, two haploid cells are formed. And at the end of Meiosis II, there are four new haploid cells.
What are some mistakes in Meiosis?
-Some sex cells can have too many chromosomes or too little.
-Zygotes from those particular sex cells either die or develop into an organism with physical and/or cognitive disabilities.
-Polyploidy is an example. This is when a DIPLOID cell is fertilized by a HAPLOID cell. Baby either miscarries or is born with severe heart defects.
-Down syndrome is caused by having an extra 21 chromosome.