VCJH Science 7 - Meiosis Flashcards
(25 cards)
Explain how sex cells differ from body cells
They have half the number of chromosomes. Only one of each pair. 23 in humans.
Define sex cell
aka gamete. They have half the usual number of chromosomes. One chromosome from each homologous pair and one sex chromosome.
Gametes are found in the reproductive organs of plants and animals. Egg is a gamete from female reproductive organs. A sperm cell is the one formed in males.
Define homologous chromosome
Have same size and shape. 22/23 of chromosome sets are homologous. Sex chromosomes (X-Y) are not.
Describe the steps of meiosis
TAMP
Prophase I - chromosomes copied before meiosis begins. Nuclear membrane dissolves
Metaphase I - chromosome PAIRS line up in middle of cell
Anaphase I- chromosomes separate from their partners to opposite sides of the cell
Telophase I- nuclear membranes reform and cell divides into two cells. CHROMATIDS (X) ARE STILL JOINED.
Prophase II- nuclear membrane dissolves in both new cells
Metaphase II- chromosomes line up in middle of cells
Anaphase II- chromatids separate to opposite sides of cells
Telophase II- nuclear membranes reform in both cells and cells divide into two new cells. Four total.
Define meiosis
It is a part process that results in formation of sperm and egg cells
Compare meiosis and mitosis
Mitosis- cell divides to form exact copy of itself Two resulting cells with full chromosomes pairs. (23x2/46 in humans)
Meiosis- cell divides to form four daughter cells with only half the chromosomes ( one from each pair). 23 in humans.
List two reasons why cells divide
Reproduce, grow, and repair
What happens to genetic material during cell division?
It is copied?
What are homologous chromosomes?
Pairs of chromosomes having the same size and structure. They carry the same genes. In humans there are 46 homologous pairs. One pair has different versions of the genes as it carries the sex chromosomes. In humans these sex chromosomes are called X and Y chromosomes.
How many daughter cells will be produced at the end of meiotic cell division?
Four
Define gametes
Sex cells. They have half the usual number of chromosomes. One chromosome from each homologous pair and one sex chromosome.
Gametes are found in the reproductive organs of plants and animals. Egg is a gamete from female reproductive organs. A sperm cell is the one formed in males.
Define diploid
The joining of two sex cells to form a cell with a pair of every chromosome. Humans have diploid body cells.
Define haploid
Cells that contain HALF the usual number of chromosomes. Examples are Sex cells- gametes - sperm/egg
Define zygote
Fertilized egg cell. Now a diploid.
Define mitosis
A proceeds of cell division where two identical new cells are created
Define chromosomes
A strand of DNA that carries the genes
Define DNA
Genetic material that determines the traits of a living thing
Offspring of sexual reproduction have fewer chromosomes than their parents have T/F
False. Have 46 just like the parent for humans
During sexual reproduction, two cells combine to form a new organism? T/F
False. Combine to form a new cell (zygote)
Sex cells are produced by cell division? T/F
True. In the process of meiosis
Sex cells have half the normal number of chromosomes? T/F
True. 23 instead of 46 in humans.
How do male chromosomes differ from female chromosomes?
One set of the chromosomes in males have an X & Y chromosome. In females this set of chromosomes has two X chromosomes.
Define homologous chromosomes
Pairs of chromosomes having the same size and structure. They carry the same genes except for one pair made up of sex chromosomes (X & Y).
Define meiosis
Type of cell division that produces haploid sex cells such as sperm and egg cells.
