Mitosis and Meiosis

Question 1

What is mitosis overall purpose?

Answer 1

• Passes along identical genetic information to daughter cells
• Cell division

Question 2

What is meiosis overall purpose?

Answer 2

• To produce gametes, the sperm and eggs, with half of the genetic information as the parent cells.
• To make haploid cells

Question 3

How many stages of mitosis?

Answer 3

• One stage. (divides only once)
• 4 phases

Question 4

How many stages of meiosis?

Answer 4

Occurs in two stages.
1. Reduction = cells become haploid
2. Division = cells further multiply

Question 5

What are the types of cells involved in mitosis?

Answer 5

• Occurs in somatic cells (body cells) of multi-cellular organisms
• May occur asexually reproducing unicellular

Question 6

What are the types of cells involved in meiosis?

Answer 6

Both female and male gametes
Ex. sperm & ova in animals
Ex. pollen & ova in flowering plants

Question 7

What is the final outcome of mitosis?

Answer 7

• Produces diploid cells with the full amount of genetic information (2n)
• Daughter cell identical to mother

Question 8

What is the final outcome of meiosis?

Answer 8

• Produces haploid cells (n) with half of the diploid number, so that 2 haploid parent cells can come together to make a diploid offspring.
• Cells are not identical to parent cells

Question 9

How many chromosomes in somatic cells after mitosis?

Answer 9

46

Question 10

How many chromosomes do human gametes have after meiosis?

Answer 10

23

Question 11

Mitosis: Prophase

Answer 11

• Chromosomes shorten, thicken and become visible, and attach to spindle fibres
• Small proteins, called centrioles, appear and move to opposite sides of the cell
• The nucleolus disappears and the nuclear membrane starts to dissolve

Question 12

Mitosis: Metaphase

Answer 12

• Spindle fibres begin moving and aligning the chromosomes at the cell’s equator
• The chromosomes are pulled toward the centre
  of the cell
• Sister chromatids’ centromeres become aligned at the centre or equator of the cell

Question 13

Mitosis: Anaphase

Answer 13

the process that separates the duplicated genetic material carried in the nucleus of a parent cell into two identical daughter cells.

Question 14

Mitosis: Telophase

Answer 14

• Chromosomes reach opposite poles of the cell
• They begin to uncoil and take the form of chromatin
• The spindle fibres dissolve
• Nuclear membranes reform around each set of daughter chromosomes
• RESULT: TWO DAUGHTER NUCLEI!

Question 15

Cytokinesis - Last part of M phase (follows mitosis)

Answer 15

• Division of cell contents (cytoplasm and organelles)
• The cell membrane pinches inwards forming a cleavage furrow (halving) in animal cells

Question 16

Interphase

Answer 16

Not part of mitosis. Takes place prior to division and immediately following cytokinesis. Consists of the G1, S and G2 phases of the cell cycle.

Question 17

Spindle Fibers

Answer 17

Thin proteins that pull chromosomes apart

Question 18

Centrioles

Answer 18

Help assemble the spindle fibres (not found in plant cells)

Question 19

Meiosis: early prophase 1

Answer 19

DNA is doubled

Question 20

Meiosis: Late prophase I

Answer 20

• Chromosome pairs called “Homologous Chromosomes” overlap and carry out “crossover

Question 21

Meiosis: Metaphase I

Answer 21

• Chromosomes move to the equator of the cell and line up in pairs

Question 22

Meiosis: Anaphase I

Answer 22

Entire chromosomes pulling apart

Question 23

Meiosis: Telophase I

Answer 23

• Nuclear membrane forms
• Nuclei are haploid as they have only one member of original chromosome pairs (genetically different)
• Each chromatid different from each other

Question 24

Meiosis: Prophase II

Answer 24

• Nuclear membrane dissolves
• Spindle fibers form

Question 25

Meiosis: Metaphase II

Answer 25

Chromosomes line up at the equator and are still attached at the centromere

Question 26

Meiosis: Anaphase II

Answer 26

- Sister chromatids separate to opposite poles - Nuclear membranes form around chromatids now called chromosomes

Question 27

Meiosis: Telophase II

Answer 27

Second nuclear division completed and 4 daughter cells formed.

Question 28

What is crossover?

Answer 28

Special event in Meiosis which creates genetic variation between the gametes of each parent. Occurs during prophase I where genes are shuffled between homologous chromosomes.

Question 29

What is a homologous pair?

Answer 29

A set of one maternal and one paternal chromosome that pair up with each other inside a cell during fertilization. (Tetrad and bivalent)

Question 30

What is the process by which chromosomes pair up?

Answer 30

Chiasmata/crossover

Question 31

Spermatogenesis

Answer 31

Cytoplasm is equally divided during each cell division and results in 4 equal sized sperm cells

Question 32

Oogenesis

Answer 32

Cytoplasm of the female gametes does not divide equally during each of the two cell divisions of meiosis. One of the daughter cells receives most of the cytoplasm. Other cells die and the final product of oogenesis is a single egg cell.