Mitosis and Meiosis

Question 1

What is mitosis?

Answer 1

Cell division, occurs throughout the body and makes somatic cells. Helps you to grow and repair damage.

Question 2

Interphase

Answer 2

1. Not technically a phase of mitosis, but occurs before the process begins.
2. During the synthesis phase, DNA is copied, chromosomes are replicated.
3. Interphase is the resting stage, where is the cell isn’t actively dividing. The cell spends the most time in this phase, and continues to perform regular cell functions.
4. Afterward, chromosomes (chromatids) have doubled, but the cell has 46 chromosomes.

Question 3

Centromere

Answer 3

Region that holds together each chromosome and duplicate piece of DNA.

Question 4

Chromatid

Answer 4

An individual chromosome, or piece of DNA.

Question 5

4 Stages of Mitosis

Answer 5

1. Prophase
2. Metaphase
3. Anaphase
4. Telophase

Question 6

Prophase

Answer 6

1. Centrioles move to opposite sides of the cell and form a mitotic spindle.
2. The chromosomes condense and become visible
3. Nuclear membrane begins to break up.

Question 7

Centriole

Answer 7

Organelle that helps develop spindle fibers during cell division.

Question 8

Mitotic Spindle

Answer 8

Bunch of fibers formed during prophase. Attaches to chromosomes at their centromeres, and help to push/pull them during mitosis.

Question 9

Metaphase plate

Answer 9

Equator/middle of cell.

Question 10

Metaphase

Answer 10

1. Spindle fibers help chromosomes to line up at the metaphase plate.
2. Spindle fibers attach to centromeres.
3. Centrioles go to opposite poles.

Question 11

Cleavage furrow

Answer 11

Area where the cell pinches inward.

Question 12

Anaphase

Answer 12

1. Centromere splits in two, so each chromatid separates from its partner.
2. Spindle fibers shorten and move new chromosomes to opposite sides of the cell.
3. Cell begins physically splitting in two

Question 13

Telophase

Answer 13

1. A nuclear membrane forms in each new cell
2. 2 identical daughter cells result, each with 46 chromosomes.
3. Cytokinesis occurs
4. Afterward, daughter cells enter interphase.

Question 14

Cytokinesis

Answer 14

Cytoplasm divides, occurring during telophase

Question 15

Where does mitosis occur in plants?

Answer 15

Only occurs in meristems (growing regions).

Question 16

Apical meristem

Answer 16

Found at tip of stem and tip of root, allows for growth in length.

Question 17

Later meristem

Answer 17

Allows for growth in width.

Question 18

One gene- one protein theory

Answer 18

A gene is a portion of a chromosome that gives rise to one protein molecule. A chromosome contains many genes and could create hundreds of proteins.

Question 19

Gene expression

Answer 19

A gene is expressed when it creates a protein. A gene is a portion of a chromosome.

Question 20

Haploid

Answer 20

The amount of chromosomes is half that of the diploid number. 23 in humans. Sex cells (sperm and ova) are haploid.

Question 21

Zygote

Answer 21

1. Diploid cell

2. Formed when a sperm fertilizes an ovum, and begins to undergo mitosis.

Question 22

What occurs during meiosis?

Answer 22

1. The cell undergoes DNA replication during interphase, like during mitosis. At this point, the cells still have 46 chromosomes.
2. Replicated chromosomes are split up over the course of 2 sets of divisions.
3. First set of division establishes differences between mitosis and meiosis.

Question 23

Synapsis

Answer 23

Homologous chromosomes line up. 1a finds 1b, etc, forming 23 pairs. These chromosomes are not identical. Consists of 4 chromatids (a tetrad).

Question 24

Prophase 1

Answer 24

1. Normal prophase events occur: chromosomes condense.
2. Synapsis occurs
3. Crossing over takes place- like segments on homologous chromosomes are exchanged

Question 25

Recombinant Chromosomes

Answer 25

New chromosomes created by crossing over, which causes variety among offspring. Also means that gametes are not identical, unlike daughter cells created by mitosis.

Question 26

Metaphase 1

Answer 26

1. Chromosomes still line up in the middle of the cell, but they stay in pairs. 23 pairs line up. 2. Independent assortment of chromosomes- the way that chromosomes line up during this phase affects the outcome of genetic information in gametes. 3. Genes on non homologous chromosomes are inherited independently, linked genes on the same chromosome are inherited together, but can be separated by crossing over.

Question 27

Anaphase 1

Answer 27

1. In meiosis, the centromeres do not divide | 2. Homologous pairs separate. A pair of chromatids and a centromere move to opposite sides of the cell.

Question 28

Telophase 1

Answer 28

1. Cells still finish cytokinesis, nuclear membranes form | 2. The two new cells have 23 replicated chromosomes of 2 identical chromatids, making them haploid by this phase.

Question 29

Meiosis 2

Answer 29

1. Nearly identical to mitosis 2. In interphase 2, the chromosomes don't replicate. 3. The cells are starting with 23 replicated chromosomes 4. Forms 4 haploid cells that stop dividing unless fertilization triggers new cell cycles.

Question 30

Spermatogenesis

Answer 30

1. Formation of sperm that requires meiosis 2. Starts with a spermatogonium, which undergoes meiosis and produces 4 functional sperm cells. 3. Occurs daily, beginning at puberty and lasting for life

Question 31

Spermatogonium

Answer 31

Diploid cell located in seminiferous tubules located in the testes. Will eventually undergo meiosis.

Question 32

Where are oocytes found?

Answer 32

The ovaries

Question 33

Oogenesis

Answer 33

1. Formation of female egg through meiosis 2. Produces 1 functional ovum from an oocyte every month. 3. Occurs on a monthly basis beginning at puberty and ending at menopause (46-53)

Question 34

Polar bodies

Answer 34

The two daughter cells formed through oogenesis that don't receive organelles and therefore disintegrate.

Question 35

Genetic Variation

Answer 35

Genetic differences within or among a population

Question 36

Causes of genetic variation among offspring

Answer 36

1. Independent assortment of chromosomes during metaphase 1 of meiosis 2. Crossing over during synapsis in prophase 1 of meiosis 3. Random fertilization