Mitosis/meiosis (Cell Division)

Front 1

Why does replication of DNA have to occur before the start of mitosis and meiosis?

Back 1

DNA must be replicated in order to have the correct number of chromosomes present in daughter cells and gametes.

Front 2

What are gametes?

Back 2

Sex cells including sperm and eggs.

Front 3

What is isogamy?

Back 3

The production of sex cells that are approximately the same size.

Front 4

What is heterogamy?

Back 4

The production of gametes that are of markedly different sizes. Eg. The human egg cell is almost 20 times larger than a sperm cell.

Front 5

What is cytokinesis?

Back 5

The splitting of the cytoplasm

Front 6

What are the four stages of the cell cycle?

Back 6

1. Interphase G1,
2. Interphase S,
3. Interphase G2,
4. M phase - Mitosis & cytokinesis

Front 7

What happens in the G1 phase of the cell cycle?

Back 7

G1 stands for the "1st gap". During this stage the cells grows and senses whether all conditions are "go" for division.

Front 8

What happens in the S phase of the cell cycle?

Back 8

Replication of DNA

Front 9

What happens in the G2 phase of the cell cycle?

Back 9

G2 stands for the "2nd gap". The cell continues to grow in size and checks that the chromosomes have been fully copied and that the stage is set for the actual division of the cell into two daughter cells.

Front 10

What happens in the "M" phase of the cell cycle?

Back 10

"M" refers to mitosis/cytokinesis. During this phase prophase, metaphase, anaphase, and telophase occur.

Front 11

Name the four divisional stages of mitosis.

Back 11

prophase, anaphase, metaphase, and telophase

Front 12

What is the stage between cell division called?

Back 12

interphase

Front 13

What happens during prophase of mitosis?

Back 13

1. Replicated chromosomes condense<br />2. Spindle fibers (microtubules) form and grow. <br /><br />The nuclear envelope begins to break down allowing cytoplasm and nucleoplasm to mix.

Front 14

What happens in metaphase of mitosis?

Back 14

Replicated chromosomes line up along the "equator" of the cell. Microtubules (spindle fibers) are attached to each chromosome at the centromere.

Front 15

What happens during anaphase of mitosis?

Back 15

The centromeres "split" and the spindle fibers shorten pulling each sister chromatid to opposites poles (sides) of the cell.

Front 16

What happens during telophase of mitosis?

Back 16

The nuclear envelope reforms around daughter nuclei. Chromosomes uncondense. Cytokinesis divides the cytoplasm and the daughter cells are produced. The original cell no longer exists - it has become two daughter cells.

Front 17

What is diploid?

Back 17

a full compliment of chromosomes

Front 18

What is haploid?

Back 18

half the diploid number of chromosomes

Front 19

What is the cell plate?

Back 19

In plant cells, which have non-living rigid cell wall composed of cellulose, pieces of new cellulose begins forming in the center of the parent cell, working 3-dimensionally to the outside dividing the plant cell in two down the center. This is the cell plate. NOTE: Since animal cells do not have a cell wall, cell plates do not form.

Front 20

What is the pinching in two of the parent cell called during telophase?

Back 20

cytokinesis

Front 21

What is it called when mitosis goes wild and cells become immortal?

Back 21

cancer

Front 22

If we could figure out how to regulate this substance in normal cells which prevents chromosomal degradation we could practically be immortal.

Back 22

telomerase

Front 23

What is telomerase?

Back 23

the enzyme (see the "ase" ending) that prevents chromosomal degradation

Front 24

In reference to cancer, what is the "multiple hit" model?

Back 24

This describes the fact that multiple mutations are required for cancer to occur. These can be inherited aberrations, or caused by the environment. If you get enough of these "hits" in a lifetime you can develop a cancer.

Front 25

What is the purpose of mitosis?

Back 25

to provide identical copies of the parent cell with no variation

Front 26

What is the purpose of meiosis?

Back 26

to provide sex cells (eggs and sperm) that are haploid

Front 27

What are human body cells called?

Back 27

somatic cells

Front 28

How many chromosomes do human somatic cells have?

Back 28

46

Front 29

What is the genetic makeup of the oogonium in the human?

Back 29

2N

Front 30

What is the genetic makeup of the human primary oocyte?

Back 30

2N

Front 31

What is the genetic makeup of the secondary oocyte?

Back 31

haploid - N

Front 32

What is the genetic makeup of the ovum?

Back 32

haploid - N

Front 33

What are the polar bodies formed during oogenesis?

Back 33

Polar bodies are the result on an uneven cytokinetic division of the cytoplasm occurring during oogenesis in telophase 1 & 2. This means that two polar bodies are formed by the end of oogenesis. In humans these tend to disintegrate leaving only a single ovum at the end of oogenesis.

Front 34

How many eggs are produced at the completion of oogenesis?

Back 34

one

Front 35

How many sperm cells are produced at the end of spermatogenesis?

Back 35

four

Front 36

What is the genetic makeup of the spermatogonium?

Back 36

2N

Front 37

What is the makeup of the primary spermatocyte?

Back 37

2N

Front 38

What is the makeup of the secondary spermatocyte?

Back 38

N - haploid

Front 39

What is the genetic makeup of the spermatid?

Back 39

N - haploid

Front 40

What is a homologous pair?

Back 40

chromosomes which have the same genes and similar sequences

Front 41

How many cytokinetic divisions occur in mitosis?

Back 41

one

Front 42

How many cytokinetic divisions occur in meiosis?

Back 42

two

Front 43

What is the purpose of meiosis?

Back 43

to produce haploid gametes and allow for variation to occur

Front 44

Which of the phases of meiosis is the one in which genetic variation occurs?

Back 44

prophase 1

Front 45

What is the process called when homologous chromosomes come together in Prophase 1?

Back 45

synapsis

Front 46

What happens during synapsis?

Back 46

During synapsis homologous chromosomes come to line along side of one another forming a tetrad.

Front 47

What is crossing over?

Back 47

Crossing over may occur during prophase 1 of meiosis when homologous pairs of chromosomes overlap and exchange pieces of genetic information at corresponding loci (locations on the chromosome). This is what permits variation and is the engine which drives evolution.

Front 48

What is the purpose of sex?

Back 48

to shuffle the genetic deck in prophase 1 to get new combinations that are adaptive

Front 49

What is an adaptive trait?

Back 49

One that increases an organism's chance of surviving to the age of reproduction and passing that trait to the next generation. Adaptive traits tend to accumulate in gene pools.

Front 50

What is a maladaptive trait?

Back 50

a trait that decreases the chances of survival to the age of reproduction<br />Maladaptive traits do not accumulate in the gene pool for this very reason.

Front 51

How does metaphase of mitosis and metaphase of Meiosis 1 differ?

Back 51

In mitosis individual duplicated chromosomes line up on the equator and pulled apart during anaphase to produce daughter cells with the same number of chromosomes as the parent cell. In Meiosis 1 metaphase, tetrads line up at the equator and homologues are pulled apart reducing chromosome number in half making haploid gametes.

Front 52

How many autosomes and sex chromosomes are found in a human karyotype?

Back 52

In humans there are 22 pairs of autosomes and one pair of sex chromosomes.

Front 53

Which sex chromosome is markedly smaller than its counterpart?

Back 53

the male "Y" chromosome

Front 54

When an egg and a sperm unite what is the product called?

Back 54

a zygote

Front 55

What is the process called when the male and female gametes unite to form a zygote?

Back 55

fertilization