Cell Cycle

Question 1

New cells arise as a result of three intricate processes:

Answer 1

Synthesis and replication of chromosomes, division of the nucleus (Mitosis), and cell division/cytokinesis.

Question 2

What are the two primary phases of the cell cycle of mitosis?

Answer 2

Interphase and Mitotic Phase

Question 3

Mitosis results in what kind of daughter cells?

Answer 3

Identical daughter cells

Question 4

What is the purpose of mitosis?

Answer 4

To produce new cells for growth and for the replacement of worn out cells

Question 5

The stage of the cell cycle where DNA replication occurs is…

Answer 5

Interphase

Question 6

What occurs in late interphase?

Answer 6

Chromosomes have replicated but are so extended that they cannot be seen individually, making them chromatin

Question 7

What occurs in Prophase?

Answer 7

Chromosomes shorten and thicken. Each replicated chromosome becomes visible as a pair of sisterchromatids joined by a duplicated but unseparated centromeere which attaches to the spindle fibres.

Question 8

What do centrioles do?

Answer 8

Produce spindle fibres

Question 9

What do spindle fibres do?

Answer 9

Attach to centromeres of chromatids and separate them

Question 10

What occurs during Metaphase?

Answer 10

The spindle fibres align the sister chromatids along an imaginary equator half way in between the two centrioles at the opposite end of the cell.

Question 11

What is Anaphase?

Answer 11

When the two sister chromatids separate at their centromeres giving rise to two daughter chromosomes which move toward opposite poles

Question 12

What is Telophase?

Answer 12

The chromosomes uncoil and chromatin reforms. A nuclear membrane forms around each chromosome set and cytokinesis is underway

Question 13

During mitosis, the nuclear membrane of a cell disappears and then re-forms respectively during…

Answer 13

Prophase and Telophase

Question 14

What are adult somatic stem cells?

Answer 14

Undifferent cells found in tissues or organs with the primary role to replenish dying cells and regenerate damaged tissues

Question 15

What are embryonic stem cells?

Answer 15

They come from the inner cell mass of early embryos or blastocysts that can eventually differentiate into specialized cells of the body

Question 16

Diploid cells (2n) are produced from what cell cycle process?

Answer 16

Mitosis

Question 17

Haploid cells (n) are produced by what cell cycle process?

Answer 17

Meiosis

Question 18

How are identical twins formed?

Answer 18

Called mono zygotic twins, they arise from one fertilized egg

Question 19

What are Dizygotic twins?

Answer 19

Come from two different eggs, fertilized by two different sperms and the zygotes then have different information (fraternal)

Question 20

Meiosis is

Answer 20

The formation of gametes

Question 21

Homologous pairs are found in what cell cycle?

Answer 21

Meiosis

Question 22

What are gametes?

Answer 22

Egg and sperm

Question 23

In meiosis, what happens to the chromosome number of originally 46 (of human)?

Answer 23

Reduced to half. In humans that would be 23

Question 24

Human sex cells have 23 chromosomes and are considered…

Answer 24

Haploid (n)

Question 25

Somatic cells have 46 chromosome and are considered...

Answer 25

Diploid (2n)

Question 26

Union of the egg and sperm (haploids) produce and zygote with....

Answer 26

46 chromosomes (diploid)

Question 27

What does recombination of genes ensure?

Answer 27

Each offspring gets genetic information from each of the parents - variation is essential for natural selection.

Question 28

What is natural selection?

Answer 28

Survival of the fittest

Question 29

Mitosis after meiosis is for the sake of...

Answer 29

growth

Question 30

How many pairs of chromosomes are found in a zygote/human?

Answer 30

23 pairs

Question 31

How many pairs of chromosomes are homologous and what are they referred to as?

Answer 31

22, Autosomes

Question 32

How many pairs of sex chromosomes are there and what is their purpose?

Answer 32

1 and they determine the gender

Question 33

How is gender determined?

Answer 33

Females have two X chromosomes (XX), Men have one X and one Y (XY)

Question 34

Are sex chromosome homologous?

Answer 34

No, even though they behave as though they are

Question 35

In general, Meiosis involves:

Answer 35

A single DNA replication and two nuclear divisions

Question 36

Homologous pairs separate during...

Answer 36

Meiosis 1

Question 37

Sister chromatids separate during

Answer 37

Meiosis 2

Question 38

The process of meiosis produces how many cells?

Answer 38

4

Question 39

What occurs in prophase 1

Answer 39

chromosomes which have been replicated in Interphase now appear as sister chromatids attached by the centromere. Tetrads form allowing crossing over to occur.

Question 40

What occurs in Metaphase 1?

Answer 40

Homologous chromosomes align at the equatorial plate of the cell

Question 41

What occurs in Anaphase 1?

Answer 41

Homologous chromosomes separate but sister chromatids stay together.

Question 42

What occurs in Telophase 1?

Answer 42

Daughter cells contain only one chromosome of the homologous pair.

Question 43

What does not happen in prophase 2?

Answer 43

DNA replication

Question 44

What occurs in metaphase 2?

Answer 44

chromosomes align at the equatorial plate

Question 45

What occurs in Anaphase 2?

Answer 45

The centromeres divide and sister chromatids separate and move to each pole

Question 46

What occurs in telophase 2?

Answer 46

Cell division is complete with the production of 4 haploid daughter cells

Question 47

Mitosis only occurs in...

Answer 47

Somatic cells

Question 48

Meiosis only occurs in...

Answer 48

Ovaries and Testes

Question 49

How many daughter cells are produced for Meiosis and Mitosis?

Answer 49

Mitosis = 2, Meiosis = 4

Question 50

In meiosis, daughter cells are the same as parent cells. True of False?

Answer 50

False

Question 51

How many divisions are in the mitotic cycle?

Answer 51

1

Question 52

Does crossing over occur in mitosis?

Answer 52

no

Question 53

The term for gamete formation is...

Answer 53

Gametogenisis

Question 54

Two meiotic divisions in females do not result in four equally mature gametes as in male, but...

Answer 54

One large ovum that requires the nutrients and organelles for possible future divisions from the 2-3 polar bodies.

Question 55

What happens to the used polar bodies?

Answer 55

they are usually discarded.

Question 56

Unequal cleavage occurs in

Answer 56

Oogenisis

Question 57

Equal cleavage occurs in

Answer 57

Spermatogensis

Question 58

What is Nondisjunction?

Answer 58

When homologous chromosomes do not separate during meiosis and instead, move to the same pole

Question 59

What happens what nondisjunction occurs?

Answer 59

Gametes end up with more or less than the required number of chromosomes making cells lack of have too much genetic information to function properly

Question 60

In humans, non disjunction produces gametes with (#s)

Answer 60

22 or 24 chromosomes

Question 61

A zygote with three chromosomes in place of the normal pair is called

Answer 61

Trisomy

Question 62

A zygote that has a single chromosome in place of a homologous pair is called

Answer 62

Monosomy

Question 63

What is a karyotype?

Answer 63

The pictures of arranged homologous pairs

Question 64

What is Chorion Villus Sampling or Biopsy?

Answer 64

cells from the outer membrane of the embryo are removed and used for karyotyping to detect chromosomal disorders

Question 65

What is Amniocentesis

Answer 65

The using of a syringe to draw amniotic fluid which contains cells from the fetus allowing karyotypes to be prepared and analyzed to detect chromosomal abnormalities.