Cell cycle And Applications Of Mitosis, Meiosis And Its Diseases

Question 1

involves the distribution of identical genetic material or DNA to two daughter cells.
What is most remarkable is the fidelity with which the DNA is passed along, without dilution or error, from one generation to the next.

Answer 1

Cell division

Question 2

In eukaryotic cells, or cells with a nucleus, the stages of the cell cycle are divided into two major phases:

Answer 2

Interphase and Mitotic Phase

Question 3

• Almost 90% of the cycle is takes up with Interphase.
• DNA in the nucleus is replicated but chromosomes not yet visible.
• In order for a cell to move from interphase into
the mitotic phase,
many internal and external conditions must be met. The three stages of interphase are called G1, S, and G2

Answer 3

Interphase

Question 4

• This is the first phase in the normal cell cycle.
• Involves preparation for synthesis and replication
of the cellular
machinery.
• Typically the longest phase of the cell cycle. Cells remain in G1 for about 10 hours of the 24 total hours of the cell cycle.

Answer 4

G1 Phase

Question 5

• The cellular content of the
DNA is
duplicated in this stage of the cell cycle.
• The length
of S phase varies according to the total DNA that the particular cell contains

Answer 5

S Phase

Question 6

• During this stage of the cell cycle, the cell synthesizes the proteins required to assemble the machinery required
for the separation of duplicated chromosomes.
• G2 is shorter, lasting only 3 to 4 hours in most cells

Answer 6

G2 Phase

Question 7

Is a process of cell division which results in the production of two daughter cells from a single parent cell.

Answer 7

Mitosis

Question 8

Stages of Mitosis

Answer 8

Prophase
Prometaphase
Metaphase
Anaphase
Telophase
Cytokinesis

Question 9

In this stage, the chromatin in the nucleus begins to condense and becomes visible and now called chromosomes.

Answer 9

Prophase

Question 10

• In this stage, the nuclear membrane dissolves,
marking the
beginning of the prometaphase.
• Proteins attach to the centromeres creating the kinetochores and the chromosomes begin moving.

Answer 10

Prometaphase

Question 11

• The movement chromosomes
results to the their alignment along the middle of the cell nucleus.
This process helps to ensure that in the next phase, when the chromosomes are separated, each new nucleus will receive one copy of each chromosome.

Answer 11

Metaphase

Question 12

• The pair of aligned chromosome separate at the kinetochores and move to the opposite sides of the cell.

Answer 12

Anaphase

Question 13

• Chromatids arrive at the opposite poles of the cell.
• New membranes form around the daughter nuclei.
The chromosomes disperse and no longer visible
• The spindle fibers
disperse, and
cytokinesis or the partitioning of the cell may also begin during this stage.

Answer 13

Telophase

Question 14

in animal cells, cytokinesis results when a fiber ring composed of a protein called actin located around the center of the cell contracts pinching the cell into two daughter cells, each with one nucleus.

Answer 14

Cytokinesis

Question 15

a critical control point in the Cell Cycle
where ‘stop’ and ‘go-ahead’ signals can regulate the cell cycle.

Answer 15

Checkpoint

Question 16

have built-in ‘stop’ signals that halt the cell
cycles and checkpoints until overridden by ‘go-ahead’ signals.

Answer 16

Animal cells

Question 17

The G1 checkpoint ensures that the cell is large enough to divide and that enough nutrients are available to support the resulting daughter cells.

Answer 17

G1 checkpoint

Question 18

• ensures that DNA replication in S phase has been successfully completed.

Answer 18

G2 checkpoint

Question 19

ensures that all of the chromosomes are attached to the mitotic spindle by a kinetochore

Answer 19

Metaphase checkpoint

Question 20

Is a process where a single cell divides twice to produce four cells containing half the original amount of genetic information.
These cells are our sex cells- sperm in males, eggs in females.

Answer 20

Meiosis

Question 21

Separates
pairs chromosomes to halve number (diploid to haploid).
of homologous the chromosome

Answer 21

First Mitotic Division

Question 22

pertains to one pair of chromosomes with the same gene sequence, loci, chromosomal length, and centromere location.

Answer 22

Homologous Chromosome

Question 23

has been subdivided into
five
substages:
leptonema, zygonema, pachynema, diplonema, and diakinesis.

Answer 23

Prophase 1

Question 24

Replicated
chromosomes have coiled and are already visible.
The number of
chromosomes present is the same as the number in the diploid cell.

Answer 24

Leptonema

Question 25

Homologue chromosomes begin to pair and twist around each other in a highly specific manner. The pairing is called synapsis. And because the pair consists of four chromatids it is referred to as bivalent tetrad.

Answer 25

Zygonema

Question 26

Homologue chromosomes begin to pair and twist around each other in a highly specific manner. The pairing is called

Answer 26

Synapsis

Question 27

And because the pair consists of four chromatids it is referred to as

Answer 27

Bivalent tetrad

Question 28

Chromosomes become much shorter and thicker. A form of physical exchange between homologues takes place at specific regions. The process of physical exchange of chromosome region called crossing-over. Through the mechanism of crossing-over, the parts of the homologous chromosomes are recombined (genetic recombination).

Answer 28

Pachynema

Question 29

The process of physical exchange of chromosome region

Answer 29

Crossing over

Question 30

The area of contact between two non-sister chromatids,

Answer 30

Chiasma

Question 31

The two pairs of sister chromatids begin to separate from each other. It is at this point where crossingover is shown to have taken place. The area of contact between two non-sister chromatids, called chiasma, become evident.

Answer 31

Diplonema

Question 32

The four chromatids of each tetrad are even more condensed. Also in this stage the nuclear envelope starts to disappear.

Answer 32

Diakinesis

Question 33

The spindle apparatus is completely formed and the microtubules are attached TO the centromere regions of the homologues. The synapsed tetrads are found aligned at the metaphase plate (the equatorial plane of the cell) instead of only replicated chromosomes.

Answer 33

Metaphase 1

Question 34

Chromosomes in each tetrad separate and migrate toward the opposite poles. The sister chromatids (dyads) remain attached at their respective centromere regions.

Answer 34

Anaphase 1

Question 35

The dyads complete their migration to the poles. New nuclear membranes may form. In most species, cytokinesis follows, producing two daughter cells. Each has a nucleus containing only one set of chromosomes (haploid level) in a replicated form.

Answer 35

Telophase 1

Question 36

The events in the second meiotic division are quite similar to mitotic division. The difference lies, however, in the number of chromosomes that each daughter cell receives. While the original chromosome number is maintained in mitosis, the number is reduced to half in meiosis.

Answer 36

Second mitotic division

Question 37

The dyads contract.

Answer 37

Prophase 2

Question 38

The centromeres are directed to the equatorial plate and then divide.

Answer 38

Metaphase 2

Question 39

The sister chromatids move away from each other and migrate to the opposite poles of the spindle fiber.

Answer 39

Anaphase 2

Question 40

The chromatids are at the poles, forming two groups of chromosomes. A nuclear membrane forms around each set of chromosomes and cytokinesis follows. The chromosomes uncoil and extend.

Answer 40

Telophase 2

Question 41

is the physical process of cell division, which divides the cytoplasm of a parental cell into daughter cells.

Answer 41

Cytokinesis

Question 42

• Mitosis ensures that the number of chromosomes of the parent cell is identical to its two daughter cells.

Answer 42

Keeps chromosome number constant

Question 43

• Mitosis helps in the splitting of chromosomes during cell division and generates two new daughter cells.

Answer 43

Maintains genetic stability in daughter cells

Question 44

Mitosis ensures the growth of an offspring. Human life starts with a zygote;

Answer 44

Helps in growth and development of zygotes

Question 45

Important for the development of embryos and important for the growth and development of our bodies.

Answer 45

Allows the organism to grow, repair and reproduce • Important

Question 46

A technique employed in biotechnology to produce identical copies of cell or DNA fragments.

Answer 46

Cloning

Question 47

Stem cells are a group of cells that can be directed to form specialized cells in the body.

Answer 47

Stem cell regeneration

Question 48

Cell and tissue culture is effective for large scale production.

Answer 48

Cell and Tissue Culture

Question 49

Research on cell division provides new clues how to curb the growth of tumors by stopping their cells from proliferating.

Answer 49

Help one grasps how cancer develops and could provide clues in stopping cancer

Question 50

Type of cell division that produces four cells, each with half the parenter t chromosomes as the

Answer 50

Significance or Application of Meiosis

Question 51

• Only possible through meiosis. • Gametes are sex cells responsible for sexual reproduction which contain half the number of chromosomes of all other cells in the organism. • They are haploid. • When male and female gametes combine in fertilization they create an embryo with the full complement of chromosomes (diploid)

Answer 51

Formation of Gametes

Question 52

• In animals and plants, reproductive cells called gametes are the vehicles that transmit genes from one generation to the next. During fertilization, male and female gametes (sperms and eggs) unite, thereby passing on genes of both parents to their offspring.

Answer 52

Expression of Genetic Information

Question 53

Meiosis maintains the fixed number of chromosomes in sexually reproducing organisms, the most important contribution in reproduction.

Answer 53

Maintenance of Chromosome Number

Question 54

During meiosis, the homologous pairs of chromosomes are divided in half to form haploid cells, and this separation, or assortment, of homologous chromosomes is random.

Answer 54

Assortment of Chromosomes

Question 55

contains a mixture of genes from the organism's mother and father.

Answer 55

Haploid Cell

Question 56

scrambles pieces of maternal and paternal genes, which ensures that genes assort independently from one another.

Answer 56

Recombination

Question 57

A genetic rearrangement between nonsister chromatids involving the exchange of corresponding segment of DNA molecules, begins during pairing and synaptonemal complex formation, and iS completed while homologs are in synapsis.

Answer 57

Crossing over

Question 58

A change in nucleotide sequence of the DNA in a cell.

Answer 58

Mutation

Question 59

is a disease in which some of the body's cells uncontrolaby and spread gher parts of the body.

Answer 59

Cancer

Question 60

Tumor development involves number of mutations:

Answer 60

1. Genetic mutation 2. Hyperplasia 3. Dysplasia 4. In situ cancer 5. Invasive cancer

Question 61

a condition that the altered cell and its descendants grow and divide too often

Answer 61

Hyperplasia

Question 62

condition in which the cell's descendants mutated and divide excessively and look abnormal.

Answer 62

Dysplasia

Question 63

cells are abnormal and tumor are still contained within its tissue of origin.

Answer 63

In situ cancer

Question 64

Some cells have additional mutations and allow tumors to invade other tissues

Answer 64

Invasive cancer

Question 65

In chromosomnal aberration in which one or more chromosomes are present in extra copies

Answer 65

Aneuploidy

Question 66

• Most common aneuploidy • There is an extra chromosome

Answer 66

Trisomy

Question 67

(trisomy 21). It is usually caused by an extra copy of chromosome 21 (trisomy 21). Characteristics: decreased muscle tone, stocker build, asymmetrical skull, slanting eyes and mild to moderate mental retardation.

Answer 67

Down syndrome

Question 68

(trisomy 13), a serious rare genetic disorder caused by having and additional copy of chromosome 13 in some or all of the body's cells.

Answer 68

Patau syndrome

Question 69

Another type of aneuploidy in which there is a missing chromosome.

Answer 69

Monosomy

Question 70

in which female has a missing or damaged X chromosome. X instead of XX or XY. Often have a short stature, low hairline, abnormal eye features, and bone development and a "caved-in" appearance to the chest.

Answer 70

Turner syndrome,

Question 71

men with this condition are usually sterile and tend to have longer arms and legs and to be a taller than their peers. Often shy and quiet and have a higher incidence of speech delay.

Answer 71

Klinefelter's syndrome (XXY),