Mitosis

Question 1

What happens in mitosis?

Answer 1

A cell makes an identical copy of itself?

Question 2

What would happen if there was no mitosis?

Answer 2

Cell death and eventually death of the organism.

Question 3

Describe the importance of DNA within the cellular chain of command

Answer 3

DNA is the controlling material within a cell as it controls the production of all other cellular organelles and materials.

Question 4

What is the cellular chain of command?

Answer 4

The controlling material within a cell is the DNA which is found in the nucleus of the cell. It is the DNA which controls the production of all other cellular organelles and materials. This is because DNA serves as the template (pattern) molecule for the production of RNA (and new DNA). The RNA serves as the template for the production of all cellular proteins, and, in turn, the proteins serve to produce all cellular materials. Because of this “cellular chain of command”, it is only necessary to duplicate cellular DNA to pass it on to the new (daughter) cell and the new DNA will then cause the production of all the necessary cellular material in the daughter cell.

Question 5

What is chromatin? What happens to chromatin once cell division occurs?

Answer 5

A disorganized mass of DNA strands prior to cell division. As cellular reproduction begins this disorganized mass of strands organizes into a clearly defined set of individual chromosomes.

Question 6

What is the diploid number and the haploid number?

Answer 6

Human cells contain 46 chromosomes…. All cells of the human body contain this full number of chromosomes called the diploid (2n) number.
The exception is the sex cells (egg and sperm cells)- They contain half the number of chromosomes which is called the haploid (n) number.

Question 7

Cell reproduction produces ….

Answer 7

Two new daughter cells which are identical to the original

Question 8

Why do cells reproduce?

Answer 8

To enable the organism to grown and to repair dying cells

Question 9

Cellular reproduction involves the replication of ….

Answer 9

DNA in which the number of chromosomes stays the same.

Question 10

What happens as DNA replication takes place ?

Answer 10

each original chromosome produces an identical copy of itself

Question 11

What are sister chromatids? What are they connected to?

Answer 11

The identical copies of each chromosome which are connected to each other at a point called the centromere.

Question 12

What happens as the cell divides ?

Answer 12

The sister chromatids separate forming identical independent chromosomes which are distributed, one from each pair, into the two identical daughter cells formed during cell reproduction.

Question 13

Most of a cell’s life is spent in which phase?

Answer 13

Interphase, when no cell division is occurring

Question 14

What are the three parts of interphase?

Answer 14

G1- the cell size and the number of organelles increase
S- replication of DNA occurs
G2- nuclear proteins are duplicated

Question 15

What is the M phase?

Answer 15

Mitosis, consisting of prophase, metaphase, anaphase and telophase

Question 16

What occurs in prophase?

Answer 16

In the prophase stage, the chromosomes (DNA) have already replicated in the preceding S stage and appear as sister chromatids held together at a point called the centromere. The nuclear membrane breaks apart and protein microtubules (which will later orient the chromosomes) begin to take shape radiating from each pole of the cell. The microtubules (collectively called the spindle) extend out toward each pair of chromatids.

Question 17

What happens in metaphase?

Answer 17

At the start of metaphase, microtubules become more definite and become attached to each centromere of the sister chromatids. The chromatids begin to move toward the center of the cell. As metaphase continues, the microtubules arrange the sister chromatids in a line at the center of the cell called the metaphase plate.

Question 18

What happens in anaphase?

Answer 18

As anaphase begins, each set of sister chromatids divides and the two separated chromatids (now, each called a chromosome) begin to move toward opposite ends (poles) of the cell, probably through some mechanism related to shortening of the microtubules. As anaphase continues, the cell begins to develop a cleavage furrow which will eventually become the division between two cells.

Question 19

What happens in telophase?

Answer 19

In telophase, the spindle disappears, new nuclear membranes form around each set of separate chromosomes, and the cleavage furrow (an indentation of the membrane between the two nearly separate daughter cells) deepens. The separation of the joined structure into two cells, called cytokinesis, is accomplished by a structure called the contractile ring which slowly forms a constriction between the two daughter cells.

Question 20

the sister chromatids are arranged in a line across the center of a cell known as the ….

Answer 20

Metaphase plate

Question 21

The microtubules that help out in cell division collectively form a …..

Answer 21

spindle

Question 22

What is the separation into two cells known as ?

Answer 22

Cytokinesis

Question 23

What is a cleavage furrow?

Answer 23

Formed across the center of the cell during anaphase, this furrow will eventually become the division between two cells.

Question 24

What structure helps to separate the two cells in cytokinesis?

Answer 24

The Contractile Ring slowly forms a constriction between the two daughter cells.

Question 25

Why is mitosis important?

Answer 25

The body’s ability to replicate cells is essential to its ability to carry out processes that enable the survival of the body. Without a steady population of cells that can perform specific functions, the collaborative action of tissues, organs, and body systems would cease.
New cells need to be created so that when old ones die or are damaged, the body can continue to function.