Chapter 12: The Cell Cycle

Question 1

Define Cell Division

Answer 1

The reproduction of cells.

Question 2

Define Cell Cycle

Answer 2

An ordered sequence of events in the life of a cell, from its origin in the division of a parent cell until its own division into two. The eukaryotic cell cycle is composed of interphase (including G1, S, and G2 Phases) and M phase (including mitosis and cytokinesis).

Question 3

Most cell division results in genetically _____ daughter cells.

Answer 3

Identical

Question 4

Define Genome

Answer 4

The genetic material of an organism or a virus.

Question 5

The typical length of DNA in a human cell is _____.

Answer 5

2m

Question 6

Define Chromosome

Answer 6

A cellular structure consisting of one DNA molecule and associated protein molecules. A eukaryotic cell typically has multiple, linear chromosomes, which are located in the nucleus. A prokaryotic cell often has a single, circular chromosome, which is found in the nucleoid, a region that is enclosed by the membrane.

Question 7

Define Chromatin

Answer 7

The complex of DNA and proteins that makes up eukaryotic chromosomes. When the cell is not dividing chromatin exists in its dispersed form, as a mass of very long, thin fibers.

Question 8

Define Somatic Cells

Answer 8

Any cell in a multicellular organism except a sperm or egg or their precursors.

Question 9

How many chromosomes do somatic cells contain?

Answer 9

46

Question 10

Define Gamete

Answer 10

A haploid reproductive cell, such as an egg or sperm, that is formed by meiosis or is the descendant of cells formed by meiosis. Gametes unite during sexual reproduction to produce a diploid zygote.

Question 11

Each duplicated chromosome consists of _____.

Answer 11

Two sister chromatids.

Question 12

Define Sister Chromatids

Answer 12

Two copies of a duplicated chromosome attached to each other by proteins at the centromere and, sometimes, along the arms. While joined, two sister chromatids make up one chromosome. Chromatids are eventually separated during mitosis or meiosis II.

Question 13

The two chromatids, each containing an identical DNA molecule, are typically attached all along their lengths by protein complexes called _____.

Answer 13

Cohesins

Question 14

Define Centromere

Answer 14

In a duplicated chromosome, the region on each sister chromatid where it is most closely attached to its sister chromatid by proteins that bind to the centromeric DNA.

Question 15

Once the sister chromatids separate, they are no longer called sister chromatids; rather, they are considered ______.

Answer 15

Chromosomes

Question 16

Define Mitosis

Answer 16

A process of nuclear division in eukaryotic cells conventionally divided into 5 stages: Prophase, Prometaphase, Metaphase, Anaphase, Telophase. Mitosis conserves chromosome numbers by allocating replicated chromosomes equally to each of the daughter nuclei. PP-MAT

Question 17

Define Cytokinesis

Answer 17

The division of the cytoplasm to form two separate daughter cells immediately after mitosis, meiosis I, or meiosis II.

Question 18

Define Mitotic (M) Phase

Answer 18

The phase of the cell cycle that includes mitosis and cytokinesis.

Question 19

The _____ phase is the shortest portion of the cell cycle.

Answer 19

Mitotic

Question 20

Define Interphase

Answer 20

The period in the cell cycle when the cell is not dividing. During interphase, cellular metabolic activity is high, chromosomes and organelles are duplicated, and cell size may increase. Interphase often accounts for about 90% of the cell cycle.

Question 21

What are the three phases that interphase can be divided in?

Answer 21

G1-S-G2

Question 22

Define G1 Phase

Answer 22

The first gap, or growth phase, of the cell cycle, consisting of the portion of interphase before DNA synthesis begins.

Question 23

Define S Phase

Answer 23

The synthesis phase of the cell cycle; the portion of interphase during which DNA is replicated.

Question 24

Define G2 Phase

Answer 24

The second gap, or growth phase, of the cell cycle, consisting of the portion of interphase after DNA synthesis occurs.

Question 25

What are the phases that mitosis can be broken down to?

Answer 25

Prophase-Prometaphase-Metaphase-Anaphase-Telophase. PP-MAT

Question 26

Define Prophase

Answer 26

The first stage of mitosis, in which the chromatin condenses into discrete chromosomes visible with a light microscope, the Mitotic spindle begins to form, and the nucleolus disappears but the nucleus remains in tact.

Question 27

Define Prometaphase

Answer 27

The second stage of mitosis, in which the nuclear envelope fragments and the spindle microtubules attach to the kinetochores of the chromosomes.

Question 28

Define Metaphase

Answer 28

The third stage of mitosis, in which the spindle is complete and the chromosomes, attached to the microtubules at their kinetochores, are all aligned at the metaphase plate.

Question 29

Define Anaphase

Answer 29

The fourth stage of mitosis, in which the chromatids of each chromosome have separated and the daughter chromosomes are moving to the poles of the cell.

Question 30

Define Telophase

Answer 30

The fifth and final stage of mitosis, in which daughter nuclei are forming and cytokinesis has typically begun.

Question 31

Define Mitotic Spindle

Answer 31

An assemblage of microtubules and associated proteins that is involved in the movement of chromosomes during mitosis.