Chapter 12: The Cell Cycle

Question 1

Cell division

Answer 1

The reproduction of cells

Question 2

Genome

Answer 2

The genetic maturely of an organism or virus; the complete complement of an organism’s or virus’s genes along with its non coding nucleic acid sequences

Question 3

Chromosomes

Answer 3

A cellular structure consisting of one DNA molecule and associated protein molecules. A duplicated chromosome structure has two DNA molecules

Question 4

Chromatin

Answer 4

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 that are not visible with a light microscope

Question 5

Somatic cell

Answer 5

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

Contains 46 chromosomes in humans

Question 6

Gamete

Answer 6

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 7

Sister chromatids

Answer 7

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 8

Centromere

Answer 8

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 centromere cells DNA. Other proteins condense the chromatin in that region so it appears as a narrow waist on the duplicated chromosome.

An unduplicated chromosome has 1 centromere

Question 9

Mitosis

Answer 9

A process of nuclear division in eukaryotic cells conventionally divided into five stages. Mitosis conserves chromosome number by allocating replicated chromosomes equally to each of the daughter nuclei.

Prophase, Prometaphase, metaphase, anaphase, and telophase

Question 10

Duplication of chromosomes

Answer 10

IN an undivided cel, chromosomes are in long thin chromatin fibers

Once duplicated, the chromosome consists of two sister chromatids.

Molecular and mechanical processes separate the sister chromatids into two chromosomes and distribute them to two daughter cells.

Question 11

Cell Cycle

Answer 11

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 and M phase

Question 12

Mitotic or M phase

Answer 12

The phase of the cell cycle that include mitosis and cytokinesis

Question 13

Interphase

Answer 13

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 14

Stages of Interphase

Answer 14

G1 phase - the first growth phase of the cycle. Consists of the portion of interphase before DNA synthesis begins

S phase - the synthesis phase of the cell cycle; the portion of interphase during which DNA is replicated

G2 phase - the second growth phase of the cell cycle, consisting of the portion of interphase after DNA synthesis occurs

Question 15

Prophase

Answer 15

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 intact

Question 16

Prometaphase

Answer 16

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

Question 17

Metaphase

Answer 17

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

Question 18

Anaphase

Answer 18

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 19

Telophase

Answer 19

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

Question 20

Cytokinesis

Answer 20

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

Question 21

Cleavage

Answer 21

The process of cytokinesis in animal cells, characterized by pinching of the plasma membrane

Question 22

Cleavage furrow

Answer 22

The first sign of cleavage in an animal cell; a shallow groove around the cell in the cell surface near the old metaphase plate.

Plants cells have cell plate instead

Question 23

Mitotic Spindle

Answer 23

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

Question 24

Centrosome

Answer 24

A structure present in the cytoplasm of animal cells that functions as a microtubule-organizing center and is important during cell division. Each centrosome has two centromeres during interphase

Question 25

Kinetochore

Answer 25

A structure of proteins attached to the centromere that links each sister chromatid to the mitotic spindle

Question 26

Metaphase plate

Answer 26

An imaginary structure located at a plane midway between the two poles of a cell in metaphase on which the centromere of all the duplicated chromosomes are located

Question 27

Cell Cycle Control System

Answer 27

A cyclically operating set of molecules in the eukaryotic cell that both triggers and coordinated key events in the cell cycle

Question 28

Checkpoint

Answer 28

A control point in the cell cycle where stop and go-ahead signals can regulate the cycle

Question 29

Cyclin

Answer 29

A cellular protein that occurs in a cyclically fluctuating concentration and that plays an important role in regulating the cell cycle

Question 30

Cyclin Dependent Kinase

Answer 30

A protein kinase that is only active when attached to a particular cyclin

Question 31

M phase Promoting Factor

Answer 31

M Phase promoting factor or maturing; a protein complex required for a cell or progress from late interphase to mitosis. The active form consists of cyclin and a protein kinase

Question 32

G0 Phase

Answer 32

A non dividing state occupied by cells that have left the cell cycle, sometimes reversible

Question 33

Growth Factor

Answer 33

A local regulator that acts on nearby cells to stimulate cell division. It is a protein released by certain cells

Question 34

G1 Checkpoint

Answer 34

Before the S phase

Checks for nutrients, growth factors, and DNA damages

Question 35

G2 Checkpoint

Answer 35

Before mitosis

Checks for cell size and DNA replication

Question 36

M Checkpoint

Answer 36

Occurs at the end of a metaphase

Checks for chromosome spindle attachment