Controlled Mitosis

Question 1

Cells not actively reproducing (undergoing mitosis) are outside of the cell cycle in _____, the reproductive resting state, and continue to perform all their usual differentiated functions.

Answer 1

G (subscript 0)

Question 2

Among all normal cells capable of mitosis, the step of leaving G (subscript 0) and entering the first phase of the cell cycle, _____, is severely _____.

Answer 2

1. G (subscript 1)

2. restricted

Question 3

Once a cell enters the cell cycle, it responds only to _____ signals.

Answer 3

internal

Question 4

Cells that are in the cell cycle must either progress through the cycle or be arrested at some point in the cycle. Cells that are arrested are _____ and usually _____.

Answer 4

1. nonfunctional

2. die

Question 5

_____ _____ _____ are activated at checkpoints during the cell cycle and determine how much oncogene expression is needed to allow sufficient cell division to occur for events such as normal wound healing but not lead to excessive cell _____.

Answer 5

1. Suppressor gene products

2. division

Question 6

List four requirements for a cell before it can enter the cell cycle:

Answer 6

1. The cell has retained its mitotic ability.
2. A need for cell division exists.
3. Adequate nutritional stores are present.
4. Sufficient energy supply for cell division exists.

Question 7

_____ _____ controls are checks placed on the cell before it can enter the cell cycle.

Answer 7

Restriction point

Question 8

The presence of external events that inform the cell of a need for cell division are sent to the cell’s nucleus through a process known as _____ _____.

Answer 8

signal transduction

Question 9

Signal transduction communicates information about events, conditions, and substances external to the cell to reach the _____ and then influence whether the cell divides, undergoes apoptosis, or performs its differentiated functions.

Answer 9

nucleus

Question 10

_____ _____ are a variety of promitotic substances that enter a cell nucleus and signal to the cell that a specific gene transcription or mitosis is needed.

Answer 10

Transcription factors

Question 11

When the promitotic signal transduction pathway in a cell segment is activated, one of the first responses is the activation of _____ that increase the intracellular concentration of a variety of tyrosine kinase (TK) _____.

Answer 11

1. enzymes

2. enzymes

Question 12

The end result of the activation of any promitotic signal transduction pathway is the increased production of _____ _____.

Answer 12

transcription factors

Question 13

List two types of transcription factors:

Answer 13

1. proteins

2. electrolytes

Question 14

_____ _____ _____ control the expression of oncogene products.

Answer 14

Suppressor gene products

Question 15

_____ _____ are always promitotic.

Answer 15

Oncogene products

Question 16

_____ is exerted at every phase of the cell cycle.

Answer 16

Control

Question 17

Activation of most of the promitotic gene products requires the addition of a _____ group to their structures.

Answer 17

phosphate

Question 18

These promitotic products can be _____ by removing a _____ group from their structures.

Answer 18

1. deactivated

2. phosphate

Question 19

_____ is the first phase of the cell cycle.

Answer 19

G (subscript 1)

Question 20

_____ are a group of promitotic proteins produced by specific oncogenes that, upon activation, propel the cell forward through all phases of the reproduction cycle.

Answer 20

Cyclins

Question 21

Cyclin activation requires the attachment of a phosphorous molecule to the cyclin structure, a process known as _____.

Answer 21

phosphorylation

Question 22

Tyrosine kinase (TK) enzymes activate many transcription factors at different steps in the signal transduction pathway, and they activate _____ in the cell cycle.

Answer 22

cyclins

Question 23

Tyrosine kinase (TK) enzymes are products of _____.

Answer 23

oncogenes

Question 24

Cyclins are activated by _____-_____ _____, or CDKs.that combine with cyclins to form complexes that start the cellular reproductive processes.

Answer 24

cyclin-dependent kinases

Question 25

The type of cyclins present in a cell during mitosis varies by the _____ of the cycle.

Answer 25

phase

Question 26

More than 20 different families of cyclins have been identified (_____ through _____).

Answer 26

1. A

2. T

Question 27

The most common signal for leaving G (subscript 0) and entering G (subscript 1) is the formation of the complex _____.

Answer 27

cyclin-D/CDK

Question 28

All of the cyclins and CDKs are made in the cell in response to specific _____ activation.

Answer 28

oncogene

Question 29

When the cell is to move into the S phase, additional cyclin-CDK complexes form to promote DNA transcription and protein synthesis with a greater expression of promitotic cyclins by _____ and a reduced expression of _____ _____ _____ that inhibit cell division.

Answer 29

1. oncogenes

2. suppressor gene products

Question 30

Progression into S phase requires that regulator proteins be _____ to work with transcription factors.

Answer 30

phosphorylated

Question 31

A major regulator of the cell cycle for many types of normal cells is the _____ suppressor gene product known as the “guardian of the genome” that restricts the progression of cells from G (subscript 1) into S phase.

Answer 31

Tp53

Question 32

DNA replication is the major activity of _____ phase.

Answer 32

S

Question 33

The _____ phase of the cell cycle is characterized by intense protein synthesis for proteins that are important in M phase and for those that provide routine cell maintenance.

Answer 33

G (subscript 2)

Question 34

_____ phase is the part of the cell cycle in which true _____ occurs, resulting in two new daughter cells.

Answer 34

1. M

2. mitosis

Question 35

List the five sub phases of M phase:

Answer 35

1. prophase
2. prometaphase
3. metaphase
4. anaphase
5. telophase

Question 36

Microtubular spindle fibers form from the centrioles as a result of the interaction of cyclins and an activating enzyme called _____ _____.

Answer 36

aurora kinase

Question 37

_____ occurs in which each chromosome is pulled apart at the centriole so that the two sets of chromosomes are separated within the single large cell.

Answer 37

nucleokinesis

Question 38

_____ is the separating of the cell into two new cells with each having a complete set of chromosomes after nucleokinesis.

Answer 38

Cytokinesis

Question 39

Programmed cell death is also known as _____.

Answer 39

apoptosis

Question 40

When cells are damaged, _____ triggers earlier cell death than when programmed.

Answer 40

apoptosis

Question 41

The shortening of _____ DNA is a major signal for normal apoptosis.

Answer 41

telomeric

Question 42

Shortening of the telomeres at each tip of the cell’s chromosomes occurs with each round of _____ _____.

Answer 42

cell division

Question 43

The enzyme _____ is produced in the cell during fetal life and maintains telomeric DNA which depletes as the cell divides for the preprogrammed number of times until the telomeric DNA is completely gone, unraveling the chromosome forming fragments that triggers self-destruction.

Answer 43

telomerase