Controlled Mitosis Flashcards
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.
G (subscript 0)
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 _____.
- G (subscript 1)
2. restricted
Once a cell enters the cell cycle, it responds only to _____ signals.
internal
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 _____.
- nonfunctional
2. die
_____ _____ _____ 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 _____.
- Suppressor gene products
2. division
List four requirements for a cell before it can enter the cell cycle:
- The cell has retained its mitotic ability.
- A need for cell division exists.
- Adequate nutritional stores are present.
- Sufficient energy supply for cell division exists.
_____ _____ controls are checks placed on the cell before it can enter the cell cycle.
Restriction point
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 _____ _____.
signal transduction
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.
nucleus
_____ _____ 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.
Transcription factors
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) _____.
- enzymes
2. enzymes
The end result of the activation of any promitotic signal transduction pathway is the increased production of _____ _____.
transcription factors
List two types of transcription factors:
- proteins
2. electrolytes
_____ _____ _____ control the expression of oncogene products.
Suppressor gene products
_____ _____ are always promitotic.
Oncogene products
_____ is exerted at every phase of the cell cycle.
Control
Activation of most of the promitotic gene products requires the addition of a _____ group to their structures.
phosphate
These promitotic products can be _____ by removing a _____ group from their structures.
- deactivated
2. phosphate
_____ is the first phase of the cell cycle.
G (subscript 1)
_____ are a group of promitotic proteins produced by specific oncogenes that, upon activation, propel the cell forward through all phases of the reproduction cycle.
Cyclins
Cyclin activation requires the attachment of a phosphorous molecule to the cyclin structure, a process known as _____.
phosphorylation
Tyrosine kinase (TK) enzymes activate many transcription factors at different steps in the signal transduction pathway, and they activate _____ in the cell cycle.
cyclins
Tyrosine kinase (TK) enzymes are products of _____.
oncogenes
Cyclins are activated by _____-_____ _____, or CDKs.that combine with cyclins to form complexes that start the cellular reproductive processes.
cyclin-dependent kinases
The type of cyclins present in a cell during mitosis varies by the _____ of the cycle.
phase
More than 20 different families of cyclins have been identified (_____ through _____).
- A
2. T
The most common signal for leaving G (subscript 0) and entering G (subscript 1) is the formation of the complex _____.
cyclin-D/CDK
All of the cyclins and CDKs are made in the cell in response to specific _____ activation.
oncogene
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.
- oncogenes
2. suppressor gene products
Progression into S phase requires that regulator proteins be _____ to work with transcription factors.
phosphorylated
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.
Tp53
DNA replication is the major activity of _____ phase.
S
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.
G (subscript 2)
_____ phase is the part of the cell cycle in which true _____ occurs, resulting in two new daughter cells.
- M
2. mitosis
List the five sub phases of M phase:
- prophase
- prometaphase
- metaphase
- anaphase
- telophase
Microtubular spindle fibers form from the centrioles as a result of the interaction of cyclins and an activating enzyme called _____ _____.
aurora kinase
_____ 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.
nucleokinesis
_____ is the separating of the cell into two new cells with each having a complete set of chromosomes after nucleokinesis.
Cytokinesis
Programmed cell death is also known as _____.
apoptosis
When cells are damaged, _____ triggers earlier cell death than when programmed.
apoptosis
The shortening of _____ DNA is a major signal for normal apoptosis.
telomeric
Shortening of the telomeres at each tip of the cell’s chromosomes occurs with each round of _____ _____.
cell division
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.
telomerase
