Cell Cycle Flashcards
The life of a cell from the time it is first formed during the division of a parent cell until its division into two daughter cells
- involves the distribution of DNA to daughter cells
cell cycle
If the division of a cell becomes uncontrolled, what happens?
It becomes cancer cells
(cancer - uncontrolled cell growth)
Functions of the Division of Cells
- for reproduction
- for growth and development
- Tissue renewal - to regenerate/replace old dead cells
dispersed DNA with its associated proteins (histones) found in a chromosome
Chromatin
packaged and organized structures containing DNA, condensed
Chromosome
Chromosomes can be _________ and ______________
duplicated and unduplicated (sometimes called chromatid)
What phase spends the longest time in Cell Cycle
Interphase (especially Gap 1 phase)
A phase in interphase where these events happen:
- Growth of cytoplasm and doubling of organelles
- Produce proteins, enzymes, nutrients, and energy
- Highest rate of protein synthesis
- Movement of centrioles
First Gap Phase
A phase in interphase where these events happen:
- The cell synthesizes a copy of its DNA in a very notable process called DNA replication (when an existing DNA produces another copy of itself)
S phase (Synthesis)
A phase in interphase where these events happen:
- Continued growth, further maturation, and the production of materials that are necessary for cell division to occur
- Protein synthesis but not at a rate similar to that of the G1 phase
- Preparation for the m phase
Second Gap Phase
A phase in interphase where these events happen:
- Mitosis or Meiosis
- maybe cytokinesis
M phase
the physical process of cell division, which divides the cytoplasm of a parental cell into two daughter cells. It occurs concurrently with two types of nuclear division called mitosis and meiosis, which occur in animal cells.
- marked by the formation of cleavage furrow in animal cells
- plant cell - formation of cell plates
- begins in anaphase-telophase
cytokinesis
Cells in _________ are not actively preparing to divide. The cell is in a quiescent (inactive) stage that occurs when cells exit the cell cycle. Some cells enter this phase temporarily until an external signal triggers the onset of G1. Other cells that never or rarely divide, such as mature cardiac muscle and nerve cells, remain in here permanently.
G0 Phase
a stage in the eukaryotic cell cycle at which the cell examines internal and external cues and “decides” whether or not to move forward with division.
- Ensure that the phases are done correctly for the cell to proceed
checkpoint
The molecule inside cells that contains the genetic information responsible for the development and function of an organism. These molecules allow this information to be passed from one generation to the next.
Deoxyribonucleic Acid (DNA)
Checkpoints in Cell Cycle
- G1 checkpoint, at the G1/S transition
- G2 checkpoint, at the G2/M transition
- M checkpoint, the spindle checkpoint, at the transition from metaphase to anaphase
a checkpoint that is the main decision point for a cell – that is, the primary point at which it must choose whether or not to divide.
- is the environment favorable?
- checks for size, nutrients, growth factors, DNA damage
- enters cell cycle and proceeds to s phase
- G1 checkpoint
What happens when a cell doesn’t get a go-ahead cue from the G1 Checkpoint?
it may leave the cell cycle and enter a resting state called the G0 phase. Some cells stay permanently G0, while others resume dividing if conditions improve.
if unrepairable - apoptosis
A checkpoint that checks for DNA damage and DNA replication completeness
is the environment favorable?
- enters mitosis
G2 Checkpoint
what happens if there are errors in G2 checkpoint
If the checkpoint mechanisms detect problems with the DNA, the cell cycle is halted, and the cell attempts to either complete DNA replication or repair the damaged DNA.
If the damage is irreparable, the cell may undergo apoptosis or programmed cell death. This self-destruction mechanism ensures that damaged DNA is not passed on to daughter cells and is important in preventing cancer.
in this checkpoint, the cell examines whether all the sister chromatids are correctly attached to the spindle microtubules. Because the separation of the sister chromatids during anaphase is an irreversible step, the cycle will not proceed until all the chromosomes are firmly attached to at least two spindle fibers from opposite poles of the cell.
- triggers anaphase and proceeds to cytokinesis
M checkpoint
(Cell Cycle Control System)
to ensure that they replicate all their DNA and organelles, and divide in an orderly manner, eukaryotic cells possess a complex network of ___________________
regulatory proteins
This regulation stops the cell to proceed the cell cycle
- p53
negative regulation
This regulation allows the cell to proceed if they pass the checkpoints
- cyclin and kinase
positive regulation
family of regulatory proteins that control the progression of the cell cycle. They activate cyclin-dependent kinases (CDKs), which control cell cycle processes through phosphorylation. When a _______ and CDK form a complex, the complex will bind to a target protein and modify it via phosphorylation.
- regulatory proteins whose concentrations rise and fall at specific times during the eukaryotic cell cycle
Cyclin
enzymes that catalyze the phosphorylation of a protein resulting in a change affecting that protein’s function. is present all throughout the cell cycle but is only activated by the cyclin (Cyclin-CDK Complex)
-phosphorylation - turning on
- dephosphorylation - turning off
Kinase (Cdk)
Cyclin D
G1-Cdk
-from 1st gap phase until the end of the cell cycle (because of mitogens -Most eukaryotic cells only divide in the presence of mitogens. Mitogens stimulate cell division by increasing the amount of G1 cyclins, which trigger cells to enter Start)
- Initiates the presence of the other cyclins
- pairs with Cdk 4
