Cell Proliferation and Mitosis Flashcards
What is proliferation?
Physiological process of cell division
Results in an increased number of cells
Occurs in almost every tissue
What causes rate of proliferation to decrease
Cell differentiation
Cell that are unable to proliferate
Cardiac myocytes
Neurons
Cells that can resume proliferation from G0
Skin fibroblasts, smooth muscle cells, epithelial cells of internal organs
Cell that undergo continual proliferation
Blood cells, skin epithelial cells
Factors that contribute to and regulate proliferation
Environmental - nutrients, temperature, pH, oxygen
Positive and negative - cell adhesion, growth factors
Intracellular - p53, cytochrome C, Bcl proteins
What is the purpose of germ cell
Give rise to the gametes
Make it possible for organisms to reproduce
Meiosis and Mitosis
What are somatic cells
Give rise to all cell in the body apart from gametes
Cells are differentiated
Mitosis
What are the two main phases of cell cycle
S-phase: DNA synthesis
M-phase: Nuclear division, cytoplasmic division
What are the four phases of the cell cycle
G1 phase
S-phase
G2 phase
M-phase
What is the purpose of gap phases
Allow cell to grow
Monitor internal and external conditions
What is the purpose of G1 checkpoint
Makes sure the cell is large enough to enter S-phase
If conditions unfavourable - can enter G0
What is the purpose of G1 checkpoint
Makes sure the cell is large enough to enter S-phase
If conditions unfavourable - can enter G0
What is the point of G2 checkpoint
Makes sure the cell has been completely replicated
replication errors have been corrected
the cell is large enough the divide
How is cell cycle contolled
Fixed amount of time for each event
information from the cell cycle events and external environment (cyclins and CDKs)
Characteristics of CDK’s
At the heart of the cell cycle control system
Activity is cyclic as the cell progresses through the cell cycle
Each CDK modifies specific proteins that initiate or regulate events in the cell cycle
Dependant on cyclins for their activity
How to cyclins regulate CDK activity
Regulatory proteins bind to CDK resulting in phosphorylation and activation
These proteins are found in varied concentration throughout the cell cycle
What does disruption of cyclin activity result in
Cell cycle arrest or uncontrolled proliferation
What happens in S-phase
Chromosomes undergo replication
New DNA is synthesised - duplicate constructed
Chromosome only visible during the division
What happens in prophase
Chromosomes condense and are visible and threadlike
Nuclear membrane and nucleoli disappear
Mitotic spindle forms
Centrosomes move away from each other
What happens in prometaphase
Nuclear envelop fragments
Microtubules attach to the chromatids at the kinetochores
Other microtubules interact connecting from different poles
What happens in metaphase
Centrosomes are now at opposite poles
Chromosomes are lined up on the metaphase plate
all chromosome are attached to each of the poles
What happens in anaphase
connection between chromatids at the centromere are cleaved
Chromosomes are pulled to opposite poles as cell elongates
Anaphase ends when the chromosomes reach the poles
What happens in anaphase
connection between chromatids at the centromere are cleaved
Chromosomes are pulled to opposite poles as cell elongates
Anaphase ends when the chromosomes reach the poles
What happens in telophase
Nuclear envelope forms
Nucleolus appears
Cytoplasm divides
Chromosomes become less dense
What occurs in cytokinesis
Contractile ring begins to assemble
Actin and myosin filament
Divide the cytoplasm in two
Creates two daughter cells
What is cell proliferation involved in
Aging, regenerative medicine and oncogensis
Why is cell proliferation important
critical to regulation of development
Maintaining size, morphology and function of organs
