G1 describes what stage of the cell cycle?
Preparation for DNA synthesis
Proofreading of DNA synthesis
S phase describes what stage of the cell cycle?
G2 describes what stage of the cell cycle?
M phase describes what stage of the cell cycle?
What is mitotic spindle composed of?
When does chromosome packaging occur?
In S phase after DNA replication
After S phase
In M phase
There are many histone genes that can make lots of histones to match the production of DNA during S phase.
What is the process of mitosis?
Prophase (microtubules disassemble and reassociate at centrioles) -> Metaphase (nuclear envelope breaks down and kinetochores develop and spindle fibres attach to them) -> Anaphase (chromosomes seperate and chromatids are pulled to opposite ends of the cell) -> Telophase (new nuclear envelope forms, condensed chromatin expands and nucleoli reappear).
Metaphase (nuclear envelope breaks down and kinetochores develop and spindle fibres attach to them) -> Prophase (microtubules disassemble and reassociate at centrioles) -> Anaphase (chromosomes seperate and chromatids are pulled to opposite ends of the cell) -> Telophase (new nuclear envelope forms, condensed chromatin expands and nucleoli reappear).
SPACER - CELL PROLIF 1,2,3 CONTINUE AFTER FLUID COMPARTMENTS
What are the three main fluid compartments in the body?
Red blood cells
[K+] in interstitial fluid > [K+] in the intracellular fluid
Osmolarity takes into the concentration of what two types of solutes?
In normal conditions the ICF and ECF tend to be in equilibrium at an osmolarity of around ~289mOsmol/L
A 300Mm solution of glucose = A 300Mm solution of NaCl
If there is not osmotic balance, how can the cell try to bring back balance?
Selective opening and closing of ion channels
Opening all the ion channels
Pumping water out via active transport pumps
Tonicity only considers which type of solute?
The osmotic pressure is dependent on the total concentration of all solutes.
The osmotic pressure is the pressure applied to prevent inward flow of water across a semi-permeable membrane.
With osmolarity problems, the permeable solute will move to concentrations of lower permeable solute. With tonicity problems, water will move to the area with the highest concentration of non-permeable solute.
A small change in the concentration of organic ions creates a small potential difference across the membrane.
If K+ leaves the cell, the negative charge created in the cell will attract the positive K+ back into the cell and therefore there is typically no net movement of ions.
Why is Goldmann's equation more useful than Nernst's?
Goldmann's equation takes into account all of the organic ions that are involved in the resting membrane potential and also their permeabilities whereas Nernst's only takes into account one type of ion and not the permeability.
Nernst's equation takes into account all of the organic ions that are involved in the resting membrane potential and also their permeabilities whereas Goldmann's only takes into account one type of ion and not the permeability.
Ions with a greater concentration outside of the cell always have a negative equilibrium potential.
Ions with a greater concentration inside the cell always have a negative equilibrium potential.
The RMP of a cell is closest to potassium because potassium is the most permeable ion. RMP is determined by the membranes high permeability to potassium.
Necrosis damages surrounding cells because of hydrolytic enzyme release from what organelle?
Controlled cell death
Uncontrolled cell death
What is happening in the first stage of apoptosis?
The cell shrivels
The nucleus fragments
The plasma membrane breaks down
Cytochrome C is released from the mitochondria
Apoptotic bodies are produced and macrophages engulf them via phagocytosis
What is happening in the second stage of apoptosis?
What is happening in the third stage of apoptosis?
The ECM are basement membrane are needed for development of cells. Without these factors, the cell has a disorganised structure.
Why do burns victims not have a good prognosis?
The basement membrane is sometimes destroyed which contains stem cells. Absence of these stem cells means that cell proliferation cannot take place and thus skin doesn't regrow.
The cytoskeleton is sometimes destroyed which contains stem cells. Absence of these stem cells means that cell proliferation cannot take place and thus skin doesn't regrow.
The granular layer of epidermis is sometimes destroyed which contains stem cells. Absence of these stem cells means that cell proliferation cannot take place and thus skin doesn't regrow.
Integrins are heterodimeric receptors that are bound to ECM trigger active intracellular responses that impact on cell proliferation / attachments.
Various cell factors may tell the cell to do which of the following things?
Proliferate (Growth factors)
Become dormant (Survival factors)
Differentiate (Differentiation factors)
Undergo apoptosis (Death signal)
Necrotise (Necrotic factors)
Expand (Expansive factor)
Mitogenic growth factors have effect from the start of G1 until which stage of the cell cycle?
R point - 3/4 through G1
When growth factors bind to tyrosine kinase receptors, what happens intracellularly?
Tyr residues are phosphorylated which generates internal effects
Tyr residues are dephosphorylated which generates internal effects
Phosphorylation of Tyr residues produces intracellular effects
Tyrosine phosphorylation is associated with cancer cell death.
Proteins recognise phosphorylated tyrosine domains. GDP is then substituted for GTP in RAS. Why is the hydrolysis of GTP important?
It terminates cell proliferation signals which prevents excessive cell proliferation.
GTP hydrolysis occurs in cancer and leads to excessive cell proliferation.
Without checkpoints that regulate the cell cycle, such as the role of TGF-b, loss of checkpoints occur and genomic instability and thus cell proliferation occurs.
Cyclin proteins increase the quantity of Cyclin dependent kinases.
Growth factors and Integrins result in Cyclin D production which helps to progress the cell through the cell cycle
pRb is the guardian of S phase.
The function of CDK inhibitors such as p21 is to inhibit the cell cycle and prevent excessive cell proliferation (e.g. if damaged DNA is detected).
If a CDK inhibitor is translocated from the cytoplasm to the nucleus, its inhibitory effect is stopped.
What are triggers for apoptosis to occur?
Breakages in DNA strands
Unregulated growth factor signals
Which protein receives information about metabolic disorders and genetic damage within the cell and initiates repair (minor) or apoptosis (major)?
The intrinsic pathway that initiates apoptosis involves what signal that causes release of cytochrome c?
BCL-2 can keep Cytochrome C trapped in the mitochondria; prevent apoptosis.