--Dictyostelium discoideum (ameboid cells) feed onbacteria and multiply
by mitosis
Chemotaxis in dictyostelium:
--Cells have asignalling system that meausres the density of dictostelium
in relation to the bacerial food source. At low levels of resources,
Dictyostelium undergoes chnage in life cycle. it does this by:
--the cell must be receptors on the cell surface, the organism must have
the enzymatic machinery and cell biological machinery to release cAMP
from inside the cell which leads to:
--Cells aggregte and form tight cell to cell conacts mediate by cell
surface adhesion molecule which are expressed upon cAMP signalling.
The responses of multicellular organisms:
-- The maintenance of the internal milieu is the condition of a free and
independent life *definition of physiology*
The nature of the cellular communication between tissues:
--Endocrine signalling, paracrine, autocrine, signals may be both
endocrine and paracrine e.g. adrenaline.
Nature of signsls a cell might be responding to:
--Small polar molecules e.g. Adrenaline (adrenrgic receptors)
Acetylcholine (choline receptors)
--Peptides e.g. insulin/growth factors
--Proteins e.g. Apoproteins B-100
--steroids hormones
--Gases in soluton: Nitric oxide, ethylene
Binding of ligans to receptors/ signals sensed y receptors
--Receptors may be located on outsied and transversing the plasma
membrane -7TMS, RTKs.
--Nuclear-steroid receptors for membrane permeant signals.
Information flow at tagrget cell: Signal tranduction --> Reception -->
Transduction --> Responses
Generalsities of signalling:
--Intracellualr signalling mechasnims are consreved
--Mechansms serve many differnt processes : sight, smell, taste, response
to growth factors, hormones. These are all coupled by gene-protein
coupled receptors through 7-tms receptors
--Specificty of ligand recognistion -precise sterochrmistry of
ligand/receptors
--cells are responisive or not - adrenalin acts on hepatocytes to alter
glcogen metabolism - but not on erythrocytes
Pharmacology of Receptors:
--The variety of ligands recognized by a receptor:
--Agonists: promotes a cell response
--Antagonists: depromotes a cell response
Michaelis-menten for sigmalling:
--Equilibrium constant for association:
Kass = [RL]/[R][L] unitd M-1
by mitosis
Chemotaxis in dictyostelium:
--Cells have asignalling system that meausres the density of dictostelium
in relation to the bacerial food source. At low levels of resources,
Dictyostelium undergoes chnage in life cycle. it does this by:
--the cell must be receptors on the cell surface, the organism must have
the enzymatic machinery and cell biological machinery to release cAMP
from inside the cell which leads to:
--Cells aggregte and form tight cell to cell conacts mediate by cell
surface adhesion molecule which are expressed upon cAMP signalling.
The responses of multicellular organisms:
-- The maintenance of the internal milieu is the condition of a free and
independent life *definition of physiology*
The nature of the cellular communication between tissues:
--Endocrine signalling, paracrine, autocrine, signals may be both
endocrine and paracrine e.g. adrenaline.
Nature of signsls a cell might be responding to:
--Small polar molecules e.g. Adrenaline (adrenrgic receptors)
Acetylcholine (choline receptors)
--Peptides e.g. insulin/growth factors
--Proteins e.g. Apoproteins B-100
--steroids hormones
--Gases in soluton: Nitric oxide, ethylene
Binding of ligans to receptors/ signals sensed y receptors
--Receptors may be located on outsied and transversing the plasma
membrane -7TMS, RTKs.
--Nuclear-steroid receptors for membrane permeant signals.
Information flow at tagrget cell: Signal tranduction --> Reception -->
Transduction --> Responses
Generalsities of signalling:
--Intracellualr signalling mechasnims are consreved
--Mechansms serve many differnt processes : sight, smell, taste, response
to growth factors, hormones. These are all coupled by gene-protein
coupled receptors through 7-tms receptors
--Specificty of ligand recognistion -precise sterochrmistry of
ligand/receptors
--cells are responisive or not - adrenalin acts on hepatocytes to alter
glcogen metabolism - but not on erythrocytes
Pharmacology of Receptors:
--The variety of ligands recognized by a receptor:
--Agonists: promotes a cell response
--Antagonists: depromotes a cell response
Michaelis-menten for sigmalling:
--Equilibrium constant for association:
Kass = [RL]/[R][L] unitd M-1
