random Flashcards
peripheral proteins
important as enzymes
can be removed without disrupting the integrity of the membrane
attached through electrostatic interactions
animal cells membranes contain
cholesterol
decrease membrane permeability to small water soluble molecules
cholesterol
insert themselves into the lipid bilayer
lipids in the cell membrane
phospholipids
cholesterol
sphingolipids
sphingolipids
head group may either be a phospholipid or a glycolipid
have specific protein attached
found in high proportions in lipid raft
Transmembrane proteins
Contain hydrophobic stretches that allow the protein to span the entire membrane 1-12 times
• A single hydrophobic stretch consists of 20-25 hydrophobic amino acids in a row
• Protein is non-covalently attached to the membrane
lipid anchored
Attached directly to membrane lipid, often covalently
• Other times the protein is attached to the lipid by a
carbohydrate bridge
• Protein is to one side of the membrane only
• Common in lipid rafts
extracellular matrix
Composed of glycoprotein (proteoglycans) and protein fibers
muscular dystrophy
- Unable to produce proper form of dystrophin
- Anchors the cytoskeleton to the extracellular matrix
- Important for shock absorption
- Results in muscles that are easily damaged
Malignant Cancer
Cancer cells able to break free from the extra-cellular matrix can migrate to other locations in the body
Fick’s Law of Diffusion
An equation that relates the rules governing diffusion
• Diffusion rate will directly increase when the concentration gradient, surface area, or membrane permeability increase
• Membrane permeability is proportional to lipid solubility
liposomes
• Attractive option to deliver drugs to tissues
• Drug is carried in hydrophilic compartment
• Hydrophobic drugs can also be carried in the membrane interior
• Well tolerated, non-immunogenic
• Phospholipids naturally occur in the body
• Sugars can be added to the external face to protect against immune
destruction
• Overcome solubility and toxicity issues
• Membrane proteins can be used
to traffic the liposome to the correct tissue
where are gap junctions found
conduction system of the heart, smooth muscle
cytokine
local communication
signaling ligand is secreted from the cell
Small and water soluble: able to freely diffuse in the extracellular fluid
It may bind to a receptor on the same cell-autocrine signaling
- IL-2 binds to Thelper cells of the immune system
* Reinforces Thelper cell activation
It may bind to a receptor on a cell located in the nearby environment- paracrine signaling
- Nitric oxide (NO) released from endothelial cells that line capillaries
- Causes local smooth muscle cells to dilate
- Increases blood flow to the area
Exocrine glands secrete their products into duct systems
• Bile is stored in the gall bladder and travels to the small intestine when
secreted into the duct system
• Endocrine glands secrete their products into the blood
- Products are called hormones • Epinephrine, insulin, etc.
- Glands have various locations in the body
- Target cells can be located very far away
• Intracellular receptors:
Examples include steroid hormones such as cortisol
Extracellular receptors:
Examples include epinephrine and insulin
Integrin receptors:
Binding of the extracellular ligand leads to changes in the arrangement of the cytoskeleton or alters enzyme activity
Receptor channels:
• The receptor is a transmembrane channel
• Called chemically-gated ion channels/ligand-gated ion channels
• Ligand is frequently neurotransmitter
• Binding of neurotransmitter triggers the opening of the
ion channel
• Ions are able to enter/exit according to their gradient
• Used in synaptic transmission
• Signal jumps from one neuron to another
• Binding of ligand can also cause the channel to close
Receptor enzymes:
Ligand binds to receptor and an intracellular enzyme is activated
• Amplifies the signal significantly
G-Protein coupled receptors
- Ligand binds to receptor and an intracellular enzyme is activated
- Amplifies the signal
- Ligand binding can also trigger the opening of an ion channel
