FoM:L3- Biomembranes Flashcards
What are amphiphatic phospholipids?
- phospholipids that have a polar and non-polar region
- form membranes that define exterior edges of animal cells and divide organelles into compartments
Describe the structure of a phospholipid in detail…
- 2 OH groups in glycerol are linked to fatty acids, 3rd is phosphorylated
- phosphate is further linked to a small, polar, alcohol head group (phosphatidyl…choline, serine, ethanolamine, inositol)
What are the 2 faces of a membrane called?
cytosolic and exoplasmic
Describe the 2 faces of membranes
- asymmetrical in lipid composition
- cell damage can cause deviation from these asymmetries
Give an example of a specific phospholipid in mitochondria
cardiolipin - greater insulation
What are flippases?
enzymes that can move phospholipids around, to mark the cell for apoptosis
What is the inner leaflet mostly made of?
sphinomyelin and phosphatidylcholine
What is the outer leaflet made of?
phosphatidylinositol, phosphatidylserine and phosphatidylethanolamine
What are sphingolipids?
- contain sphingosine instead of glycerol
What are glycolipids?
- carbohydrates combined with simple lipids (glucose and galactose)
- for example blood group antigens
How lipid structure link to properties?
- lipids contain fatty acids; saturated or unsaturated
- saturated are more compact; membrane less fluid
- unsaturated are less compact; membrane is more fluid
What does: 22:6n-3 mean?
- 22 C atoms
- 6 double bonds
- location of first double bond
Why do we need membrane flexibility?
- membranes need to change shape to perform their function
- movement to allow changes in the shape of proteins (eg rhodopsin)
- physical movement of cells (phagocytosis)
What are lipid rafts?
lipid-dense areas with high amounts of cholesterol making them more structured and rigid. Involved in signalling
What receptors are lipids directly involved with?
- G protein coupled receptors
- Nuclear receptors
What is a property of lipids that allows them to function?
- easily metabolised
- allows fluidity in membrane
- bilayer formation
- form lipid rafts
What is endocytosis?
substance moving into a cell without it having to pass through the membrane
Outline the process of endocytosis
membrane folds inwards and takes in extracellular substances in a small sphere - vesicle
What is receptor mediated endocytosis?
- specific endocytosis
- selective uptake of larger molecules (e.g. LDL)
What is pinocytosis?
non-selective uptake of fluids and solutes in vesicles
What does receptor mediated endocytosis form?
coated pits
What is exocytosis?
contents of the cell vesicle are released to the exterior through the fusion of the vesicle with the cell membrane
What is Chédiak–Higashi syndrome?
- rare autosomal recessive disorder
- mutation of a lysosomal trafficking regulator protein
- decrease in phagocytosis
What is CEDNIK syndrome?
- rare congenital condition - failure of intracellular vesicle fusion
- abnormal deposition of
epidermal lipids and proteases
What are the 3 types of membrane proteins?
- integral
- peripheral
- transmembrane
What are integral membrane proteins?
- in the lipid bilayer
- Transport
What are peripheral membrane proteins?
- not embedded in bilayer
- support
- transport
- cell signalling
