Membrane & lipids Flashcards
What are the primary functions of cell membranes?
- Keep toxic substances out of cells
- Enable receptors and channels for specific molecules
- Separate vital metabolic processes within organelles
What are the three main types of membrane lipids?
- Phospholipids
- Cholesterol
- Glycolipids
What is the role of cholesterol in cell membranes?
Essential for membrane structural integrity and fluidity
What are the main components of biomembrane structure?
- Proteins
- Lipids
What are the two categories of membrane proteins?
- Peripheral
- Integral
What is the function of glycoproteins in cell membranes?
Aid cell-to-cell communication and transport across the membrane
What is the structure of the nucleus?
- Two membranes: outer and inner
- Complete nuclear membrane = four rows of phospholipids
What is the primary role of the endoplasmic reticulum (ER)?
Interconnected network for organelle communication and lipid transfer
What modifications occur in the ER for protein folding?
- Signal peptide removal
- N-linked glycosylation
- Disulphide bond formation
What characterizes the Golgi apparatus?
Fused, flat membrane-enclosed cisternae that sort proteins
What is vesicular transport?
Movement of liquid enclosed by a lipid bilayer during secretion and uptake
What are the compartments created by mitochondria membranes?
- Intermembrane space
- Matrix
What are the features of non-membrane bound organelles?
- Solid structures
- No need for a membrane
What distinguishes sphingolipids from other phospholipids?
Contain an amide bond between a fatty acid and sphingosine
What is the main organelle for lipid biosynthesis?
Endoplasmic reticulum (ER)
What are the types of phospholipids in bilayers?
- Phosphatidylcholine (PC)
- Phosphatidylethanolamine (PE)
- Phosphatidylserine (PS)
- Phosphatidylinositol (PI)
What is the significance of membrane fluidity?
Influences barrier function and cell shape changes
True or False: Cholesterol has no effect on the thickness of sphingomyelin bilayers.
True
Fill in the blank: Phospholipids are composed of _______.
two fatty acids, a glycerol unit, a phosphate group, and a polar molecule
What is the role of lipid droplets in cells?
Storage of lipids and energy
What are the functions of cellular lipids?
- Energy storage
- Intracellular signalling
What is the structure of phospholipids?
Composed of two fatty acids, a glycerol unit, a phosphate group, and a polar molecule
What effect does temperature have on lipid bilayer fluidity?
Increases fluidity at higher temperatures and solidifies at lower temperatures
