U2 Cells: The fluid mosaic model Flashcards
What is the fluid mosaic model?
The fluid mosaic model, first proposed in 1972, describes the plasma membrane as a mosaic of phospholipids, cholesterol, and proteins that move freely and fluidly in the plane of the membrane.
How does fluidity play a role in the model?
The fluidity allows the membrane to part and flow around a fine needle, and once removed, it will flow back together seamlessly.
What are the principal components of the plasma membrane?
The principal components of the plasma membrane are lipids, proteins, and carbohydrate groups attached to some of the lipids and proteins.
What is the percentage of the components in the membrane?
The proteins account for about 50% of the composition by mass, lipids account for 40% and carbohydrates account for 10%.
How does the fluidity affect the membrane?
The fluidity of the plasma membrane allows cells to recognise each other and maintain a secure boundary around the cell.
How are phospholipids arranged?
Phospholipids are arranged in a bilayer, making up the plasma membrane’s basic fabric. They are amphipathic, having both hydrophilic and hydrophobic parts.
How does the hydrophilic part work?
The hydrophilic part of a phospholipid is its head, which contains a negatively charged phosphate group. and an additional small group. These hydrophilic heads face outward, contacting aqueous fluid inside and outside the cell. Water, a polar molecule readily forms electrostatic interactions with the phospholipid heads.
How does the hydrophobic part work?
The hydrophobic part consists of its long, non-polar fatty acid tails, which can interact with other non polar molecules but not with water. These tails, can interact with other non polar molecules but not with water. These tails are more energetically favourable for phospholipids to tuck away in the interior of the membrane, shielding them from the surrounding water.
What is the second major component of the plasma membrane?
Proteins are the second major component of the plasma membrane, with two main categories: integral and peripheral.
What is the function of the integral membranes?
Integral membrane proteins are integrated into the membrane and have at least one hydrophobic region that anchors them to the hydrophobic core. They extend all the way across the membrane and may have as many as twelve different membrane-spanning sections.
What is the function of the peripheral proteins?
Peripheral proteins may associate with the membrane by attachment to a lipid that is inserted in the bilayer , or they may be bonded to the phospholipid through an oligosaccharide
How does the cholesterol affect the fluidity?
Cholesterol, another type of lipid embedded among the membrane’s phospholipids, helps minimise the effects of temperature on fluidity.
