cell membrane Flashcards
function of cell membrane inside cells (5)
-Separate organelles form the cytoplasm so that specific metabolic reactions can happen in them e.g respiration in mitochondria and photosynthesis in chloroplasts
-Control the entry and exit of materials organelles e.g mitochondria
-Provide an internal support system e.g endoplasmic reticulum
-Isolate enzymes that might damage the cell e.g lysosomes
-Provide surfaces for reactions e.g protein synthesis on RER
what are the structures of membrane (5)
-Phospholipid Bilayer
-Intrinsic Protein : channel proteins, carrier proteins
-Extrinsic protein
-Glycolipids,glycoproteins
-Cholesterol
What are membranes mainly composed of?
-Phospholipid
Phosphate head - HYDROPHILIC
Fatty tails - HYDROPHOBIC
Why are cell membranes partially permeable
-Because they allow small molecules through but not large ones
What happens if you shake phospholipids in water
-They arrange themselves in micelles, with the hydrophobic tails inwards, away from the water and the hydrophilic heads interacting with the water
what kind of molecules can pass through the membrane
Small/lipid-soluble and non polar molecules can diffuse through the bilayer
-Why is it called the Fluid mosaic model
-Fluid because phospholipids can move around
-Mosaic because proteins are scattered through the bilayer like tiles in a mosaic
Bilayer function
-Forms a barrier to dissolved substances.
-The centre of the bilayer is hydrophobic so doesn’t allow water soluble substances (like ions and polar molecules) through it.
-But it does allow small, non polar molecules like C02 to diffuse through.
What is cholesterol
-Steroid (fat)
-A type of lipid which fits between the phospholipid.
-Embedded throughout membrane to help with stability
-Reduces fluidity at higher temperatures.
-Helps to maintain the shape of animal cells which don’t have cell walls.
Function of cholesterol
-Restricts the movement of other molecules in the membrane
what do peripheral proteins do
-Act as receptors for hormones neurotransmitters, or are involved in cell recognition
-Many are glycoproteins.
What are Glycoproteins and Glycolipids
-Glycoproteins: Carbohydrate chain attached to protein
-Glycolipids: Carbohydrate chain attached to phospholipid
Function of glycoproteins and glycolipids
-They are used as receptor molecules, binding with hormones or neurotransmitters to trigger a series of chemical reactions within the cell itself.
