Biological Membranes Flashcards
What is the function of the phospholipid bilayer?
-It allows diffusion of lipid-soluble substances across the membrane
-prevents exit and entry of polar substances
What is the function of cholesterol embedded in the cell membrane
It reduces the fluidity of the cell membrane
What is the function of a glycolipid?
It acts as cell markers for other cells
Which allows them to attach to each other to form tissues
What is a glycoprotein?
A protein with a carbohydrate chain attached
What is the functions of a glycoprotein?
- act as a recognition site for foreign cells and specific chemicals
What is the model called that is used to describe the structure and function of the cell-surface membrane?
The fluid-mosaic model
How does temperature affect membrane structure?
- high temperature increase the kinetic energy of the phospholipids
- this causes the membrane to lose its structure and channel proteins to denature
- so as a result the permeability of the membrane increases
How do solvents affect membrane structure?
Solvents that are non-polar can dissolve the membrane
As a result the permeability of the membrane increases
What is cohesion?
The force of attraction between water molecules that makes them stick to each other
How does the polarity of water molecules cause cohesion?
Cohesion occurs when the positively charged hydrogen atom of one water molecule is attracted to the negatively charged oxygen atom of another water molecule
- this forms a hydrogen bond between the two molecules
Define osmosis
The net movement of water across a selectively permeable membrane, from an area of high water potential to an area of low water potential
Is osmosis an active or passive process?
Passive
If a lot of water enters an animal cell what will it undergo?
Bursting/lysis
If a lot of water enters a plant cell what will it become?
Turgid
What is diffusion?
The spread out of the particles of any substance in the form of a solution or a gas, resulting in the net movement form an area of high concentration to an area of low concentration
What is the structure of ATP?
-its made up of the Pentose sugar ribose
-the nitrogenous base, adenine
-and three inorganic phosphate groups
What is the function of ATP?
- its a source of energy for biochemical processes
- it phosphorylates other biological molecules to make them more reactive
How is ATP broken down?
Through a condensation reaction catalysed by the enzyme ATP hydrolase
What’s the structure of saturated fatty acids?
No double bonds present in the hydrocarbon chain. Every carbon atom is saturated with the maximum number of hydrogen atoms it can bond with
Where are saturated fats commonly found?
In animal products
-like butter lard and meat
In plant oils
- like palm and coconut oil
What’s the structure of unsaturated fatty acids?
Always have one or more double bonds present in the hydrocarbon chain
What features prevent particles from passing through membranes via simple diffusion?
- polar
-charged
-hydrophilic
-large
