BIOLOGY-CELL TRANSPORT Flashcards
What is the entry and exit of molecules in the cells controlled by?
The cell surface membrane
What does the cell surface membrane surround?
The cytoplasm of the cell
How is the membrane described as
Partially permeable
What does the cell membrane consist of?
Proteins
Glycoproteins
Phospholipids
Carbohydrates
What does the phospholipid molecules form?
Double layer that are constantly moving around one another
Explain why the model for membrane structure is known as a fluid Mosiac model
The model is said to be fluid because the phospholipids are able to move
The model is said to be Mosiac because the proteins are randomly distributed. It’s called a model because it is the theory we have the most evidence for
What is the selective permeability of the cell membrane related to?
To the type and distribution of specific proteins and phospholipid molecule present in the membrane
What are intrinsic proteins?
Membrane proteins which are embedded completely or partly within the lipid bilayer of the membrane
What are extrinsic proteins?
Loosely bound proteins that are located outside the membrane
What are the hydrophobic tails attracted towards
Towards each other
Which molecules does the phospholipid bilayer allow?
Lipid soluble molecules
How does the phospholipid bilayer allow lipids soluble to pass?
By simple diffusion which prevents the passage of small polar molecules like ions
What does cholesterol do?
Decreases permeability and increases the stability of the membrane
What does more cholesterol mean?
less fluidity of the membrane
Do all types of cell have the same cholesterol?
No
What is the function of channel proteins?
They are like Pores within the membrane that only allow specific charge ions to move across the membrane by facilitated diffusion
What type of structures do proteins have?
Specific tertiary structures, so they are specific and can only transport molecules that are complementary to the shape of the channel protein
What is the function of carrier proteins?
The aid the transport of ions and large molecules, for example, glucose and amino acids, by facilitated diffusion and active transport
What do carrier proteins have?
Have a binding site at a substrate that changes shape and their specific to each substance in due to shape of binding sote
What are receptor proteins?
Cell communications
Where are enzymes embedded?
In cell membrane