KA1- Membranes Flashcards
What do cell membranes consist of?
A fluid bilayer of phospholipids with proteins
What is the cell membrane?
The boundary that separates the internal living contents of a cell from its surroundings
What does the cell membrane control?
The flow of materials in and out of the cell
What are cell organelles bounded by?
Membranes
What do organelles like the mitochondria and chloroplasts have?
Inner folds and compartments
What do these inner folds and compartments allow?
The cell to be divided into sections, with substrates for series of reactions concentrated into particular compartments
Where does the citric acid cycle occur?
In the central matrix of the mitochondrion
What do internal cell membranes provide?
A large surface area studded with enzymes, on which reactions can happen
What is diffusion?
The net movement of molecules from a region of high to low concentration, along a concentration gradient
What can small molecules do?
Diffuse freely through the phospholipid bilayer
How are large or charged molecules transported?
Pores or carrier proteins
What is active transport?
The movement of molecules and ions across the cell membrane from low to high concentration, against a concentration gradient
What is needed for active transport?
Protein pumps in the membrane (which are specific for a particular ion or molecule) and a supply of ATP
What is a multi-enzyme complex?
The way enzymes are organised into a specific order for maximum efficiency in a metabolic pathway
