2. Membrane Permeability The plasma membrane is selectively permeable, because it allows certain substances to pass through it, while preventing the passage of others. • Lipids –
• Na+ -
• K+ -
• H2O –
• O2 & CO2 –
3. Membrane Gradients (Potential)
The plasma membrane maintains an electrochemical gradient produced by the influence of concentration and electrical gradients of ions and molecules in the ICF and ECF. This is important to help move substances across the membrane (Ex: a substance may move from an area of high concentration to an area of low concentration to reach a balance)
2. Cytoplasm
The Cytoplasm of a cell consists of the cytosol and organelles .
Cytosol (intracellular fluid or ICF) is the fluid that surrounds the organelles within the cell. Cytosol is 75-90% water, and includes ions, carbohydrates, lipids and proteins (glucose, AA’s, FA’s, ATP and waste products). **Most chemical reactions occur in the CYTOSOL ** Organelles are structures with specialized shape and function that contribute to cellular growth, maintenance and reproduction. Each organelle has a specific set of enzymes to aid specific reactions and serves as a functional area for specific biochemical processes. Organelles often cooperate for the benefit of the cells balance.
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