Cellular Transport

Homeostasis All the previous topics discussed are important in maintaining homeostasis. Homeostasis is the ability of the cell to efficiently seek and maintain a condition of equilibrium within the cell when dealing with external changes. Homeostasis must be maintained in order for the cell to survive.

Diffusion Moving from area of high concentration to low concentration Stops when it reaches equilibrium Equilibrium is when substances are spread out equally

Diffusion Passive transport is diffusion Requires no energy High to low concentrations Two types Simple diffusion Moving along membrane with no assistance Facilitated diffusion Substances moving across membrane either by protein channel or protein carrier. Concentration gradie

Simple diffusion

Facilitated Diffusion Protein ChannelProtein Carrier

Osmosis Diffusion of water across a selectively permeable membrane from high to low concentration. An unequal distribution of particles called a concentration gradient controls osmosis

3 different Conditions of the Cell Isotonic- where the water concentration in the cell is similar to the concentration outside the cell. Hypotonic- where the water concentration is greater inside the cell compared to outside the cell. Hypertonic- where the water concentration is lower inside the cell compared to outside the cell.

Cont.

Active Transport Substances move across the membrane from low to high concentration (against the concentration gradient) Requires energy produced by the cell (ATP) May need help of proteins to help move across gradient Causes conformational change in proteins

Active Transport Classic example of Active Transport is the Sodium/Potassium pump (Na+/K+)

Other forms of Transport Endocytosis Phagocytosis Pinocytosis Exocytosis

Endocytosis Process in which cells take in materials from outside the cell by engulfing and fusing with plasma membrane. Pinocytosis- liquids taken into cell Phagocytosis- ingesting of particle by the cell

Exocytosis Where the cell release material to the outside of the cell by fusing with the cell membrane

Endocytosis vs. Exocytosis Endocytosis on the top, Exocytosis on the bottom