Cellular Transport

Homeostasis ***Remember the 8 Characteristics of Living Things: maintain a stable internal environment. --Homeostasis: the process by which organisms keep internal conditions relatively constant despite changes in the external environment.

(CELL MEMBRANE AND CELL WALL) What part of the cell helps to maintain homeostasis (control what enters and leaves the cell)? CELL BOUNDARIES (CELL MEMBRANE AND CELL WALL)

Cell Boundaries 1. Plasma Membrane, Cell Membrane, Phospholipid Bilayer

Types of Boundaries 1. Plasma Membrane, Cell Membrane, Phospholipid Bilayer Functions Regulates what enters and leaves the cell

Types of Boundaries 1. Plasma Membrane, Cell Membrane, Phospholipid Bilayer Functions Regulates what enters and leaves the cell Provides protection

Types of Boundaries 1. Plasma Membrane, Cell Membrane, Phospholipid Bilayer Functions Regulates what enters and leaves the cell Provides protection Provides support

Types of Boundaries 1. Plasma Membrane, Cell Membrane, Phospholipid Bilayer Made up of lipids

Types of Boundaries 1. Plasma Membrane, Cell Membrane, Phospholipid Bilayer Made up of lipids Have proteins stuck in the membrane

Types of Boundaries 2. Cell Walls Are present in plant cells (fungi and many prokaryotes) but not animal cells

Types of Boundaries 2. Cell Walls Are present in plant cells (fungi and many prokaryotes) but not animal cells Lies outside of the cell membrane

Types of Boundaries 2. Cell Walls Are present in plant cells (fungi and many prokaryotes) but not animal cells Lies outside of the cell membrane Made up of cellulose

Types of Boundaries 2. Cell Walls Are present in plant cells (fungi and many prokaryotes) but not animal cells Lies outside of the cell membrane Made up of cellulose Functions: Provides protection

Types of Boundaries 2. Cell Walls Are present in plant cells (fungi and many prokaryotes) but not animal cells Lies outside of the cell membrane Made up of cellulose Functions: Provides protection Provides support

Moving Across Cell Boundaries

Concentration Cytoplasm of a cell contains a solution of many different substances in water. Substances dissolved in the water are the solutes Ex. glucose, Na+, etc. In a solution particles are moving constantly Think about the lemonade example

Diffusion Diffusion: molecules move from an area of higher concentration to an area of lower concentration

Diffusion Diffusion: molecules move from an area of higher concentration to an area of lower concentration Concentration Gradient Diffusion Animation: http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_diffusion_works.html

Diffusion Diffusion: molecules move from an area of higher concentration to an area of lower concentration Concentration Gradient Equilibrium: when the concentration of the solute is the same throughout the system (there is still movement but at an equal rate) http://www.youtube.com/watch?v=4okcNTOkPmM

Diffusion Diffusion: molecules move from an area of higher concentration to an area of lower concentration Concentration Gradient Equilibrium: when the concentration of the solute is the same throughout the system (there is still movement but at an equal rate) Diffusion does NOT require energy

Osmosis When substances are too large to move across the membrane, water may move across the membrane to balance the concentration on either side of the membrane.

Osmosis When substances are too large to move across the membrane, water may move across the membrane to balance the concentration on either side of the membrane. Osmosis: diffusion of water through a selectively permeable membrane

Osmosis When substances are too large to move across the membrane, water may move across the membrane to balance the concentration on either side of the membrane. Osmosis: diffusion of water through a selectively permeable membrane Semi-permeable membrane: allows some substances to cross

Passive Transport Diffusion and Osmosis do NOT require energy They are considered PASSIVE forms of transport Facilitated Diffusion: movement of specific molecules across cell membranes through protein channels.

Active Transport Sometimes cells must move materials in the opposite direction (against the concentration gradient) This requires ENERGY Active Transport