March 6, 2018 Objective: To create a model of the cell membrane To explain the structure of the cell membrane Journal: What does it mean to have a phobia of something? What is an example of a phobia?

Key Terms What do you think are the definitions of the following words? Hydrophobic Hydrophilic

Key Terms Defined Hydrophobic: Molecules repel and try to stay away from water Hydrophilic: Molecules are attracted to and tend to be found next to water

Phospholipids The structure of the phospholipid molecule generally consists of two nonpolar hydrophobic tails and a polar hydrophilic head.

Cell Membrane Structure Phospholipids form a Phospholipid Bilayer Phosphate groups = outside Fatty acid tails = middle Occurs because of the locations of the water

Structure Determines Function The cell membrane structure helps it regulate what can and cannot pass through the phospholipid bilayer because it is selectively permeable

What can pass through the membrane? Small, nonpolar substances pass through directly

Other Ways to Pass Through the Phospholipid Bilayer Membrane proteins to allow specific substances across the membrane at specific times Membrane proteins can be found on top of or within the phospholipid bilayer

Types of Membrane Proteins

Receptor Proteins Found on the outside of your cells Sense surroundings by binding substances outside the cell

Cell-Surface Proteins Similar to a nametag Identify each type of cell

Transport Proteins Allows certain necessary substances that cannot pass through the cell membrane into and out of the cell

Transport Proteins Channel Proteins: Serve as a tunnel that allow SPECIFIC substances through Carrier Proteins: bind specific substances on one side of the cell membrane, changes shape and allows the substance out on the other side of the cell membrane

http://www.youtube.com/watch?v=LKN5sq5dtW4

March 13, 2018 Objectives: To differentiate between osmosis and diffusion To describe how molecules can move down a concentration gradient Journal: What are the two types of transport proteins?

Cell Transport

Types of Transport Passive Transport Active Transport

Passive Transport When substances diffuse across the cell membrane down their concentration gradient

Types of Passive Transport Simple Diffusion Facilitated Diffusion Osmosis

Simple Diffusion Substances pass directly through the phospholipids from an area of higher concentration to an area of lower concentration Small, nonpolar substances only

Facilitated Diffusion Substances that cannot pass directly through the membrane diffuse through protein channels

Osmosis Facilitated diffusion of water through aquaporins Allows the cell to maintain water balance

Predicting Water Movement The direction the water moves depends on the concentration of the cell’s environment

Hypertonic Water moves out of the cell so the cell shrinks There is more solute outside the cell than inside the cell

Hypotonic Water moves in There is more solute inside the cell than outside the cell Cell gains water and expands

Isotonic There is the same concentration of water inside the cell and outside the cell Equilibrium is reached Cell stays the same size

Active Transport Transport of substances against their concentration gradients Requires energy (ATP) Uses carrier proteins

Sodium-Potassium Pump Three sodium ions are pumped out of the cell for every two potassium ions brought inside Requires energy Prevents sodium from building up inside the cell, which would cause the cell to burst due to osmosis bringing in too much water

Endocytosis The movement of large substances into a cell using a vesicle The cell membrane forms a pouch around the substance that closes and then pinches off inside the cell Pinocytosis: also known as cellular drinking, engulfing liquid particles Phagocytosis: engulfing solid particles

Exocytosis The movement of large substances out of a cell using a vesicle Vesicles inside the cell fuse with the cell membrane and are released outside the cell Used to remove waste products