Chapter 7 Section 7-3 & Section 7-4

Section 7-3 Movement Through The Membranes

The Cell Membrane Key Concept: The cell membrane regulates what enters and leaves the cell and also provides protection and support

The Cell Membrane The cell takes in nutrients and expels wastes plus cell products through the cell membrane The Basic Structure Of Nearly All Cell Membranes Is The LIPID BILAYER

LIPID BILAYERS Form Automatically When Certain Lipids Are Dissolved In Water Tough Flexible Structure Strong Barrier Between Cell Contents And Its Surroundings

LIPID BILAYERS

In Addition To The Bilayer, The Cell Membrane Contains: Fluid Mosaic Model In Addition To The Bilayer, The Cell Membrane Contains: Proteins That Form Channels & Pumps Proteins with Carbohydrates That Form Antigenic Sites Communication Sites

Diffusion All Living Cells Contain And Are Surrounded By Liquid. THE CELL MEMBRANE REGULATES THE MOVEMENT OF MOLECULES FROM ONE SIDE OF THE MEMBRANE TO THE OTHER

Is A Solution Of Many Different Substances In Water Cytoplasm Is A Solution Of Many Different Substances In Water

A liquid mixture of 2 or more substances evenly mixed. Solution A liquid mixture of 2 or more substances evenly mixed. Solvent The liquid in which the substances are mixed Solute Substances dissolved in the Solvent

Molecules Are Moving Constantly In A Solution: Molecules Are Moving Constantly They Collide and Bounce off each other This causes them to spread out randomly Resulting In: Movement from an area of higher concentration to an area of lower concentration

DIFFUSION Molecules move away from an area of higher concentration to an area of lower Concentration Equilibrium Concentration of a solute is the same throughout the solution

Diffusion Causes Many Substances To Move Across A Cell Membrane But: Key Concept: Diffusion Causes Many Substances To Move Across A Cell Membrane But: Does NOT Require The Cell To Use Energy

Diffusion & Cells Substances that can diffuse across cell membranes will do so until equilibrium is reached Diffusion continues after equilibrium but the rates in and out are equal

Facilitated Diffusion Molecules that can easily diffuse across the cell membrane: Alcohol Water Small Lipids

Facilitated Diffusion Other molecules can not pass through the cell membrane but still get into the cell. HOW?

Facilitated Diffusion Through Protein Channels in the Cell Membrane that allow a substance to cross. Allows Diffusion In Both Directions Each Channel Substance Specific DOES NOT REQUIRE ENERGY

The Diffusion Of Water Through A Selectively Permeable Membrane OSMOSIS Key Concept: The Diffusion Of Water Through A Selectively Permeable Membrane

Osmosis Permeable Membrane Impermeable Membrane Substance Can Easily Cross Impermeable Membrane Substance Cannot Cross Selectively Permeable Membrane Some Substances Can Cross, Others Cannot

The Tonics Hypotonic Isotonic Hypertonic Less concentrated solution Equally concentrated solution Hypertonic More Highly concentrated solution

The Tonics

Osmotic Pressure Pressure exerted on the hypertonic side of a selectively permeable membrane May cause cells to shrink or burst

Active Transport Moves Material Across A Cell Membrane Against A Concentration Gradient (from area of Lower concentration into an area of Higher concentration)

Active Transport Requires Energy

Active Transport Endocytosis Exocytosis Used to bring in large molecules, food, and whole cells Exocytosis Membrane surrounded material from inside the cell fuses with the cell membrane, releasing the contents.

The Diversity of Cellular Life Section 7-4 The Diversity of Cellular Life

The differences in living things begins with cells: The ways in which cells are specialized to perform certain tasks The ways in which cells associate with one another to form multicellular organisms.

Unicellular Organisms Unicellular organisms are made up of only one cell. Bacteria and fungus, for example Unicellular organisms dominate life on Earth.

Colonial Organisms Unicellular organisms that live in groups of same species Algae, for example They are attached to one another They have few specialized structures

Multicellular Organisms Organisms made of many interdependent cells Such as humans and animals Cells are specialized Each performs a specific role or function Has specific form

Levels of Organization The levels of organization in a multicellular organism are: 1. Individual cells 2. Tissues 3. Organs 4. Organ systems

Tissues A group of similar cells that perform a particular function Most animals have four main types of tissue: Muscle Epithelial: cover or line body surfaces, such as skin Nervous Connective Tissue: bone, blood, cartilage, and lymph

Organs & Organ Systems Organs = Many groups of tissues Muscles are organs made of muscle, nerve, and connective tissue Each tissue performs an essential function for the organs Organ Systems = A group of organs working together to perform a specific function There are 11 major organ systems Include muscular, skeletal, and nervous systems