7-2 Cell Structure

Cell Wall Provides structure

and protection for the cell

Mostly carbohydrates Protein fibers

reinforce Found in plants,

fungi, algae, and most bacteria

7-2

Cell Membrane Regulates what goes in/out of a cell

Selectively permeable Fluid Mosaic Model

Made up of a “mosaic” of different molecules Molecules flow laterally

Outsideof cell

Insideof cell(cytoplasm)

Cellmembrane

Proteins

Proteinchannel Lipid bilayer

Carbohydratechains

7-2

Cell Membrane Lipid bilayer

Phospholipids have a polar head and non-polar tail

Polar head is attracted to water (hydrophilic)

Non-polar tail repels water (hydrophobic)

Proteins Carbohydrates

Proteins

Proteinchannel Lipid bilayer

Carbohydratechains

7-2

Lipid Bilayer7-2

7-2 Cell Transport

Diffusion Diffusion is the natural movement of particles from an

area of high concentration to a area of low concentration Spontaneous (needs no energy) Due to random particle motion and collisions

Concentration of solute will eventually reach equilibrium No net diffusion but particles are still moving

7-3

Diffusion7-3

Osmosis Osmosis is the diffusion

of water across a membrane

3 types of solutions:1. Hypertonic- solution

has a higher concentration of solutes than the cell

2. Isotonic- the concentration of solutes is the same inside and outside the cell

3. Hypotonic- solution has a lower concentration of solutes than the cell

7-3

Osmosis7-3

Facilitated Diffusion Uses integral

membrane proteins Channel or Carrier

High Low concentration

Uses no energy Molecule specific

Often for large or polar molecules

7-3

Active Transport Low High concentration

Against concentration gradient Uses energy Larger molecules use

endocytosis (in) and exocytosis (out)

Types of endocytosis: Phagocytosis (solid particles, mostly

food) Pinocytosis (liquids)

7-3

7-3

Cell Transport

Passive

Diffusion

Standard Facilitated

Channel Proteins

Carrier Proteins

Active

Molecular

Protein Pumps

Bulk

Endocytosis

Exocytosis

7-4 The Diversity of Cellular Life

Unicellular vs. Multicellular Organisms

7-4

Unicellular Multicellular• Single cell• The most common organisms• Simple• Reproduce quickly

• Many cells• Great variety• Cells perform different tasks (cell specialization)• Evolved from unicellular organisms

Organization in a Multicellular Organism

7-4

Cell Specialization Cells in multicellular

organisms are specialized to perform specific functions

Unique shapes, proteins, and organelle makeup

Stem cells are undifferentiated “blanks” that can become many cell types

7-4