CELL Structure REVIEW

• Cell Theory/Cell size• Types of cells:

Prokaryotes VS Eukaryotes

• Cell Membrane and how substances move across the membrane

• Cell Organelles

CELLS AND THEIR ENVIRONMENT REVIEW

• PASSIVE TRANSPORT : Diffusion, Osmosis

• Crossing the membrane

• ACTIVE TRANSPORT: Moving against a concentration gradient

• Moving in Vessicles

• Membrane Receptor Proteins

Cell Theory

• 1) All Living things are made of one or more cells

• Cells are the basic units of life

• All cells come from existing cells

Cell Size

• Small cells can exchange substances more readily than large cells because small objects have a higher surface area to volume ratio than larger objects

• SMALL CELLS FUNCTION MORE EFFICIENTLY THAN LARGE CELLS.

• 100 TRILLION CELLS IN HUMAN BODY

Common features of cells

• Cell Membrane: Encloses the cell and separates the cell interior, the cytoplasm, from its surroundings.Regulates what enters and leaves the cells-including gases, nutrients and wastes.

• Cytoskeleton: Small fibers in cell providing structural support.

• Ribosomes:Cell structures where proteins are made.

• DNA:Provides instruction for making proteins and allows cell to reproduce.

PROKARYOTES

• • Smallest, simplest cells.

• Single celled organism that lacks a nucleus and other internal compartments. (Therefore, not able to carry our specialized functions)

• 3.5 billion yrs old

Prokaryotes continued

• • For two billion yrs, they were the only organisms on earth.

• Bacteria=most common prokaryote. Can cause infections and cause food to spoil.

Characteristics of a Prokaryote

• They can live in a broad range of environmental conditions.

• Many grow and divide rapidly.

• Some do not need oxygen to survive.

• Some make their own food.

• Circular molecule of DNA.

• Have Cell Wall• Some have

polysaccharide capsule• Flagella

Eukaryotic Cell

• Evolved 2.5 billion yrs ago.

• NUCLEUS!

• Has internal compartments called organelles!

• Cilia and/or flagella

• Cytoskeleton (Actin fibers, Microtubules, Intermediate fibers)

Eukaryote continued

• Cell membrane: Fluid like soap bubbles!

• Double layer of polar heads and non polar tails

• Allows lipids and substances that dissolve in lipids to pass through.

• Contains different kinds of proteins.

Membrane proteins of cell membrane

• Proteins are made of amino acids. Some amino acids are polar and some are non polar. This attraction holds the proteins in the bilayer.

• MARKER PROTEINS: attach to carbohydrate on the surface and advertise the cell type.

• Receptor PROTEINS: bind specific substances , such as signal molecules, outside the cell.

• TRANSPORT PROTEINS: Help in movement of substances in/out of cell.

CELL ORGANELLES to Know

• The nucleus• Ribosomes• Endoplasmic

Reticulum (smooth and rough)

• Vesicle• Golgi apparatus

• Lysosomes• Mitochondria

(Mitochondrial DNA)

Plant cell

• • Features unique to plant cells (Eukaryotes too!): Cell Wall

• Chloroplasts• Central Vacuole

Cells and their Environment

• This section describes how substances move through other substances according to their concentrations in solutions. It also describes how substances move across cell membranes through channels.

•

Passive Transport

• • Passive Transport: Movement across the cell membrane that does not require energy from the cell.

• Concentration Gradient: Difference in the concentration of a substance across a space.

Diffusion and Osmosis: Types of Passive Transport

• Diffusion: Movement of a substance from an area of high to low concentration, Until equilibrium is reached. This is a movement DOWN the concentration gradient

• Osmosis: The diffusion of water through a selectively permeable membrane down a concentration gradient.

Possibilities for the direction of water movement:Hypertonic

• If the Fluid outside of the cell has low concentration of water molecules than inside, then the outside fluid is hypertonic. The water will diffuse out of the cell and the cell will shrink

•

Hypotonic

• If the fluid outside has a higher concentration of water than inside the cell, Then the outside solution is hypotonic and water will diffuse into the cell and the cell will swell!

•

Isotonic Solution

• If the fluid outside the cell has the same amount of water concentration as the fluid inside the cell, then the fluid outside is ISOTONIC and water will diffuse into and out of the cell at equal rates. Cell stays same size.

•

How do polar molecules pass over the membrane?

• Remember, most ions and polar molecules cannot pass across the cell membranes because they cannot pass through the non polar interior of the lipid bilayer. They can cross if they have help from a transport protein. These proteins have channels in them.

• Diffusion through ion channels is still a type of passive transport!

Facilitated Diffusion

• CARRIER PROTEINS are used to carry substances across the membrane and release them on the other side. (Example: Transporting sugars and amino acids DOWN the concentration gradient.)

• This transport is called Facilitated diffusion.

Carrier proteins used to transport substances

•

Active Transport: Transporting substances UP the concentration

gradient

• Movement against a concentration gradient.

• Active transport requires the cell to use energy.

• Most of this energy is supplied by ATP!

Example of Active Transport: Sodium potassium pump

What about stuff that is too big to be transported by carrier

proteins?

• Vesicles move large substances across the membrane.

• Movement of substances into the cell by a vesicle is called ENDOCYTOSIS

• Movement of a substance out of the cell by a vesicle is called EXOCYTOSIS.

Cell Cycle

•

Binary Fission

•

Mitosis (PMAT)

•

Meiosis

•