Chemical Reactions in Living Organisms

Exergonic
When a chemical reaction releases energy to make the reaction occur.

Energonic
When a chemical reaction requires energy to make the reaction occur.

Chemical reaction
When 2 or more substances interact with one another to form 1 or more different substances.

Activation energy
The amount of energy that most chemical reactions in a cell need to get started.

Catalyst
A substance that increases rate of reaction but does not actually participate in the reaction.

Anabolism
Reactions that make or synthesize molecules.
Example=protein synthesis

Catabolism
Reactions that brake down molecules.
Example=digestive

Irreversible chemical reaction
Arrow pointing in one direction. Happens in 1 direction only.

Reversible chemical reaction
Arrow points in 2 directions. Depending on the conditions, the reactions can happen in 2 directions.

Reactant
Always where the arrow begins.

Products
Always where the arrow ends.

Phosphorylation
Adding of a phosphate group to a protein by ATP.

Bulk Transport
Movement of large molecules across cell membranes and involves the formation of transport vesicles.

Endocytosis
INWARD movement of transport vesicles.
1) outward movement of large molecules
2) transport vesicle containing the macromolecule, moves towards cell membrane
3) transport vesicle fuses with the cell membrane: bilayer fuse and rearrange
4) contents of vesicle spill out of the cell with no break in membrane

Exocytosis
OUTWARD movement of transport vesicles.
1) inward movement of a macromolecule
2) the macromolecules approach the membrane and are enclosed by the extending bilayer (forms packet)
3) the pocket pinches off, forming a vesicle
4) the contents of the vesicle are released inside the cell at the appropriate locations

Pinocytosis
Cellular drinking, the cell gulps droplets of liquid into tiny vesicles.

Receptor Mediated Endocytosis
Receptor proteins on the surface of the membrane bind specifically to certain macromolecules. The pocket is formed (vesicle then snaps off). Vesicle moves to the appropriate location inside of the cell. The receptor proteins get recycled to the cell membrane.

Equilibrium
When concentration of a substance becomes equal over the available area as a consequence of diffusion.

Concentration gradient
Difference in concentration of a substance between 2 areas or points

Osmosis
Diffusion of water (low to high). Special case of the difference of water across a selectively permeable membrane.

Solute
Substance that dissolves.

Solvent
Substance in which the substance dissolves.

Tanicity
The ability of a solution to cause a cell to take up or lose water.

Isotonic
Causes NO net movement of water.

Hypertonic
Causes a net movement of water OUT of the cell.

Hypotonic
Causes a net movement of water IN to a cell.

Flaccid
Isotonic solution, the cell membrane of a plant cell is not closely attached to the cell wall.

Turgid
Hypotonic solution, the cell membrane of a plant cell is fully stretched. (BEST FOR PLANT CELL)

Lysis
Hypotonic solution, cell membrane of an animal cell breaks open (too much water).

Plasmolysis
Hypertonic solution, cell membrane of a plant cell shrinks away from the cell (BAD).

Osmoregulation
Mechanisms by which they can control the amount of water entering or leaving the cell and thus maintain a correct water balance.

Metabolism
All the chemical reactions that occur in a living cell.

Voltage
Difference of energy (electrical) between 2 points that makes electrons flow which then creates electricity.

Membrane potential
Difference in charge across a cell membrane.

Neutrons
Nerve cells

Animal Cells
Are more negative on the inside and more positive on the outside.

Ion Pump
Type of active transport that transfers ions across a cell membrane.

Hydrophobic
Hates water.

Hydrophillic
Loves water.

Permeable
All substances can pass through.

Integral proteins
Spread out over most of the bilayer, firmly attached

Peripheral proteins
Partly embedded with bilayer, loosely attached

Channel Proteins
Create a hydrophillic channel so the specific molecule can cross the bilayer.

Amiphipatic
Hydrophillic and hydrophobic portions

Head/tail
Loves water/hates water

Fluid Mosaic Model Features
Fluidity of the lipid layer-moves very well, very fluid
Sidedness-always there for a purpose. move laterally
Selectively permeable- always allows some things in and not others

Concentration
Amount of any substance (g) in a specific volume or area

Diffusion
Tendency of a substance or molecule to move from an area of high concentration to an area or low concentration.

Semi permeable
Allows some substances in, but does not let harmful substances to come into the cell.

Competitive Inhibition
Molecule that mimics the real substrate and fools the enzyme. Reversible. Triangle is inside the enzyme.

Non-Competitive Inhibition
Binds to a site other than the active. Irreversible. Outside of the enzyme.

Active Transport
Transport processes occur with energy.

Passive Transport
Transport processes occur without energy.