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activation energy
The minimum amount of energy required to trigger a chemical reaction
active site
the site on an enzyme that attaches to a substrate
active transport
movement of molecules through protein channels in the membrane from low to high concentration requiring energy (ATP)
ADP
(Adenosine Diphosphate) The compound that remains when a phosphate group is removed from ATP, releasing energy
ATP
(adenosine triphosphate) main energy source that cells use for most of their work
Catalyst
a substance that initiates or accelerates a chemical reaction without itself being affected or used during the reaction
Cell membrane
thin, flexible barrier around a cell; regulates what enters and leaves the cell
cell wall
a rigid structure that surrounds the cell membrane and provides support to the cell. Only found in plant cells and some bacteria.
concentration gradient
a measure of how the concentration of a solution changes from one place to another
cytoplasm
a jellylike fluid inside the cell in which the organelles are suspended
denatured
Enzymes that are destroyed by high temps (or changes in pH) that change their 3D structure so they can no longer function properly
endoplasmic reticulum
a cell structure that forms a maze of passageways in which proteins and other materials are carried from one part of the cell to another
enzyme
protein that acts as a biological catalyst
flaccid
lacking firmness or stiffness. Flaccid cells are plant cells that have lost water via osmosis.
golgi apparatus
A system of membranes that modifies and packages proteins for export by the cell
induced fit model
change in the shape of an enzyme's active site that enhances the fit between the active site and its substrate(s)
lock and key theory
This theory says that the enzymes active site is exactly complementary to the structure of the substrate.
lysosome
membrane-bound vacuole containing digestive enzymes that can break down proteins, nucleic acids, and polysaccharides
mitochondria
Powerhouse of the cell, organelle that is the site of ATP (energy) production
osmosis
diffusion of water molecules through a semipermeable membrane from a place of higher water potential to a place of low water potential until equilibrium is achieved
passive transport
transport of a substance across a cell membrane by diffusion - movement from high concentration to low concentration (WITH the concentration gradient).
Doesn't require energy.
phagocytosis
process in which cells engulf and digest microorganisms and cellular debris using their cell membrane.
pinocytosis
‘cell eating’, which involves the uptake of small liquid/dissolved particles through the cell membrane.
plasmolysis
when a cell is in a hypertonic environment, the cell will lose water to its surroundings, shrink, and its plasma membrane will pull away from the wall
ribosome
site of protein synthesis
semipermeable membrane
a membrane that allows some molecules to pass through but not others
substrate
The reactant on which an enzyme works.
turgor
a cell's swelling against its cell wall caused by the pressure of the cell's contents
vacuole
cell organelle that stores materials such as water, salts, proteins, and carbohydrates
vesicle
small membrane-bound sac that functions in moving products into, out of, and within a cell
enzyme inhibitor
any substance or molecule that slows down the rate of an enzyme-controlled reaction by affecting the enzyme molecule in some way. It could:
- sit in the active site
- change the shape of the active site
Limiting factors (enzyme controlled reactions)
Enzyme controlled reactions can be slowed down by:
- temperature (too cold)
- temperature (too hot - denatures enzyme)
- pH (denatures enzyme)
- not enough substrate
- too much substrate (not enough enzyme)
anabolic reactions
enzymes are used to build molecules
catabolic reactions
enzymes are used to break apart molecules
enzyme specificity
the concept that each enzyme is designed to work on a specific substrate, allowing only certain reactions to occur
Hypotonic
a solution with a lower concentration of solutes
Hypertonic
a solution with a higher concentration of solutes
isotonic
a solution with an equal concentration of solutes, resulting in no net movement of water across a semipermeable membrane.
lysed
when an animal cell is placed in a hypotonic solution, causing it to gain water, swell, and eventually burst
shrivels up
when an animal cell is placed in a hypertonic solution an it loses water
plasmolysed
when a plant cell is placed in a hypertonic solution and loses sufficient amount of water and turgor pressure that its cell membrane detaches from the cell wall
flaccid
when a plant cell is placed in a hypertonic solution and loses water and turgor pressure, but doesn’t become plasmolysed
turgid
when a plant cell is placed in a hypotonic solution and gains water and turgor pressure builds up
