Chapters 5 and 6

depending on the weather, the proportions of phospholipids change in plants as well as bacteria and archaea

penetrate the hydrophobic interior of the lipid bilayer

not embedded in the lipid bilayer at all; loosely bound to the surface of the membrane

helps a certain substance or class of closely related substances to cross the membrane

a protein built into the membrane may be an enzyme with its active site exposed to substances in the adjacent solution

a receptor may have a binding site with a specific shape that fits the shape of a chemical messenger, such as a hormone

some glycoproteins serve as identification tags that are specifically recognized by membrane proteins of other cells

membrane proteins of adjacent cells may hook together in various kinds of junctions (gap or tight)

microfilaments or other elements of cytoskeleton may be noncovalently bound to membrane proteins; help maintain cell shape

carbohydrates covalently bonded to lipids

carbohydrates covalently bonded to proteins

transmembrane proteins that helps certain substances to cross the membrane

function by having a hydrophilic channel that certain molecules or atomic ions use as a tunnel through the membrane

passage of water molecules through the plasma membrane of certain cells is greatly facilitated by channel proteins

hold onto their passengers and change shape to allow them across the membrane

movement of particles of any substance so they spread out into the available space

region along which the density of a substance increases or decreases

requires no energy to transport

selectively permeable artificial membrane separating two sugar solutions

diffusion of free water across a selectively permeable membrane whether artificial of cellular

ability of a surrounding solution to cause a cell to gain or lose water

same tonicity for a cell

the cell will lose water, shrivel, and most likely die

water will enter the cell faster than it leaves, and the cell will swell and burst (lyse) like an overfilled water balloon

control of solute concentrations and water balance

very firm; healthy state for most plant cells

limp; the plant wilts

causes the plant to wilt and can lead to plant death

many polar molecules and ions impeded by the lipid bilayer of the membrane diffuse passively with the help of transport proteins that span the membrane

channel proteins that transport ions

open or close in response to a stimulus

the cell needs to expend energy. Transport Proteins move solutes against their concentration gradients which are carrier proteins rather than channel proteins

exchanges Na+ for K+ across the plasma membrane of animal cells

voltage across a membrane, ranges from about 50-200 millivolts

combination of forces acting on an ion

a transport protein that generates voltage across a membrane

electrogenic pump of plants, fungi, and bacteria. Actively transports protons out of the cell

a transport protein can couple the "downhill" diffusion of the solute to the "uphill" transport of a second substance against its own concentration gradient

the cell secretes certain biological molecules by the fusion of vesicles with the plasma membrane

the cell takes in molecules and particulate matter by forming new vesicles from the plasma membrane

a cell engulfs a particle by extending pseudopodia around it and packaging it within a membraneous sac called a food vacuole

a cell continually "gulps" droplets of extracellular fluid into tiny vesicles, formed by in-foldings of the plasma membrane

a specialized type of pinocytosis that enables the cell to acquire bulk quantities of specific substances, even though those substances may not be very concentrated in the extracellular fluid

totality of an organism's chemical reactions. Emergent property arises form orderly interactions between molecules

a specific molecule is altered in a series of defined steps, resulting in a product

breakdown pathways; cellular respiration

consume energy to build complicated models from simpler ones

study of how energy flows through living organisms

capacity to cause change

energy associated with the relative motion of objects

kinetic energy associated with the random movement of atoms or molecules

an object that is not moving but has energy of the matter possessed in a location or structure

potential energy available for release in a chemical reaction

study of the energy transformations that occur in a collection of matter

energy of the universe is constant

every energy transfer or transformation increases the entropy of the universe

measure of the molecular disorder or randomness

entropy proceeding without requiring an input of energy

portion of a system's energy that can perform work when temperature and pressure are uniform throughout the system, as in a living cell

potential energy stored within the chemical bonds of organic molecules like glucose and ATP

proceeds with a net release of free energy

one that absorbs free energy from its surroundings

pushing of endergonic reactions that would not occur spontaneously, such as the synthesis of polymers from monomers

the pumping of substances across membranes against the direction of spontaneous movement

beating of cilia, concentration of muscle cells, and the movement of chromosomes during cellular reproduction

use of na exergonic process to drive an endergonic one

contains the sugar ribose, with the nitrogenous base adenine and a chain of three phosphate groups bonded to it

exergonic reaction releasing 7.3 kcal of energy per mole of ATP hydrolyzed

the recipient with the phosphate group covalently bonded to it

ATP can be regenerated by the addition of phosphate to ADP

macromolecule that acts as a catalyst

a chemical agent that speeds up a reaction without being consumed by the reaction

energy required to contort the reactant molecules so the bonds can break/free energy of activation

process in which a catalyst selectively speeds up a reaction

reactant an enzyme acts on

enzyme binds to its substrate

a pocket or groove on the surface of the enzyme where catalysis occurs

brings chemical groups of the active site into positions that enhance their ability to catalyze the chemical reaction

adjuncts may be bound tightly to the enzyme as permanent residents, or may bind loosely and reversibly along with the substrate

a cofactor that's an organic molecule

reduce the productivity of enzymes by blocking substates from entering active sites

impede enzymatic reactions by binding to another part of the enzyme

a substrate molecule binding to one active site in a multi subunit enzyme triggers a shape change in all the subunits, increasing catalytic activity at the other active sites

a metabolic pathway is halted by the inhibitory binding of its end product to an enzyme that acts early in the pathway