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AB205 - Exam 2
Karp Ch. 3, 8
118
Biology
Undergraduate 2
09/21/2011

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Term
bioenergetics
Definition
study of the various types of energy transformations that occur in living organisms
Term
energy
Definition
the capacity to do work, that is to change or move something
Term
thermodynamics
Definition
study of the changes in energy that accompany events in the universe
Term
1st law of thermodynamics
Definition
law of conservation of energy; energy can be neither created nor destroyed, but can only be converted from one form to another
Term
transduction
Definition
the act of energy changing forms
Term
exothermic
Definition
reaction that lose heat
Term
endothermic
Definition
reactions that gain heat
Term
2nd law of thermodynamics
Definition
events in the universe tend to proceed "downhill" from a state of higher energy to a state of lower energy; there is decreasing free energy to do work
Term
spontaneous
Definition
events that are thermodynamically favorable and can occur without the input of external energy
Term
entropy
Definition
measure of disorder and chaos; associated with the random movements
Term
exergonic
Definition
processes that are thermodynamically favorable; spontaneous
Term
endergonic
Definition
processes that are thermodynamically unfavorable; not spontaneous
Term
equilibrium constant (Keq)
Definition
ratio of the concentration of products to the concentration of reactants
Term
standard-free energy change
Definition
(delta G degree prime) the free energy released when reactants are converted to produces under standard conditions
Term
steady state
Definition
the concentrations of reactants and produces remain relatively constant
Term
enzymes
Definition
mediators of metabolism, responsible for virtually every reaction in a cell
Term
cofactors
Definition
parts of the enzymes that are not proteins; can be inorganic or organic (coenzymes)
Term
substrates
Definition
reactants bound by an enzyme
Term
activation energy (E_A)
Definition
the sufficient kinetic energy required by reactants to overcome a barrier
Term
transition state
Definition
when reactants are at the crest of the energy hump and ready to be converted to products
Term
enzyme-substrate (ES) complex
Definition
the complex an enzyme makes with its substrate to help it make and break bonds
Term
active site
Definition
the part of the enzyme that is directly involved in binding the substrate
Term
induced fit
Definition
conformation shifts so that the complementary fit between the enzyme and reactants is improved
Term
turnover number
Definition
maximum number of molecules of substrate that can be converted to product by one enzyme molecule per unit time
Term
Michaelis constant (K_M)
Definition
the substrate concentration when the reaction velocity is one-half of the maximum velocity
Term
enzyme inhibitors
Definition
molecules that are able to bind to an enzyme and decrease its activity
Term
irreversible inhibitors
Definition
bind very tightly to an enzyme, often with a covalent bond to one of the amino acid residues
Term
competitive inhibitors
Definition
reversible inhibitors that compete with a substrate for access to the active site of an enzyme
Term
noncompetitive inhibition
Definition
substrate and inhibitor do not compete for the same binding site; the inhibitor acts at a site other than the enzyme's active site
Term
metabolism
Definition
collection of biochemical reactions that occur within a cell; tremendous diversity of molecular conversions
Term
metabolic pathways
Definition
sequence of chemical reactions in which each reaction is catalyzed by a specific enzyme, and the product of one reaction is the substrate for the next
Term
metabolic intermediates
Definition
compounds formed in each step of a metabolic pathway that lead ultimately to the formation of an end product
Term
metabolic intermediates
Definition
compounds formed in each step of a metabolic pathway that lead ultimately to the formation of an end product
Term
catabolic pathways
Definition
where disassembley of complex molecules to form simpler products occurs; make raw materials available and energy to build other molecules or perform tasks
Term
anabolic pathway
Definition
where the synthesis of more complex compounds from simpler starting materials occurs; use energy
Term
oxidation-reduction (redox) reaction
Definition
reaction that involves a change in the electronic state of the reactants (electrons are transferred from one reactant to another)
Term
LEO says GER
Definition
loss of electrons --> oxidation
gain of electrons --> reduction
Term
reducing agent
Definition
the sunstance that is oxidized
Term
oxidizing agent
Definition
the substance that is reduced
Term
glycolysis
Definition
occurs in the cytosol, leads to formation of pyruvate; 1st step in glucose metabolism
Term
tricarboxylic aicd (TCA) cycle
Definition
2nd step in glucose metabolism; occurs in mitochondria leads to the final oxidation of the carbon atoms to carbon dioxide
Term
dehydrogenase
Definition
enzyme that catalyzes a reaction that involves the transfer of a hydride ion
Term
substrate-level phosphorylation
Definition
occurs by transfer of a phosphate group from one of the stubstrates to ADP
Term
transfer potential
Definition
measure of the ability of a molecule to transfer any group to another molecule
Term
anaerobic pathway
Definition
can proceed in the absence of molecular oxygen
Term
fermentation
Definition
anaerobic 2nd step of glucose metabolism; occurs in cytosol; used when O2 is low to continue ATP production
Term
reducing power
Definition
important measure of the cell's usable energy content, related to resevoir of NADPH
Term
protein kinases
Definition
enzymes that transfer phosphate groups to other proteins; regulate such diverse activities as hormone action, cell division, and gene expression
Term
allosteric modulation
Definition
mechanism whereby the activity of an enzyme is either inhibited or stimulated by a compound that binds to an allosteric site on the enzyme
Term
allosteric site
Definition
site that is spatially distinct from the enzyme's active site
Term
feedback inhibition
Definition
type of allosteric modulation in which the enzyme catalyzing the first committed step in a metabolic pathway is temporarily inactivated when the concentration of the end product of that pathway reaches a certain level
Term
gluconeogenesis
Definition
anabolic pathway leading to the synthesis of glucose
Term
plasma membrane
Definition
separates cell from environment, 5-10nm, thin, fragile; functions: scaffold for biochemical activities, selectively permeable membrane, compartmentalization, intercellular communication
Term
signal transduction
Definition
response of cell to external stimuli
Term
receptors
Definition
combine with specific molecules having a complementary structure
Term
ligands
Definition
specific molecules that bind with receptors
Term
fluid-mosaic model
Definition
membranes as dynamic structures in which both lipids and associated proteins are mobile and capable of moving within the membrane to engage in interactions with other membrane molecules
Term
amphipathic
Definition
contain both hydrophilic and hydrophobic regions
Term
phospholipids
Definition
lipids that contain a phosphate group; majority of membrane lipids
Term
phosphoglyceride
Definition
lipid built on a glycerol backbone with a phosphate group; majority of membrane phospholipids
Term
head group
Definition
highly water-soluble domain at one end of a membrane phospholipid
Term
sphingolipids
Definition
membrane lipid;sphingosine linked to a fatty acid by its amino group
Term
glycolipid
Definition
sphingosine-based lipid molecules linked to carbohydrates, often active components of plasma membrane
Term
cholesterol
Definition
sterol found in animal cells that can constitute up to 50% of the lipid in the plasma membrane; realtive conc. effects the membrane fluidity
Term
liposomes
Definition
phospholipid molecules assemble spontaneous to form the walls of fluid-filled spherical vesicles
Term
glycosylation
Definition
addition of a carbohydrate
Term
ogliosaccharides
Definition
branched hydrophilic saccharides typically having having fewer than about 15 sugars per chain
Term
integral proteins
Definition
penetrate the lipid bilayer
Term
transmembrane proteins
Definition
pass entirely through the lipid bilayer and have domains that protrude from both the extracellualr and cytoplasmic sides of the membrane
Term
peripheral proteins
Definition
located entirely outside of the lipid bilayer on either cytoplasmic or extracellular side
Term
lipid-anchored proteins
Definition
located outside the lipid bilayer, on either extracellular or cytoplasmic side, but are covalently linked to a lipid molecule that is situated with in the bilayer
Term
freeze-fracture replication
Definition
tissue is frozen solid and then struck with a knife blade, which fractures it into two; facture plane often takes a path between the two leaflets of the lipid bilayer; once the membranes are spolit, metals deposited on their exposed surface to form a shadowed replica, which is viewed in the electron microscope;
Term
transmembrane domains
Definition
segments of a protein embedded within the membrane; have a simple structure; consist of about 20 nonpolar amino acids in an alpha helix
Term
GPI-anchored proteins
Definition
peripheral membrane proteins that are anchored via linkage to a glycosylphophatidylionsitol molecule of the bilayer
Term
transition temperature
Definition
where the fluidity of the membrane changes from liquid to gel
Term
lipid rafts
Definition
microdomains within a cellular membrane that possess decreased fluidity due to the presence of cholesterol, glycolipids, and phospholipids contain longer, saturated fatty acids
Term
cell fusion
Definition
technique whereby two different types of cells or cells from two species, can be fused to produce one cell with a common cytoplasm and a single membrane
Term
diffusion
Definition
spontaneous process in which a substance moves from a region of high concentration to a region of low concentration
Term
electrochemical gradient
Definition
concentration difference of the substances and electric difference of the charged particles
Term
partition coefficient
Definition
the ratio of its solubility in a nonpolar solvent to that in water under polar condiations
Term
fluorescence recovery after photobleaching (FRAP)
Definition
cells are first labeled by link to a fluorescent dye then irradiated by a sharply focused laser which bleach the fluorescent molecules in its path; random movements of molecules in to bleached area gives rate of diffusion
Term
single-particle tracking (SPT)
Definition
individual membrane proteins are labeled, movement of molecules are followed by computer enhanced video microscopy
Term
diffusion
Definition
spontaneous process in which a substance moves from a region of high concentration to a region of low concentration
Term
electrochemical gradient
Definition
a chemical gradient (concentration of substances) and an electronic gradient (difference in charge)
Term
semipermeable
Definition
membrane property of being freely permeable to water while allowing much slower passage to small ions and polar solutes
Term
osmosis
Definition
water moving from a region of lower solute conc. to a region of higher solute conc.
Term
hypertonic
Definition
higher concentration of solute comparitively
Term
hypotonic
Definition
lower solute concentration comparatively
Term
iostonic
Definition
equal solute concentration comparitively
Term
plasmolysis
Definition
when plant cell placed into a hypertonic medium and the volume shrinks
Term
conductance
Definition
rapid movement of ions
Term
ion channels
Definition
openings in the membrane that are permeable to specific ions; made from integral proteins
Term
gated
Definition
exist in open or closed form and respond to signals to switch forms
Term
voltage-gated channels
Definition
depend on difference in ionic charge across the membrance (i.e. Na+ channels)
Term
ligand-gated channels
Definition
depend on the binding of specific molecule (usually not solute) (i.e. neurotransmitters)
Term
mechano-gated channels
Definition
depend on mechanical forces applied to membrane (i.e. stereocilia on the hair cells of ears)
Term
facilitative transporter
Definition
transmembrane protein that binds a specific substance and changes conformation so as to facilitate diffusion of the substance down its conc. gradient
Term
facilitated diffusion
Definition
process by which the diffusion rate of a substance is increased through interaction with a substance-specific membrane protein
Term
active transport
Definition
energy-requiring process in which a substance binds to a specific transmembrane protein, changing its conformation to allow passage of the substance through the membrane against the electrochemical gradient
Term
cotransport
Definition
process that couples the movement of two solutes across a membrane, termed symport if the two solutes are moved in the same direction and antiport if the two move in opposite directions
Term
dendrites
Definition
fine extension from cell body in neuron, which receive incoming information from external sources
Term
axon
Definition
single extension from cell body, which conducts outgoing impulses away from cell body toward target cells
Term
terminal knob
Definition
site where impulses are transmitted from neuron to target cell
Term
membrane potential
Definition
voltage caused by difference of charge particles across non excitable cells
Term
resting potential
Definition
voltage caused by difference of charged particle in excitable cells (muscle and nerve)
Term
depolarization
Definition
movement of voltage toward zero
Term
threshold
Definition
certain voltage point of nerve cell at which an AP is generated
Term
action potential
Definition
collective changes in membrane potential, beginning with depolarization to threshold and ending with return to resting potential, that occur with stimulation of an excitable cell and act as the basis for neural communication
Term
nerve impulse
Definition
propagation of an AP down the length of the nerve
Term
saltatory conduction
Definition
nerve impulse jumps from node to node of Ranvier without activating the membrance inbetween (in myelinated cells)
Term
myelin sheaths
Definition
lipid-rich material wrapped around most neurons in the vertebrate body
Term
synapses
Definition
junctions between neurons and target cells
Term
synaptic cleft
Definition
gap between neuron and target cell (20 to 50 nm)
Term
presynaptic cell
Definition
neuron before synapse
Term
postsynaptic cell
Definition
neuron, muscle cell, or gland cell after synapse
Term
neuromuscular junctions
Definition
synapse between the terminal branches of an axon and a skeletal muscle cell
Term
synaptic vesicles
Definition
storage sites for the chemical transmitters that act on postsynaptic cells
Term
neurotransmitters
Definition
chemical transmitters released to act on postsynaptic cell
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