metabolism Flashcards
electron exchange
either by transferring electrons from one atom to another; sharing electrons between atoms
ionic chemical bond
formed when electrons are donated by one atom to another
covalent chemical bond
formed when two atoms share a pair of electrons
polar covalent bond
if one atom is more electronegative than the other the electron is shared unequally
bond length
attractive and repulsive forces are in balance when nuclei separated by defined distance
bond strength
measured by amount of energy needed to break that bond expressed in kilocalories
double bond
four electrons can be shared; 2 coming from each atom
ions
molecules carrying plus or minus charges
hydrophobic
molecules are uncharged and form few or no hydrogen bonds and do not dissolve in water
acids
substances that release protons to form H30+ when they dissolve in water
bases
alkaline; substance that accepts protons to form OH-
chemical bond strength
in water-kcal; covalent-90, ionic-3, hydrogen-1, van der waals-0.1
electrostatic attraction
form between permanent dipoles-polar covalent; fully charged ions- ionic bonds
isomer
molecules with the same chemical formula but different structures
optical isomer
molecules that are mirror image pairs
sugar groups
multiple hydroxyl groups, either one aldehyde or ketone group
sucrose
disaccharide of glucose and fructose
condensation reaction
molecule of water is expelled as a bond is formed between OH group on one sugar to OH group on another sugar
hydrolysis
molecule of water is consumed; two monosaccharides are formed
glycoprotein
smaller oligosaccharides are covalently linked to proteins
glycolipid
smaller oligosaccharides are covalently linked to lipids
fatty acid
hydrophylic carboxylic acid head; hydrophobic hydrocarbon chain
saturated tail
no double bonds between carbon atoms
triacylglycerol
consist of three fatty acid chains joined to a glycerol molecule
phospholipid
cell membrane; 2 fatty acid tails; glycerol joined to phosphate group which is joined to hydrophilic polar group
glycosidic bond
covalent bond between two sugar molecules
amphiphilic
molecules with both hydrophobic and hydrophilic regions
common amino acids
20 commonly found amino acids with n-amino beginning and c-carboxyl terminus
L-form proteins
opitcal isomer form found in all eukaryotic protiens
catabolism
break down food stuff generating energy
anabolic
biosynthetic; drive the synthesis molecules
second thermodynamic law
isolated system; the degree of disorder only increases
entropy
amount of disorder in a system is quantified and expressed as this
first thermodynamic law
energy can be converted but never created or destroyed
oxidation
one molecule loses an electron
reduction
one molecule gains an elecron
free energy
measures the portion of a systems energy that can perform work
free energy change
^ is change; ^G=^H-T^S
enthalpy
symbolized by H; total energy in a system
entropy
the randomness or disorder of a system
spontaneous reaction
enthalpy must decrease or entropy must increase
exergonic reaction
net release of free energy; ^G is negative, cellular respiration is example
endergonic reaction
absorbs free energy; molecule synthesis
energy coupling
the use of an exergonic reaction to power an endergonic reaction
enzyme active site
substrate is held there by hydrogen bonds and ionic bonds
cofactor
nonprotein helpers; may be bound tightly to enzyme or reversibly with substrate
coenzyme
if cofactor is organic; such as vitamins
competitive inhibitor
reduce the productivity of enzymes by blocking substrates from active sites
competitive overcome
increase the concentration of substrate so that active sites become available
noncompetitive inhibitors
bind to another part of the enzyme and impede enzymatic reactions
irreversible enzyme inhibitors
often toxins and poisons that bind covalently
allosteric regulation
proteins function at one site is affected by the binding of a regulatory molecule at a separate site
enzyme cooperativity
binding of one substrate to active site locks all subunit active sites in active conformation
allosteric inhibitor
stabilizes inactive form for one or if multiple subunits all active sites
allosteric activator
stabilizes active form for one or if multiple subunits all active sites
feedback inhibition
allosteric regulation where metabolic pathway is switched off by binding of product to early enzyme in the pathway
