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54 terms

Fox Physiology Ch. 4

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enzyme
biological catalysts that increase the rate of chemical reactions; most are proteins
ribozymes
molecules of RNA that demonstrate enzymatic activity
catalyst
a chemical that increases the rate of a chemical reaction, is not itself changed during the reaction, and it does not change the nature of the reaction
activation energy
the amount of energy required for a reaction to proceed
substrates
the molecules that fit into the active sites of certain enzymes
lock and key model
model of enzymatic activity where substrate A & B fit perfectly into the enzyme, are affected, and leave the active sites (leaving the enzyme unchanged)
induced fit model
model of enzymatic activity where substrate A & B fit into the active sites, induce a conformational change in the enzyme, and leave the active sites changed
Alkaline Phosphatase
diseases resulting in high blood plasma concentration of this enzyme: obstructive jaundice (gallbladder stones), Paget's disease, and carcinoma of bone
Acid Phosphatase
diseases resulting in high blood plasma concentration of this enzyme: benign hypertrophy of prostate, cancer of prostate
Amylase
diseases resulting in high blood plasma concentration of this enzyme: pancreatitis, perforated peptic ulcer
Aldolase
diseases resulting in high blood plasma concentration of this enzyme: muscular dystrophy
Creatine kinase
diseases resulting in high blood plasma concentration of this enzyme: muscular dystrophy, myocardial infarction
Lactate dehydrogenase
diseases resulting in high blood plasma concentration of this enzyme: myocardial infarction, liver disease, renal disease, pernicious anemia
Transaminases
diseases resulting in high blood plasma concentration of this enzyme: myocardial infarction, hepatitis, muscular dystrophy
aspartate
the amino acid from which the enzyme AST is derived
alanine
the amino acid from which the enzyme ALT is derived
isoenzymes
enzymes with same functions but slightly different "models" in different organs
kidneys
major organs that can fail with an extremely elevated creatine-phosphokinase level (CK)
MM
form of creatine-phosphokinase released from damage to skeletal muscle
BB
form of creatine-phosphokinase released from damage to the brain
MB
form of creatine-phosphokinase released from damage/disease to the heart
factors affecting enzyme rate
temperature and pH of a solution, concentration of cofactors and coenzymes, concentration of enzyme and substrate, stimulatory and inhibitory effects of products
pH optimum
specific for each enzyme; an enzyme will work best at body temperature and this
cofactors
metal ions (Ca2+, Mg2+, etc) that induce a conformational change in an enzyme that allows substrates to bind
coenzymes
organic molecules, from water-soluble vitamins, needed for functions of some enzymes
enzyme activation
phosphorylation is an example of this; required for many enzymes to properly function; prompted by the environment and turnover of enzyme proteins
law of mass action
reversible reactions will be driven from higher to lower concentration
saturation
when the relationship between substrate concentration and reaction rate reaches a plateau of maximum velocity
metabolic pathway
process of moving from initial substrate to intermediates to final products
end product inhibition
a form of negative feedback where products inhibit the production of more product
allosteric inhibition
specific mechanism of end product inhibition where a product inhibits a specific enzymatic step by binding to the enzyme and conformationally changing it
inborn errors
the idea that genetic mutations prevent translation of an enzyme and diseases may arise (ex. hypercholesterolemia)
phenylketonuria
inborn error with an increase in phenylpyruvic acid resulting in mental retardation, epilepsy (aka PKU)
albinism
inborn error with a lack of melanin resulting in a susceptibility to skin cancer
maple syrup disease
inborn error with an increase in leucine, isoleucine, and valine resulting in the degeneration of the brain, early death
homocystinuria
inborn error with accumulation of homocystine resulting in mental retardation, eye problems
lactose intolerance
inborn error where lactose is not utilized resulting in diarrhea
glucose 6 phosphate deficiency
inborn error with accumulation of glycogen in the liver resulting in liver enlargement, hypoglycemia (aka Gierke's disease)
glycogen phosphorylase
inborn error with accumulation of glycogen in muscles resulting in muscle fatigue and pain
Gaucher's disease
inborn error with lipid accumulation resulting in liver/spleen enlargement, brain degeneration
Tay-Sachs disease
inborn error with lipid accumulation resulting in brain degeneration, death by age five
hypercholesterolemia
inborn error with high blood cholesterol resulting in atherosclerosis of coronary and large arteries
bioenergetics
the flow of energy in living systems
first law of thermodynamics
energy cannot be created or destroyed, but can be transferred from one form to another
second law of thermodynamics
the amount of entropy/disorder increases during every energy transformation
endergonic
reactions requiring an input of energy (result in a rise of free energy)
exergonic
reactions releasing an output of energy (result in less free energy)
reduction
gain of electrons (or of H in biosystems)
oxidation
loss of electrons (or of H in biosystems)
reducing agent
species that induces reductions, and is therefore itself oxidized
oxidizing agent
species that induces oxidation, and is therefore itself reduced
niacin
coenzyme NAD is derived from this B vitamin
riboflavin
coenzyme FAD is derived from this B vitamin
pernicious anemia
extremely low levels of vitamin B12; can resemble leukemia symptomatically