Metabolism Flashcards
Energy:
Capacity to do work
Chemical Work
making and breaking of chemical bonds
Transport Work
moving ions, molecules, and larger particles
can create concentration gradients
Mechanical work
used for movement
first law of thermodynamics
-law of conservation of energy
-“total amount of energy in the universe is constant”
-closed system
second law of thermodynamics
-push to entropy
-“processes move from state of order to disorder”
Activation energy
the energy that msut be put into reactants before a reaction can proceed
Exergonic reactions
energy is released
products have less energy than the starting substance
endergonic reactions
energy input required
product has more energy than starting substances
large activation energy makes reactions
irreversible
enzymes are
catalytic molecules
enzyme function (7)
- speed the rate at which reactions approach equilibrium
- nearly all enzymes are proteins
- highly specific
- enzymes are very efficient
- enzymes are subject to a variety of controls
- larger than substrates (reactants)
- few kinds of RNAs also show enzymatic activity (e.g. ribozymes)
an enzyme speeds up a chemical reaction without
being altered or consumed
isozymes
catalyze same reaction, but under different conditions
enzymes may be
activated, inactivated, or modulated
-coenzymes, vitamins
-chemical modulators: temperature and pH
reversible enzymatic reactions obey
the law of mass action (forward and in reverse)
Isozyme example: tyrosine
-the amino acid, tyrosine, is converted to melanin (brown pigment) by the enzyme tyrosinase
-siamese cats and himalayan rabbits have a specific isozyme of tyrosinase that is heat sensitive
-increase temprature, decrease activity of enzyme
-enzyme does not work at core body temperature, but is active in cooler regions of the body (face and tail)
law of mass action:
when a reaction is at equilibrium, the ratio of the products and substrates remains constant
(rate of reaction forward= rate of reaction reverse)
factors that influence the rate of an enzyme-catalyzed reaction (5)
-temperature
-pH
-substrate concentration
-non-substrate chemicals that bind to the enzyme (competitive inhibitors & allosteric modulators)
-metabolic pathways (feedback inhibition or end-product inhibition)
A group of metabolic pathways resembles
a road map
Cells Regulate their Metabolic Pathways (5)
- controlling enzyme concentrations
- producing allosteric and covalent modulators
- using different enzymes for reversible reactions
- isolating enzymes within organelles
- maintaining optimum ratio of ATP to ADP
Energy Utilization or Metabolism consists of 2 pathways:
catabolic and anabolic
Catabolic Pathways
-extract energy for ATP production
-dependent on exergonic reactions
Anabolic Pathways
-synthesis pathways
-energy converted to chemical bonds
-dependent on endergonic reactions
ATP production has 2 methods
- substrate-level phosphorylation
- oxidative phosphorylation
glycogen
-storage form of glucose in liver and skeletal muscle
-converted to glucose or glucose 6-phosphate
gluoneogenesis is
the conversion of noncarbohydrate molecules (lactic acid, amino acids, glycerol) into a glucose molecule
lipid catabolism involves
lipolysis and beta oxidation
deamination of an amino acid produces ammonia and a
keto acid
