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Class notes Biology
- Course
- Biology
- Institution
- 12th Grade
Intro to Metabolism indicates all needed information for metabolism.
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Intro to MetabolismEnergy: the ability to do work, and all living things devote a large part of their
existence to collecting, processing, storing, and using energy.
- variety of forms, including light, sound, mechanical energy, chemical
energy, electrical energy, radiation and heat.
TWO TYPES OF ENERGY
Kinetic energy is the energy that causes objects to move. This is the energy that is
being used up.
Potential energy is energy that is stored for later use.
Much of the work done in living cells involves the transformation of PE into KE.
Metabolism: The sum of all chemical reactions occurring in a living cell or
organism.
Anabolic Reaction
- process of using energy
(endothermic) to build larger
molecules from smaller
- Requires energy
(endothermic)
Catabolic Reaction
- process of breaking down
compounds into smaller molecules
- releases energy (exothermic)
Thermodynamics: a branch of science that deals with the relationship between all
forms of energy.
2 laws of thermodynamics
1. First law of thermodynamics: The first law of thermodynamics states that
energy can be changed from one form to another, but it cannot be created
or destroyed. The amount of energy in the universe is always conserved.
2. Second law of thermodynamics: The second law of thermodynamics states
that the disorder (called “entropy”) in the universe is always increasing. Each
time energy is used, some will be converted (“lost”) to heat (random motion).
REDOX REACTIONS:
Oxidation is Loss of Electrons .
Substances that are oxidized are called
reducing agents because they cause the
reduction of other substances.
Reduction is Gain of Electrons.
Substances that are reduced are called
oxidizing agents because they cause the
oxidation of other substances
How is energy transferred in redox reactions during the metabolism of living
things?
, Electrons that are transferred from one atom or molecule to another atom or
molecule carry energy with them. This energy can be stored or released in
molecules that are involved in a metabolic process (such as photosynthesis or
cellular respiration).
Reduced molecules or atoms receive an electron from oxidized molecules or
atoms. Consequently, reduced molecules or atoms are raised to higher energy
levels and oxidized molecules or atoms have lowered energy levels.
Reduced molecules or atoms are raised to higher energy levels because electrons
repel each other. Adding more electrons to an atom is like pressing down on a
spring. Just as pushing on a spring increases the potential energy of the spring,
adding more electrons increases the potential energy of the atom.
Specialized molecules, called energy carriers or coenzymes, become reduced and
oxidized as electrons are shuttled from one enzyme to the next through metabolic
pathways, delivering or harvesting energy at each stage.
Nicotinamide Adenine Dinucleotide (NAD+): hydrogen-accepting coenzyme that is
a key player in the transfer of energy.
NADH: reduced energy rich form
When oxidized (electrons lost), NAD+ is
electron-deficient. It is in a low-energy
state, so it carries a positive overall
ionic charge (as indicated by the
positive symbol on the top right-hand
side).
NAD+ readily accepts H atoms and
their associated high-energy
electrons as they are stripped from
the higher-energy molecules in the
pathways that are donating them.
When NAD+ accepts a hydrogen
proton and two electrons from the
active site of an enzyme, it becomes
its reduced, energy-rich form, NADH.
ATP(Adenosine triphosphate): currency of the
cells, ATP stores and releases energy is in its
structure. It is used to provide the energy to
drive endothermic reactions involving enzymes,
such as the synthesis of polypeptides, DNA, and
complex polysaccharides.
ATP + H20 ↔ ADP + Pi + H+
ALL energy originates from the Sun. Photosynthesis
(anabolic) and cellular respiration (catabolic) are
complimentary processes that provide the necessary
energy transformations required to feed entire
ecosystem and provide every organism with the
necessary usable energy to fuel their cellular work.
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