Ch. 6 Metabolism Flashcards
what is energy?
the capacity to do work
forms of energy
- potential energy
- kinetic energy
potential energy
stored energy
kinetic energy
energy of motion
where does energy come from?
- main source of energy on Earth: the sun
- energy is captured and stored in organic molecules
how do cells use energy
- chemical work
- mechanical work
- electrochemical work
- thermal work/ heat
First Law of Thermodynamics
energy cannot be created nor destroyed
- the total amount of energy before and after every conversion always remains the same
- amount of energy in the universe remains the same
One- way flow of energy
the sun is the primary source of energy for life
- producers: trap energy from the sun and convert it to chemical energy
- all organisms use the energy stored in organic compounds to do work
Law of Conservation of Mass
matter cannot be created nor destroyed
~ matter only changes in form
Second Law of Thermodynamics
energy is always flowing from high energy forms to lower energy forms
- energy tends to disperse spontaneously
- *no conversion is 100% efficient, some energy is always lost as heat to the environment**
entropy
measure of disorder/randomness/dispersion of energy in a system
exergonic reaction
energy is released
- products have less energy that starting substance
- to retrieve energy stored in bonds of organic compounds
endergonic reaction
energy input required
- products have more energy than starting substance
- to store energy in bonds of organic compounds
ATP’s role
to carry energy
*made up of adenine, ribose, and phosphates
1 phosphate: adenosine monophosphate
2 phosphates: adenosine diphosphate
3 phosphates : adenosine triphosphate
phosphorylation
transfer of a phosphate from one molecule to another
-when ATP gives up a phosphate group: ADP is formed
-ATP can reform when ADP binds to another phosphate group
phosphorylation processes help drive metabolic reactions (both exergonic and endergonic)
oxidative phosphorylation
production of ATP during cellular respiration where there’s involvement of oxidized molecules in the process
chemiosmosis
- used during the light reaction of photosynthesis to harness energy of sunlight
- generate ATP from catabolism of glucose
anabolic reactions
small molecules are assembled into larger ones’
- also called ‘biosynthetic
- products have more stored energy
catabolic reactions
large molecules are broken down into small ones
- also called ‘degradative’
- products have less stored energy
metabolic pathways
- photosynthesis is biosynthetic
- cellular respiration is degradative
Activation energy
amount of energy required to cause molecular bonds to break
enzymes and activation energy
enzyme reduce amount of energy (activation) necessary to start the reaction
-proteins that acts at a catalytic molecules
features of enzymes (1)
enzymes do not make anything happen that could not happen on its own– just speed it up
features of enzymes (2)
reactions do not alter or use up enzyme molecules
features of enzymes (3)
the same enzyme usually works for the forward and backwards of a reaction
features of enzymes (4)
each type of enzyme recognizes and binds to only certain substrates
enzyme/substrate complex
- substrates binds enzyme at the active site (lock and key)
- enzyme is then released to be used again if needed
factors that affect enzyme reactiosn
- temperature (internal and external)
- pH value (external and internal)
- enzyme synthesis
- presence of regulatory on the enzyme
- cofactors- make them more reactive
- coenzymes-transfer protons and electrons
- ions-effect chemical charge can slow or quicken an enzyme
types of enzyme inhibitors
- allosteric inhibitors
- allosteric activators
allosteric inhibitors
modify the active site of the enzyme so that substrate binding is reduce/prevented
allosteric activators
modify the active site of the enzyme so that affinity for the substrate increases
what do statins do?
- class of drugs that reduce cholesterol levels
- compounds are inhibitors of the enzyme HMG-CoA reductase, the enzyme that synthesizes cholesterol from lipids in the body
what does acetaminophen do?
also called “Tylenol”
- is an inhibitor of the enzyme: cyclooxygenase
- effective in providing relief from fever and inflammation
cofactors
inorganic ion like iron (Fe++), magnesium (Mg++), and zinc (Zn++)
- helps enzymes become catalysts*
- one example of an enzyme that requires a metal ion as a cofactor is the enzyme DNA polymerase
REDOX reactions
most energy pathways are a combination of reduction and oxidation reactions
- oxidation and reduction usually occur together
- shift of an electron from one compound to another removes some potential energy from first compound (oxidized) and increase the potential energy for the second compound (reduced)
electron carriers
- bind, carry high energy between compounds
- must derive from the B vitamin group
- these compounds can be easily reduced or oxidized
- NAD: nicotinamide adenine dinucleotide
- NAD+: oxidized
- NADH: reduced
biolumeniscence
enzyme-mediated reactions that release energy as fluorescent light
-luciferase is the enzyme that interact with an oxidized substance luciferin in order to produce the byproduct: oxyluciferin
the chemical reaction producing oxylucerfin produces light
