gen bio 1 exam 3 Flashcards
cellular metabolism
The chemical reactions that occur in cells, including those
that use and release energy
metabolic pathways
ordered series of chemical reactions that build or break
down a molecule
ways cells respond to the environment:
*Building and breaking down macromolecules
* Transporting proteins across cell membranes
* Packaging materials into vesicles,
* Dividing, mutating, dying, etc.
catabolism reaction
starts from a larger molecule and breaks down to a smaller one and releases energy
anabolism reaction
starts from a smaller molecule and combines with energy to create a larger molecule
1st law of thermodynamics
Energy is conserved. Energy cannot be created nor destroyed, but only transferred and transformed.
kinetic energy
energy in motion
Ex: thermal energy, electricity, electromagnetic radiation (e.g. light/photons), sound waves
potential energy
stored energy
Ex. gravity or chemical bonds
what happens to energy when a chemical bond is broken
may be converted into light, heat, new chemical bonds
By breaking a bond, potential energy can be converted to kinetic energy such as light and
thermal energy (heat)
total energy in a molecule is measured in…
Enthalpy (H)
ΔH =
potential energy of product – potential energy of reactant
A chemical reaction that has reactants of high potential energy and low kinetic energy can result in products with…
low potential energy and high kinetic energy. This produces a –ΔH
exothermic reactions have a…
–ΔH; usually produces heat
A chemical reaction that has reactants of low potential energy and high kinetic energy can result in products with…
high potential energy and low kinetic energy. This produces a +ΔH
endothermic reactions have a…
+ΔH
high entropy means..
high disorder
Entropy, S =
amount of disorder
ΔS =
Entropy of product – Entropy of reactant
high entropy reactants and low entropy products result in a…
–ΔS
Gibbs free energy describes…
determines whether a chemical reaction is spontaneous or non-spontaneous and whether energy is stored or released
ΔG =
ΔH - TΔS
the symbols in the gibbs free energy equation:
ΔH = Potential energy of product – Potential energy of reactant
ΔS = Entropy of product – Entropy of reactant
T = Temperature
Conversion: T in Kelvin = Celsius +273
more energy is unavailable to do work when a reaction occurs at higher temperature because….
an increase in temperature increases entropy
a spontaneous reaction (exergonic), has a..
-ΔG and releases energy
a non-spontaneous reaction (endergonic), has a…
+ΔG, requires an input of energy to proceed; stores energy
a +ΔH means +ΔG and vice versa
…
Chemical energy can drive non-spontaneous
reactions via:
- Harnessing energy by breaking
(cleavage) of chemical bonds (ATP to
ADP or AMP) - Electron transfer (via redox reactions)
ATP stores a large amount of potential energy
in the form of…
phosphanyhydride bonds
when ATP is hydrolyzed…
energy is released
ATP hydrolysis (breaking a phosphoanhydride
bond)…
releases free energy (-ΔG), an exergonic
reaction
Exergonic reactions can provide energy for
endergonic reactions like cellular
respiration
…
Redox reactions transfer energy via…
electrons
redox reaction
chemical reaction involving the loss or
gain of one of more electrons
oxidation
loss of electrons; when product has less electrons than reactant
reduction
gain of electrons; when product has more electrons than reactant
catalyst
a substance that increases the rate of a reaction
without being consumed
enzyme
a catalyst that speeds up the rate of a biochemical
reaction
* most are proteins
substrate
Substance the enzyme acts upon
When a substrate binds to the
active site of an enzyme, the
enzyme slightly changes its
shape to better accommodate
the substrate → creates a
more precise fit → facilitates
the chemical reaction
…
conformational change
a change in the shape of a molecule such as a protein
Enzymes lower the activation energies of chemical
reactions → Amount of enzymes and enzyme activity
determine which biochemical reactions will proceed
…
Enzyme levels and activity are tightly regulated in cells in order to…
maintain homeostasis and organismal health
3 mechanisms for enzyme regulation:
- molecular regulation
- Compartmentalization
- Feedback inhibition
Molecular regulation of enzymes
Mechanism that regulates enzyme activity through the action of inhibitors or activators
enzyme inhibitors
molecules or substances that reduce the activity of an
enzyme
- Leads to reduction in amount of products
- Substrates may accumulate
3 Mechanisms for enzyme inhibition:
- Competitive inhibition
- Non-competitive inhibition
- Allosteric inhibition
competitive inhibition
A molecule or substance competes with the substrate for binding to an active site (substrate unable to bind to enzyme)→ decreased enzyme activity
* A competitive inhibitor usually resembles the structure or shape of a substrate