BIOL 1201 Chapter : BIOL 1201 EXAM TWO
BIOL 1201 EXAM TWO
September 8, 2017
You need 3 bonds to join 4 monomers together (which forms a polymer)
When two monomers are joined together, one molecule of water is produced (dehydration
synthesis or condensation reaction)
Primary structure
• Description of covalent bonds, or peptide bonds (strong bonds)
• The sequence of amino acids
Secondary structure
• Repeated spatial patterns
o Alpha helix or beta pleated sheet
• Entirely stabilized by hydrogen bonds (much weaker than covalent bonds)
Tertiary structure
• 3-D pattern of folding
• Largely stabilized by weak bonds (but not completely)
o Hydrogen, hydrophobic interaction
Quaternary structure
• 3-D pattern of joining several different polypeptide chains
• Largely stabilized by wear bonds
o Hydrogen, hydrophobic
• Not connecting the two chains with a peptide bond
Chemical reactions
• Occur any time two or more atoms, ions, or molecules collide in such a way that they
produce a new substance
Free Energy and Chemical Reactions
• Spontaneous: release free energy (exergonic)
o Spontaneous means a reaction can happen without energy, but that does not mean
it is going to
o /\G < 0
• Non-spontaneous: require free energy (endergonic)
o /\G > 0
o Most biological reactions are non-spontaneous
Changed in Free Energy
• /\G = /\H – T/\S
• G = free energy
• H = enthalpy
• T = temperature (K: always positive)
• S = entropy
o The measure of disorder
Living vs. Non-Living Systems
• Living
o Highly organized
o High energy
o fast
• Non-Living
o Less organized
o Lower energy
o Very slow
o Most chemical reactions happen so slowly that they cannot be useful biologically
• How do living systems accomplish this?
o External energy source (the sun)
o Organic catalyst (enzyme)
• Enzymes
o Almost all are proteins
▪ Catalytic RNAs ribozymes
o Large globular proteins
o Catalysts speed up the rate of the reaction, but are not used up during the
reaction (they can be used over and over again)
o Enzymes are highly specific (one enzyme usually only catalyzes one specific
reaction)
o How does an enzyme speed up the rate of the reaction?
▪ An enzyme speeds up the rate by aligning the substrates so that the
reaction will actually happen
o How can you regulate the rate of an enzyme-catalyzed reaction?
▪
September 15, 2017
Induced-Fit Model
• The substrate binds to the active sit of the enzyme
• This alters the shape of the enzyme
• Creating a fit that lowers the activation energy
• Enzymes catalyze reactions by aligning the substrates right
Competitive Inhibition
• When something blocks the active site so the substrate cannot get to the enzyme
Non-Competitive Inhibition
• When the inhibitor somewhere other than the active site (changes the shape of the
enzyme)
Allosteric Inhibition
• The enzyme naturally alternates between the active and inactive form even without am
inhibitor being present
• The enzyme can also be stabilized in the active form
Q: What do the following have in common?
• Roundup (glyphosate)
• Anti-bacterial hand cleaner (tricolsan)
• Viagra (sildenafil)
• Aleve (naproxen sodium)
A: They are all enzyme inhibitors
Cells
• The minimum organization of living matter
• Fluid-Mosaic Model
o Cell membrane
