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BIOCHEM ExamI
| Question | Answer |
|---|---|
| Animate matter | -Is organized (structure/function specialization) -Consumes energy to build order (grow and reproduce) -Senses and responds to environment -Evolves (biological diversity) |
| Common structural features of bacteria | -Ribosomes for protein synthesis -Nucleoid containing single circular DNA -Pili for adhesion -Flagella for locomotion -CEll envelope: either gram (+) or (-) |
| Component of an Animal Cell | -Ribosomes -Peroxisome -Lysosomes -Transport vessicles -cytoskeleton -Golgi -Nucleous & Nucleolous -Smooth & Rough ER -Plasma Membrane -Nuclear Envelope |
| What percentage of a cell is dry weight? | 25-30% |
| What percentage of the dry weight in a cell is made up of proteins? | 50% |
| In a cell, what level of organization contains the strongest bonds? | Primary (Sugars, AA, nucleotides) linked by covalent bonds at ~400 kJ/mol |
| Centrifugation | Fc = mea = meω2r S = m(1 – vρ)/6πηrs |
| Universal features of living cells | All cells have a nucleus or nucleoid, a plasma membrane, and cytoplasm |
| What is the difference between cytoplasm and cytosol? | cytosol is defined as that portion of the cytoplasm that remains in the supernatant after gentle breakage of the plasma membrane and centrifugation of the resulting extract at 150,000 g for 1 hour. |
| What is the supernatant? | concentrated solution of enzymes, RNA, monomeric subunits, metabolites & inorganic ions |
| How many bulk elements are essential for life? What are they? | 10; H C N O P S Cl Na Ca K |
| What is a trace element and how any are there? | element required of life only in trace amounts; 12 |
| What is a Svedburg? | The unit in which a protein (especially a ribosome) is measured |
| Define van der Waals interaction. | A momentarily induced dipole due to weak attraction and interaction between molecules |
| Greatest potential energy occurs at what formation around the C-C bond in ethane? | Eclipsed |
| Methyl | R-CH3 |
| Ethyl | R-CH2CH3 |
| PHENYL | R-C6H6 (Aromatic) |
| CARBONYL ALDEHYDE | R-CO-H |
| CARBONYL KETONE | R-CO-R' |
| HYDROXYL | R-OH |
| ETHER | R-O-R' |
| ESTER | R-COO-R' |
| ANHYDRIDE | R-COOCO-R' |
| AMINO | R-NH2 |
| AMIDO | R-CO-NH2 |
| SULFHYDRYL | R-SH |
| DISULFIDE | R-SS-R' |
| THISESTER | R-COS-R' |
| PHOSPHORYL | R-OPOO-OH |
| Achiral molecule | Rotated molecule CAN be superimposed on its mirror image |
| Chiral molecule | Rotated molecule CANNOT be superimposed on its mirror image because all four substituents are different |
| Enantiomer | mirror image of a molecule |
| Diastereomer | pairs of stereoisomers that are not mirrow images |
| Biological complexity | n!/r!(n – r)! |
| Define Open, Isolated & Closed Systems | -Open: System and Surroundings exchange both energy and matter -Closed: only energey is exchanged -Isolated: neither energy nor matter is exchanged |
| Define terms for the equation EInternal = EKinetic + EPotential | -System has internal energy, EInternal -EKinetic is translational, rotational, vibrational -EPotential is electronic, bonds |
| What is the equation of the conservation of energy? | ΔEInternal = q – w where q is heat absorbed and w is work done |
| How are volume and pressure related? | at constant pressure volume can change, allowing work of expansion: w = PΔV |
| What is the equation of the change in enthalpy? | ΔH ≡ ΔEInternal + PΔV = q |
| What is enthalpy? | heat content of a system |
| If ΔH < 0 & q < 0 is the system exothermic or endothermic? | exothermic |
| If ΔH > 0 & q > 0 is the system exothermic or endothermic? | endothermic |
| State the equation for change in Gibbs free energy & indicate what values signify spontaneous reactions | ΔG = ΔHSystem – TΔSSystem ΔG < 0 is spontaneous |
| Define endergonic. | A chemical reaction that consumes energy (ΔG is positive) |
| Define exergonic | A chemical reaction that releases energy (ΔG is negative) |
| A strong Hydrogen [H] bond will always be what shape? | Linear |
| How many [H] bonds does one molecule of H2O form in ice? | 4 bonds; 2 giving and 2 accepting e- |
| How many [H] bonds does one molecule of H2O have in liquid, on average? | 3.4 bonds |
| Define flickering cluster | Liquid water molecules held together by [H] bonds that are constantly being broken and reformed every 1-20 ps |
| Define the hydrophobic effect | forces, but not true bonds, holding nonpolar regions together; help form micelles & bilayers |
| List noncovalent interactions from weakest to strongest. | van der Waals < hydrophobic < [H] bonds < ionic |
| Osmosis | water movement across a semipermeable membrane driven by differences in osmotic pressure |
| Isotonic | solutions of equal osmolarity on both sides of the membrane |
| Hypertonic | a higher osmolarity (solute concentration) is outside the cytosol & the cell shrinks as water flows out |
| hypotonic | lower osmolarity (solute concentration) outside the cytosol & swells as water enters in |
| What is the equation for pH? | -log[H+] |
| What is the pH for 1.0 x 10-8 M HCL? What is the pOH? | pH = 8 pOH = 6 |
| What is more acidic, gastric juice or red wine? | Gastric Juice (pH = 1.5) Red wine (pH = 3.7) |
| What is more acidic, saliva or tears? | Saliva pH = 6.5 (same as milk) Tears pH = 7.2 (same as blood) |
| Define the Henderson-Hasselbach equation | pH = pKa + log [A-]/[HA] |
| Define buffer region. | The area = pKa (+/-)1 that is "resistant" to a change in pH from the addition of OH |
| What is the alpha-carbon in an amino acid? | the C-2 chiral center |
| How can you easily recognize an L or D amino acid? | Holding your hands palms up: -thumbs will be facing outward, representing amino group (given that COO- is oriented above alpha C & R is below) -if the amino group is on the left, L -if the amino group is on the right, D |
| Do intracellular environments promote oxidation or reduction? | Reduction |
| Do extracellular environments promote oxidation or reduction? | Oxidation |
| Name the only two amino acids suitable for buffering at pH = 7.0 | Cys & Hist |
| What is the average molecular weight of Amino Acid residue corrected for occurance? | 110 g/mol |
| Zwitterion | a dipolar ion with spacially separated positive and negative charges |
| define isoelectric pH. | pH at which the net electric charge is zero. pI = (pk1 + pK2)/2 |
| What type of bonds hold proteins together? | peptide bonds |
| How are peptide bonds formed? | dehydration synthesis |
| How are peptide bonds broken? | hydrolysis |
| How do peptide bonds compare to covalent bonds? | -shorter, stronger -double bond character -resonance -no rotation -planar -trans |
| How are amino acids written and read? | Amino to carboxyl, left to right (conventionally) |
| What is the pKa of an amino acid that is 6 residue groups apart? | pKa ~8.0 *For all residue groups >= 4 apart, pKa will remain approximately the same (around 8.0) since the two ends are so far apart inductive effect is basically zero |
| when are proteins least soluble? | at their pI -molecules are not attracting or repelling one another |
| What is the omega loop? | defined structure within the tertiary structure of a PPT chain without a recurring pattern -no two are alike -not a motif |
| What are the important bonds of a primary struture? | Peptide & disulfide bonds |
| What are the important bonds of a secondary struture? | [H] bonds |
| What are the important bonds of a tertiary struture? | Ionic, [H] bonds, van der Waals & hydrophobic effect |
| What are the important bonds of a quaternary struture? | Ionic, [H] bonds, van der Waals & hydrophobic effect |
| What affects pKa more: the inductive effect or the electrostatic effect? | electrostatic effect: stronger & operates over longer distances |
Created by:
crystalannskinner
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