bio 02 midterm1a_key

7/25/2019 Bio 02 Midterm1a_key

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multiple choice (circle correct answer(s)) [2 pt each unless marked]1. Molecules which possess both hydrophobic and hydrophilic regions are called

A. fatty acidsB. amphipathicC.reducedD.aliphatic

2. The organelle that modies membrane proteins with polysaccharide chains andsorts membrane products to different cellular compartments is the:A. chloroplastB.cytosolC.endoplasmic reticulumD.golgi apparatus

3. Circle all of the organelles that are widely considered to have derivedendosymbiotically in bacteria (4 pts)A.nucleusB. chloroplastC.lysosomeD. mitochondriaE. golgi apparatus

4. Most of the dry (non-water) mass of cells is in the form of:A. phospholipidsB. cytoskeletonC.polymeric macromoleculesD.small molecules like amino acids

5. A micron is how many meters?A.10 -3

B.10 -5

C.10 -6

D.10 -9

6. Which is the most reduced form of carbon?A.CH 3 OH (methanol)B.CH 4 (methane)C.CO 2D.CH 2 O (formaldehyde)

7. What changes when a competitive inhibitor of an enzyme is added to a reaction?A. VmaxB. KMC.Equilibrium concentrationsD.The enzyme active site

BIO 002 MIDTERM EXAM 1A Feb 19, 2010 SPRING 2010

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8. The type of bond between nucleotides in DNA is called aA. condensation bondB. polar covalent bondC.peptide bondD.phosphodiester bond

9. Which statement is false ?A. An enzyme is a catalyst.B. Both electron and light microscopy allow you to watch living cells and tissue.C.It took about 200 years before the discovery of cells and the recognition that all

living things are made of cells.D.A homologous gene from a human being can rescue a thermosensitive essential

mutant gene in Yeast.

10.Margarine contains vegetable-derived fatty acids that are articially_______________ by bubbling hydrogen gas through them. The resultinghydrogenation reaction _____________ the fatty acid chains (4 pts).

A. unsaturated; reducesB. unsaturated; oxidizesC.saturated; reducesD.saturated; oxidizes

true or false [2 pt each]11.More complex organisms like humans have larger genomes than less complex

organisms like amoebasA.TrueB.False

12.Without chloroplast organelles, prokaryotes are incapable of performingphotosynthesis.A.TrueB.False

13.When an enzyme is added to a reaction, its K or equilibrium must be recalculated.A.TrueB.False

14.Membrane proteins are made by cytosolic ribosomes after the ribosomes attach tothe endoplasmic reticulum.

A.TrueB.False

15.The phosphate group that differs between NADH and NADPH has functionalconsequences for their reduction/oxidation potential.A.TrueB.False


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connections16.Draw lines connecting terms and their denitions or properties (2 pt).

Actin laments pull chromosomes, acts like "railroad tracks"for vesicle and organelle movement

Intermediate laments strengthen the cell mechanically

Microtubules generate contractile forces like in muscle

17.Draw lines connecting terms and their denitions or properties (3 pts).

Arabidopsis fruit y, important for genetics

Saccharomyces transparent worm

Drosophila small plant

Caenorhabditis brewer's yeast


GTP base

Guanosine nucleotide

Guanine nucleoside


Leucine hydrophobic

Cysteine aromatic

Lysine basic

Tryptophan sulfur-containing

20.Draw lines connecting one-letter abbreviations with amino acids (3 pts).

D Glycine

G Glutamic Acid

E Alanine

A Aspartic Acid


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ll-in-the-blank (4 pts).

1. ______________ reactions break down food molecules for energy and smallmolecules and ______________ reactions build up macromolecules inbiosynthesis. catabolic, anabolic

2. Macromolecules are made of subunits held together by ______________ bonds,while macromolecular complexes are typically held together by _______________bonds and interactions. covalent, noncovalent

3. Two activated carriers differ by a phosphate group. One is predominantly in thereduced form ______________ where it participates in reducing other molecules inbiosynthesis. The other is predominantly in the oxidized form ____________ whereit participates in oxidizing food molecules. NADPH, NAD+

4. Many of the macromolecules in a cell are built up through _____________ reactionsthat generate water, and are broken down through the reverse ____________reactions that consume water. condensation, hydrolysis

5. (6 pts) An enzyme _______________ a specic reaction by lowering its_____________ energy, but it does not change the thermodynamics of the reactionas specied by its ___________ energy. catalyzes, activation, free or standard free

short answer6. Which four atomic elements make up most of living matter? Give the full names. (4

pts) Carbon, Hydrogen, Nitrogen, and Oxygen.

7. What is the approximate volume of a typical mitochondrion in cubic meters? Showwork and give units for full credit. (4 pts) Mitochondria are 1-10 microns (+2) the sizeof bacteria because they originated endosymbiotically from bacteria (+2). (10 -5 )3 =10 -15 cubic meters or 4pi/3 (5 x 10 -6 )3 = about 4 * 125 * 10 -18 cubic meters = 5 x 10 -16

cubic meters (+1 for right math and +1 for right units).

8. Explain why the formation and repair of lipid bilayers is spontaneous. Include in yourexplanation a discussion of the role of entropy and why it increases during theformation and repair of lipid bilayers. (4pts)

Lipid bilayers spontaneously form and repair because phospholipids areamphipathic / have hydrophilic and hydrophobic ends (+1). Exposure of hydrophobicends to water causes a "cage-like" ordering of water molecules (+2). The entropy ofthe water increases during formation and repair of bilayers which more thancompensates for the increase in order of the bilayer, increasing entropy of theuniverse according to the second law of thermodynamics (+1).


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9. Explain how and where in the cell new lipid bilayers are synthesized.A. (2 pts) Which organelle is involved, and where in that organelle does synthesis

occur? The cytosolic face (+1) of the ER (+1)

B. (1 pt) What problem for the cell does this synthesis pathway create? addition

occurs in only the cytosolic monolayer. (+1)

C. (1 pt) What is the name for an important family of enzymes involved in lipidbilayer synthesis that solves this problem? Flippases (+1)

D. (2 pts) What reaction do these enzymes catalyze and why are enzymesnecessary for this? They ip-op phospholipids (+1) which is necessary becauseip-opping between monolayers is rare (+1). (+1 for catalyze reaction or loweractivation energy)

10. A G:C base-pair has one more hydrogen bond than an A:T base-pair. Suppose that one hydrogen bond contributes [ -0.616 ln(5) ] kcal/mole in

standard free energy stabilization to a base-pair. Use the fact that RT = 0.616 when using natural logarithms to the base e at 37C. Consider separately the two reactions A + T A:T and G + C G:C at 37C.

How many times larger will the equilibrium constant be for the G + C G:C

reaction over the A + T A:T reaction? Show work for full credit. (6 pts)

K_GC/K_AT = exp(x 0.616 ln(5) /RT) / exp(x /RT)= exp(x /RT) * exp( 0.616 ln(5) /RT) / exp(x /RT)

= exp( 0.616 ln(5) / 0.616)+2 for writing down correct relationship between f.e. and e.c. at equilibrium +2for writing the correct ratio of equilibrium constants between the two systemsor assuming ! G_GC = 1.5 * ! G_AT, +2 for solving correctly . Full credit for

11.Consider the reaction X Y with ! G = -6.4 kcal/mole, and a sequentially coupled

reaction Y Z with some unknown ! G. If the concentration ratio [Z]/[X] is e 1 at

equilibrium at 37C, what is the ! G of the reaction Y Z? Use the fact that RT at

37C is 0.616 when using base e logarithms and show units (6 pts).

! G XZ = RT ln(e 1 ) = 0.616 (+2)

0 = ! G XY + ! G YZ 6.4 + x =

! GYZ = 6.4 + 0.616 = 7.016 kcal/mole (+1 for units)


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bio 02 midterm1a_key

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