BIOC6007 Worksheet 1 –

(2 10 mm)/(1 mm/s) 2 10 sBiomolecular Structure and Chemical Bonding.

Biochemistry (or the introductory chapters of an equivalent

ANSWERS TO BE SUBMITTED ELECTRONICALLY VIA

Q1. The properties and biological activities of biomolecules are largelyvaryethane(CH3CH3).The ascorbicfunctional groups, it is important to be able to identifydetermined by their

7. Identification of Functional Groups Figures 1–15 andshow some common functional groupsQF2. Figures 1–15 and 1–16 in Lehninger 1–16 show some common functional groupsshows some common functional groups circle and identify by name eachof biomolecules. Because the properties and biological activities of biomolecules arelargely determined by their functional groups, it is important to be able to identify them.

text).

Answer The properties of theTHE NEXT any othermolecules the two Qschemical structure. Because 1

QF1. Explain whydifferent impurities, the is of the in water may

by their group thegroups, it is important to

Q3.To study you should have some (a about the acid, of orlipid) in the you the from first needs to How it youother

conducting signals throughout the organism’s nervous system. Some axonal processes can be as longas 2 m—for example, the axons that originate in your spinal cord and terminate in the muscles of yourtoes. Small membrane-enclosed vesicles carrying materials essential to axonal function move along mi-crotubules of the cytoskeleton, from the cell body to the tips of the axons. If the average velocity of avesicle is 1 mm/s, how long does it take a vesicle to move from a cell body in the spinal cord to theaxonal tip in the toes?

Answer Transport time equals distance traveled/velocity, or

6 6

or about 23 days!

Reference: Chapters 1, 2 and 3 of Lehninger Principles of6. Is Synthetic Vitamin C as Good as the Natural Vitamin? A claim put forth by some purveyors of

health foods is that vitamins obtained from natural sources are more healthful than those obtained bychemical synthesis. For example, pure L-ascorbic acid (vitamin C) extracted from rose hips is betterthan pure L-ascorbic acid manufactured in a chemical plant. Are the vitamins from the two sources dif-ferent? Can the body distinguish a vitamin’s source?

TURNITIN BEFORE vitamin—like LECTUREcompound—are determined by its

BIOC6007 Worksheetvitamin– Forcesfromand formsources are structurally identical,their properties are identical, and no organism can distinguish between them. If different vitaminpreparations contain ethanol (CH3CH2OH)biologicalmoreeffectssoluble mixtures than is withthe source. acid in such preparations, however, is identical.

them. Using the figure given on page 3 (Figures 1–15 of Lehninger) which

of biomolecules. Because the properties and biological activities of biomolecules are largely deter-minedfunctionalfunctional compounds below. able to identify them. In each of the compoundsbelow, circle and identify by name each functional group.

In each of the compounds below, circle and identify by name each functional group.

HO

H C OH HO P

H3N

H

C

H

C OH

H

H

C

C

OH

OHH

C

O

C

H H H HEthanolamine

(a)Glycerol

(b)

O

C

Phosphoenolpyruvate,an intermediate inglucose metabolism

(c)

CH2

CH2

H

C

O

NH H C NH3

C O HO C H

H3N

H

C

C

H

OH

H

H3C

C

C

OH

CH3

H

H

C

C

OH

OH

CH3

Threonine, anamino acid

(d)

CH2OHPantothenate,

a vitamin(e)

CH2OHD-Glucosamine

(f )

QF3. In studying a particular biomolecule (a protein, nucleic acid, carbohy-drate, or lipid) in the laboratory, the biochemist first needs to separate it from otherbiomolecules in the sample—that is, to purify it. Specific purification techniques aredescribed later in the course. However, by looking at the monomeric subunits of abiomolecule,a particular biomolecule ideasprotein, nucleiccharacteristicscarbohydrate,molecule thatwould allowlaboratory,separatebiochemistother molecules.separatewouldfrom separate (a) aminoacids from fatty acids and (b) nucleotides from glucose?

QF4. When we cook an egg the proteins denature, but do not degrade. Why? Answerwith a definition of molecular denaturation vs degradation and discuss the relativeresistance of weak forces and strong forces to heating.

biomolecules in the sample—that is, to purify it. Specific purificationtechniques are described later in the course. However, looking at themonomeric subunits of a biomolecule, you should have some ideas about thecharacteristics of the molecule that would allow you to separate it from othermolecules.How would you separate

(a) An amino acids from fatty acids(b) nucleotides from glucose?

Q4. Why does water have a dipole? Draw a molecule of water to illustrateyour answer.

Q5. Why is water a good solvent for polar biomolecules such as sugars,nucleic acids and most amino acids?

Q6. Describe how the properties of water cause partition of hydrophobic andhydrophilic molecules. (Another way to think about this question is “Why domembrane phospholipids and sterols form a bilayer in the presence ofwater?”)

Q7. Which type of bond is stronger: A. A hydrogen bond? B. An C-H bond? C.An ionic bond?

Q8. Protein folding and protein-protein interactions are mediated primarily byvan der Waals, hydrogen bonding and the so-called hydrophobic effect. Whyis it important that weak forces, and not strong forces, mediate biomolecularrecognition?

Q9. Acetic acid is a weak acid and in water is in equilibrium between a neutralform and an ionized form.

CH3COOH⇔ CH3COO- + H+

If the pKa of acetic acid is approximately 4.5. What fraction of the acetic acidwill be in the neutral (uncharged form) at a) pH 3.5 b) 4.5 and c) 5.5

Q10. Explain why the amino acid Alanine is chiral whereas the amino acidGlycine is not.