BCHM 307 Exam 1 2 Combined Updated

pg. 1 BCHM 307 Exam 1 & 2 Combined Updated Actual Exam Questions and Correct Detailed Answers (Verified Answers) Already Graded A+

BCHM 307 EXAM 1/ Questions and 100% verified Answers

All amino acids are based upon the same general structure which includes - Correct Answer - an alpha carbon, an amino group, a carboxyl group and a R group

There are 4 different substituents attached to the alpha-carbon, thus most amino acids are __. __ is the only exception because its R group is H. - Correct Answer - chiral; gLYCINE

Name the four types of small biological molecules. Which three are capable of forming polymeric structures? What are the names of the polymeric structures that are formed?

• Correct Answer - Amino acids, monosaccharides, nucleotides, and lipids are the four

types of biological small molecules. Amino acids, monosaccharides, and nucleotides can form polymers of proteins, polysaccharides, and nucleic acids, respectively.

A healthy diet must include some protein. Assuming you had a way to measure the amount of each element in a sample of food, which element would you measure in order to tell whether the food contained protein? - Correct Answer - You should measure the nitrogen content, since this would indicate the presence of protein (neither lipids nor carbohydrates contain appreciable amounts of nitrogen).

Which has the greater entropy, a polymeric molecule or a mixture of its constituent monomers? - Correct Answer - The polymeric molecule is more ordered and thus has less entropy. A mixture of constituent monomers has a large number of different arrangements (like the balls scattered on a pool table) and thus has greater entropy. 1 / 4

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What amino acids have hydrophobic R groups? - Correct Answer - alanine, valine, phenylalanine, tryptophan, leucine, isoleucine, methionine, proline

What amino acids have polar R groups? - Correct Answer - serine threonine, tyrosine, asparagine, glutamine, cysteine, histidine

Cysteine and histidine have R groups that can what? - Correct Answer - ionize via cation

What amino acids have charged polar R groups? - Correct Answer - lysine, arginine, aspartate, glutamate

Why are most enzymes globular rather than fibrous proteins - Correct Answer - A globular protein can bind substrates in a sheltered active site and can support an arrangement of functional groups that facilitates the reaction and stabilizes the transition state. Most fibrous proteins are rigid and extended and therefore cannot surround the substrate to sequester it or promote its chemical transformation.

Which compound has a higher boiling point, H2O or H2S? Explain. - Correct Answer - Water has the higher boiling point because, although each molecule has the same geometry and can form hydrogen bonds with its neighbors, the hydrogen bonds formed between water molecules are stronger than those formed between H2S molecules. The electronegativity difference between H and O is greater than that between H and S and results in greater differences in the partial charges on the atoms in the water molecule.

Explain why water forms nearly spherical droplets on the surface of a freshly waxed car.Why doesn't water bead on a clean windshield? - Correct Answer - The waxed car is a hydrophobic surface. To minimize its interaction with the hydrophobic molecules (wax), each water drop minimizes its surface area by becoming a sphere (the geometrical shape with the lowest possible ratio of surface to volume). Water does not bead on glass, because the glass presents a hydrophilic surface with which the water molecules can interact. This allows the water to spread out.

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pg. 3 Molecules with a polar or charged groups are said to be what? - Correct Answer – Hydrophilic

What kind of lipid is cholesterol? - Correct Answer - amphiphilic isoprenoid

Why do double bonds affect the melting point of a substance? - Correct Answer - causes kinks which means that they can't pack tightly therefore lowering the melting point

What kind of diffusion across the lipid membrane is rapid? - Correct Answer - lateral

What kind of diffusion across the lipid membrane is thermodynamically unfavroable? - Correct Answer - transverse

What does scramblase do? - Correct Answer - moves lipids in either direction, toward equilibrium

What does flippase do? - Correct Answer - moves lipid from lumen to cytosol

What does floppase do? - Correct Answer - moves lipids from cytosol to lumen

Some amino acids are made directly from common metabolic intermediates.. alanine is made from ___ - Correct Answer - pyruvate

Some amino acids are made as products from long and complex pathways.. aromatic amino acids from the ___ - Correct Answer - shikimic acid pathway

The essential amino acids - Correct Answer - 1. Arginine

• Histidine
• Isoleucine
• Leucine 3 / 4

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• Lysine
• Methionine
• Phenylalanine
• Threonine
• Tryptophan
• Valine

Individual hydration of dispersed nonpolar molecules does what to the entropy of the system? - Correct Answer - decrease it

The aggregation of the nonpolar molecules does what to the entropy of the system? - Correct Answer - increase it

Myosin has two heads and a long tail, where do the heads bind? - Correct Answer - actin and an adenine nucleotide

What drives the physical movement of myosin? - Correct Answer - ATP hydrolysis

Myosin-actin reaction cycle - Correct Answer - 1. ATP binding alters the conformation of the myosin head so that it releases actin

• The rapid hydrolysis of ATP to ADP + Pi triggers a conformational change that rotates

the myosin lever and increases the affinity of myosin for actin

• Myosin binds to an actin subunit further along the thin filament
• Binding to actin causes ADP and Pi to be released. Myosin lever returns to its original

position and causes the power stroke. ATP replaces the lost ADP to repeat the cycle

Kinesin has two globular heads and two light chains, what do the two light chains interact with? - Correct Answer - the vesicles (the cargo)

What does kinesin move along? - Correct Answer - microtubules

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