Final Exam BIOCHEM

Sort the gradient profiles expected for each of the four samples depicted in the figure. Drag the appropriate items to their respective bins.

dense DNA

Identify three possible components of a DNA nucleotide.

deoxyribose, phosphate group, thymine

In their first round of screening, Beadle and Tatum plated spores on minimal medium. The purpose of this screen was to _______

determine whether any auxotrophic mutants had been generated

A(n) _____ bond joins these two oxygen atoms. a. ionic b. quadruple covalent c. single covalent d. double covalent e. hydrogen

double covalent

In eukaryotic cells DNA has the appearance of a _____.

double helix

The tendency of an atom to pull electrons toward itself is referred to as its _____.

electronegativity

Ionic compounds can be readily dissolved in water because the high dielectric constant of water screens and decreases the ________ force between the oppositely charged ions.

electrostatic

The reaction ADP + P --> ATP is a(n) _____ reaction.

endergonic

This graph illustrates a(n) _____ reaction.

endergonic

Which of these reactions requires a net input of energy from its surroundings?

endergonic

What is the correct label for "A"?

energy of activation

Given the following peptide SEPIMAPVEYPK Estimate the net charge at pH=7. Assume the pKa values given in the table above.

-1

Calculate to three decimal places the charge on α-melanotropin at pHpH value of 11. Express your answer using three decimal places.

-1.827

Based on the half-life expression for a first-order reaction, determine its constant of proportionality?"

0.693

You have a racemic mixture of d-2-butanol and l-2-butanol. The d isomer rotates polarized light by +13.5∘. What is the rotation of the polarization of light of your mixture? Express your answer in degrees.

0∘

If trypsin cleavage gave two peptides, then where is(are) the S−S bond(s)?

1. Cys 1 - Cys 3 2. Cys 11 - Cys 15

The amino alcohol is a polar part of a glycerophospholipid and, thus, a hydrophilic (water-loving) section of the molecule. What is the common name for the amino alcohol present in the glycerophospholipid shown in Part A? Enter the common name of the amino alcohol.

ethanolamine

A(n) _____ reaction occurs spontaneously.

exergonic

The energy for an endergonic reaction comes from a(n) _____ reaction.

exergonic

The reaction A --> B + C + heat is released in a(n) _____ reaction.

exergonic

Hershey and Chase used _____ to radioactively label the T2 phage's proteins.

35S

What is the complementary DNA sequence to 5′ ATGCTTGACTG 3′?

5′ CAGTCAAGCAT 3′

Where would RNA polymerase attach?

A

In cells, what is usually the immediate source of energy for an endergonic reaction?

ATP

Categorize each of the following carbohydrates as an aldopentose, aldohexose, or ketohexose. Drag the appropriate items to their respective bins.

Aldohexose: Gulose Aldopentose: Lxysose, Xylose Ketohexose: Psicose

Select the statement that is incorrect.

All carbohydrates have the general formula Cn(H2O)n .

Examine the molecular model of the K+ channel KcsA from Streptomyces lividans. Regions with charged amino acids can be found primarily in all of the following locations, EXCEPT in __________.

the transmembrane region

Which terms describe two atoms when they form a bond in which electrons are completely transferred from one atom to the other?

Anion and cation.

Review the molecular model of the sarcomere from skeletal muscle. Which component of the actin / tropomyosin / troponin complex in the sarcomere is able to bind to four calcium ions?

the troponin C subunit of the troponin heterotrimer

For which of the following may GFP fusion technology NOT be a good technique to use?

for target proteins whose structure is altered by a GFP fusion

Each water molecule is joined to _____ other water molecules by ____ bonds.

four ... hydrogen

Look again at the molecular model of the K+ channel KcsA from Streptomyces lividans. In what state are the K+ ions when they reside in the spacious 10-angstrom diameter cavity, prior to translocating through the selectivity pore?

fully hydrated

What is energy coupling?

the use of energy released from an exergonic reaction to drive an endergonic reaction

Do you think apamine is synthesized in the form CNCKAPETALCARRCQQH, or is it more likely a product of proteolytic cleavage of a larger peptide? Explain.

Apamine does not have an N-terminal methionine, so at least some proteolytic cleavage must be involved in its synthesis.

Which of the following polysaccharides are NOT constituents of the fibrous parts of plants?

glucans

Maltose has a (1→4) α linkage between glucose and ________.

glucose

From the previous part, estimate the H−O bond energy. Express your answer with the appropriate units.

Bond energy =463 kJmol

What will happen to the rates of the forward and reverse reactions when a catalyst is added?

Both forward and reverse rates increase.

Identify Structure A.

glycoprotein

The minor groove contains less information about the identity of base pairs than the major groove because of the

glycosidic bond angles and structure of pyrimidine bases.

Two monosaccharides are joined by a __________ to make a __________.

glycosidic bond, disaccharide

In this reaction ______.

heat has been released to the environment

Plant cells and animal cells share many of the same structures, but each type of cell also has unique structures. In this activity, you will indicate which cell structures are found only in plant cells, only in animal cells, or in both plant and animal cells.

Drag each cell structure to the appropriate bin. If a structure is found in both plant cells and animal cells, drag it to the "both" bin.

Which of these DNA molecules is the shortest?

E

Which of the following effects is NOT true?

If stripped Hb is treated with 2,3-BPG, the O2-binding curve for Hb will shift left.

When the reactions in part (B) are repeated in the presence of 12 μM of an uncompetitive inhibitor, the y-intercept of the Lineweaver-Burk plot is 0.352 (μmol−1 ml s). Calculate K′I for this inhibitor. Express your answer with the appropriate units.

K′I = 1.45×10^−7 M

In eukaryotic nerve cells, K+ concentrations at rest are __________.

higher inside the cell than outside the cell

The side chain of ________ has a pKa in the physiological pH range and is therefore often involved in proton transfer during enzymatic catalysis.

histidine

The conserved residues in the hemoglobins and myoglobins include the ________ proximal and distal to the heme iron.

histidines

The letter C indicates _____.

histones

If a mixture of these three substrates was presented to elastase with the concentration of each peptide equal to 0.5 mmmm, which would be digested most rapidly? Which most slowly? (Assume enzyme is present in excess.) Rank from most rapidly to most slowly.

Most Rapidly PAPA(Down)F PAPA(Down)A PAPA(Down)G Most Slowly

Which monomers make up RNA?

Nucleotides

The strength of a stimulus (for example, whether you feel a slight pain versus an intense pain) determines the number of action potentials sent along an axon. As the graphs show, a strong stimulus produces more action potentials spaced more closely together than a weak stimulus. The time between when a first action potential ends and a second action potential can be triggered is determined by the axon's refractory period. A second action potential cannot be triggered until the end of the refractory period.

how long it takes for the voltage-gated Na+ channels to reactivate at the end of an action potential

Which of these two possible hydrogen-bonding interactions is more likely to occur? (Hint: Consider resonance structures for formamide.)

hydrogen bond 1

in each case, tell whether a sngle-nucleotide change s sufficient for the mutaton

in each case a single base change could give rise to the mutation

What happens to these physical properties as the strength of intermolecular forces increases? Drag each item to the appropriate bin.

increase: Melting Point, Boiling Point, Viscosity, Surface Tension Decrease: Vapor Pressure

Which of the following would increase the rate of the reverse reaction?

increasing the concentration of ammonia

In a DNA double helix an adenine of one strand always pairs with a(n) _____ of the complementary strand, and a guanine of one strand always pairs with a(n) _____ of the complementary strand.

thymine ... cytosine

What behavior is observed if the voltage across a neuronal membrane is set to -20 mV?

The sodium channel opens, and Na+ ions flow in.

Is this a fairly efficient enzyme? (See table below)

Yes, this is a very efficient enzyme.

If you were to try and pair a thymine with a cytosine (a non Watson-Crick base pairing), then would you expect to see any stability with respect to the hydrogen bonding (assuming the geometrical configurations of both bases were favorable to each other)? If yes, then how many hydrogen bonds could form between these two bases?

Yes, two hydrogen bonds could form between thymine and cytosine.

A reaction at its lowest energy state for the system and with equal rates in the forward and reverse directions is said to be at ________.

equilibrium

Fetal Hemobglobin

false

The secondary structure of a protein results from _____.

hydrogen bonds

calcium regulates muscle contraction by binding to

myosin

The nucleotide sequence of a polynucleotide chain is called the ________ structure.

primary

All proteins are synthesized by ribosomes in the cell. Some ribosomes float freely in the cytosol, while others are bound to the surface of the endoplasmic reticulum. Most proteins made by free ribosomes function in the cytosol. Proteins made by bound ribosomes either function within the endomembrane system or pass through it and are secreted from the cell. Which of the following proteins are synthesized by bound ribosomes?

insulin ER protein lysosomal enzyme

at B146 (HC3) h

the effect is an increase in oxygen affinty

In salt, what is the nature of the bond between sodium and chlorine?

ionic

An enzyme _____.

is an organic catalyst

As a result of its involvement in a reaction, an enzyme _____

is unchanged

which would be better for seperationL Gel or iso

iso

What type of protein secondary structure does the structure shown here (Figure 1) represent?

β-sheet

For the structure on the right, add either H or O−H to create the enantiomer of the structure on the left. Drag the appropriate labels to their respective targets.

just flip the Hs and OHs

Calculate kcat/KM for the enzyme reaction. Express your answer to two significant figures and include the appropriate units.

kcat/KMkcat/KM = 8.50×10^7 (M⋅s)−1

Classify the carbohydrate tagatose by both the carbonyl group and the number of carbon atoms. Enter the classification (e.g., aldotriose).

ketohexose

Beginning within the nucleus, the first step leading to the synthesis of a polypeptide is _____.

transferring of information from DNA to messenger RNA

After allowing phages grown with bacteria in a medium that contained 32P and 35S, Hershey and Chase used a centrifuge to separate the phage ghosts from the infected cell. They then examined the infected cells and found that they contained _____, which demonstrated that _____ is the phage's genetic material.

labeled DNA ... DNA

Which sugar molecule listed below has the following name? β-D-galactopyranosyl(1→ 4)β-D-glucopyranose

lactose

The Beadle and Tatum experiments were based on all of the following assumptions except that _______

two strains of auxotrophic Neurospora that grow on minimal medium supplemented with biotin have mutations in the same gene

Inhalation and exhalation move air into and out of the lungs. What happens when you inhale and exhale? Drag the labels to the correct locations on the flowchart to identify the steps of inhalation and exhalation.

(1) Diaphram and rib muscles contract (2) Lung volume increases. (3) Air moves into the nose and down the trachea, bronchi, and bronchioles. (4) Air enters alveoli. (5) Oxygen diffuses into the blood, CO2 diffuses into alveoli. (6) Diaphragm and rib muscles relax. (7) Lung volume decreases. (8) Air moves out of the alveoli. (9) Air moves up bronchioles, bronchi, and trachea. (10) Air leaves nose or mouth.

In an enzyme-catalyzed reaction, the reactant species to which the enzyme binds is called the substrate. The substrate is then converted into products by a series of steps. The lock-and-key model explains the steps involved in an enzyme-catalyzed reaction. Label the following diagram that illustrates the lock-and-key model of enzyme activity. Drag the appropriate labels to their respective targets.

left to right Active Site ---> Enzyme Substrate Complex ----> Enzyme ------> Products

Sort the gradient profiles expected for each of the four samples depicted in the figure. Drag the appropriate items to their respective bins.

light DNA

Estimate the net charge at pH=12. Assume the pKa values given in the table above. Express your answer as an integer.

-4

List two differences you would expect to see in the composition of lipids in the E. coli membrane when the cells are incubated at 25 ∘C∘C compared to incubation at 37 ∘C∘C. Match the words in the left column to the appropriate blanks in the sentences on the right. Make certain each sentence is complete before submitting your answer.

. The membranes of cells grown at 25 °C would have (i) shorter fatty acids with (ii) a greater number of cis- double bonds compared to the membranes of cells grown at 37 °C.

The rate constant for a certain reaction is k = 8.30×10−3 s−1 . If the initial reactant concentration was 0.850 M, what will the concentration be after 4.00 minutes? Express your answer with the appropriate units.

0.116 M

Now assume you wish to make a buffer at the same pH, using the same substances, but want the total phosphate molarity ([HPO42−]+)([H2PO42−]) to equal 0.30. What concentration of the KH2PO4 would be required?

0.13 M

Suppose you wanted to make a buffer of exactly pH 7.00 using KH2PO4 and Na2HPO4. If the final solution was 0.10 MM in KH2PO4 what concentration of Na2HPO4 would you need? (pKa for H3PO4, H2PO−4, and HPO42− are 2.14, 6.86, and 12.40, respectively.)

0.14M

Now assume you wish to make a buffer at the same pH, using the same substances, but want the total phosphate molarity ([HPO42−]+[H2PO4−]) to equal 0.30. What concentration of the Na2HPO4would be required?

0.17 M

Each gram of mammalian skeletal muscle consumes ATP at a rate of about 1×10−3mol/min1×10−3mol/min during contraction. To bridge the short interval between the moderate demand for ATP met by aerobic metabolism and the high demand met by anaerobic ATP production, muscles carry a small reserve of the compound creatine phosphate which, due to its high phosphoryl group transfer potential (see the figure on the left), is capable of phosphorylating ADP very efficiently. The reaction is catalyzed by the enzyme creatine kinase: Because the equilibrium lies well to the right, virtually all of the muscle ADP or AMP is converted to ATP as long as creatine phosphate is available. Concentrations of ATP and creatine phosphate in muscle are about 4 mMmM and 25 mMmM, respectively, and the density of muscle tissue can be taken to be about 1.2 g/cm3g/cm3.How long could contraction continue using ATP alone? Express your answer to one significant figure and include the appropriate units.

0.2 s

Complete this vocabulary exercise relating to the three types of enzyme inhibitors. Drag the words on the left to the appropriate blanks in the sentences on the right. Each word is used only once.

1. A (n)competitive inhibitor has a structure that is so similar to the substrate that it can bond to the enzyme just like the substrate. 2. A (n)noncompetitive inhibitor binds to a site on the enzyme that is not the active site. 3. Usually, a(n) irreversible inhibitor forms a covalent bond with an amino acid side group within the active site, which prevents the substrate from entering the active site or prevents catalytic activity. 4. The competitive inhibitor competes with the substrate for the active site on the enzyme. 5. When the noncompetitive inhibitor is bonded to the enzyme, the shape of the enzyme is distorted. 6. Enzyme inhibitors disrupt normal interactions between an enzyme and its substrate.

Complete this vocabulary exercise relating to enzymes. Match the words in the left-hand column to the appropriate blank in the sentences in the right-hand column.

1. An enzyme is denaturedwhen it loses its native conformation and its biological activity. 2. An enzyme is considered a catalystbecause it speeds up chemical reactions without being used up. 3. An enzyme is considered specificbecause of its ability to recognize the shape of a particular molecule. 4. A cofactor, such as a vitamin, binds to an enzyme and plays a role in catalysis. 5. When properly aligned, the enzyme and substrate form an enzyme-substrate (ES)complex. 6. A substrate binds to an enzyme at the active site, where the reaction occurs. 7. In a catalyzed reaction a reactant is often called a substrate.

Shown above is a schematic diagram of the E. coli leader peptidase (Lep) which has several basic amino acids in a cytoplasmic loop. Propose a mutant of Lep that would be a test of the "inside positive" rule for the orientation of proteins in membranes. Match the words in the left column to the appropriate blanks in the sentences on the right. Make certain each sentence is complete before submitting your answer.

1. Make a mutant Lep that substitutes noncharged residues for the (+) charged side chains in the loop, and put (+) charged side chains in terminal positions. 2. If the inside-positive rule applies, the mutant ought to have the reversed orientation in the membrane.

It is possible to make a buffer that functions well near pH 7 using citric acid, which contains only carboxylate groups. Drag the terms on the left to the appropriate blanks on the right to complete the sentences.

1. Successive deprotonation increase the (-) charge density on resulting anion. 2. This results in unfavourable electrostatic repulsions between the carboxylate anion which reduce the likelihood that a proton would dissociate. 3. It is more favourable for proton to remain bound to reduce unfavourable charge repulsions.

Complete the following vocabulary exercise relating to the level of structure in proteins. Match the words in the left-hand column with the appropriate blank in the sentences in the right-hand column.

1. Tertiary structure is achieved when a protein folds into a compact, three-dimensional shape stabilized by interactions between side-chain R groups of amino acids 2. Primary structure is the sequence of amino acids in a protein. 3. Secondary structure describes the alpha-helices and beta-sheets that are formed by hydrogen bonding between backbone atoms located near each other in the polypeptide chain. 4. Quaternary structure is the result of two or more protein subunits assembling to form a larger, biologically active protein complex.

Suppose that an artificial non-gated K+ channel could be inserted into the plasma membrane of an axon at resting potential (membrane potential = -70 mV). Assume that the axon has not recently produced an action potential. What would happen when an artificial K+ channel is inserted into an axon membrane at resting potential? Answer questions 1-4 by selecting only from the three answer choices to the left of each question. Drag the correct answer to the right of each question.

1. out of the cell 2. promote 3. impede 4. causes a hyperpolarization

The enzyme urease catalyzes the hydrolysis of urea to ammonia plus carbon dioxide. At 21 ∘C the uncatalyzed reaction has an activation energy of about 125 kJ/mol, whereas in the presence of urease the activation energy is lowered to about 46 kJ/mol. By what factor does urease increase the velocity of the reaction? Express your answer using two significant figures.

1.1⋅10^14

An individual "step" by a myosin head in one cycle pulls the thin filament about 15 nmnm. How many steps must each actin fiber make in one contraction? Express your answer as integer.

10 step(s)

Using the in table below, calculate the average amino acid residue weight in a protein of typical composition. This is a useful number to know for approximate calculations.

110.76

What is the pH of an aqueous solution with the hydronium ion concentration[H3O+] = 2 x 10-14 M ?

13.7

Aquaporin-1 exists in the cell membrane as a tetramer. Each monomer is a water channel that can hold 4 molecules of water at a time. How many water molecules would be present in a complete aquaporin complex in the membrane of a red blood cell at one time?

16

In the second step of the cloning procedure, DNA fragments produced by a restriction enzyme are inserted into a cloning vector that has been cut by the same enzyme. The vector used in this tutorial is a plasmid. To clone the vgp gene into the plasmid below, a restriction enzyme must do all of the following: cut the human DNA on both sides of the vgp gene, but not inside the gene cut the plasmid without cutting inside the ampicillin resistance gene (ampR ), shown in blue (The importance of the ampR gene will be explained in Part C.) produce sticky ends when it cuts both the human DNA and the plasmid, so that the human DNA fragments can combine with the plasmid Answer questions 1-4 by selecting from the answer choices on the left. Drag the correct answer to the right of each question.

1: BamHI, HaeIII, and HindIII 2: BamHI, EcoRI, and HaeIII 3: BamHI, EcoRI, and HindIII 4: BamHI only

Match the following characteristics to α helices, β sheets, or both. 1) 5.4Å/turnA) α helices2) antiparallel arrangementB) β sheets3) large dipole momentC) both4) extensive H-bonding network

1:A; 2:B; 3:A; 4:C

Match the appropriate cells with the correct immune response. 1) T lymphocytesA) adaptive immune response2) B lymphocytesB) humoral immune response3) macrophagesC) cellular immune response4) immunoglobulins

1:C; 2:B; 3:B; 4:B

Arrange the order of events in the correct sequence for the conversion of β-D-galactose to lactose. 1) β-D-galactose-1-phosphate is converted to UDP-galactose. 2) ATP transfers a phosphate group to yield β-D-galactose-1-phosphate. 3) β-D-glucose reacts with UDP-galactose.

2-1-3

what PH gradient would u choose

2-7

Identify three possible components of a DNA nucleotide.

2-deoxyribose, phosphate group, thymine

Calculate to three decimal places the charge on α-melanotropin at pHpH value of 5. Express your answer using three decimal places.

2.104

Determine KM in the absence of inhibitor.

2.48 mmol/L

Determine KM in the presence of inhibitor.

2.55 mmol/L

Consider a small protein containing 101 amino acid residues. The protein will have 200 bonds about which rotation can occur. Assume that three orientations are possible about each of these bonds. Based on these assumptions, about how many random-coil conformations will be possible for this protein? Express your answers using two significant figures.

2.7×10^95

Determine Vmax in the presence of inhibitor.

2.97 (mmol/L)min−1

The lipid portion of a typical bilayer is about 30Å thick .Calculate the minimum number of residues in an αα-helix required to span this distance. Express your answer as an integer.

20 residues

Assuming that the T155 side chain cannot H-bond to the oxyanion intermediate, by how much (in kJ/mol) does N155 appear to stabilize the transition state at 37 ∘C? Express your answer to two significant figures and include the appropriate units.

20 kJ/mol

Base analysis of DNA from maize (corn) shows it to have 23 mole percent cytosine (moles per 100 moles total nucleotide). What are the percentages of the other three bases? What is the percentage of guanine?

23%

Choose the equation for a first-order reaction.

ln[A]t/[A]0=−kt

GFP fusion technology would be best used for which of the following experiments?

localizing the compartment where Golgi proteins are found

If a strand of DNA has the nitrogen base sequence 5'-ATTTGC-3', what will be the sequence of the matching strand?

3'-TAAACG-5'

What is this an image of?

loops

Write the complementary sequence for the following DNA sequence, in order from 3' to 5': 5′−CGATATTGAGCTAAGCTT−3′

3′− GCTATAACTCGATTCGAA −5′

How many H2H2 molecules are needed to completely hydrogenate the following triacylglycerol molecule? (Figure 2) Express your answer numerically as an integer.

4

How many chiral carbon atoms does the monosaccharide galactose have?

4

This atom can form up to _____ single covalent bond(s).

4

If you sketch the titration curve for α-melanotropin (SerTyrSerMetGluHisPheArgTrpGlyLysProVal), near what pHpH values would you expect the curve to exhibit inflections? Assume the pKaspKas of the NN- and CC-termini are 7.9 and 3.8, respectively. For side chains, assume the pKapKa values given. Express your answers as integers from lowest to highest separated by commas.

4,7,9,10,12

A solution is made by mixing 9.00 mmol (millimoles) of HA and 3.00 mmol of the strong base. What is the resulting pH? Express the pH numerically to two decimal places.

4.95

A new potential heart medicine, code-named X-281, is being tested by a pharmaceutical company, Pharma-pill. As a research technician at Pharma-pill, you are told that X-281 is a monoprotic weak acid, but because of security concerns, the actual chemical formula must remain top secret. The company is interested in the drug's Ka value because only the dissociated form of the chemical is active in preventing cholesterol buildup in arteries. To find the pKa of X-281, you prepare a 0.094 M test solution of X-281. The pH of the solution is determined to be 3.00. What is the pKa of X-281?

4.96

Which of the following DNA sequences is one strand of a restriction enzyme recognition sequence?

5' GGATCC 3'

Support your answer with the calculation of the pI of the mutant at pH=5.5. Assume that the only factors impacting the change in the pI are the side chains of the mutant protein.

5.1

Determine Vmax in the absence of inhibitor.

5.13 (mmol/L)min−1

Estimate the percent oxygen saturation of blood at 30 mmHgmmHg, the approximate partial pressure of O2O2 in venous blood. Express your answer using two significant figures.

56%

Using the data in the figure below, repeat the calculation of the previous part if the pH drops to 6.8 in capillaries but goes back to 7.4 as CO2 is unloaded in the lungs. The Bohr effect in hemoglobin. Express your answer using two significant figures.

63%

A zero-order reaction has a constant rate of 4.50×10−4 M/s . If after 80.0 seconds the concentration has dropped to 3.50×10−2 M, what was the initial concentration? Express your answer with the appropriate units.

7.10×10−2 M

Carbonated cola is more acidic than coffee or even orange juice because cola contains phosphoric acid. What is the molar concentration of [H3O+] in a cola that has a pH of 3.120? (For help with significant figures, see Hint 3.)

7.59 × 10−4

If a DNA double helix is 100 nucleotide pairs long and contains 25 adenine bases, how many guanine bases does it contain?

75

Explain in about one sentence why it is important to animals for the major carbohydrate storage polymer, glycogen, to be branched rather than unbranched. Drag the terms on the left to the appropriate blanks on the right to complete the sentences.

A branched polymer has far more terminal glucose residues than an unbranched polymer of equivalent molecular weight, thereby allowing a larger number of terminal glucose residues to be mobilized in the face of an energy demand. It seems likely that the enzyme and the polymer coevolved to meet the potential need for rapid mobilization.

Which of the following statements is not true of most cellular redox reactions?

A hydrogen atom is transferred to the atom that loses an electron.

Which of the following statements is NOT true?

A protein stripped of its cofactor or metal ion is known as a holoprotein.

To help achieve proper base pairing and hence form a double helix, which condition must be met?

A purine base must pair with a pyrimidine base.

Classify each statement as an example of adhesion, cohesion, or surface tension. Drag each statement to the appropriate bin.

ADHESION- Water molecules cling tothe side of a beaker. Water molecules clingto plant cell walls. COHESION- Water molecules areattracted to each other. A drop of water spilled on a tableforms a drop on the table, ratherthan spreading out over the surface. SURFACE TENSION- A water strider runs across a pondwithout breaking the surface. A sewing needle floats when itis placed gently on top ofwater in a bucket.

What is the structural difference between ATP and dATP?

ATP has a 2' OH and 3' OH dATP has a 2' H and 3' OH

Which term describes an electrical signal generated by neurons?

Action potential.

You have an enzymatic reaction proceeding at the optimum pH and optimum temperature. You add a competitive inhibitor to the reaction and notice that the reaction slows down. What can you do to speed the reaction up again?

Add more substrate; it will outcompete the inhibitor and increase the reaction rate.

An action potential moves along an axon due to the sequential opening of voltage-gated Na+ channels. The diagram below shows voltage-gated Na+ channels separated by a short distance in the plasma membrane of an axon. Initially (left panel), only channel (a) is open. Within a very short time (right panel), channel (b) also opens. Which statement correctly describes what causes the second voltage-gated Na+ channel to open?

After the first channel opens, the movement of many types of ions (both inside and outside the cell) alters the distribution of charges near the second channel, causing it to open.

Which of the following definitions are correct?1) An antigen is the substance that elicits an immune response.2) An epitope is a portion on the surface of an invading particle to which specific antibodies bind.3) An antibody is a specific immunoglobulin that binds to an antigen.

All of the listed definitions are correct.

Which of the following are distinguishing features of different disaccharides? 1) the arrangement of different monomer units 2) the configuration of the anomeric hydroxyl group of each residue 3) the two specific sugar molecules and their stereoconfigurations 4) the carbons involved in the linkage

All of the listed items are features.

The instructions for assembling polypeptides are contained in DNA. Consequently, mutations in DNA sometimes affect protein structure. A mutation will initially affect a protein's primary structure, but changes at higher levels of structure may follow. Point mutations are mutations that affect a single nucleotide pair in DNA. The figure below shows different types of point mutations and the effects they have on protein primary structure. In this activity, you will examine three different mutations. Drag the white and purple labels to the white targets to indicate what each mutant mRNA codon codes for. (You will probably need to consult the codon table for mRNA .) Drag the pink labels to the pink targets to indicate the type of mutation. Drag the blue labels to the blue targets to indicate the effect on the polypeptide's primary structure. Labels may be used once, more than once, or not at all.

Amino Acid: Val, Glu, Stop. Type of Mutation: substitution, substitution, substitution. Effect on Polypeptide: missense, silent, nonsense.

Which statement correctly describes amphipathic (or amphiphilic) helices and sheets?

Amphipathic helices and sheets have predominantly hydrophilic (or hydrophobic) residues on one face.

If a mutated DNA sequence produces a protein that differs in one central amino acid from the normal protein, which of the following kinds of mutations could have occurred?

An addition mutation and a deletion mutation.

Which of the following is not attached to the central carbon atom in an amino acid? An amino functional group An oxygen A side chain ("R group") A carboxyl functional group

An oxygen

Which of the following monosaccharides are ketoses? 1) xylulose 2) idose 3) tagatose 4) psicose

Answers 1, 3, and 4 are ketoses.

Identify the amino acids in the following tripeptide.

Arg-Val-Tyr

What is the sequence of angiotensin II?

Asp-Arg-Val-Tyr-Ile-Met-Pro-Phe

Which of the following events could result in a frameshift mutation?

Base deletion

Which of the following outcomes would be most likely if the Hershey-Chase experiments were repeated without the step involving the blender?

Both preparations of infected bacteria would exhibit radioactivity.

If a DNA-binding protein "reads" a short stretch of DNA and detects the following "second" genetic code provided by the functional groups located on each base as H-HD-CH3-HA-HA-HA-HA-HD, then what is the corresponding sequence of bases?

C-T-G-A

Hydrogenation of a monounsaturated fatty acid yields a saturated fatty acid. Oleic acid, CH3(CH2)7CH=CH(CH2)7CO2H, is a monounsaturated fatty acid. Predict the product of its hydrogenation: Express your answer as a condensed structural formula.

CH3(CH2)7CH=CH(CH2)7CO2Holeicacid H2⟶Pd catalyst product CH_3(CH_2)_16CO_2H

Why is Ca2+ important to the process of sarcomere shortening?

Ca2+ binds to the troponin complex, which results in exposure of the myosin binding sites on actin.

Suggest a method for separating the peptides produced by chymotrypsin treatment.

Chromatography on a cationic column, at pH=7 Electrophoresis

Consider the last two steps in the alcoholic fermentation of glucose by brewer's yeast:pyruvate+NADH+2H+⟶ethanol+NAD++CO2 Calculate the nonequilibrium concentration of ethanol in yeast cells, if ΔG=−38.3kJ/mol for this reaction at pH=7.4 and 37∘C when the reactants and products are at the concentrations given above.

Concentration =0.527 M

What do these answers tell you about the role of ATP in providing energy to cells?

Creatine phosphate must be continually produced in active muscle.

Spell out the full name of the amino acid.

D-Asparagine

Spell out the full name of the amino acid.

D-Threonine

Spell out the full name of the amino acid.

D-Valine

The radioactive isotope 32P labels the T2 phage's _____.

DNA

Which of the following statements best represents the central conclusion of the Hershey-Chase experiments?

DNA is the identity of the hereditary material in phage T2.

What enzyme forms covalent bonds between restriction fragments?

DNA ligase

If a DNA sequence is altered from TAGCTGA to TAGTGA, what kind of mutation has occurred?

Deletion.

What are the N-terminal and C-terminal residues for the following peptide sequence?Peptide sequence: EASY

E is the N-terminal residue; Y is the C-terminal residue

What is the role of Glu 270 and Arg 145 in catalysis? Match the words in the left column to the appropriate blanks in the sentences on the right. Make certain each sentence is complete before submitting your answer.

E270 acts as a GBC (general base catalyst) in step one and as a GAC (general acid catalyst) in step two. R145 provides specific ion-ion interactions with the CC-terminal carboxylate

Which of the following are sources of cholesterol for the body? Check all that apply.

Eating meats and eggs Drinking milk Synthesis in the liver from carbohydrates Synthesis in the liver from fats

What is the efficiency of the process in terms of the percentage of the available free energy change captured in ATP? Express your answer using three significant figures.

Efficiency = 35.9%

Which term describes the degree to which an element attracts electrons?

Electronegativity.

Sort the parts of a nucleic acid according to whether each occurs exclusively in DNA, exclusively in RNA, or in both types of nucleic acid.

Exclusively in DNA : Deoxribose and thymine Exclusively in RNA : Uracil and Ribose Both DNA and RNA : Adenine, Guanine, Cytosine and phosphate

What is the standard potential, E∘cell, for this galvanic cell? Use the given standard reduction potentials in your calculation as appropriate. Express your answer to three decimal places and include the appropriate units.

E∘cell =0.567 V

Glycine cannot serve as a buffer because it has two ionizable groups.

False

True or false? A codon is a group of three bases that can specify more than one amino acid.

False

True or false? The potential energy of a membrane potential comes solely from the difference in electrical charge across the membrane.

False

There are two properties that affect the conduction speed of an action potential along an axon: the axon's diameter and whether or not the axon is myelinated. Rank the axons from slowest to fastest conduction speed. If two axons have the same conduction speed, place one on top of the other.

Fastest - myelinated vertebrate axon 30μm Next - non myelinated invertebrate axon - 40μm next - non myelinated invertebrate axon - 30μm slowest - non myelinated invertebrate axon -20μm.

_____ are surface appendages that allow a bacterium to stick to a surface.

Fimbriae

The steady-state kinetics of an enzyme are studied in the absence and presence of an inhibitor (inhibitor A). The initial rate is given as a function of substrate concentration in the following table: v[(mmol/L)min−1] [S] (mmol/L) No inhibitor Inhibitor A 1.25 1.72 0.98 1.67 2.04 1.17 2.50 2.63 1.47 5.00 3.33 1.96 10.00 4.17 2.38 What kind of inhibition (competitive, uncompetitive, or mixed) is involved?

mixed

Which of the following can be inferred from the Beadle and Tatum experiments?

For a mutation resulting in the production of a defective enzyme involved in a biosynthetic pathway, the compound preceding the corresponding step will accumulate.

Explain this observation. Match the words in the left column to the appropriate blanks in the sentences on the right. Make certain each sentence is complete before submitting your answer.

In the former case, the binding epitope is composed of regions of the protein that are distant in primary sequence, but close in the folded structure (a discontinuous epitope). In the latter case, the binding epitope is composed of a contiguous amino acid sequence (a continuous epitope).

Consider a situation in which the enzyme is operating at optimum temperature and pH, and has been saturated with substrate. What is your best option for increasing the rate of the reaction?

Increase the enzyme concentration

What kind of bond is formed when lithium and fluorine combine to form lithium fluoride?

Ionic

What is the fate of the phosphate group that is removed when ATP is converted to ADP?

It is acquired by a reactant in an endergonic reaction.

The Hershey and Chase experiments involved the preparation of two different types of radioactively labeled phage. Which of the following best explains why two preparations were required?

It was necessary that each of the two phage components, DNA and protein, be identifiable upon recovery at the end of the experiment.

If ATP was removed from the cell, would the muscle be stiff or flaccid?

It would be stiff because the myosin head would be unable to release the actin binding site

What is the equilibrium constant for the reaction shown below at 25 ∘C?

K =17.6

Calculate the equilibrium constant K for the isomerization of glucose-1-phosphate to fructose-6-phosphate at 298 K. Express your answer numerically using two significant figures.

K =9.6

Rank the following compounds in order of decreasing boiling point: potassium bromide (KBr), carbon tetrafluoride (CF4), and chloroform (CHCl3) Rank from highest to lowest boiling point. To rank items as equivalent, overlap them.

KBr > CHCl3 > CF4

Calculate the equilibrium constant, and the equilibrium fraction of GAP from the above, at 37 ∘C. Express your answer using two significant figures.

Keq = 5.4×10−2

Find a start signal, and write the amino acid sequence that is coded for.5'...GCCAUGUUUCCGAGUUAUCCCAAAGAUAAAAAAGAG...3' Spell out the full name of the peptide. Name peptide using the one-letter abbreviations.

MFPSYPKDKKE

The epidermal growth factor receptor has a single transmembrane helix. Find it in this partial sequence:...RGPKIPSIATGMVGALLLLVVALGIGILFMRRRH... Enter the sequence.

MVGALLLLVVALGIGILFM

If malate concentration in yeast mitochondria is 0.4 mM, what is the maximum concentration of oxaloacetate needed to make the reaction exergonic at pH 7.0 and 37 ∘C? Express your answer with the appropriate units.

Maximum concentration = 2.63×10−4 mM

During translation, nucleotide base triplets (codons) in mRNA are read in sequence in the 5' → 3' direction along the mRNA. Amino acids are specified by the string of codons. What amino acid sequence does the following mRNA nucleotide sequence specify? 5′−AUGGCAAGAAAA−3′ Express the sequence of amino acids using the three-letter abbreviations, separated by hyphens (e.g., Met-Ser-Thr-Lys-Gly).

Met-Ala-Arg-Lys

Before a molecule of mRNA can be translated into a protein on the ribosome, the mRNA must first be transcribed from a sequence of DNA. What amino acid sequence does the following DNA template sequence specify 3′−TACAGAACGGTA−5′3′−TACAGAACGGTA−5′ Express the sequence of amino acids using the three-letter abbreviations, separated by hyphens (e.g., Met-Ser-His-Lys-Gly).

Met-Ser-Cys-His

Rank the following from most acidic to least acidic. Rank these items from most acidic to least acidic. To rank items as equivalent, overlap them.

Most Acidic [H3O+] = 10-2 > pH = 3 > pH = 5 > [H3O+] = 10-6 > pH = 14 Least Acidic

Describe the electrodes in this nickel-copper galvanic cell. Drag the appropriate items to their respective bins.

Nickle: anode, loses mass Copper: cathode, gains mass

Which mutation(s) would not change the remainder of the reading frame of a gene sequence that follows the mutation(s)?

One addition and one deletion mutation.

In the third step of the cloning procedure,all of the plasmids that were created in the second step are incubated with bacteria. The bacteria do not have an ampR gene on their own chromosome. As shown below, at least four classes of bacteria result. Notice that only one class contains the vgp gene

Only grow in medium without ampicillin: No plasmid Only grow in medium containing ampicillin:NONE Grow in both media: Recombinant plasmid with vgp gene Nonrecombinant Plasmid Recombinant plasmid with no vgp gene

Glycine and proline are both non-polar amino acids, and both are very likely to be found at the surface of proteins. What physical characteristic of each is responsible for this observation?1) Both glycine and proline are small.2) Glycine is small, and proline is rigid.3) The side chains of both these amino acids make favorable interactions with molecules near the surface of proteins.4) Both amino acids make strong interactions with each other and therefore are likely to be found next to each other in a protein.

Only statement 2 is correct.

Which of the following statements about the Bohr effect are true? 1) This is the effect of pH on the binding of O2 to Hb. 2) As blood travels from lung to tissue, there is a drop in pH, causing Hb to unload more oxygen than if there were no change in pH. 3) As blood travels from lung to tissue, there is an increase in pH, causing Hb to unload more oxygen than if there were no change in pH. 4) Myoglobin and Hb exhibit similar pH profiles.

Only statements 1 and 2 are correct.

Which of the following characteristics are true about a typical peptide (amide) bond?1) The bond is planar.2) There is free rotation about the carbonyl carbon and nitrogen bond.3) There is substantial double-bond character to this bond.4) There is a net negative charge on nitrogen and net positive charge on oxygen.

Only statements 1 and 3 are correct.

Hemoglobin (Hb) can be viewed as having two quaternary states, a low oxygen affinity state (T), and a high oxygen affinity state (R). Which of the following statements about the binding of O2 by Hb are true? 1) Upon binding a molecule of oxygen, Hb undergoes a conformational change that makes the binding of subsequent O2 molecules easier. 2) The conformational change induced in Hb upon binding oxygen is the result of a small movement (0.2 Å) of the iron cation in the center of heme. 3) Site-directed mutagenesis studies have indicated that the cooperativity of O2 binding in Hb is attributable to the movement of the F helix in Hb. 4) Site-directed mutagenesis studies in which the proximal His residues of the F helix have been replaced by glycines have indicated the mutant protein still shows cooperativity of O2 binding.

Only statements 1, 2, and 3 are true.

Which statements regarding shape and charge complementarity are true? 1) Charge complementarity occurs when specific noncovalent binding interactions occur between two contacting surfaces. 2) The "charge" interactions can be charge-charge, H-bonding, or van der Waals interactions. 3) Shape complementarity refers to the intimate contact made between an antibody and its target antigen. 4) Shape and charge complementarity explain exclusively the interactions between an antibody and its target antigen.

Only statements 1, 2, and 3 are true.

A typical relaxed sarcomere is about 2.3 μmμm in length and contracts to about 2 μmμm in length. Within the sarcomere, the thin filaments are about 1 μmμm long and the thick filaments are about 1.5 μmμm long. Calculate the overlap of thick and thin filaments in the relaxed and contracted sarcomere. Express your answers using two significant figures separated by a comms.

Overlap per thin filament in relaxed sarcomere,overlap per thin filament in contracted sarcomere =0.60,0.75 μmμm

Which of the following statements is true of the bonds in a water molecule?

Oxygen holds electrons more tightly than hydrogen does, and the net charge is zero.

Which of the following statements is most likely to be true in the case of the feedback-regulated enzymatic pathway shown?

P4 binds E1 and deactivates it.

The following describe the binding of oxygen to human myoglobin at 37 ∘C P50 Express your answer to two significant figures and include the appropriate units.

P50 = 2.6 mmHg

Sort these nucleotide building blocks by their name or classification.

Phosphate

The four levels of protein structure are primary, secondary, tertiary, and quaternary structure. Review the levels of protein structure by clicking the image below. Drag each label into the appropriate bin depending on whether it applies to primary, secondary, tertiary, or quaternary structure.

Primary Structure- amino acid sequence Secondary Structure- result from hydrogen bonding bestrewn the backbone constituens of the poly peptide, alpha helix, beta pleated sheet Tertiary Structure- the overall shape of a polypeptide, results from interactions between side chains (R groups) of amino acids Quaternary Structure- The aggregation of multiple polypeptide subunits.

Determine whether each term describes the primary, secondary, or tertiary structure of proteins (or forces relating to the primary, secondary, or tertiary structure of proteins). Drag each item to the appropriate bin.

Primary structure: amide bond secondary structure: beta-pleated sheet alpha helix tertiary structure: disulfide bond salt bridge

Sort these nucleotide building blocks by their name or classification.

Purine

Sort these nucleotide building blocks by their name or classification.

Pyrimidine

Which of these is NOT a lipid?

RNA

A ________ plot describes which structures in a polypeptide are sterically possible and which are not based on the angles of rotation about the backbone Namide -Cα and Cα-Ccarbonyl bonds.

Ramachandran

Sort these nucleotide building blocks by their name or classification.

Ribose

Indicate whether the structures shown are R or S in the absolute system.

S R

Which of the following compounds is not a monosaccharide?

Sucrose

If ΔHDH = -80.0 kJ and ΔSDS = -0.300 kJ/K , the reaction is spontaneous below a certain temperature. Calculate that temperature. Express your answer numerically in kelvins.

T =267K

At what temperature would you expect the unfolding of lysozyme to become favorable?

T =354K

The catalytic efficiency of many enzymes depends on pHpH. Chymotrypsin shows a maximum value of kcat/KMkcat/KM at pHpH 8. Detailed analysis shows that kcatkcat increases rapidly between pHpH 6 and 7 and remains constant at higher pHpH. KMKM increases rapidly between pHpH 8 and 10. Suggest explanations for these observations. Match the words in the left column to the appropriate blanks in the sentences on the right. Make certain each sentence is complete before submitting your answer.

The change in kcatkcat between pHpH 6 and pHpH 7 must involve loss of a proton in the active site. The best candidate is His 57. The increase in K M at higher p H must involve a change in the binding site. The group involved is probably the N-terminus at Ile 16, created by the cleavage that activates chymotrypsin.

View the side groups in the model, with attention to the water channel. What do the numerous aromatic rings on the surface of the channel suggest about the chemical properties of the channel?

The channel will have significant hydrophobic properties

Axons insulated by a(n) _____ are able to conduct impulses faster that those not so insulated.

myelin sheath

Suggest a saturated fatty acid that should melt below 30 ∘C∘C

n-octanoic acid

In gel electrophoresis DNA molecules migrate from _____ to _____ ends of the gel.

negative ... positive

What is the net charge on the following peptide at pH = 0?Peptide sequence: DSVK

net charge = +2

The hydrides of group 5A are NH3, PH3, AsH3, and SbH3. Arrange them from highest to lowest boiling point. Rank the molecules from highest to lowest boiling point. To rank items as equivalent, overlap them.

The decreasing order of the hydrides of Group 5A is as follows: NH3 > SbH3 > AsH3 > PH3

The value you calculated in part D represents the strength of the H-bond between N155 and the oxyanion in the transition state. This value is higher than typical H-bonds in water. How might this observation be rationalized? Hint: Coulomb's Law. Match the words in the left column to the appropriate blanks in the sentences on the right. Make certain each sentence is complete before submitting your answer.

The dielectric constant, εε, is lower in the enzyme active site than it is in water; thus, Coulomb,s law predicts a stronger interaction between the H-bond donor and acceptor.

Is your list exhaustive?

no

You have added an irreversible inhibitor to a sample of enzyme and substrate. At this point, the reaction has stopped completely. What can you do to regain the activity of the enzyme?

The enzyme is inactive at this point. New enzyme must be added to regain enzyme activity.

Subtilisin is used in some laundry detergents to help remove protein-type stains. What unusual kind of stability does this suggest for subtilisin?

The enzyme must be stable both to the presence of detergents and to moderately high temperatures.

Is the folded form of the protein stable at 25 ∘C

The folded form of the protein is not stable at 25 ∘C

Explain why α-helices are most commonly observed in transmembrane protein sequences when the distance from one side of a membrane to the other can be spanned by significantly fewer amino acids in a β-strand conformation.

The helical conformation spanning the bilayer satisfies all the main-chain HH-bond donors and acceptors within the helix, whereas the strand would be unable to form intramolecular HH-bonds to satisfy it.

Why do you suppose that the influenza virus protein that binds the virus to an infected cell is called hemagglutinin? Hemagglutination is the clumping together of red blood cells. Drag the terms on the left to the appropriate blanks on the right to complete the sentences.

The influenza hemagglutinin on the virus particle binds to the surface of any cell that contains sialic acid. When it binds to the surface of erythrocytes, this causes the cells to agglutinate, or to aggregate, or clump.

Which side of the organelle membrane is positive, and which is negative?

The inside of the organelle is negative with respect to the outside.

Which statement about the binding of oxygen to heme is NOT true?

The iron ion bound to the porphyrin group is +3.

An impulse relayed along a myelinated axon "jumps" from _____ to _____.

node of Ranvier ... node of Ranvier

How many OH groups are attached to the sugar of ddATP?

none

the transfer of genetic information flows from DNA to protein

none of the listed statements are true

DNA is composed of building blocks called _____.

nucleotides

Based on the location of this residue and the differences between Lys and Asp, suggest a rationale for the observed reduction in O2O2-binding affinity. Match the words in the left column to the appropriate blanks in the sentences on the right. Make certain each sentence is complete before submitting your answer.

The negative charge on the Asp side chain can form salt bridges with the other ( + )-charged side chains in the BPG-binding pocket and stabilize the T-state. In essence, the Asp side chain is mimicking the negative charge on BPG.

Which of the following statements about DNA structure is true?

The nucleic acid strands in a DNA molecule are oriented antiparallel to each other, meaning they run in opposite directions.

What can be said about an exothermic reaction with a negative entropy change?

The reaction is spontaneous at low temperatures.

What would happen to the rate of the forward reaction if the concentration of nitrogen were decreased?

The reaction rate would decrease .

A particular solvent with ΔS∘vap=112.9J/(K⋅mol) and ΔH∘vap=38.0kJ/mol is being considered for an experiment. In the experiment, which is to be run at 75 ∘C, the solvent must not boil. Based on the total entropy change associated with the vaporization reaction, would this solvent be suitable and why or why not?

The solvent would not be suitable because ΔStotal>0.

What is the structural relationship between glucose and galactose?

They are epimers.

Facilitated diffusion is a type of _______.

passive transport

The answer you have obtained is an absurdly high value for the cell and in fact is never approached in reality. Explain why

This glucose-6-phosphate concentration is never reached because glucose-6-phosphate is continuously consumed by other reactions, and so the reaction never reaches true thermodynamic equilibrium.

Which curve is which? Drag the appropriate labels to their respective targets.

Top curve- Facilitated Bottom curve- nonmediated diffusion

Tertiary structure is NOT directly dependent on ____

peptide bonds

Tautomers of nucleotide bases are isomers that differ from each other in the location of one hydrogen atom in the molecule.

True

This is an image of a _____.

phage

Drag the terms on the left to complete the sentences on the right.

When molecules move down their concentration gradient, they move from where they are more concentrated to where they are less concentrated. Diffusion across a biological membrane is called passive transport

Scientists can track the movement of proteins through the endomembrane system using an approach known as a pulse-chase experiment. This experiment involves the "pulse" phase: Cells are exposed to a high concentration of a radioactively labeled amino acid for a short period to tag proteins that are being synthesized. the "chase" phase: Any unincorporated radioactively labeled amino acids are washed away and large amounts of the same, but unlabeled, amino acid are added. Based on these data, what is the most likely function of the cells in this experiment?

phagocytosis

The unequal sharing of electrons within a water molecule makes the water molecule _____.

polar

The letter A indicates _____.

a DNA double helix

Generally speaking, which of the following mutations would most severely affect the protein coded for by a gene?

a frameshift deletion at the beginning of the gene

Identify the reaction that occurs when the acid HBrHBr is added to the buffer solution. Drag each label to the appropriate target

add HBr: HBr(aq)+KF(aq) ----> HBr(aq)+KF(aq)

Identify the reaction that occurs when the base KOHKOH is added to the buffer solution. Drag each label to the appropriate target.

add KOH: KOH(aq)+HF(aq)KOH(aq)+HF(aq)

Sort the gradient profiles expected for each of the four samples depicted in the figure. Drag the appropriate items to their respective bins.

after one generation

Sort the gradient profiles expected for each of the four samples depicted in the figure. Drag the appropriate items to their respective bins.

after two generations

non covalent bonds are important

all ofthe listed statements are valid reasons for this importance

When t=t1/2, what is the value of −kt1/2 ?

-0.693

Proteins are polymers of _____

amino acids

Which storage polysaccharide has the following characteristics? is a polymer of glucose has α(1→ 4) linkages is largely helical in its structure

amylose

An ionic bond involves _____.

an attraction between ions of opposite charge

Atoms with the same number of protons but with different electrical charges _____.

are different ions

Calculate the molecular weight of α-melanotropin, using data in the table below. Express your answer to two decimal places and include the appropriate units.

1623.93 g/mol

A nerve impulse moves away from a neuron's cell body along _____.

axons

If one strand of DNA has the sequence 5'-C-T-T-G-C-G-T-T-A-3', what sequence would appear opposite it on the other strand?

3'- G-A-A-C-G-C-A-A-T -5

Identify the three main parts of the structure of adenosine triphosphate (ATP).

A is triphosphate, B is ribose, and C is adenine.

Which of these cannot rapidly pass directly through the phospholipids of the plasma membrane?

B, C, and D

Which set of compounds would form a buffer in aqueous solution? Drag each item to the appropriate bin.

Buffer: HF and KF HCN and NaCN Not a Buffer: NaBr and KBr HCN and NaF NaCl and KCl HBr and NaBr NaF and NaOH

In a Haworth projection for glucose, what would be the position (above or below the ring) for the hydroxyl groups at C-2, C-3, and C-4?

C-2: below; C-3: above; C-4: below

Which part of an amino acid is always acidic?

Carboxyl functional group

Which of the following statements regarding the folding of proteins is NOT true?

Hydrophobic residues pack together because the side chains are attracted to each other through weak Van der Waals interactions

The weak acid HAHA is 2% ionized (dissociated) in a 0.20 M solution. What is Ka for this acid?

Ka =8.2×10−5

What is a monosaccharide with 6 carbons and a ketone group called?

Ketohexose

In a bacterium, where are proteins synthesized?

ribosomes

Which term describes the difference in electrical charge across a membrane?

Membrane potential.

The mode of replication of DNA is BEST described as ________.

semi-conservative

For an amino acid such as aspartic acid, what impact do you expect the two neighboring carboxylic acids to have on the pKa values for each?

The acid with the lower pKa value would increase the pKa value for the other acid

Why is the entropy change so favorable for this reaction? Match the words in the left column to the appropriate blanks in the sentences on the right. Make certain each sentence is complete before submitting your answer.

The decomposition products are both gases, and therefore have significantly more translational and rotational freedom compared to the initial solid. Thus, entropy increases.

Will the fraction denatured increase or decrease with increasing temperature?

The fraction denatured will increase with increasing temperature.

What is the function of Structure E?

stabilization of the phospholipids

The nontemplate strand is also called the "sense strand." Explain.

The nontemplate DNA strand has the same base sequence as the RNA transcribed from that DNA molecule (although with thymine replaced by uracil).

In order to insert a human gene into a plasmid, both must _____

be cut by the same restriction enzyme

Use the table to sort the following ten codons into one of the three bins, according to whether they code for a start codon, an in-sequence amino acid, or a stop codon. Drag each item to the appropriate bin.

start/methionine AUG stop codon UAA UAG UGA amino acid AAA AUC CAC GCA ACU UGC

Which class of lipids does the following molecule belong to?

steroids

What name is given to the reactants in an enzymatically catalyzed reaction?

substrate

Which of the following sugars would NOT yield a positive Fehling's test (red color change)?

sucrose

If a segment of DNA were replicated without any errors, the replicated strand would have the following sequence of nucleotides: 5' - ACTACGTGA - 3' Sort the following replicated DNA sequences by the type of point mutation each contains (frameshift, base substitution, or neither), as compared to the correct sequence shown above. Sort the items into the appropriate bins.

frameshift mutations: 5'-ACTTACGTGA-3' , 5'-ACTCGTGA-3' base substitution mutations: 5'-ACTACGTGT-3', 5'- ACTAAGTGA-3'

Which of the following bands of the sarcomere does NOT change size during muscle contraction?

the A band

All amino acids have a chiral α-carbon EXCEPT ________.

glycine

What name is given to the bond between water molecules?

hydrogen

In a favorable reaction the free energy of the products is ________ than the free energy of the reactants.

less

In general, enzymes are what kinds of molecules?

proteins

Which polymers are composed of amino acids?

proteins

Structure A is a _____.

solute

Suppose calcium ion is maintained within an organelle at a concentration 1000 times greater than outside the organelle (T=37∘C)(T=37∘C). What is the contribution of Ca2+Ca2+ to the membrane potential? Express your answer to three significant figures and include the appropriate units.

Δψ = -92.2 mV

What type of protein secondary structure does the structure shown here (Figure 2) represent?

α-helix

In the diagram, (a), (b), and (c) represent three points along a vertebrate axon where electrodes were implanted to detect action potentials. Under normal conditions, when this neuron produces an action potential, the action potential passes through point (a) first, followed by point (b), and then point (c). Suppose, however, that an action potential is artificially triggered at the point indicated by the red arrow. In what sequence would the action potential pass through points (a), (b), and (c)? Enter the sequence in which the action potential would pass through the points. Enter the letters in the correct order separated by commas. For example if the order is point (c), then (b), then (a), enter c, b, a. If the action potential would not pass though a point, do not include that point in your answer.

b,a,c

What best explains how Na+ ions are excluded while K+ ions are allowed to pass through the selectivity channel?

the higher stability of the hydrated form of Na+ compared with the dehydrated form of Na+ within the selectivity channel

Examine the molecular model of the yeast G-actin monomer. The folding of a loop in subdomain 2 of actin into an alpha helix occurs when __________.

bound ATP is hydrolyzed to ADP

In this reaction _____.

the products have less potential energy than the reactants

Calculate the value of ΔG∘ for the folding of lysozyme at 25 ∘C. Express your answer with the appropriate units.

ΔG= -44.6 kJmol

A circular double-stranded DNA molecule contains 4200 base pairs. In solution the molecule is in a B-form helix, with about 10.5 base pairs per turn. The DNA circle has 12 superhelical turns. What is its superhelix density σ? Express your answer using two significant figures.

σ =3.0×10−2

Using the data in the figure (to one significant figure) and table, estimate the extinction coefficient (in units of cm2/mgcm2/mg) for vasopressin, using radiation with λλ= 280 nmnm. Express your answer using one significant figure.

ϵϵ =0.9 cm2/mg

Under these conditions, what percentage of the oxygen bound in the lungs is delivered to the tissues? Express your answer using two significant figures.

42%

Refer again to the graph. (Figure 1) In which region is the enzyme saturated with substrate?

region C

Which nucleotide will base‑pair with the enol form of 5‑bromouracil?

Guanine

0.35 M acetic acid

pH = 2.61

This figure is an example of a(n) __

saturated fat

Complete the following sentences about carbohydrates. Match the words in the left-hand column with the appropriate blank in the sentences in the right-hand column.

1. A carbohydrate that yields many monosaccharides when hydrolyzed is a polysaccharide . 2. A monosaccharide cannot be hydrolyzed any further. 3. A simple sugar is composed of equal parts carbon and water, which gave rise to the general name of any sugar as a carbohydrate . 4. Lactose, the sugar in milk, is a disaccharide, because it can be split into two monosaccharides.

This figure reviews the structure of a phospholipid. Drag the terms on the left to the appropriate blanks on the right to complete the sentences.

1. A phospholipid has a "head" made up of a glycerol molecule attached to a single phosphate group, which is attached to another small molecule. 2. Phospholipids vary in the small molecules attached to the phosphate group. The phospholipid shown in the figure has a choline group attached to phosphate. 3. Because the phosphate group and its attachments are either charged or polar, the phospholipid head is hydrophilic, which means it has an affinity for water. 4. A phospholipid also has two "tails" made up of two fatty acidmolecules, which consist of a carboxyl group with a long hydrocarbon chain attached. 5. Because the C-H bonds in the fatty acid tails are relatively nonpolar, the phospholipid tails are hydrophobic, which means they are excluded from water.

This diagram shows the changes in charge distribution that occur across an axon membrane as an action potential propagates from left to right. The region where the action potential is occurring is shown in orange. Seven locations along the axon are marked by the letters a through g. Match the letter of each location along the axon with the correct description of what is occurring at that position.

1. At location c , the membrane potential changes sign (from a positive value to a negative value) and the voltage-gated K+ channels are open. 2. At location f , the axon membrane reaches threshold and the voltage-gated Na+ channels open. 3. At location a, the voltage-gated Na+ channels reactivate. 4. At location d, the voltage-gated Na+ channels are inactivating and the voltage-gated K+ channels are opening. 5. At location g, the axon membrane is at resting potential. 6. At location b, the voltage-gated K+ channels are closing. 7. At location e, the membrane potential changes sign (from a negative value to a positive value) and the voltage-gated Na+ channels are open.

How many peptides would result if this peptide were treated with (1) cyanogen bromide, or (2) trypsin, or (3) chymotrypsin? Match the numbers of peptides in the left column to the appropriate blanks for the treating compounds on the right.

1. Cyanogen bromide: 2 peptides 2. Trypsin: no cleavage 3. Chymotrypsin:2 peptides

The equilibrium membrane potentials to be expected across a membrane at 37∘C∘C, with a NaClNaCl concentration of 0.10 MM on the right and 0.01 MM on the left, given the following conditions.(a) Membrane permeable only to Na+Na+. ΔψΔψ =+0.0615 VV(b) Membrane permeable only to Cl−Cl−. ΔψΔψ =-0.0615 VV(c) Membrane equally permeable to both ions. ΔψΔψ = 0 VVWill any appreciable transport of material take place in establishing the membrane potential? Briefly explain each answer. Match the words in the left column to the appropriate blanks in the sentences on the right. Make certain each sentence is complete before submitting your answer.

1. For (a) - No., because the concentration of ions won't be in equilibrium. 2. For (b) - No., because the concentration of ions won't be in equilibrium. 3. For (c) - Yes., because the concentrations of ions will equalize.

Complete the following sentences. Match the words in the left-hand column with the appropriate blank in the sentences in the right-hand column.

1. If a carbohydrate, like xylulose, has five carbon atoms and a carbonyl group on the second carbon, it is called a(n) ketopentose. 2. Any carbohydrate with the carbonyl group on the second carbon is a(n) ketose. 3. The most common carbohydrate, glucose, has six carbon atoms. 4. A monosaccharide is a(n) aldose if the carbonyl group is on the end of the carbon chain. 5. Glyceraldehyde is an example of a(n) aldotriose, because it has three carbon atoms. 6. With the carbonyl group on the end of a six-carbon chain, the carbohydrate would be classified as a(n) aldohexose.

If all creatine phosphate were converted into ATP and utilized as well, how long could contraction continue? Express your answer to two significant figures and include the appropriate units.

1.3 s

Suppose the concentration of glucose inside a cell is 0.1 mM and the cell is suspended in a glucose solution of 0.01 mM. If the processes described in parts A and B were coupled to ATP hydrolysis, how many moles of ATP would have to be hydrolyzed in order to make each process favorable? (Use the standard free energy change for ATP hydrolysis.)

1.84×10−7 molATP

Linolenic acid has cis double bonds with the formula CH3CH2CH=CHCH2CH=CHCH2CH=CH(CH2)7COOH. Write out the abbreviated systematic numbering for this fatty acid. Enter the abbreviation for the fatty acid using systematic numbering. Type Delta if the Greek symbol is required.

18:3cdelta9,12,15

Please match the correct term on the left with the appropriate structural feature of proteins listed on the right. 1) primary structureA) the interaction between two separate protein strands2) secondary structureB) the sequence of AA3) tertiary structureC) small sections of organized protein structure, such as helices4) quaternary structureD) the overall fold of a single protein strand, such as the globulin fold

1:B; 2:C; 3:D; 4:A

Match the amino acid (AA) with its correct side chain category: 1) prolineA) negatively charged polar AA2) histidineB) nonpolar aromatic AA3) alanineC) positively charged polar AA4) threonineD) nonpolar AA5) tryptophanE) polar AA6) aspartic acidF) nonpolar aliphatic AA

1:D; 2:C; 3:F; 4:E; 5:B; 6:A

Match the codon with the amino acid it encodes: 1) UCA A) Stop2) CUA B) Lys3) AAG C) Start/Met4) GUA D) Leu5) AUG E) Val6) UAG F) Ser

1:F; 2:D; 3:B; 4:E; 5:C; 6:A

Base analysis of DNA from maize (corn) shows it to have 23 mole percent cytosine (moles per 100 moles total nucleotide). What are the percentages of the other three bases? What is the percentage of adenine?

27 %

Base analysis of DNA from maize (corn) shows it to have 23 mole percent cytosine (moles per 100 moles total nucleotide). What are the percentages of the other three bases? What is the percentage of thymine?

27 %

Calculate to three decimal places the charge on α-melanotropin at pHpH value of 1. Express your answer using three decimal places.

3.998

The graph below shows the hemoglobin dissociation curves (also called equilibrium curves) for normal blood pH (the blue curve) and two other conditions. Given what you know about the Bohr shift, what is the difference in O2 saturation of hemoglobin in the lungs versus hemoglobin in exercising tissues, as represented on this graph? Keep in mind that the pH of blood in the lungs is not the same as the pH of blood in exercising tissues. Express your answer in percent, but do not include the percent sign in your answer.

57.0%

The diversity of functional groups on sugars that can form glycosidic bonds greatly increases the information content of glycans relative to oligopeptides. Consider three amino acids, A , B, and C. How many tripeptides can be formed from one molecule of each amino acid? Express your answer as an integer.

6

Bovine pancreatic trypsin inhibitor (BPT I) contains six cysteine residues that form three disulfide bonds in the native structure of BPT I. Suppose BPT I is reduced and unfolded in urea. If the reduced unfolded protein were oxidized prior to the removal of the urea, what fraction of the resulting mixture would you expect to possess native disulfide bonds? Express your answers using three significant figures.

6.67×10^-2

Calculate the pIpI (isoelectric point) of α-melanotropin. Express your answer using three decimal places.

8.813

Calculate the minimum number of residues in a ββ-strand required to span this distance. Express your answer as an integer.

9 residues

What is pKb of the conjugate base of X-281?

9.04

More strong base is added until the equivalence point is reached. What is the pH of this solution at the equivalence point if the total volume is 71.0 mL ? Express the pH numerically to two decimal places.

9.05

the fraction saturation of myoglobin at 30 mmHg, the partial pressure of O2 in venous blood Express your answer using two significant figures.

92 %

Estimate the percent oxygen saturation of blood at 100 mmHgmmHg, the approximate partial pressure of O2O2 in the lungs. Express your answer using two significant figures.

99 %

Label the following diagram of water molecules, indicating the location of bonds and the partial charges on the atoms. Drag the labels to their appropriate locations on the diagram of the water molecules below. Labels can be used once, more than once, or not at all.

A Covalent Bond B Delta - C Hydrogen Bond D Delta + E Delta + F Covalent Bond G Delta - H Hydrogen Bond

Which of the following statements about the formation of polypeptides from amino acids is true?

A bond forms between the carboxyl functional group of one amino acid and the amino functional group of the other amino acid.

Watch the animation and identify the correct conditions for forming a hydrogen bond.

A hydrogen bond is possible with only certain hydrogen-containing compounds. Hydrogen bonding occurs when a hydrogen atom is covalently bonded to an N, O, or F atom A hydrogen atom acquires a partial positive charge when it is covalently bonded to an F atom

On the basis of these data, suggest what features of amino acid sequence dictate the specificity of proteolytic cleavage by elastase. Match the words in the left column to the appropriate blanks in the sentences on the right. Make certain each sentence is complete before submitting your answer.

A hydrophobic residue seems to be favored at the position C-terminal to the site of bond cleavage. Elastase always requires a small residue (like Ala) to the N-terminal side.

Which of the following statements about mutations is false?

A knock-out mutation results in a total absence of the mutated protein.

When a base substitution mutation occurs, one nucleotide in a replicating DNA sequence is substituted for another, which results in the production of a mutant strand of DNA. The result of the mutation depends on how the substituted nucleotide base alters the string of amino acids coded by the mutant DNA. The three types of base substitution mutations are nonsense mutations, missense mutations, and silent mutations. Each type is defined by how it affects protein synthesis. Label the four mutated DNA segments shown below according to the type of point mutation each represents. Use the codon table above to determine how each mutation would affect the amino acid coding for each segment. Drag the labels to their appropriate locations to identify the type of point mutation shown.

A) silent mutation B) nonsense mutation C) missense mutation D) frameshift mutation

Which of the following statements about globular proteins are true?1) The protein folds to make itself as compact as possible.2) The packing of the protein is such that hydrophilic residues appear on the surface where they can interact with an aqueous environment.3) Irregularities of the protein's surface allow for the formation of clefts, which are often where the protein promotes a chemical transformation.4) Regions of secondary structures folding on one another are examples of the protein's tertiary structure.

All of the listed statements are correct.

Which of the following statements about protein quaternary structure are correct?1) It involves a complex of two or more proteins interacting with each other.2) The subunits of the structure can be either identical or different.3) The interactions between subunits can give rise to indefinite growth of polymeric complexes.4) Most assemblies of protein subunits have one or more defined axis of rotation.

All of the listed statements are correct.

Why do you suppose the Dalai Lama's hemoglobin has a P50P50 higher than normal (where "normal" = 27 mmHgmmHg)?

Because Dalai Lama's concentration of 2,3-BPG is increased.

Why might crocodiles have a hemoglobin that is responsive to HCO−3 instead of 2,3-BPG? Recall that crocodiles hold their prey underwater to kill them.

As the crocodile stays underwater, its hemoglobin delivers most of the bound O2 as a result of increased binding of HCO−3 to the T conformation.

The structure that regulates the passage of material into and out of this bacterial cell is indicated by the letter _____

C

Which of the following statements is true about a protein that is in an aqueous solution that has a pH equal to the pI of the protein?

At pH = pI, there is no net charge on the protein.

At PO2 = 40 mm Hg, which statement about the saturation of either myoglobin (Mb) or hemoglobin (Hb) is true?

At this partial pressure of oxygen, Mb would be almost completely saturated but Hb would not.

________ between amide protons and carbonyl oxygens is necessary to stabilize a regular folding of protein secondary structure.

Hydrogen bonding

A red blood cell placed in a hypertonic solution will shrink in a process called crenation. A red blood cell placed in a hypotonic solution will swell and potentially burst in a process called hemolysis. To prevent crenation or hemolysis, a cell must be placed in an isotonic solution such as 0.9% (m/v) NaCl or 5.0% (m/v) glucose. This does not mean that a cell has a 5.0% (m/v) glucose concentration; it just means that 5.0% (m/v) glucose will exert the same osmotic pressure as the solution inside the cell, which contains several different solutes. A red blood cell is placed into each of the following solutions. Indicate whether crenation, hemolysis, or neither will occur. Solution A: 3.21% (m/v) NaCl Solution B: 1.65% (m/v) glucose Solution C: distilled H2O Solution D: 6.97% (m/v) glucose Solution E: 5.0% (m/v) glucose and 0.9%(m/v) NaCl Drag each solution to the appropriate bin.

CRENATION: A, D, E HEMOLYSIS: B, C NEITHER:

The DNA-containing region of this bacterial cell is indicated by the letter _____.

D

the -Stahl experiment demonstrated which of the following about DNA replication

DNA replicated semi conservitively

If you were to set up a PCR reaction (in vitro DNA synthesis) with a DNA template, primers,DNA polymerase, dATP, dGTP, dCTP, dTTP and a small amount of ddATP, what would be the result?

DNA synthesis might be terminated after the addition of any adenine base (at random). DNA molecules of many different lengths would be produced.

If you assume maximum sequence similarity between α-melanotropin and β-melanotropin, then what must the sequence of the latter be?(α-melanotropin-SerTyrSerMetGluHisPheArgTrpGlyLysProVal) Drag the appropriate labels to their respective targets so that the maximum sequence similarity to the order of α-melanotropin will be shown.

DSGPYK MEHFR WGSPPK

Sort these nucleotide building blocks by their name or classification.

Deoxyribose

What is the predominant intermolecular force in the liquid state of each of these compounds: hydrogen fluoride (HF), carbon tetrabromide (CBr4), and hydrogen chloride (HCl)? Drag the appropriate items to their respective bins.

Dipole-dipole forces HCl Hydrogen bonding HF Dispersion forces CBr4

Enalapril is administered in pill form, but enalaprilat must be administered intravenously. Why do you suppose enalapril works as a pill, but enalaprilat does not?

Enalaprilat is too polar to cross membranes, whereas enalapril can cross membranes to get from the gut to circulation.

Which of the following statements are true with respect to enzyme activity

Enzymes are regenerated when the reaction is completed. Enzymes affect the reaction pathway by forming an enzyme-substrate complex. Enzymes speed up the reaction rate.

In a liver cell at 37 ∘C the concentrations of both phosphate and glucose are normally maintained at about 5 mM each. What would be the equilibrium concentration of glucose-6-phosphate, according to the above data? Express your answer to two significant figures and include the appropriate units.

Equilibrium concentration = 1.2×10−7 M

A red blood cell has been placed into three different solutions. One solution is isotonic to the cell, one solution is hypotonic to the cell, and one solution is hypertonic to the cell. Determine which type of solution is in each beaker based on the cell's reaction. Drag each item to the appropriate bin.

For a cell in an isotonic solution, water flows into the cell to the same extent that it flows out of the cell. If a cell is in a hypotonic solution, water flows into the cell, which causes it to swell and potentially burst. For a cell in a hypertonic solution, water flows out of the cell, which causes it to shrink.

Is the effect of the N155T mutation what you would expect for a residue that makes up part of the oxyanion hole? How do the reported values of kcat and KM support your answer? Check all that apply.

For a mutation of a residue that only interacts with the oxyanion intermediate, one would not expect KM to change significantly kcat should be reduced due to the loss of enthalpic stabilization of the transition state. The oxyanion is formed after S binds.

Now consider three sugars-glucose, glucuronic acid, and N-acetylglucosamine. Use shorthand (e.g., Glcα(1→4)GlcUAβ(1→4)GlcNAc) to represent 10 trisaccharides with the sequence Glc−GlcUA−GluNAc. Check all that apply.

Glcα(1→3)GlcUAα(1→4)GlcNAc Glcα(1→2)GlcUAβ(1→4)GlcNAc Glcβ(1→3)GlcUAβ(1→4)GlcNAc Glcα(1→2)GlcUAβ(1→3)GlcNAc Glcα(1→4)GlcUAβ(1→6)GlcNAc Glcβ(1→4)GlcUAβ(1→6)GlcNAc Glcα(1→2)GlcUAα(1→3)GlcNAc Glcα(1→4)GlcUAβ(1→3)GlcNAc Glcα(1→4)GlcUAα(1→4)GlcNAc Glcβ(1→4)GlcUAβ(1→4)GlcNAc

Devise a way to calculate ΔH for the reaction H2O(g)⟶2H(g)+O(g) Drag the appropriate labels to their respective targets. Note: not all labels will be us

H2O --> H2 + 1/2O2 H2 --> 2H 1/2O2 --> O 248 926

Rank the following compounds in order of decreasing vapor pressure. Rank from highest to lowest vapor pressure. To rank items as equivalent, overlap them.

HIghest CH4 > CH3CH(CH3)CH2CH3 > CH3CH2CH2CH2CH3 > CH3CH2CH2CH2OH Lowest

Who demonstrated that DNA is the genetic material of the T2 phage?

Hershey and Chase

Place these hydrocarbons in order of decreasing boiling point. Rank from highest to lowest boiling point. To rank items as equivalent, overlap them.

Highest BP Paraffin > Heptadecane > Octane > 2,2,4 - trimethylpentane > ethane Lowest BP

The ability of restriction enzymes to cut DNA at specific sites makes DNA cloning possible. The diagram below shows a section of human DNA that contains an imaginary gene for video game proficiency (the vgp gene), shown in red. Shaded areas mark the restriction sites (also called recognition sites) of four restriction enzymes: EcoRI, HaeIII, BamHI, and HindIII. Arrows indicate where each enzyme cuts the two DNA strands. Which enzyme(s) will produce a DNA fragment that contains the entire vgp gene (shown in red) and has "sticky ends"? Select all that apply.

HindIII BamHI

The brackets are indicating a(n) _____ bond.

Hydrogen

Which of these bonds is weakest?

Hydrogen Bonds are weaker than covalent bonds because they do not involve sharing of electrons, and they are weaker than ionic bonds because they involve the attraction of partial (not full) opposite charges.

Watch the animation and identify the correct conditions for forming a hydrogen bond. Check all that apply.

Hydrogen bonding occurs when a hydrogen atom is covalently bonded to an N, O, or F atom. A hydrogen bond is possible with only certain hydrogen-containing compounds. A hydrogen atom acquires a partial positive charge when it is covalently bonded to an F atom

Gaseous hydrogen burns in the presence of oxygen to form water: 2H2 + O2 → 2H2 O + energy Which molecule is oxidized and what kind of bond is formed?

Hydrogen, polar.

In some reactions, in which a protein molecule is binding to a specific site on DNA, a rate greater than that predicted by the diffusion limit is observed. Suggest an explanation. [Hint: The protein molecule can also bind weakly and nonspecifically to any DNA site.] Match the words in the left column to the appropriate blanks in the sentences on the right. Make certain each sentence is complete before submitting your answer.

If the protein can bind to a random location on the DNA and slide along until it finds the specific site, a more efficient one-dimensional search replaces an entropically less favorable three-dimensional search.

Theoretical and experimental measurements show that in many cases, the contributions of ionic and hydrogen-bonding interactions to ΔH for protein folding are close to zero. Provide an explanation for this result. (HintHint: Consider the environment in which protein folding occurs.) Drag the terms on the left to the appropriate blanks on the right to complete the sentences.

In a protein that is in the UNFOLDED state, there are many interactions between the solvent (water) and the ionic species (or HYDROGEN BOND donors and acceptors). In contrast, in a FOLDED protein, these interactions are replaced by the formation of favorable INTRAMOLECULAR ionic or HYDROGEN BONDING interactions. The favorable H is obtained by the formation of the INTRAMOLECULAR bonds in the FOLDED protein. This energy is offset by the energy needed BREAK to all the solvent interactions, which causes the protein to go from UNFOLDED the to the FOLDED state.

Resting neurons are most permeable to which of the following ions?

K+.

Enalaprilat is a competitive inhibitor of the angiotensin-converting enzyme (ACE), which cleaves the blood-pressure regulating peptide angiotensin I. ACE has a KM = 12 μM for angiotensin I, which is present in plasma at a concentration of 75 μM. When enalaprilat is present at 2.4 nM, the activity of ACE in plasma is 10% of its uninhibited activity. What is the value of KI for enalaprilat? Express your answer to two significant figures and include the appropriate units.

KI = 3.7×10^−11 M

Acetylene, C2H2, can be converted to ethane, C2H6, by a process known as hydrogenation. The reaction is C2H2(g)+2H2(g)⇌C2H6(g) Given the following data at standard conditions (all pressures equal to 1 atm and the common reference temperature 298 K), what is the value of Kp for this reaction? SubstanceG∘f(kJ/molkJ/mol)C2H2(g);209.2H2(g) ;0 C2H6(g);−32.89

Kp =2.7×1042

For the reaction of A and B forming C, A(g)+B(s)⇌2C(g) how will the reaction respond to each of the following changes at equilibrium? Drag the appropriate items to their respective bins.

Leftward Shift: double the concentrations of A and C, halve the concentration of A, No Shift:quadruple the concentration of B Rightward Shift: double the concentration of A, halve the concentration of C

For the decomposition of A to B and C, A(s)⇌B(g)+C(g) how will the reaction respond to each of the following changes at equilibrium? Drag the appropriate items to their respective bins.

Leftward Shift: double the concentrationsof both products No Shift: add more A, double the concentrationsof both products and thendouble the container volume, double the concentrationof B and halve theconcentration of C Rightward Shift: double the concentrationsof both products and thenquadruple the container volume, double the container volume

Identify the predominant type of intermolecular force in each of the following compounds. Drag each item to the appropriate bin.

London: CF4 Dipole-Dipole: OF2, CHF3 Hydrogen Bonding: HF

Undergoing moderate activity, an average person will generate about 350 kJ of heat per hour. Using the heat of combustion of palmitic acid (ΔH=−9977.6kJ/mol) as an approximate value for fatty substances, estimate how many grams of fat would be required per day to sustain this level, if all were burned for heat.

Mass = 216 g

The denaturing of proteins occurs when the stabilizing forces are altered. Below is the set of processes in which proteins are denatured. Classify the following processes according to the denaturing agent involved. Drag the appropriate items to their respective bins.

Mechanical action: beating of eggs Chemical action:preparation of yogurt by adding bacteria cultures straightening frizzy and tangled hair using hair conditioner action of gastric juices on consumed food heating action:preparation of bread from mixed dough by baking

The graph presents three activation energy profiles for a chemical reaction (the hydrolysis of sucrose): an uncatalyzed reaction, and the same reaction catalyzed by two different enzymes. Rank these by reaction rate, as measured by the rate of product formation (from the most product formed to the least product formed). To rank items as equivalent, overlap them.

Most Product formed reaction catalyzed by enzyme B > reaction catalyzed by enzyme A > Background Image uncatalyzed reaction Least Product formed

Rank the following substances in order from most soluble in water to least soluble in water:propane, C3H8; methanol, CH3OH; copper sulfate, CuSO4; and butane, C4H10. Rank from most to least soluble in water. To rank items as equivalent, overlap them.

Most Soluble Copper Sulfate > Methanol > Butane > Propane Least Soluble

Assuming constant pressure, rank these reactions from most energy released by the system to most energy absorbed by the system, based on the following descriptions: A. Surroundings get colder and the system decreases in volume. B. Surroundings get hotter and the system expands in volume. C. Surroundings get hotter and the system decreases in volume. D. Surroundings get hotter and the system does not change in volume. Also assume that the magnitude of the volume and temperature changes are similar among the reactions.

Most energy released Reaction B > Reaction D > Reaction C > Reaction A Most energy absorbed

How is hemoglobin's affinity for oxygen affected by the presence or absence of oxygen? Rank hemoglobin molecules with the described conditions from most likely to bind oxygen molecules to most likely to release oxygen molecules. (For help approaching this problem, open Hint 1.)

Most likely to bind oxygen molecules: 3 bound O2, PO2 = 100 mmHg 1 bound O2, PO2 = 100 mmHg 3 bound O2, PO2 = 40 mmHg 1 bound O2, PO2 = 40 mmHg, Most likely to release oxygen molecules

Rank the following substances in order from most soluble in water to least soluble in water:octane C8H18; pentanol C5H11OH; table salt NaCl; and pentane C5H12. Rank from most to least soluble in water. To rank items as equivalent, overlap them.

Most solubule NaCl > Pentanol > Pentane > Octane Least soluble

Would you expect Neurospora crassa DNA to have a higher or lower TmTm than human DNA? Explain.

Neurospora crassa DNA has a higher GC content Neurospora crassa DNA has a higher GC content than human DNA, therefore its T m is greater. than human DNA, therefore its TmTm is greater Neurospora crassa DNA has a higher GC content than human DNA, therefore its T m is greater. .

The estimate obtained in Part A is surely too large. Give one reason why.

Not all of these conformations will be sterically possible.

What peptides are expected to be produced when α-melanotropin (SerTyrSerMetGluHisPheArgTrpGlyLysProVal) is cleaved by cyanogen bromide

SYSM,EHFRWGKPV

What peptides are expected to be produced when α-melanotropin (SerTyrSerMetGluHisPheArgTrpGlyLysProVal) is cleaved by trypsin

SYSMEHFR,WGKPV

Which of the following represent the function of glycoproteins, a group of biomolecules that contain both protein and carbohydrates? 1) They can serve as hormones. 2) They are involved in cell adhesion and cellular recognition. 3) They help in transporting suspended lipids through bloodstream. 4) They can serve as an aid to increase the viscosity of various bodily fluids.

Only statements 1, 2, and 4 are correct

Which statements about the generation of antibody diversity are true? 1) The gene sequences corresponding to the IgG CDR loop mutate at a high rate. 2) The heavy and light chain gene sequences are rearranged and spliced, creating many different sequence combinations. 3) Splicing and mutations are preprogrammed based on the organism's environment. 4) There are approximately 10 billion different IgG sequences that can be generated from the immunoglobulin gene library within the human genome.

Only statements 1, 2, and 4 are true.

Which of the following statements regarding Anfinsen's denaturing experiments with ribonuclease A are valid?1) Exposing the denatured protein to air oxidation and then dialysis to remove urea restored the protein to its original functionality.2) Removing urea by dialysis and then allowing air oxidation of the denatured protein restored the protein to its original functionality.3) Denaturing the protein with both urea and β-mercaptoethanol yielded an inactive protein.4) Protein folding is determined by its primary sequence.

Only statements 2, 3, and 4 are valid.

Which channel is mainly responsible for the resting potential of a neuron?

Potassium leak channel.

A reducing sugar will undergo the Fehling reaction, which requires a (potential) free aldehyde group. Which of the disaccharides shown in the figure below are reducing and which are nonreducing

Reducing: Cellobiose Maltose Lactose Gentiobiose Nonreducing: Sucrose Trehalose

Subtilisin does have a problem in that it becomes inactivated by oxidation of a methionine close to the active site. Suggest a way to make a better subtilisin. Match the words in the left column to the appropriate blanks in the sentences on the right. Make certain each sentence is complete before submitting your answer.

Replace the methionine, by site-directed mutagenesis, with another residue. Because methionine is quite hydrophobic, a hydrophobic replacement would seem appropriate. A single base change in the Met codon could yield Phe, Leu, Ile, or Val.

What peptides are expected to be produced when α-melanotropin (SerTyrSerMetGluHisPheArgTrpGlyLysProVal) is cleaved by thermolysin

SYS,MEHFRWGKP,V

The melanocyte-stimulating peptide hormone α-melanotropin has the following sequence:Ser-Tyr-Ser-Met-Glu-His-Phe-Arg-Trp-Gly-Lys-Pro-Val Write the sequence using the one-letter abbreviations.

SYSMEHFRWGKPV

What type of cell makes up the myelin sheath of a motor neuron?

Schwann cells

What is a potential limitation of GFP?

Short wavelengths of excitation light can damage the cell's DNA.

A semipermeable membrane is placed between the following solutions. Which solution will decrease in volume?

Solution A: 1.4% (m/v) starch

A semipermeable membrane is placed between the following solutions. Which solution will increase in volume?

Solution D: 12.4% (m/v) NaCl

Human and sperm whale myoglobin have very similar primary structures. Which of the following statements are correct?1) The two proteins are very likely related evolutionarily.2) The differences in the sequences in many instances represent a conservative change (such L for I).3) The differences in the sequences in many instances represent a nonconservative change (such as D for A).4) There is no correlation between the two proteins, since they originate from very different species.

Statements 1 and 2 are correct.

The side chain of histidine has a typical pKa value in the range of 6.5-7.4. However, when analyzing the pKa values in a particular protein, scientists determined that one particular His residue has an unusually low pKa value of 4.8. Which of the following statements correctly explain this anomaly?1) The microenvironment around a residue can impact its pKa value.2) A positively charged amino acid must be in close proximity to this residue.3) A negatively charged amino acid must be in close proximity to this residue.4) This residue must be located on the surface of the protein.

Statements 1 and 2 are correct.

Which statements about β and γ turns are correct?1) Their purpose is to reverse the direction of the polypeptide chain.2) There are two types, I and II, which differ mainly in the conformation about the i+1 and i+2 residue amide bond.3) They typically contain large, hydrophobic residues.4) Their conformation is held in place through H bonds.

Statements 1, 2, and 4 are correct.

What features of these two different hormones explain the locations of their receptors? Match the words in the left column to the appropriate blanks in the sentences on the right. Make certain each sentence is complete before submitting your answer.

Steroid hormones are generally hydrophobic and can cross the outer membrane bilayer by nonmediated diffusion. Peptide hormones are generally water soluble proteins/oligopeptides that would not easily cross the outer membrane of a cell.

Explain the differences in the pH values between the solutions in the previous parts.

Strong acids have a lower pH in comparison with a weak acid of the same concentration because they produce more hydrogen ions in solution. For acetic acid more H+ dissociates as the concentration of HA increases.

The table shown here lists the specific heat of several substances. SubstanceSpecific heatJ/g/∘CJ/g/∘Cwater4.18ethyl alcohol2.44benzene1.80sulfuric acid1.40 Based on the information in the table, which of the following statements are true?

Sulfuric acid is less resistant to temperature change than water. More heat is required to raise the temperature of 1 g of water 1 ∘Cthan to raise the temperature of 1 g of ethyl alcohol 1 ∘C Water has a high specific heat due to the hydrogen bonding between water molecules. Benzene is more resistant to temperature change than sulfuric acid.

Which statement about the polarity of DNA strands is true?

The 3' end has a free OH group

What is important in cloning the GFP cDNA into the vector?

The GFP cDNA is in the same reading frame as the target protein.

DNA polymerase requires both a template, to be copied, and a primer, which provides a 3′ hydroxyl from which polymerase can extend. Yet this molecule supports DNA polymerase activity.pTGACACAGGTTTAGCCCATCGATGGG−OH Explain. Drag the terms on the left to the appropriate blanks on the right to complete the sentence.

The GGG at the 3' terminus can pair with the internal CCC there by providing a duplex segment that can bind DNA polymerase, a 3' hydroxyl terminus, and a template for nucleotide addition (GATTTGGACACAGT-5')

Which of the following statements about antibody structure is NOT true?

The constant domains are located at the ends of the Y-like fork of the antibody, where they form two identical binding sites for antigens.

Because ions carry a charge (positive or negative), their transport across a membrane is governed not only by concentration gradients across the membrane but also by differences in charge across the membrane (also referred to as membrane potential). Together, the concentration (chemical) gradient and the charge difference (electrical gradient) across the plasma membrane make up the electrochemical gradient. Consider the plasma membrane of an animal cell that contains a sodium-potassium pump as well as two non-gated (always open) ion channels: a Na+ channel and a K+ channel. The effect of the sodium-potassium pump on the concentrations of Na+ and K+ as well as the distribution of charge across the plasma membrane is indicated in the figure below.

The diffusion of Na+ ions into the cell is facilitated by the Na+ concentration gradient across the plasma membrane. The diffusion of K+ ions out of the cell is impeded by the electrical gradient across the plasma membrane. The electrochemical gradient is larger for Na+ than for K+.

T B92

The effect is the disrupted abilty to ligate to the heme iron

Which of the following statements about protein folding and structure are true?

The native structure of a protein is entirely encoded in its amino acid sequence. Chaperones, like the GroEL-ES complex, work by providing a sequestered environment in which proteins can safely explore the conformational space towards productive folding. Misfolded proteins are thermodynamically stable versions of a protein. Misfolded proteins often aggregate in large structures in the cell.

Is the pI of the mutant protein predicted to be greater than, less than, or the same as the pI of the normal protein?

The pI of the mutant protein predicted to be less than the pI of the normal protein.

What can be said about an endothermic reaction with a negative entropy change?

The reaction is spontaneous in the reverse direction at all temperatures.

The Haber process is typically carried out at a temperature of approximately 500∘C. What would happen to the rate of the forward reaction if the temperature were lowered to 100∘C?

The reaction rate would decrease .

The _____ is the bacterial structure that acts as a selective barrier, allowing nutrients to enter the cell and wastes to leave the cell.

plasma membrane

If a mixture was prepared containing 1 M glucose-6-phosphate and 1×10−3M glucose-1-phosphate, what would be the thermodynamically favored direction for the reaction?

The reverse reaction is favored

Which channel maintains the concentration gradients of ions across a neuronal membrane?

The sodium-potassium pump moving Na+ ions out and K+ ions in.

The Foundation Figure began by discussing the importance and relevance of protein structure. Fill in the blanks in the paragraph below with a word or phrase from the word bank that best completes the sentence. Match the words in the left column to the appropriate blanks in the sentences on the right.

The structure of a protein dictates the partners with which it can interact. Therefore, the structure of a protein is directly related to its function. The contours of a protein determine the shape that its interaction partner must have, whereas the surface chemistry of a protein determines the kinds of chemical interactions that the protein will make with its interaction partner (e.g. Coulombic interactions or hydrogen bonding). Therefore, a protein will only bind to molecules that have the appropriate shape and chemistry (i.e. only those that are complementary to the protein).

In this molecule, what type of bond is found between the oxygen and hydrogens?

polar covalent

What is the function of a bacterium's capsule?

protection

If, in addition to the constraints on glucose concentration listed previously, we have in the liver cell ATP concentration = 3 mM and ADP concentration = 1 mM, what is the theoretical concentration of glucose-6-phosphate at equilibrium at pH=7.4 and 37 ∘C? Express your answer to three significant figures and include the appropriate units.

Theoretical concentration =47.5 M

Enzymes work by _____

reducing EA

The structure of a chloroplast is closely tied to its function as the site of photosynthesis. Some of the following statements are true for chloroplasts; others are true for mitochondria.

They contain the green pigment chlorophyll. They have membranous sacs called thylakoids that are surrounded by a fluid called stroma. They are the sites of reactions that convert solar energy into chemical energy.

The specific interaction between an antibody and antigen occurs by virtue of both shape and ________ complementarity.

charge

What kind of inhibitor is inhibitor B?

competitive

A reaction at equilibrium can be driven in one direction or the other by changing the ________ of reactants or products

concentration

Look at the graph of reaction rate versus substrate concentration for an enzyme. (Figure 1) In which region does the reaction rate remain constant?

region C

What do you expect the sign of ΔS to be for this process? Explain your answer. Match the words in the left column to the appropriate blanks in the sentences on the right. Make certain each sentence is complete before submitting your answer.

This process reduces the entropy of the solvent water, which becomes more ordered in the clathrate structures. This is the hydrophobic effect.

A short 8-residue sequence of a polypeptide is determined to have φ angles ranging from -65 degrees to -80 degrees and ψ angles ranging from -40 degrees to -50 degrees. What conclusion can be drawn from this data?

This segment has helical content.

The chemical element ________ has a role in both transfer of energy as well as in the structure of nucleic acids.

phosphorus

Guanine and adenine are purines found in DNA.

True

Hydrogen bonds share features of both covalent and noncovalent bonds.

True

True or false? Enzymes in the digestive tract catalyze hydrolysis reactions.

True

Within a six-base DNA recognition sequence, an enzyme that cuts between the 3rd and 4th bases from the 5' end will generate blunt ends.

True

If the sequence ATGCATGTCAATTGA were mutated such that a base were inserted after the first G and the third T were deleted, how many amino acids would be changed in the mutant protein?

Two

If apamine does not react with iodoacetate, then how many disulfide bonds are present?

Two disulfides.

Part 3 Classify these amino acids as acidic, basic, neutral polar, or neutral nonpolar. Drag each item to the appropriate bin.

Tyrosine is nuetral non-polar according to mastering

Synthesis of sugar polymers is enzyme catalyzed and requires activated monomers like ________ in lactose biosynthesis.

UDP-galactose

Substances with weak intermolecular forces tend to be in the gas state at room temperature. Moderate intermolecular forces are required to liquefy or solidify a substance at room temperature. Classify the types of intermolecular forces as moderate or weak. Drag each item to the appropriate bin.

Weak: Dipole-Dipole, London-Dispersion Moderate: Hydrogen Bonding, ion-dipole

The diagram below shows the five main transport proteins that control the distribution of Na+ and K+ ions across the plasma membrane of an axon. Assume that the membrane is at resting potential---the membrane potential of the axon remains constant at about -70 mV. Drag the arrows onto the diagram to show the direction of Na+ (gray arrows) and K+ (red arrows) movement through each transport protein at resting potential. If no ions move through a transport protein at resting potential, leave that target blank.

a and b. blank c. Na+ up, K+ down d. K+ up e. Na+ down

Under most circumstances, once an axon's membrane potential reaches threshold (about -55 mV in mammals), an action potential is automatically triggered. The graph below shows the changes in membrane potential that occur in an axon membrane that is initially at resting potential. In response to a stimulus, the membrane slowly depolarizes until the membrane potential reaches a particular value, called threshold. At threshold, a rapid depolarization of the membrane occurs and an action potential is initiated. Drag the labels onto the flowchart to show the sequence of events that occurs once the membrane potential reaches threshold. You may use a label once or not at all.

a).many voltage-gated Na+ channels open b).Na+ ions rush into the cell c).membrane potential rises (depolarizes) rapidly

Drag the labels to their appropriate locations on the diagram of the neurons below. Targets of Group 2 indicate the locations of gated ion channels.

a. cell body b. myelin sheath c. synaptic terminal d. axon hillock e. nucleus f. location of voltage-gated channels g. location of ligans-gated channels h. axon i. dendrite

The diagram below depicts the transport of carbon dioxide in blood, from body tissues to the lungs. Drag the labels to their appropriate locations on the diagram.

a. respiration produces CO2 b. formation of carbonic acid catalyzed by carbonic anhydrase c. CO2 binds to hemoglobin d. bicarbonate ion transported in blood e. carbonic acid converted back to CO2 and water f. CO2 releases from hemoglobin g. CO2 leaves the system

The fixed pattern of changes in membrane potential during an action potential is coordinated by the sequential opening and closing of voltage-gated ion channels. Can you identify the status (open/closed) of the voltage-gated Na+ and K+ channels during each phase of an action potential? Drag the appropriate labels onto the graph to indicate the status (open or closed) of the voltage-gated Na+ and K+ channels during each phase of an action potential. Labels may be used once, more than once, or not at all.

a.) resting potential Na+ channels are close, K+ channels are closed b.) rising potential Na+ channels open K+ channels closed c.) falling phase Na+ channels closed K+ channels open d.) undershoot Na+ channel closed K+ channels open e.) resting potential Na+ channels closed K+ channels closed

Sphingomyelin contains a fatty acid linked by an ________ bond and phosphocholine linked via the C-3 hydroxyl group of sphingosine.

amide

A function of cholesterol that does not harm health is its role _____.

as a component of animal cell membranes

View the molecular model of the myosin-actin interaction. The actin-binding cleft in myosin contacts residues 335-372 in the actin monomer. What can sterically block this association and keep the muscle in a relaxed state?

binding by tropomyosin

A solution of vasopressin is placed in a 0.5-cmcm-thick cuvette. Its absorbance at 280 nmnm is found to be 1.3. What is the concentration of vasopressin, in mg/cm3mg/cm3 . Express your answer using three significant figures.

c =2.77 mg/cm3

Some solutes are able to pass directly through the lipid bilayer of a plasma membrane, whereas other solutes require a transport protein or other mechanism to cross between the inside and the outside of a cell. The fact that the plasma membrane is permeable to some solutes but not others is what is referred to as selective permeability. Which of the following molecules can cross the lipid bilayer of a membrane directly, without a transport protein or other mechanism? Select all that apply.

carbon dioxide oxygen lipids water

A neuron's nucleus is located in its _____.

cell body

What name is given to the rigid structure, found outside the plasma membrane, that surrounds and supports the bacterial cell?

cell wall

What type of bond is joining the two hydrogen atoms?

covalent

A nerve impulse moves toward a neuron's cell body along _____.

dendrites

Select the INCORRECT association.

exergonic ... uphill

The two strands of a DNA double helix are held together by _____ that form between pairs of nitrogenous bases.

hydrogen bonds

An amphipathic molecule provides the foundation for biological membranes because they have both ________ and ________ functional groups.

hydrophilic, hydrophobic

X-Gal is included in the growth medium on which cells transformed with bacterial plasmids are grown. The reason X-Gal is included is to _______.

identify bacteria that contain a recombinant plasmid

Review the mammalian voltage-dependent K+ channel of the Shaker family. Closing of the channel in response to membrane depolarization relies primarily on essential arginine residues located where?

in the extracellular voltage sensor domain

Consider the enzyme-catalyzed reaction with Vmax=164 (μmol/L)min−1 and KM=32 μmol/L . If the total enzyme concentration was 1 nmol/Lnmol/L, how many molecules of substrate can a molecule of enzyme process in each minute? Express your answer to three significant figures.

kcat = 1.64×10^5 min−1

Initial rate data for an enzyme that obeys Michaelis-Menten kinetics are shown in the following table. When the enzyme concentration is 3 nmol ml−1, a Lineweaver-Burk plot of this data gives a line with a y-intercept of 0.00426 (μmol−1 ml s). [S] μM v0 (μmol ml−1 s−1) 320 169 160 132 80.0 92.0 40.0 57.2 20.0 32.6 10.0 17.5 Calculate kcat for the reaction. Calculate KM for the enzyme.

kcat = 7.82×10^4 s−1 KM = 124 μM

In the following Fischer projection, the hydroxyl group on the chiral carbon furthest from the carbonyl group points _____, meaning that this is the _____ isomer of mannose.

left / L

Using the pKa in the table below and the Henderson-Hasselbalch equation, calculate the approximate net charge on each of the four common ribonucleoside 5′-monophosphates (rNMPs) at pH 3.8. If a mixture of these rNMPs was placed in an electrophoresis apparatus, as shown, draw four bands to predict the direction and relative migration rate of each. Drag the appropriate labels to their respective targets.

left CMP AMP GMP UMP right

Biochemistry is focused on four biological molecules: proteins, carbohydrates, nucleic acids, and lipids. Of these, which are NOT polymers?

lipids

A(n) _____ refers to two or more atoms held together by covalent bonds.

molecule

Where is a bacterial cell's DNA found?

nucleoid region

Which of these is rich in unsaturated fats?

olive oil

The majority of solutes that diffuse across the plasma membrane cannot move directly through the lipid bilayer. The passive movement of such solutes (down their concentration gradients without the input of cellular energy) requires the presence of specific transport proteins, either channels or carrier proteins. Diffusion through a transport protein in the plasma membrane is called facilitated diffusion. Sort the phrases into the appropriate bins depending on whether they are true only for channels, true only for carrier proteins, or true for both channels and carriers.

only channels: provide a continuous path across the membrane allow water molecules and small ions to flow quickly across the membrane only carriers: undergo a change in shape to transport solutes across the membrane transport primarily small polar organic molecules both channels and carriers: provide a hydrophilic path across the membrane are integral membrane proteins transport solutes down a concentration or electrochemical gradient

0.35 M hydrochloric acid

pH = .46

The weak acid HA is 2% ionized (dissociated) in a 0.20 M\M solution. What is the pH of this solution?

pH =2.4

250 mL 0.3 M phosphoric acid plus 250 mL 0.8 M KH2PO4 (pKa=2.14)

pH =2.6

0.035 M acetic acid

pH =3.11

A 500-mL sample of a 0.100 M formate buffer, pH 3.75, is treated with 5 mL of 1.00 M KOH. What is the pH following this addition?

pH =3.93

100 mL 1 M acetic acid plus 100 mL 0.5 M sodium acetate (pKa=4.76)

pH =4.5

What type of bond joins the monomers in a protein's primary structure?

peptide

A nucleotide is composed of a(n) _____.

phosphate group, a nitrogen-containing base, and a five-carbon sugar

Identify Structure D.

phospholipid bilayer of membrane

The equilibrium constant for a first-order ________ reaction is equivalent to the ratio of the rate constant for the forward and reverse reactions.

reversible

In the following Fischer projection, the hydroxyl group on the chiral carbon furthest from the carbonyl group points _____, meaning that this is the _____ isomer of tagatose.

right / D

Elastase is closely related to chymotrypsin. Suggest two kinds of amino acid residues you might expect to find in or near the active site. Check all that apply.

serine histidine

Rank the following in terms of predicted rates: the nucleation of an αα helix; the nucleation of a parallel ββ sheet; the nucleation of an antiparallel ββ sheet. Justify your predictions. Drag the appropriate items to their respective bins.

slower: The nucleation of a parallel sheet requires a noncontiguous sequence to form HH-bonding. faster: The nucleation of a helix requires four ordered contiguous residues to initiate HH-bonding. fastest: The nucleation of an antiparallel sheet requires three ordered contiguous residues to initiate HH-bonding.

What is this an image of?

supercoils

Why isn't this insect drowning?

surface tension

What part of a neuron relays signals from one neuron to another neuron or to an effector?

synaptic terminal

What is the expression for the half-life for a first-order reaction?

t1/2=0.693/k

Conserved histidine, asparagine (blue), and cysteine (yellow) residues are present on the surface of the water channel. Which of the following is LEAST likely to hydrogen-bond with a water molecule?

the R group (side chain) of the cysteine

Aquaporins allow water to pass through the channel but prevent other solutes and ions from also crossing the membrane. Protons can move with water using the same hydrogen bonding facillitated movement. What PREVENTS protons from passing through the water channel?

the chemical properties of the amine groups of the two conserved asparagines in the channel

Look at the molecular model of myosin II of striated muscle from chicken. Which part of myosin interacts directly with the actin filament?

the cleft between the lower subdomain and upper subdomain in the heavy chain motor domain

Where in a globular protein is the amino acid alanine likely to be located?

the hydrophobic interior

What prevents glycerol from passing through the water channel?

the narrow diameter (~2.8 Å) of the selectivity channel

Examine the molecular model of the actomyosin cycle (Section IV). The powerstroke is caused by a conformational change in the myosin molecule that results from __________.

the release of ADP from the catalytic site in the myosin heavy chain

Structure A is a(n) _____.

transport protein

Structure B is a _____.

transport protein

Which step of cross-bridge cycling is considered the power stroke?

when the ADP is released and the myosin cross-bridge moves to the right in the animation

When is the force of contraction of the muscle strongest?

when there is maximal overlap between the thick and thin filaments

Cells expressing the GFP fusion protein will show florescence __________.

where the GFP fusion protein is localized in the cell

A mole of XX reacts at a constant pressure of 43.0 atm via the reaction X(g)+4Y(g)→2Z(g), ΔH∘=−75.0 kJ Before the reaction, the volume of the gaseous mixture was 5.00 L. After the reaction, the volume was 2.00 L. Calculate the value of the total energy change, ΔE Delta E, in kilojoules. Express your answer with the appropriate units.

ΔE Delta E = -62.0 kJ

In the cell, depletion of GAP makes the reaction proceed. What will ΔG be if the concentration of GAP is always kept at 1/100 of the concentration of DHAP? Express your answer to two significant figures and include the appropriate units.

ΔG =-4.4 kJmol

Consider the degradation of glucose to pyruvate by the glycolytic pathway:glucose+2ADP+2Pi+2NAD+⟶2pyruvate+2ATP+2H2O+2NADH+2H Calculate ΔG for this reaction at pH=7.4 and 37∘C

ΔG =-59.0 kJmol

From your answers to Parts A and B, estimate ΔGfolding for this protein at 25 ∘C Express your answer using two significant figures.

ΔG =47.0 kJmol

Suppose the concentration of glucose inside a cell is 0.1 mM and the cell is suspended in a glucose solution of 0.01 mM. What would be the free energy change involved in transporting 10^−6 mole of glucose from the medium into the cell? Assume T= 37 ∘C.

ΔG =5.93×10^−6 kJkJ

Suppose the concentration of glucose inside a cell is 0.1 mM and the cell is suspended in a glucose solution of 0.01 mM. What would be the free energy change involved in transporting 10^−6 mole of glucose from the medium into the cell if the intracellular and extracellular concentrations were 1 mM and 10 mM, respectively?

ΔG =−5.93×10^−6 kJ

At 25 ∘C∘C the reaction from Part A has a composition as shown in the table below. Substance Pressure(atm)C2H2(g);5.55 H2(g);3.75 C2H6(g);3.25×10−2 What is the free energy change, ΔGDelta G, in kilojoules for the reaction under these conditions? Express your answer numerically in kilojoules.

ΔG Delta G = -261 kJ

The oxidation of glucose to CO2 and water is a major source of energy in aerobic organisms. It is a reaction favored mainly by a large negative enthalpy change.C6H12O6(s)+6O2(g)⟶6CO2(g)+6H2O(l) ΔH∘=−2816kJ/mol ΔS∘=+181J/mol⋅K At 37 ∘C∘C, what is the value for ΔG∘? Express your answer to four significant figures and include the appropriate units.

ΔG∘ = -2872 kJmol

Calculate ΔG∘ for the isomerization of glucose-1-phosphate to fructose-6-phosphate. Express your answer with the appropriate units.

ΔG∘ΔG∘ = -5.61 kJmol

In the overall reaction of aerobic metabolism of glucose, 32 moles of ATP are produced from ADP for every mole of glucose oxidized. Calculate the standard state free energy change for the overall reaction when glucose oxidation is coupled to the formation of ATP at 37 ∘C. Assume that the value of ΔG∘ calculated in part A closely approximates the value of ΔG∘′ for the complete oxidation of glucose. Express your answer to four significant figures and include the appropriate units.

ΔG∘′ = -1842 kJmol

This very low concentration of the desired product would be unfavorable for glycolysis. In fact, the reaction is coupled to ATPATP hydrolysis to give the overall reaction ATP+glucose⟶glucose−6−phosphate+ADP+H+ATP+glucose⟶glucose−6−phosphate+ADP+H+What is ΔG∘′ for the coupled reaction? Express your answer to three significant figures and include the appropriate units.

ΔG∘′ =-18.4 kJmol

If the protein folds entirely into αα helix with HH bonds as the only source of enthalpy of stabilization, and each mole of HH bonds contributes −5−5 kJmolkJmol to the enthalpy, estimate ΔHfolding.ΔHfolding. . Note that the ends of helices contain fewer hydrogen bonds per residue than in the middle as shown to the left. Express your answer using tree significant figures.

ΔHΔH =-480kJ/mol

What must be the enthalpy change accompanying denaturation to allow the protein to be half-denatured at 50 ∘C? Express your answer with the appropriate units.

ΔH∘ =292 kJ/mol

Using the information that lnK versus 1/T is a straight line with slope −ΔH∘/R, calculate ΔH∘ for the ionization of water. Express your answer to three significant figures and include the appropriate units.

ΔH∘ =59.0 kJmolkJmol

Based on the possibility of 2.7×10922.7×10^92 conformations, estimate the conformational entropy change on folding a mole of this protein into a native structure with only one conformation. Express your answer using three significant figures.

ΔS =-1.77kJ/K⋅mol

For a protein of 100 residues, estimate the entropy change per mole upon denaturation. Express your answer with the appropriate units.

ΔS =9.04*10^2 J/mol⋅K

What must be the sign of ΔS for the change: native → denatured

ΔS must be positive because the increase in isoenergetic conformations in the denatured state increases the entropy of the denatured state relative to the folded state.

Use these data, and the ion product at 25 ∘C, to calculate ΔS∘ for water ionization. (Hint: Use the chemical standard state for the activity of water rather than that for the biochemical standard state activity of water.) Express your answer to two significant figures and include the appropriate units.

ΔS∘ =-100 Jmol⋅K

ΔH∘=+109.6kJ/molΔG∘=−30.5kJ/mol Calculate ΔS∘ at 25 ∘C Express your answer with the appropriate units.

ΔS∘ =470 J/mol⋅K

Suppose you visit the Dalai Lama in Dharamsala, India (elevation 1460 mm), and you begin to ponder the "big questions," such as, "What is the fractional saturation of the Dalai Lama's hemoglobin?" Assuming the Dalai Lama's hemoglobin has a Hill coefficient = 3.2, and a P50 = 31 mmHg, calculate the change in fractional O2 saturation of his hemoglobin going from his lungs (where PO2 = 85 mmHg) to his capillaries (where PO2 = 25 mmHg).

ΔYO2 = 0.63

Which part of the adenosine triphosphate molecule is released when it is hydrolyzed to provide energy for biological reactions?

γ-phosphate (the terminal phosphate)