Biochemistry Exam 1 pt 1

Which part of an amino acid is always acidic? a)Amino functional group b)None of the above c)Side chain ("R group") d)Carboxyl functional group

D

In eukaryotes, the nucleus is enclosed by a double membrane called the: A. cell membrane. B. nuclear envelope. C. nucleolus. D. nucleoplasm. E. nucleosome.

B

In gel electrophoresis DNA molecules migrate from _____ to _____ ends of the gel. a)acidic ... basic b)negative ... positive c)basic ... acidic d)long ... short e)positive ... negative

B

Nearly all proteins contain: a)cobalt. b)sulfur. c)phosphorus. d)selenium. e)none of the above.

B

The assumption that a complete understanding of a living organism can be obtained solely by investigating all of its components is called _________. A. Systems biology B. Reductionism C. Emergence D. Robustness E. Feedback control

B

The following molecule is an example of which class of compounds? CH3CH2CH2COOH A) Hydrocarbon B) Acid C) Alcohol D) Aldehyde E) Ketone

B

What name is given to the reactants in an enzymatically catalyzed reaction? a)EA b)substrate c)active sites d)products e)reactors

B

Most biomolecules can be considered to be derivatives of A) Amino acids B) Carbohydrates C) Fats D) Hydrocarbons E) Alcohols

D

An organisms entire set of DNA is called A) Genome B) Genetic sequence C) Polynucleotide sequence D) Gene E) Inheritance

A

As a result of its involvement in a reaction, an enzyme _____. a)is unchanged b)loses a phosphate group c)permanently alters its shape d)is used up e)loses energy

A

Choose the amino acid that can function as a neurotransmitter A) Glutamic acid B) Alanine C) Tyrosine D) Lysine E) Cysteine

A

For the reaction A -- > B, the Keq' is 10 raised to the power of 4. If a reaction mixture originally contains 1 mmol of A and no B, which one of the following must be true? A. At equilibrium, there will be far more B than A. B. The rate of the reaction is very slow. C. The reaction requires coupling to an exergonic reaction in order to proceed. D. The reaction will proceed toward B at a very high rate. E. Delta G'° for the reaction will be large and positive.

A

In a bacterium, where are proteins synthesized? a)ribosomes b)nucleus c)peroxisome d)nucleoid region e)capsule

A

In considering protein secondary structure which of the following is INCORRECT? a)The 310 helix is right-handed and often contains proline residues. b)The most common structures are the α helix and the β sheet. c)A network of main-chain hydrogen bonds connect β strands in a β sheet. d)The β strands can be in either parallel or antiparallel configuration. e)An α helix repeats after 18 residues and has 3.6 residues per turn.

A

In glycolysis, fructose 1,6-bisphosphate is converted to two products with a standard free-energy change (delta G'°) of 23.8 kJ/mol. Under what conditions encountered in a normal cell will the free-energy change (delta G) be negative, enabling the reaction to proceed spontaneously to the right? A. Under standard conditions, enough energy is released to drive the reaction to the right. B. The reaction will not go to the right spontaneously under any conditions because the delta G'° is positive. C. The reaction will proceed spontaneously to the right if there is a high concentration of products relative to the concentration of fructose 1,6-bisphosphate. D. The reaction will proceed spontaneously to the right if there is a high concentration of fructose 1,6-bisphosphate relative to the concentration of products. E. None of the above conditions is sufficient.

A

The _____ is the bacterial structure that acts as a selective barrier, allowing nutrients to enter the cell and wastes to leave the cell. a)plasma membrane b)nucleoid region c)ribosome d)pili e)cell wall

A

The average life span of a species is about ________years A) One million B) Ten million C) Five hundred thousand D) Five million E) One hundred thousand

A

The conversion of earths atmosphere from anerobic to aerobic was due to the development of _________________ by cyanobacteria A) Photosynthesis B) Metabolism C) Chemosynthesis D) Oxidation of iron E) Fixation of nitrogen as cyanide

A

The following is an example of which reaction class? CH3Br + HSCH2CH(NH2)COOH à CH3SCH2CH(NH2)COOH + Br- + H+ A) Substitution B) Elimination C) Addition D) Isomerization E) Oxidation/Reduction

A

The tendency of an atom to pull electrons toward itself is referred to as its _____. a)Electronegativity b)polarity c)covalency d)tonicity e)ionic potential

A

The three-dimensional structure of macromolecules is formed and maintained primarily through noncovalent interactions. Which one of the following is not considered a noncovalent interaction? A. carbon-carbon bonds B. hydrogen bonds C. hydrophobic interactions D. ionic interactions E. van der Waals interactions

A

What are the N-terminal and C-terminal residues for the following peptide sequence? Peptide sequence: EASY a)E is the N-terminal residue; Y is the C-terminal residue. b)Y is the N-terminal residue; E is the C-terminal residue. c)Glutamic acid is the N-terminal residue; tryptophan is the C-terminal residue. d)Aspartic acid is the N-terminal residue; tyrosine is the C-terminal residue.

A

Which of the following amino acids contain a hydrophobic side chain A) Leucine B) Arginine C) Glutamine D) Glutamic acid E) Aspartic acid

A

Which of the following is not a component of DNA A) Uracil B) Adenine C) Cytosine D) Guanidine E) Thymine

A

Which of the following statements is FALSE? a)Proteins are the only biological polymer that can catalyze biochemical reactions. b)Proteins can transport molecules within cells and between cells. c)Proteins can be structural components of cells. d)Proteins can transmit signals between cells. e)Proteins can be both hormones and hormone receptors.

A

Identify the correct conditions for forming a hydrogen bond.

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. Hydrogen bonding occurs when a hydrogen atom is covalently bonded to an N, O, or F atom.

Which of the following is not a component of nucleic acid? A. Nucleotides B. Glucose C. Phosphate group D. Purines E. Pyrimidines

B

Biochemistry is defined as A) The study of life processes B) The study of the molecular basis of life C) The study of living organisms D) The study of organic compounds in living organisms E) The study of living compounds

B

For molecules with multiple ionizable groups, such as glycine, which of the following statements is true? a)At a pH near the pI, nearly all the molecules carry a net negative charge. b)At pH near the pI, nearly all the molecules carry no net charge. c)When the pH is near the pI, the solution is near its maximum buffering ability. d)At a pH near the pI, nearly all the molecules carry a net positive charge.

B

From the standpoint of entropy, consider the following processes: water boiling, mixing cola and root beer sodas, and assembling a house of cards. Based on your understanding, which of the following statements is true? a)Water boiling and mixing cola and root beer sodas are not favorable processes, but assembling a house of cards is. b)Water boiling and mixing cola and root beer sodas are favorable processes, but assembling a house of cards is not. c)Water boiling is a favorable process, but mixing cola and root beer sodas and assembling a house of cards are not. d)All of the listed processes are favorable.

B

In their first round of screening, Beadle and Tatum plated spores on minimal medium. The purpose of this screen was to _______. a)identify which mutants were deficient in vitamin synthesis pathways and which were deficient in amino acid synthesis pathways b)determine whether any auxotrophic mutants had been generated c)determine which of the mutants generated were auxotrophic for thiamine d)eliminate all nonmutant Neurospora from the population

B

The largest mass extinction also known as the great dying was called the A) Cenezoic extinction B) Permian extinction C) Mesozoic event D) Great ice age E) The great plague

B

The major function of carbohydrates is A) Catalysts and structural elements B) Energy sources and structural elements C) Genetic information D) Protein synthesis E) Insulation

B

The majority of Earth's species belong to which of the following classifications A) Eukaryotes B) Prokaryotes C) Viruses D) Mammals E) Archea

B

The sum total of all reactions of a organism is called A) Life B) Metabolism C) Biosynthesis D) Anabolism E) Energetics

B

Which of the following is FALSE when considering van der Waals interactions? a)The total interaction energy is the sum of the attractive and repulsive forces. b)They are not important in determining the stability of three-dimensional structures of proteins. c)Van der Waals radii can determine molecular surfaces. d)Molecules that interact by van der Waals forces do not interpenetrate.

B

Which of the following is NOT a characteristic of a living system? a)the ability to replicate and regenerate b)the ability to resist change over generations of progeny c)the ability to couple energy-releasing reactions with energy-requiring processes, thereby allowing the creation of complex molecules d)the ability to respond to changes in the environment

B

Which of the following is not a component of nucleic acid? A) Nucleotides B) Glucose C) Phosphate group D) Purines E) Pyrimidines

B

Which of the following statements about biomolecules is true? a)Lipids are responsible for the transport of substances into the cell. b)Nucleic acids (DNA/RNA) are responsible for information storage, transmission, and expression. c)Carbohydrates are responsible for the catalysis of chemical reactions. d)Proteins are broken down as a primary fuel source.

B

Which polymers are composed of amino acids? a)Nucleic acids b)Proteins c)Carbohydrates d)Monomers

B

A constant source of _______ is required for maintenance of a cell's ordered state. A) Heat B) Oxygen C) Energy D) Stimulus E) Water

C

Homeostasis is __________. a)the same as equilibrium b)the ability to maintain nutrient concentrations equal on both sides of the cell membrane c)the ability to maintain cellular conditions over time d)a function of proteins

C

In general, enzymes are what kinds of molecules? a)nucleic acids b)carbohydrates c)proteins d)lipids e)minerals

C

One of the principal methods that organisms use to obtain energy from chemical bonds is by ___________. A) Substitution reactions B) Dehydration reactions C) Oxidation/reduction reactions D) Hydration reactions E) Addition reactions

C

The Beadle and Tatum experiments were based on all of the following assumptions except that _______. a)auxotrophs fail to grow on minimal media b)X-irradiation can induce mutations. c)two strains of auxotrophic Neurospora that grow on minimal medium supplemented with biotin d)have mutations in the same gene e)supplemented media permit growth of auxotrophic strains of Neurospora

C

The chemical properties of organic molecules are determined by specific arrangements of atoms called _____________. A) Structure B) Bonds C) Functional groups D) Radicals E) Molecules

C

The following is an example of which reaction class HOOCCH=CHCOOH + H2O à HOOCCH2CH(OH)COOH A) Substitution B) Elimination C) Addition D) Isomerization E) Oxidation/Reduction

C

The following molecule is an example of which class of compounds? CH3CH2CH2COOCH2CH3 A) Hydrocarbon B) Acid C) Ester D) Ether E) Aldehyde

C

The largest molecules in living organisms are _________. A) proteins B) lipids C) nucleic acids D) carbohydrates E) steroids

C

The major carrier of chemical energy in all cells is: A. acetyl triphosphate. B. adenosine monophosphate. C. adenosine triphosphate. D. cytosine tetraphosphate. E. uridine diphosphate.

C

The most prominent function of RNA is A) Energy source B) Nutrient source C) Protein synthesis D) Structural elements E) B and C

C

The reaction A + B -- > C has a delta G'° of -20 kJ/mol at 25° C. Starting under standard conditions, one can predict that: A. at equilibrium, the concentration of B will exceed the concentration of A. B. at equilibrium, the concentration of C will be less than the concentration of A. C. at equilibrium, the concentration of C will be much greater than the concentration of A or B. D. C will rapidly break down to A + B. E. when A and B are mixed, the reaction will proceed rapidly toward formation of C.

C

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. a)Statements 1, 2, and 4 are correct. b)Statements 2, 3, and 4 are correct. c)Statements 1 and 2 are correct. d)Statements 1 and 4 are correct.

C

What can be said about an exothermic reaction with a negative entropy change? The reaction is: a)spontaneous at all temperatures. b)spontaneous at high temperatures. c)spontaneous at low temperatures. d)spontaneous in the reverse direction at all temperatures. e)nonspontaneous in either direction at all temperatures.

C

What name is given to the rigid structure, found outside the plasma membrane, that surrounds and supports the bacterial cell? a)capsule b)pili c)cell wall d)flagella e)nucleoid region

C

Which of the following classes of biomolecules are the most abundant in nature? A) Lipids B) Amino acids C) Carbohydrates D) Proteins E) Nucleotides

C

Which of the following is not considered a class of small biomolecule? A) Amino acid B) Sugar C) Nucleic Acid D) Fatty acid E) Nucleotide

C

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. a)Statements 1, 2, and 4 are valid. b)Statements 1, 2, and 4 are valid. c)Only statements 2, 3, and 4 are valid. d)All of the listed statements are valid.

C

Which part of the adenosine triphosphate molecule is released when it is hydrolyzed to provide energy for biological reactions? a)α -phosphate (the phosphate closest to ribose) b)β-phosphate (the middle phosphate) c)γ-phosphate (the terminal phosphate) d)adenine group e)ribose sugar

C

Which statements regarding the Henderson-Hasselbalch equation are true? 1) If the pH of the solution is known as is the pKa for the acid, the ratio of conjugate base to acid can be determined. 2) At pH = pKa for an acid, there is an equal amount of conjugate base to acid in solution. 3) At pH >> pKa for an acid, the acid will be mostly ionized. 4) At pH << pKa for an acid, the acid will be mostly ionized. a)1, 2, and 4 are true. b)2, 3, and 4 are true. c)1, 2, and 3 are true. d)All of the listed statements are true.

C

_____ are surface appendages that allow a bacterium to stick to a surface. a)Flagella b)Ribosomes c)Fimbriae d)Cell walls e)Mitochondria

C

lease match the correct term on the left with the appropriate structural feature of proteins listed on the right. 1) primary structure A) the interaction between two separate protein strands 2) secondary structure B) the sequence of AA 3) tertiary structure C) small sections of organized protein structure, such as helices 4) quaternary structure D) the overall fold of a single protein strand, such as the globulin fold a)1:C; 2:D; 3:A; 4:B b)1:D; 2:C; 3:B; 4:A c)1:B; 2:C; 3:D; 4:A d)1:B; 2:A; 3:D; 4:C

C

An enzyme _____. a)can bind to nearly any molecule b)is a source of energy for endergonic reactions c)is an inorganic catalyst increases the EA of a reaction d)is an organic catalyst

D

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

D

Enzymes work by _____. a)increasing the potential energy difference between reactant and product b)adding energy to a reaction c)adding a phosphate group to a reactant d)reducing EA e)decreasing the potential energy difference between reactant and product

D

Noncovalent bonds are critically important to the function of biomolecules. Which of the following is/are (a) valid reason(s) for this importance? a)Noncovalent interactions are made up of hydrogen bonding, electrostatic interactions, and dispersion forces. b)The effect of these weak interactions is cumulative. c)Their bond energies are ~10-100 times weaker than ordinary covalent bonds. d)All of the listed statements are valid reasons for this importance.

D

The field of study associated with the investigation of gene expression patterns is called: A) Proteomics B) Bioinformatics C) Genomics D) Functional genomics E) Synomics

D

The following molecule is an example of which single class of compounds? CH3CH2CH(NH2)COOH A) Amine B) Acid C) Ester D) Amino acid E) Alcohol

D

The four most abundant chemical elements in living systems are: a)sodium, potassium, nitrogen and sulfur. b)carbon, nitrogen, oxygen and potassium. c)hydrogen, oxygen, sulfur and phosphorus. d)hydrogen, carbon, nitrogen and oxygen. e)sodium, potassium, carbon and oxygen.

D

The unequal sharing of electrons within a water molecule makes the water molecule _____. a)have a low surface tension b)hydrophobic c)change easily from a liquid to gaseous form d)Polar e)ionic

D

Under standard conditions, a given reaction is endergonic (i.e., DG >0). Which of the following can render this reaction favorable: using the product immediately in the next step, maintaining a high starting-material concentration, or keeping a high product concentration? a)keeping a high product concentration b)using the product immediately in the next step c)maintaining a high starting-material concentration d)using the product immediately in the next step and maintaining a high starting-material concentration

D

What can be said about an endothermic reaction with a negative entropy change? The reaction is: a)spontaneous at all temperatures. b)spontaneous at high temperatures. c)spontaneous at low temperatures. d)spontaneous in the reverse direction at all temperatures. e)nonspontaneous in either direction at all temperatures.

D

What is the function of a bacterium's capsule? a)protein synthesis b)DNA storage c)adhesion d)protection e)propulsion

D

Where is a bacterial cell's DNA found? a)ribosomes b)nucleus c)peroxisome d)nucleoid region e)capsule

D

Which monomers make up RNA? a)Simple sugars b)Amino acids c)Polymers d)Nucleotides

D

Which of the following can be inferred from the Beadle and Tatum experiments? a)Neurospora vitamin auxotrophs do not require amino acids in order to grow. b)A given Neurospora mutant can be deficient in either a vitamin synthesis pathway or an amino acid synthesis pathway, but not in both. c)X-ray-induced mutations are confined to genes encoding enzymes. d)For a mutation resulting in the production of a defective enzyme involved in a biosynthetic pathway, the compound preceding the corresponding step will accumulate.

D

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

D

Which of the following is not characteristic of an autopoietic system? A) Autonomous B) Self-organizing C) Self-maintaining D) Intelligent E) B and D

D

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. a)Only statements 1, 2, and 3 are valid. b)Only statements 2, 3, and 4 are valid. c)Only statements 1, 3, and 4 are correct. d)All of the listed statements are correct.

D

Which statement correctly describes amphipathic (or amphiphilic) helices and sheets? a)Amphipathic helices and sheets have hydrophilic and hydrophobic residues evenly distributed throughout their structure. b)Helices are typically hydrophilic on one surface, whereas sheets usually have both hydrophilic and hydrophobic residues evenly distributed throughout their structure. c)Sheets are typically hydrophilic on one surface, whereas helices usually have both hydrophilic and hydrophobic residues evenly distributed throughout their structure. d)Amphipathic helices and sheets have predominantly hydrophilic (or hydrophobic) residues on one face.

D

All of the following classes of compounds are lipids except _______. A) fats B) sterols C) fatty acids D) phosphoglycerides E) nucleotides

E

Enzymes can accelerate reactions by: a)binding a substrate or substrates. b)lowering the energy for activation. c)correctly positioning a metal ion for catalysis. d)promoting the removal or addition of protons. e)all of the above.

E

If the delta G'° of the reaction A -- > B is -40 kJ/mol, under standard conditions the reaction: A. is at equilibrium. B. will never reach equilibrium. C. will not occur spontaneously. D. will proceed at a rapid rate. E. will proceed spontaneously from left to right.

E

Metabolism is best defined as the _________. A) Reactions of living cells B) Reactions that synthesize large molecules in living cells C) Reactions that degrade molecules in living cells D) Conversion of food molecules to energy E) Reactions that synthesize and degrade molecules in living cells

E

The following is an example of which reaction class? CH3CH2OH à CH3CHO + H2O A) Substitution B) Elimination C) Addition D) Isomerization E) Oxidation/Reduction

E

The following is an example of which reaction class? CH3CH2OH --> CH3CHO + H2O A. Substitution B. Ligation C. Addition D. Isomerization E. Dehydration

E

Which of the following classes of compounds make up most of the mass of an organism? A) Amino acids B) Proteins C) Lipids D) Carbohydrates E) Water

E

Which of the following is not a core principle of systems biology? A) Emergence B) Robustness C) Redundancy D) Modularity E) Limit of resolution

E

Which of the following is not a role played by carbohydrates in living cells? A) Energy source B) Structural support C) Intercellular communication D) Both A and B are correct E) All are roles played by carbohydrates in living cells

E

Which of the following is not a waste product of living organisms A) Carbon dioxide B) Water C) Urea D) Ammonia E) Glycine

E

Which of the following is not an example of a macromolecule? A) Nucleic acid B) Protein C) Polysaccharide D) Enzyme E) Amino acid

E

Which of the following statements is FALSE? A. Biological systems expend energy to overcome entropy. B. The entropy of an isolated system will tend to increase to a maximum value. C. The entropy of a biological system can decrease. D. Entropy is a measure of disorder. E. Biological systems are highly ordered so entropy changes are not relevant.

E

Which of the following statements is FALSE? A. Energy can be transferred between a system and the surroundings. B. Organisms are open systems as they can exchange both energy and materials with their environments. C. In biochemical processes, energy can neither be created or destroyed. D. In an open system energy can be converted from one form into another. E. Organisms are open systems as they can create energy from their environments.

E

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

Glycine

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

Histidine