Chapter 2 Quizlet

The element oxygen (O) has six electrons in its outermost shell. How many covalent bonds will O readily form?

a. none

b. one

c. two

d. three

two

An electronegative atom:

a. has a great attractive force for electrons.

b. has a great attractive force for protons.

c. repels electrons.

d. repels neutrons.

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has a great attractive force for electrons.

The chloride ion has an extra electron relative to the number of protons in its nucleus. Thus, chloride:

a. has a negative charge.

b. has lost an electron.

c. can bind a cation.

d. has a negative charge and can bind a cation.

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has a negative charge and can bind a cation.

Polar molecules of biological importance may often:

a. contain one or more electronegative atoms.

b. contain one or more electropositive atoms.

c. possess strongly polarized bonds.

d. contain one or more electronegative atoms and possess strongly polarized bonds.

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contain one or more electronegative atoms and possess strongly polarized bonds.

Ionic bonds:

a. are attractions between fully charged anions.

b. are of limited importance in living cells because of the prevalence of water.

c. are always weak..

d. All of these statements are true.

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All of these statements are true.

Which of the following statements about hydrogen bonds is true?

a. They can occur between most polar molecules.

b. They are weak attractive interactions.

c. They can be found between the two strands of a DNA molecule.

d. All of these statements are correct.

All of these statements are correct.

Which of the following is a NOT a property of water?

a. It is an essential nutrient.

b. It is a highly asymmetric molecule.

c. It is composed of two polar covalent bonds.

d. All three atoms in a water molecule can form hydrogen bonds

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It is an essential nutrient.

Observe the following reaction: HCO3- + H+ --> H2CO3

The reaction shown above is carried out in the blood to maintain:

a. low pH.

b. normal pH

c. high pH.

d. excess of H+ ions.

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normal pH.

The four major biological molecules are:

a. carbohydrates, lipids, proteins, and nucleic acids

b. carbohydrates, lipids, amino acids, and nucleic acids

c. amino acids, carbohydrates, lipids, and DNA

d. amino acids, glucose, lipids, and nucleic acids

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carbohydrates, lipids, proteins, and nucleic acids

Particular groupings of atoms that often behave as a unit and give organic molecules their physical properties, chemical reactivity and solubility in aqueous solutions are known as:

a. amphipathic groups

b. idiosyncratic groups

c. functional groups

d. aspirational groups

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functional groups

In addition to functioning as stores of chemical energy, carbohydrates:

a. are important in cellular metabolism.

b. can serve as strong building materials for biological construction.

c. can be highly water soluble.

d. can have a large number of stereoisomers.

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can serve as strong building materials for biological construction.

Which of the following carbohydrates are NOT polysaccharides?

a. glucose

b. glycogen

c. starch

d. cellulose

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glucose

The two ends of a fatty acid molecule have different properties; the hydrocarbon chain is hydrophobic, whereas the carboxyl group is hydrophilic. Molecules having both properties are called:

a. amphipathic

b. saturated

c. unsaturated

d. polyunsaturated

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amphipathic

Some of the functions of proteins include:

a. regulation.

b. antibodies.

c. growth factors.

d. All of these

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All of these

Amino acids:

a. can form peptide bonds.

b. are composed of a central carbon surrounded by an amino group, a carboxyl group, a hydrogen atom and a variable side chain.

c. can have side chains that are polar, nonpolar, or with unique properties.

d. All of these statements are true.

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All of these statements are true.

Which of the following structures of proteins is composed of two or more polypeptide chains?

a. Primary

b. Secondary

c. Tertiary

d. Quaternary

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Quaternary

Which of the following statements provides support to the notion of protein adaptations and evolution?

a. Homologous proteins isolated from different organisms can exhibit identical shapes.

b. Different versions of a protein are adapted to function in different tissues.

c. Most proteins are members of families of related molecules.

d. All of these.

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All of these.

All of the following are parts of a nucleotide EXCEPT:

a. a five-carbon sugar.

b. a six-carbon sugar.

c. a phosphate group.

d. a nitrogenous base.

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a six-carbon sugar

Which of the following is NOT found in DNA?

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a. adenine

b. uracil

c. cytosine

d. thymine

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uracil

Water has extraordinary properties to support life such as the capacity to:

a. hydrogen bonds with up to four other water molecules.

b. evaporate easily at relatively low temperatures.

c. dissolve a very limited number of substances.

d. prevent forming interactions with many other chemicals.

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hydrogen bonds with up to four other water molecules.

The destructive potential of free radicals, such as superoxide and hydroxyl radicals, is probably due to:

a. their capacity to break down water.

b. their potential to chemically alter molecules such as proteins.

c. their potential role as a cause of aging.

d. their interference with calorie-restricted diets.

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their potential to chemically alter molecules such as proteins.

The normal blood pH is about 7.4. What is the concentration of the hydrogen ion?

a. 6.6 M

b. 7.0 M

c. 7.4 M

d. None of these.

None of these.

The properties of carbon allow it to form _____ backbones.

a. trianguloid

b. branched

c. spherical

d. both trianguloid and branches are correct

branched

Which of the following statements about phospholipids is true?

a. Each one has two fatty acid chains.

b. The glycerol backbone is bonded to a small polar group.

c. Their biological function remains unknown.

d. Each one has two fatty acid chains and the glycerol backbone is bonded to a small polar group.

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Each one has two fatty acid chains and the glycerol backbone is bonded to a small polar group.

What is the consequence of placing a proline side chain within an alpha helix?

a. Proline stabilizes the folded alpha helical structure, causing it to kink.

b. Proline isomerizes to the trans form and the alpha helix is undisturbed.

c. Proline disrupts the structure of an alpha helix, causing it to kink.

d. All of these are correct.

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Proline disrupts the structure of an alpha helix, causing it to kink.

The stability of a protein, as defined by its ability to resist denaturation, could be assessed by:

a. the heat released upon melting it.

b. the temperature at which it melts.

c. the amount of detergent needed to maintain it in an unfolded conformation.

d. none of these is correct.

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the temperature at which it melts.

Amino acids are to proteins as __________ are to carbohydrates.

a. fatty acids

b. nucleic acids

c. monosaccharides

d. nucleotides

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monosaccharides

Which of the following disorders is NOT caused by protein misfolding?

a. Alzheimer's disease

b. Cystic fibrosis

c. "mad cow disease"

d. Creutzfeld-Jakob disease

Cystic fibrosis

Which of the following statements provides the best explanation for the fact that humans have six different genes encoding isoforms of the contractile protein actin?

a. Cells need large amounts of actin.

b. Actin is rapidly degraded in cells.

c. Each isoform is adapted to function in different tissues.

d. None of these.

Each isoform is adapted to function in different tissues.

The element neon (Ne) has eight electrons in its outermost electron shell. How many covalent bonds will Ne readily form?

a. none

b. one

c. two

d. four

none

Of the following elements, which is likely to form the least polar covalent bonds with hydrogen:

Nitrogen

Oxygen

Carbon

Phosphorous

Carbon

Of the following chemical bonds, which is the strongest in water?

HOH2C-CH2OH

Na-Cl

CH3COO-H

HO-H

HOH2C-CH2OH

Which of the following characteristic does NOT apply to water?

a. The water molecule is asymmetric.

b. The water molecule readily forms hydrophobic interactions.

c. The covalent bonds in water are highly polarized.

d. All three atoms in the water molecule ready form hydrogen bonds.

The water molecule readily forms hydrophobic interactions.

The major cellular macromolecules include:

a. proteins, lipids, amino acids, and carbohydrates.

b. proteins, amino acids, lipids, and nucleic acids.

c. proteins, nucleic acids, carbohydrates, and antibodies.

d. proteins, nucleic acids, carbohydrates, and lipids.

proteins, nucleic acids, carbohydrates, and lipids.

If you were to take a triaglycerol molecule and chemically break the ester bonds, you would end up with two different kinds of molecules. What is the name of the kind of molecule that would be soluble in water?

fatty acid

steroid

glycogen

glycerol

glycerol

Which of the following has been used as evidence that primitive life forms lacked both DNA and enzymes?

a.RNA can both code genetic information and act as a catalyst.

b. DNA and enzymes are only present in the most advanced cells. c. Advanced cells lack RNA.

d. All of these statements are correct.

RNA can both code genetic information and act as a catalyst.

Of the following functional groups, which would make a carbon-based compound the least polar? a.Phosphate

b. Methyl

c. Carboxyl

d. Amino

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Methyl

Cytoplasm has a pH of about 7. What is the concentration, in moles/liter, of the hydrogen ion?

7
7 x 10-7
1 x 10-7
1 x 107

1 x 10-7

Which of the following acid/base pairs act as natural buffers in living systems?

H2CO3/CO3-

H2PO4-/HPO4

histidine+/histidine

All of these are correct.

Which of the following pairs of functional groups might form weak bones with one another?

a. methyl and phosphate

b. phosphate and carboxyl

c. carboxyl and amino

d. carbonyl and methyl

carboxyl and amino

If you could grab the ends of each of the following polysaccharides and pull, which one might you be able to stretch the most?

glycogen

starch

cellulose

None of these is correct.

cellulose

What two features of the structure of cholesterol make it somewhat amphipathic?

a. the single hydroxyl along with the hydrocarbon nature of the remainder of the molecule

b. the long, branched hydrocarbon along with the four hydrocarbon rings

c. the five methyl groups along with the hydrocarbon chain

d. the three six-membered rings along with the single five-membered ring

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the single hydroxyl along with the hydrocarbon nature of the remainder of the molecule

Proteins and macromolecular structures take on their higher order structures

a. by self-assembly.

b. with the help of molecular chaperones.

c. with the help of precursor sequences that are removed from the final structure.

d. All of these are correct.

All of these are correct.

The different orders of protein structure are determined by all of the following bond types except:

peptide bonds.

phosphodiester bonds.

disulfide bridges.

hydrogen bonds.

peptide bonds.

The higher order structure of DNA shows symmetry, whereas the higher order structures of most proteins d not. Why isn't protein shape more regular like DNA?

a.DNA has one main function in cells whereas proteins have many.

b.The many different amino acid R groups on proteins confer many different shapes.

c. Some amino acids cause proteins to bend; others cause proteins to flatten.

d. All of these are correct.

d. All of these are correct.

Which amino acids would most likely reside in the membrane-anchoring domain of a membrane-embedded protein?

a. isoleucine, valine, and phenylalanine

b. phenylalanine, valine, and aspartate

c. leucine, threonine, and lysine

d. lysine, arginine, and histidine

a. isoleucine, valine, and phenylalanine

ATP is from which general category of biomolecules?

polysaccharides

proteins

nucleotides

amino acids

nucleotides

RNA is composed of nucleotides who compartments are:

a. deoxyribose sugars, phosphate groups, and the bases A, U, C, G.

b. ribose sugars, phosphate groups, and the bases A, U, C, G.

c. deoxyribose sugars, phosphate groups, and the bases A, T, C, G.

d. ribose sugars, phosphate groups, and the bases A, T, C, G.

ribose sugars, phosphate groups, and the bases A, U, C, G.

Regions of a protein molecule thought to have distinct evolutionary origins are known as: subunits.

motifs.

domains.

side chains.

domains.

Protein chips allow scientists to study:

protein structure

protein activity

protein side chains

All of these are correct.

protein activity

Self-assembly of complex molecular structures was first demonstrated in studies of:

ribosomes.

tobacco mosaic virus.

molecular chaperones.

None of these is correct.

tobacco mosaic virus.

pair of electrons shared between pairs of atoms

covalent bond

interaction between mol. governed by weaker linkages

non-covalent bonds

This (partially +) H can reach electron pair of another electronegative atom and make a weak bond called the

hydrogen bond

Molecules with asymmetric charge distribution are

polar molecules

Molecules that lack electronegative atom like O and consist of only C and H atom are

non polar molecules

______ are unstable atoms or mol. with unpaired electrons

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free radicals

These occur when non-polar molecules associate & minimize their exposure to polar molecules

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hydrophobic interactions

attractions between non polar molecules, are due to transient dipole formation

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van der Waals forces

simple organic molecules with C and H only

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hydrocarbons

Carboxylic acid & alcohols

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ester bonds

Carboxylic acid & amines

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amide bonds

large structural & functional molecules in cells. Include four major categories

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macromolecules

allow researchers to screen proteins for various activities and disorders.

protein chips

uses advanced technologies to perform large-scale studies on diverse proteins. Proteins are separated using gel electrophoresis. Proteins are identified using mass spectrometry and high speed computers.

proteomics

the entire inventory of an organism's proteins

proteome

"helper proteins" that prevent non selective interactions during protein folding

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molecular chaperones

proteins composed of subunits; it refers to the manner in which subunits interact.

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quaternary structure

non-random movements triggered by the binding of a specific molecule.

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Conformational changes

is the conformation of the entire polymer. It is stabilized by non covalent bonds. It is studied by X-ray crystallography. Proteins can be fibrous (elongated shape) or globular (compact shape) (myoglobin).

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tertiary structure

the conformation of adjacent amino acids into α-helix, β-sheet, hinges, turns, loops, or finger-like extensions

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secondary structure

sequence of amino acids in the polymer, is critical to the protein function

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primary structure

are -C—O—C- links between sugars

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Covalent Glycosidic bonds

are used as a source of readily available energy.

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Disaccharide

are found bound to cells surface proteins and lipids, and may be used for cell recognition

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Oligosaccharides

is an animal product made of branched glucose polymers.

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glycogen

plant product made of both branched and unbranched glucose polymers (spiral)

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starch

(plant cell walls) long unbranched cellulose molecule

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cellulose

unbranched polymer of n-acetylglucosamine

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chitin

diverse group of nonpolar molecules.

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lipids

made of glycerol linked by three ester bonds to three fatty acids (FAs), called as Triacyl glycerol

fats

four-ringed animal lipids that have been implicated in atherosclerosis

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steriods

binds to a variety of G proteins serves as a switch to turn on some proteins

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guanosine triphosphate (GTP)

a nucleotide that plays a key role in cellular metabolism

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Adenosine triphosphate (ATP)

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alterations to amino acid side chains after their incorporation in a poly peptide chain

post translational modifications (PTMs)