Biochemistry Learning Curve Chapter 4.1,4.2,4.3

Which of the following combinations of φ and ψ dihedral angles would be allowed in a poly-Alanine polymer? Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices -120°, + 120° +120°, +120° +180°, -180° +120°, -120° -120°, -120°

-120°, + 120°

Estimate the number of of amino acids in a typical α helix that is 30 Å long. Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices 5800 20 The number of amino acids cannot be estimated because of the irregularity of α helices. 45

20

How many turns are there in a typical α helix with a length of 4.86 nm? Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices 9 260 26 0.9

9

What does a Ramachandran plot show? Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices The dependence of protein conformation on pH. The effect of steric hindrance on the allowable dihedral angles for a protein backbone. The dependence of salt bridge formation on dielectric constant. The degree of folding of a protein.

A Ramachandran plot shows ψ versus φ. The effect of steric hindrance on the allowable dihedral angles for a protein backbone.

In aqueous solution proteins will tend to fold and bury the hydrophobic amino acids toward the protein's interior. In the process, a great deal of conformational entropy is lost by the protein as it adopts a more ordered shape. If so much entropy is lost by the protein, why does it fold? Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices The entropic loss is usually offset by the formation of interior salt bridges and hydrogen bonds. The folding process is also strongly exothermic. Loss of entropy is thermodynamically favorable. There is a larger entropic gain for the surrounding water molecules.

A process will be thermodynamically favored if it is exergonic. Here, you must consider the total free energy change by both the solute and the solvent. There is a larger entropic gain for the surrounding water molecules.

Which amino acid is most favored in an α-helical conformation? Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices Arg Asn Gly Ala Asp

Ala

A ___ is a part of a polypeptide chain that is independently stable or could undergo movement as a single entity with respect to the entire protein. Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices motif fold domain supersecondary structure

An example is the calcium-binding region of the troponin C polypeptide. domain

Which of the following bonds limits the range of conformations available for a polypeptide chain? Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices

C-N

Which type of hydrogen bond stabilizes most secondary structures? (The hydrogen bond is represented by dots, ···.) Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices C=O ··· C=O C=O ··· N-Cα C=O ··· H-N H-N ··· C=O

C=O ··· H-N

Which does not apply to circular dichroism (CD) spectroscopy? Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices examines structural asymmetry determines the aromatic content of a protein in the far UV, measures the absorbance of the peptide bond examines the fraction of a protein that is folded v

CD spectroscopy can distinguish different secondary structures. determines the aromatic content of a protein

Which of the following statements is incorrect regarding the globular and fibrous proteins? Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices Most globular proteins provide support, shape, and external protection to vertebrates. Globular proteins often contain several types of secondary structure. Fibrous proteins generally consist of one type of secondary structure. Fibrous proteins have their polypeptide chains arranged in long strands or sheets.

Collagen is an example of a fibrous protein. Most globular proteins provide support, shape, and external protection to vertebrates.

In addition to the C-N peptide bond that is not free to rotate, other single bonds may be prevented from rotating because of _____. Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices size of R groups charge of R groups steric hindrance All of the above

Consider reasons why Ψ and Φ can have any values between -180° and 180° but why many values are prohibited. All of the above

Which sequence maximizes ion-pairing for the stabilization of α helix formation at pH 7? Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices AVISNRPYGGG DAAARVVVVEV ADVKLEVRIDV ADVVKLIEVAR

Consider the effect of pH on the amino acids and the spacing of oppositely charged side chains. ADVVKLIEVAR

Which statement applies to the following sequence's α helix formation at pH 7? AIVDAEDVEID Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices Helices are not favored due to the bulkiness of side chains. Helices are favored due to strong capacity for hydrogen bonding. Helices are favored due to high hydrophobic character. Helices are not favored due to repulsion of negative charges.

Consider the effect of pH on the amino acids. Helices are not favored due to repulsion of negative charges.

A regular secondary structure occurs in a protein chain segment when _______. Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices the segment is primarily composed of aromatic amino acids the pH is near 7.0 the φ and ψ angles are the same, or nearly so, throughout the segment the dihedral angle ω is near 0°

Consistent conformation leads to a regular structure. the φ and ψ angles are the same, or nearly so, throughout the segment

The carbonyl of the first (#1) amino acid (amino end) of an α helix will hydrogen bond to the amine group of which amino acid? Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices #2 #3 #4 #5

Examine figure 4-4 (a) and that there are about 3.6 amino acids per helix turn. 5

All fibrous proteins _________. Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices are insoluble in water lack quaternary structure are stabilized by disulfide bonding have a high content of polar amino acids

Fibrous proteins have a high content of hydrophobic amino acids. are insoluble in water

A good way to predict whether an amino acid side chain is on the outside or inside of a protein is to consider its ______. Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices molecular weight three-letter abbreviation one-letter abbreviation hydropathy (polarity) none of the above

Hydrophobic cores are typical of globular proteins. hydropathy (polarity)

Which belongs to the family of intermediate filament (IF) proteins? Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices α-keratins lysozyme cellulose myoglobin

IF proteins are fibrous. α-keratins

Which of the following statements regarding β conformation is false? Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices R groups of adjacent amino acids protrude from the structure in opposite directions. In this conformation, the polypeptide chain is extended into a zigzag rather than a helical structure. Interstrand H bonds are in-line for the parallel β sheet and not in-line for the antiparallel variant. Individual segments of a β sheet are not required to be near one another in the linear sequence of the polypeptide.

Interstrand H bonds are in-line for the parallel β sheet and not in-line for the antiparallel variant.

Which statement does not apply to intrinsically disordered proteins? Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices Some serve as scavengers. They lack a hydrophobic core and have a high density of charged amino acids. They can interact with many protein partners. They are usually all α structures.

Intrinsic disorder facilitates functional and structural variation. They are usually all α structures.

Which describes a solvation layer for a hydrophobic protein solute? Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices The solvation layer is the outer layer of the protein that contains the most polar amino acids in the protein. It is a highly ordered, low-entropy layer of water surrounding a solute. It is the exterior surface of a hydrophobic solute that often contains many salt bridges. It is a layer of water around the solute that is highly randomized due to the few interactions water has with the solute.

It is a highly ordered, low-entropy layer of water surrounding a solute.

Which statement is false about myoglobin?

It is a loosely packed globular protein with about 50 internally associated water molecules.

Proteins that are folded in their thermodynamically stable and functional form(s) are considered to be ___ proteins. Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices denatured native globular crystallized

It is also considered to be the biologically active conformation of the protein. native

Which statement is true for the dihedral angle, ω, in the protein backbone? Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices Because of the restricted rotation of the peptide bond ω is always 0°. It usually equals either -180° or +180° because the of the trans orientation about the peptide bond. It may take on any value between -180° and 180° in normal proteins. The most common values of ω are -120°, -60°, +60° and +120°.

It usually equals either -180° or +180° because the of the trans orientation about the peptide bond.

What is unique about proline that is part of a β turn? Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices Its ring structure is broken. It is more protonated than other prolines. It is in the D configuration. Its N-terminal peptide bond is cis.

Its N-terminal peptide bond is cis.

Of the following secondary structures, which has not been observed in a protein before? Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices Type II β turn Type I β turn Left-handed α helix Antiparallel β conformation

Left-handed α helix

Ehlers-Danlos syndrome and osteogenesis imperfecta are caused by ____ in collagen. Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices chemical toxins causing the formation of carbon-carbon double bonds the substitution of glycine with larger residues such as cysteine or serine insufficient hydroxylation of proline residues an increase in dehydrohydroxylysinonorleucine cross-links

Maintaining the Gly-X-Y repeat is important for the maintenance of proper collagen structure. the substitution of glycine with larger residues such as cysteine or serine

Which of the following generalizations about methodologies that determine three-dimensional structure of proteins is correct? Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices NMR is limited to molecules that can be crystallized. NMR can generate information about protein conformational changes, protein folding, and interactions with other molecules. NMR is used to determine structure of proteins that are too large to be determined by x-ray crystallography. X-ray crystallography is performed on macromolecules that are in solution.

NMR can generate information about protein conformational changes, protein folding, and interactions with other molecules.

Permanent hair waving is not really permanent because ____. Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices new hair that grows has the original pattern of disulfide bonds the oxygen in air oxidizes the new disulfide bonds sunlight exposure gradually reverses the process over time the new disulfide bonds equilibrate back to their original pattern

Permanent waving involves breaking the natural disulfide bonds followed by the formation of new disulfides, but only for the hair that is treated. new hair that grows has the original pattern of disulfide bonds

Which of the following amino acids introduces a kink into an α helix and is thus rarely found in one? Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices Alanine Glycine Proline Leucine

Proline

Proteins in the same protein family have similar _______. Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices tertiary structure amino acid sequence function all of the above

Proteins in the same family are evolutionarily related. all of the above

Which is false about peptide bonds? Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices There are 6 coplanar atoms around the bond. They lack the free rotation of a regular single bond. Resonance gives the nitrogen a partial negative charge. They are shorter than a simple amine bond.

Resonance leads to partial double-bond character. Resonance gives oxygen a partial negative charge. Resonance gives the nitrogen a partial negative charge.

Which is false about peptide bonds? Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices There are 6 coplanar atoms around the bond. They lack the free rotation of a regular single bond. Resonance gives the nitrogen a partial negative charge. They are shorter than a simple amine bond.

Resonance leads to partial double-bond character. Resonance gives oxygen a partial negative charge. Resonance gives the nitrogen a partial negative charge.

What is the range of each angle plotted on a Ramachandran plot? Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices φ ranges from -180° to 180°; ψ ranges from 0° to 360° φ ranges from 0° to 180°; ψ ranges from 0° to 360° Both φ and ψ range from 0° to 360° Both φ and ψ range from -180° to 180°

Review the conventions for the dihedral angles. Both φ and ψ range from -180° to 180°

hinoceros horn is exceptionally strong because nearly 20% of the residues are ______. Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices proline in the cis configuration cysteines involved in disulfide bonding lysines forming cross-links between chains in extended β sheets

Rhinoceros horn is composed of strong α-keratins. cysteines involved in disulfide bonding

A change in ___________ changes the spatial arrangement of atoms in a protein, but does not involve the breaking of covalent bonds. Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices primary structure stereoisomer configuration conformation

Rotation about bonds (e.g. single bonds) changes the spatial arrangement of atoms in a protein. conformation

Reverse turns are classified as secondary structure because _____. Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices They are stabilized by hydrogen bonds between backbone amide groups. They only occur at interior protein positions. They link together α-helices. They are not as important as primary structure. They link together β-sheets.

Secondary structure describes main chain structure, not side chains. They are stabilized by hydrogen bonds between backbone amide groups.

Which describes the protein in silk? Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices collagen with a predominantly α helix conformation fibroin with a predominantly α helix conformation fibroin with a predominantly β sheet conformation collagen with a predominantly β sheet conformation

Silk does not stretch, but is flexible. fibroin with a predominantly β sheet conformation

Which of the following statements is false regarding intrinsically disordered proteins? Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices They tend to be rich in amino acids with charged side chains. Up to a third of human proteins can be classified as intrinsically disordered. They have significant unstructured segments. Proteins with segments that are intrinsically disordered are not fully functional.

Some intrinsically disordered proteins play important roles in protein interaction networks. Proteins with segments that are intrinsically disordered are not fully functional.

What is the best way to characterize the following structure? Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices It is an antiparallel β sheet. It is a left-handed α helix. It is a parallel β sheet. It is a right-handed α helix. https://learningcurve.macmillantech.com/question_pics/IGA.chp4.jpg

The adjacent peptides have opposite amino-to-carboxyl orientations. It is an antiparallel β sheet.

Which of the following is a deficiency disease characterized be general degeneration of connective tissue, and is caused by a lack of vitamin C? Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices Myotonic dystrophy Ehlers-Danlos syndrome Scurvy Osteogenesis imperfecta

The disease occurs in remote regions where nutritious food is scarce. It is also found on U.S. college campuses. Scurvy

A typical range for the ΔG separating the folded (active) and unfolded states in typical proteins under physiological conditions is ________. The magnitude of this ΔG indicates that the folded state is _______________ relative to the unfolded state. Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices 2000 to 6500 kJ/mol; extremely stable 20 to 65 kJ/mol; marginally stable 2000 to 6500 kJ/mol; marginally stable 20 to 65 kJ/mol; extremely stable

The folded and unfolded states are usually close in terms of the free energy. 20 to 65 kJ/mol; marginally stable

Which amino acid would provide stabilization at pH=7 if near the amino-terminal end of an α helix? Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices arginine glycine aspartate asparagine

The helix has a dipole. The partial charges of the dipole are stabilized by oppositely charged amino acids near the ends of the helix. aspartate

Which statement is true about the backbone bonds in a protein? Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices All of the backbone bonds have restricted rotation due to resonance. All have free rotation, limited only by steric constraints. Only the peptide bond has restricted rotation. All other bonds have free rotation, limited only by steric constraints. The peptide bond has restricted rotation, the N-Cα bond is restricted for proline, otherwise free rotation is only limited by steric constraints.

The peptide bond has restricted rotation, the N-Cα bond is restricted for proline, otherwise free rotation is only limited by steric constraints.

The backbone of a polypeptide chain can be pictured as a series of rigid planes, with consecutive planes sharing a common point of rotation at __________. Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices the nitrogen the carbonyl carbon the alpha carbon the side chain

The peptide bond makes six atoms coplanar. the alpha carbon

Which statement is true about the side chains (R groups) of amino acids in an α helix? Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices They alternating between pointing to the interior and exterior of the helix. They extend radially out from the helix. They point to the interior of the helix. They are randomly oriented along the helix.

The side chains are consistent in their orientation relative to the helix axis. They extend radially out from the helix.

As predicted by Pauling and Corey, peptide bonds are in the ___ configuration. Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices planar, cis nonplanar, cis planar, trans nonplanar, trans

The six atoms of the peptide group lie in a single plane. planar, trans

Which amino acid repeat is present in collagen? (X is often Pro; Y is often 4-Hyp) Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices Gly-Ala-Y-X X-X-Y Gly-X-Y Ala-Lys-X

This repeat is important for the maintenance of proper collagen structure. Gly-X-Y

Rotation about which bond changes the dihedral angle designated φ? Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices Cα-C N-Cα C-N Cα-R

There are three dihedral angles for the backbone of a protein. N-Cα

Which statement is true about disulfide bonds? Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices Extracellular proteins have primarily the oxidized sulfhydryl groups rather than disulfide bonds. They are the greatest contributor to the stability of the native structure of proteins. Disulfide bonds are fairly evenly distributed for all proteins. They are not as common for proteins inside cells due to the reducing environment.

They are not as common for proteins inside cells due to the reducing environment.

Which statement is true about salt bridges? Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices They tend to destabilize protein structures. They are stronger in the hydrophobic interior of a folded protein than on the surface. They very readily associate and dissociate in proteins. They generally contribute little to the conformation of a protein.

They are stronger in the hydrophobic interior of a folded protein than on the surface.

Numerous weak interactions are responsible for stabilizing protein conformation. Of the following, ____ are the major contributors to stabilizing the conformation of most soluble proteins. Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices hydrophobic interactions hydrogen bonds van der Waals interactions ionic interactions

They arise from the increase in entropy of the surrounding water when nonpolar groups are clustered together. hydrophobic interactions

Which statement is true about the side chains (R groups) of amino acids in an α helix? Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices They alternating between pointing to the interior and exterior of the helix. They extend radially out from the helix. They point to the interior of the helix. They are randomly oriented along the helix.

They extend radially out from the helix.

Which of the following generalizations about globular proteins is incorrect? Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices Globular proteins have a more compact shape than fibrous proteins. The globular structure derives stability from hydrophobic interactions. They generally have quaternary structure. They tend to have a dense hydrophobic core.

They generally have quaternary structure.

The protein keratin is composed of two helical strands that wrap around each other in what is called a coiled coil. The two strands remain in contact with each other over the entire length of the protein via hydrophobic interactions. What amino acid might you predict occupies multiple sites along the entire length of the keratin sequence? Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices Asp Cys Ser Val Glu

Val

Which describes a solvation layer for a hydrophobic protein solute? Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices The solvation layer is the outer layer of the protein that contains the most polar amino acids in the protein. It is a highly ordered, low-entropy layer of water surrounding a solute. It is the exterior surface of a hydrophobic solute that often contains many salt bridges. It is a layer of water around the solute that is highly randomized due to the few interactions water has with the solute.

Water has a high tendency to hydrogen bond with other water molecules It is a highly ordered, low-entropy layer of water surrounding a solute.

Which contributes the most to the stability of most proteins? Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices disulfide bonding hydrophobic interactions covalent bonding hydrogen bonding

Weak interactions provide the greatest contribution toward protein stability. hydrophobic interactions

Which describes the quaternary structure of hemoglobin?

a pair of αβ protomers; four heme groups

Which amino acid has the greatest tendency to form an α helix? Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices histidine alanine aspartate proline

alanine

Collagen, a component of connective tissues, becomes more brittle with age because of _______. Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices an accumulation of covalent cross-links an increase in the number of disulfide bonds the methylation of glycine, which decreases flexibility the degradation of 4-hydroxyproline to proline

an accumulation of covalent cross-links

Which does not apply to the most common kind of α helix? Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices is right-handed can be a mixture of L and D amino acids is stabilized by hydrogen bonding has about 3.6 amino acid residues per helix turn

can be a mixture of L and D amino acids

A change in ___________ changes the spatial arrangement of atoms in a protein, but does not involve the breaking of covalent bonds. Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices primary structure stereoisomer configuration conformation

conformation

A reagent like glutathione tends to convert __________________ by _______________. Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices sulfhydryls to disulfides; oxidation sulfhydryls to disulfides; reduction disulfides to sulfhydryls; oxidation disulfides to sulfhydryls; reduction

disulfides to sulfhydryls; reduction

The backbone of a hypothetical protein structure is shown. The protein has a single polypeptide chain. If the orange and blue regions have distinct and independent functions they are classified as __________. Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices folds protomers motifs domains https://learningcurve.macmillantech.com/question_pics/Lehn7eFigure4_19.jpg

domains

β turns are generally found on the ____ of a protein and often consist of ____ residues. Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices interior; gly and ala exterior; pro and gly interior; pro and gly exterior; gly and ala

exterior; pro and gly

A protein that consists of mostly one type of secondary structure, has a relatively simple tertiary structure and its function is to provide structural support is likely a __________ protein. Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices quaternary globular fibrous regulatory

fibrous

Polypeptides that are folded into a roughly spherical shape and may contain several types of secondary structure are classified as ________ proteins. Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices fibrous tertiary globular cluster

globular

Which amino acids are particularly common in β turns? Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices alanine and proline serine and threonine glycine and proline glycine and alanine

glycine and proline

Which of the following plays a large role in maintaining the secondary structure of proteins? Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices ionic bonds hydrophobic interactions hydrogen bonds peptide bonds

hydrogen bonds

Which describes collagen? Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices right-handed helix; forms double-stranded fibers wrapped in a left-handed fashion left-handed helix; forms double-stranded fibers wrapped in a right-handed fashion left-handed helix; forms triple-stranded fibers wrapped in a right-handed fashion right-handed helix; forms triple-stranded fibers wrapped in a left-handed fashion

left-handed helix; forms triple-stranded fibers wrapped in a right-handed fashion

Which is not made of fibrous protein? Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices silk collagen hair myoglobin

myoglobin

A protein in a functional conformation is called a ___________ protein. Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices first order native primordial homologous

native

Which is not among the most common amino acids in collagen? Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices phenylalanine alanine 4-hydroxyproline glycine

phenylalanine

The first step of the permanent waving of hair involves the ____. Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices reduction of natural disulfides breaking of hydrogen bonds dissociation of hair protofibrils all of the above

reduction of natural disulfides

Which describes the proteins in hair? Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices left-handed helix; forms triple-stranded fibers wrapped in a right-handed fashion right-handed helix; forms triple-stranded fibers wrapped in a left-handed fashion right-handed helix; forms double-stranded fibers wrapped in a left-handed fashion left-handed helix; forms double-stranded fibers wrapped in a right-handed fashion

right-handed helix; forms double-stranded fibers wrapped in a left-handed fashion

What role does vitamin C play in the synthesis of collagen? Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices the hydroxylation of proline and lysine the formation of disulfide bonds the assembly of the three-stranded superhelix Vitamin C has no role in the synthesis of collagen.

the hydroxylation of proline and lysine

A regular secondary structure occurs in a protein chain segment when _______. Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices the segment is primarily composed of aromatic amino acids the pH is near 7.0 the φ and ψ angles are the same, or nearly so, throughout the segment the dihedral angle ω is near 0°

the φ and ψ angles are the same, or nearly so, throughout the segment

By definition, quaternary structure is exhibited by proteins that have ___________. Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices an internal layering of β sheets more than one type of secondary structure two or more separate, but associating, protein chains an unusually high number of disulfide bonds

two or more separate, but associating, protein chains

Which of the following best defines the term secondary structure with respect to proteins? Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices the three-dimensional conformation of a protein in its native folded state the local spatial arrangement of the main-chain atoms in a segment of a polypeptide chain the three-dimensional structure of a multisubunit protein a description of the covalent backbone of a protein, including the sequence of the amino acids

α helices are one of the most common secondary structures in proteins. the local spatial arrangement of the main-chain atoms in a segment of a polypeptide chain

often occurs near the surface of a protein usually involves three amino acids has a hydrogen bond between the first and last amino acids in the turn makes a 180° turn in the protein chain

β turns can also connect the ends of adjacent segments of an antiparallel β sheet. usually involves three amino acids

Which is a difference between γ and β turns? Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices γ turns have three amino acids; β turns have four amino acids γ turns contain disulfide bonds; β turns have hydrogen bonds γ turns rarely contain glycine; β turns frequently contain glycine γ turns have trans proline; β turns have cis proline

γ turns have three amino acids; β turns have four amino acids