Biochem Ch. 19.3 and 19.4

The secondary structure of collagen is distinguished by A.a braided triple helix B.single α helix strands C.many α helixes wound into fibrils D.many glycoside links E.double α helix strands.

A. A braided triple helix

A chain made of more than 50 amino acids is usually referred to as a(n) A.protein B.hormone C.peptide D.enzyme E.globulin

A. Protein

The primary structure of a protein describes the ____________. A.sequence of amino acids B. R group interactions C.overall protein folding and subunit interactions D.H-bond interactions

A. Sequence of Amino Acids

Define the secondary structural level of a protein?

1. The structural level achieved when hydrogen bonds form between the carboxyl group of one amino acid and the amino group of a different amino acid 2. Includes Beta Pleated Sheets and Alpha Helixes

Fill in the blanks: The _____ of the _________ (the primary structure) provides the ___________, that interact to determine the tertiary structure of the protein. of the amino acids

1.Order 2.Amino Acids 3. R Groups

Would you expect a polypeptide with a high content of His, Met, and Leu to have more αα-helical sections or ββ-pleated sheet sections? A. αα-helical sections B. ββ-pleated sheet sections

A. Alpha Helix

Enkephalins, naturally produced opiates in the body, are found in A. thalamus and spinal cord tissue B.muscles and bone tissue C.brain and kidney tissue D.pancreas and liver tissue E.heart and lung tissue.

A. Thalamus and Spinal Cord

Which of the following is NOT an example of tertiary structure? A.triple helix B.salt bridges between ionized R groups of polar basic and polar acidic amino acids C.hydrogen bonds forming between the H of a polar R group and the O or N of another polar amino acid D.hydrophobic interactions between two amino acids with nonpolar R groups

A. Triple Helix

Proteins are formed when the ______ group of one amino acid forms a peptide bond with the _____ group of a second amino acid. A. −COO−,NH3+ B. −COO−,R group C. NH3+,R groupR D. R group; HH-bond

A. −COO−,NH3+

The fibrous protein responsible for the structure of hair and wool is A.endorphin B.keratin C.myosin D.casein E.collagen

B. Keratin

The 20 common amino acids can be classified by different _____, which can be polar or nonpolar. A.number of carbons B.R groups C.carboxyl groups D. H-bonds

B. R Groups

Disulfide bonds in a protein chain connect A.an alcohol and a carboxylic acid group B.two cysteine residues C.two asparagine residues D.tryptophan and alanine residues E.an amine and a carboxylic acid group.

B. Two Cysteine Residues

What type of bond holds the three polypeptide chains together in an individual collagen triple helix? In an individual collagen triple helix, the three polypeptide chains are held together by... A.disulfide bonds B. salt bridges C.hydrogen bonds

C. Hydrogen Bonds

When two protein chains combine to form an active protein, the structural level is ________. A.secondary B.primary C.quaternary D.tertiary E.pleated

C. Quaternary

The heme in hemoglobin is a(n) A. helix area in the hemoglobin molecule B.protein chain C.small molecule within a protein D.oxygen molecule within the hemoglobin molecule E.pleated sheet area in the hemoglobin molecule.

C. Small molecule within a protein

What kinds of interactions are NOT part of tertiary protein structure? A.hydrophilic interactions B.salt bridges C.peptide bonds D.disulfide bonds E.hydrophobic interactions

C.Peptide Bonds

What are some functions of collagen?

Collagen is a very strong structural feature in vertebrates. Structurally, three polypeptides are twisted together to form triple helices, which then bundle together to form fibrils that make up connective tissues and tendons.

Which of the following is an example of a secondary protein structure? A.dipeptide B.triglyceride C.fatty acid D.a helix E.amino acid

D. A Helix

Hemoglobin has a total of __________ protein chains in its quaternary structure. A.one B.two C.three D.four E. five

D. Four

Which of the following describes the formation of the alpha helix? A.Chains of polypeptides form sheets that stack up in a zigzag formation B.Hydrogen bonds form between the nitrogen of the amino groups and the hydrogen bonded to carbon in the R group C.It is constructed when a braid of helices intertwines D.The R groups of the amino acid point to the outside of the helix.

D. The R group of the amino acid point to the outside of the helix

Hemoglobin is an example of a protein with A.primarily an αα helix structure B.primary structure only C.two protein chains held together D.primarily a ββ-pleated sheet structure E.a globular structure.

E. A Globular Structure

The interactions that are important in the secondary structure of a protein are A.salt bridges B.peptide bonds C.disulfide bonds D.hydrophobic interactions E.hydrogen bonds.

E. Hydrogen Bonds

In an enzyme, the polypeptide chain folds into a compact shape known as the __________ structure. A.pleated B. secondary C.quaternary D.primary E.tertiary

E. Tertiary

The dipeptide abbreviated as Gly-Lys is the same as the dipeptide abbreviated as Lys-Gly. True or False

FALSE

Identify the amino acids that give strength to collagen. A.leucine B.hydroxylysine C.alanine D.hydroxyproline E. glycine F.proline

Hydroxyline and Hydroxyproline

Would Leucine and Valinne be found on the inside or outside of protein structure and why?

INSIDE; because they have non polar R groups that are hydrophobic

Identify the difference in hydrogen bonding between an αα helix and a ββ-pleated sheet.

In the α helix, hydrogen bonds form between the oxygen atom of carbonyl group and the hydrogen atom of the amino group of a peptide bond in the next turn of the helical chain. In the β-pleated sheet, hydrogen bonds occur between adjacent sections of a long polypeptide chain.

Would Aspartate and Cysteine be inside or outside of the protein and why?

OUTSIDE; because the have polar R groups that are hydrophilic

Disulfide bonds stabilize the tertiary structure of a protein. True OR False

TRUE

Define the primary structural level of a protein?

The peptide bonds between the amino acids

Define the tertiary structural level of a protein?

The protein folds into a compact structure stabilized by interactions between R groups

Collagen is one of the most prevalent proteins in the cornea. How is the structure of collagen different from that of a typical αα helix.

The structure of an α helix consists of only one polypeptide chain(s) twisted into a helix. The structure of collagen consists of three helices twisted around each other.

What happens when a primary structure forms a secondary structure?

When atoms in the backbone of a protein or peptide form hydrogen bonds within a single polypeptide or between polypeptide chains, a secondary structure results. The two most common secondary structures are the α helix and the β-pleated sheet.

secondary structure

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.

tertiary structure

structure is achieved when a protein folds into a compact, three-dimensional shape stabilized by interactions between side-chain R groups of amino acids

quaternary structure

structure is the result of two or more protein subunits assembling to form a larger, biologically active protein complex.

primary structure

structure is the sequence of amino acids in a protein.

Define the quaternary structural level of a protein?

the combination of two or more protein molecules to form an active protein