Mastering Biology: Chapter 5 (9/2/17)

Match to the correct definition 1. Primary 2. Secondary 3. Tertiary 4. Quaternary

1. (2) 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. 2. (4) structure is the result of two or more protein subunits assembling to form a larger, biologically active protein complex. 3. (3) structure is achieved when a protein folds into a compact, three-dimensional shape stabilized by interactions between side-chain R groups of amino acids. 4. (1) structure is the sequence of amino acids in a protein.

Which of the following statements about the formation of polypeptides from amino acids is true? a. A bond forms between the carboxyl functional group of one amino acid and the amino functional group of the other amino acid. b. A bond can form between any carbon and nitrogen atom in the two amino acids being joined. C. Polypeptides form by condensation or hydrolysis reactions. d. The reaction occurs through the addition of a water molecule to the amino acids.

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

There are four levels of protein structure. These figures show primary, secondary, tertiary, and quaternary protein structure. Which level(s) of protein structure may be stabilized by covalent bonds? 1. Primary, tertiary and quaternary levels of protein structure 2. None of the levels of protein structure is stabilized by covalent bonds. 3. Secondary level of protein structure

Primary, tertiary and quaternary levels of protein structure

Which polymers are composed of amino acids? a. nucleic acids b. monomers c. proteins d. carbohydrates

Proteins

These figures show the four levels of protein structure: primary, secondary, tertiary, and quaternary structure. Which level of protein structure is characteristic of some, but not all, proteins? 1. Secondary level of protein structure 2. Tertiary level of protein structure 3. Quaternary level of protein structure

Quaternary level of protein structure

Amino acids are the building blocks of proteins. There are 20 amino acids that most commonly occur in proteins. Based on the functional group making up their side chain, or R group, amino acids are classified as acidic, basic, or neutral. The physical and chemical properties of the R group determine the unique characteristics of each amino acid. Acidic amino acids have acidic R groups. Their electrically charged R groups make these molecules highly soluble in water. Basic amino acids have basic R groups. Their electrically charged R groups make these molecules highly soluble in water. Neutral (neither acidic nor basic) amino acids can be further classified as nonpolar or polar. The neutral nonpolar amino acids have R groups that contain no charged atoms; most of these amino acids are not water soluble. The neutral polar amino acids have R groups that have a dipole moment. The partial charges in their R groups make these molecules generally water soluble.

acidic - NONE basic - arginine neutral polar - glutamine, asparagine neutral nonpolar - alanine

Classify these amino acids as acidic, basic, neutral polar, or neutral nonpolar.

acidic: NONE basic: lysine neutral polar: serine neutral nonpolar: phenylalanine, proline, methionine

Classify these amino acids as acidic, basic, neutral polar, or neutral nonpolar.

acidic: glutamic acid basic: NONE neutral polar: threonine, tyrosine neutral nonpolar: valine, tryptophan

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

an oxygen

The four main categories of large biological molecules present in living systems are _____. a.nucleic acids, carbohydrates, monosaccharides, and proteins b. proteins, DNA, RNA, and steroids c. proteins, nucleic acids, carbohydrates, and lipids d. monosaccharides, lipids, polysaccharides, and proteins e. RNA, DNA, proteins, and carbohydrates

c. proteins, nucleic acids, carbohydrates and lipids

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

carboxyl functional group

which monomers make up RNA?

nucleotides

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

true