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Flashcards in Chapter 3 Deck (20):
1

α-helix (alpha-helix)

A protein secondary structure in which the polypeptide backbone coils into a spiral shape stabilized by hydrogen bonding.

2

β-pleated sheet (beta-pleated sheet)

A protein secondary structure in which the polypeptide backbone folds into the sheetlike shape stabilized by hydrogen bonding.

3

Condensation/dehydration reaction

A chemical reaction in which two molecules are joined covalently with the removal of an -OH from one and an -H from another to form water. Also called a dehydration reaction. Compare with hydrolysis.

4

Disulfide bond

A covalent bond between two sulfur atoms, typically in the side chains of certain amino acids (e.g., cysteine). Often contributes to tertiary and quaternary levels of protein structure.

5

Enzyme

A protein catalyst used by living organisms to speed up and control biological reactions.

6

Hydrolysis

A chemical reaction in which a molecule is split into smaller molecules by reacting with water. In biology, most hydrolysis reactions involve the splitting of polymers into monomers. Compare with condensation reaction.

7

Macromolecular machine

A group of proteins that assemble to carry out a particular function.

8

Macromolecule

Any very large organic molecule, usually made up of smaller molecules (monomers) joined together into a polymer. The main biological macromolecules are proteins, nucleic acids, and polysaccharides.

9

Monomer

A small molecule that can covalently bind to other similar molecules to form a larger macromolecule. Compare with polymer.

10

Oligopeptide/peptide

A chain composed of fewer than 50 amino acids linked together by peptide bonds. Often referred to simply as peptide.

11

Peptide bond

The covalent bond formed by a condensation reaction between two amino acids; links the residues in peptides and proteins.

12

Polymer

Any long molecule composed of small repeating units (monomers) bonded together. The main biological polymers are proteins, nucleic acids, and polysaccharides.

13

Polymerization

(verb: polymerize) The process by which many identical or similar small molecules (monomers) are covalently bonded to form a large molecule (polymer).

14

Polypeptide

A chain of 50 or more amino acids linked together by peptide bonds. Compare with oligopeptide and protein.

15

Primary structure

The sequence of amino acid residues in a peptide or protein; also the sequence of nucleotides in a nucleic acid. Compare with secondary, tertiary, and quaternary structure.

16

Protein

A macromolecule consisting of one or more polypeptide chains composed of 50 or more amino acids linked together. Each protein has a unique sequence of amino acids and generally possesses a characteristic three-dimensional shape.

17

Quaternary structure

In proteins, the overall three-dimensional shape formed from two or more polypeptide chains (subunits); determined by the number, relative positions, and interactions of the subunits. In single stranded nucleic acids, the hydrogen bonding between two or more distinct strands will form this level of structure through hydrophobic interactions between complementary bases. Compare with primary, secondary, and tertiary structures.

18

Secondary structure

In proteins, localized folding of a polypeptide chain into regular structures (i.e., alpha-helix and beta-pleated sheet) stabilized by hydrogen bonding between atoms of the peptide backbone. In nucleic acids, elements of structure (e.g., helices and hairpins) stabilized by hydrogen bonding and hydrophobic interactions between complementary bases. Compare with primary, tertiary, and quaternary structures.

19

Tertiary structure

The overall three-dimensional shape of a single polypeptide chain, resulting from multiple interactions among the amino acid side chains and the peptide backbone. In single-stranded nucleic acids, the three-dimensional shape is formed by hydrogen bonding and hydrophobic interactions between complementary bases. Compare with primary, secondary, and quaternary structure.

20

van der Waals interactions

A weak electrical attraction between two nonpolar molecules that have been brought together through hydrophobic interactions. Often contributes to tertiary and quaternary structures in proteins.