Chapter 5.3-5.3

Question 1

fat

Answer 1

A lipid consisting of three fatty acids linked to one glycerol molecule; also called a triacylglycerol or triglyceride.

Question 2

triaglycerol

Answer 2

Three fatty acids linked to one glycerol molecule; also called a fat or a triglyceride.

Question 3

unsaturated fatty acid

Answer 3

A fatty acid possessing one or more double bonds between the carbons in the hydrocarbon tail. Such bonding reduces the number of hydrogen atoms attached to the carbon skeleton.

Question 4

saturated fatty acid

Answer 4

A fatty acid in which all carbons in the hydrocarbon tail are connected by single bonds, thus maximizing the number of hydrogen atoms that are attached to the carbon skeleton.

Question 5

trans fat

Answer 5

An unsaturated fat containing one or more trans double bonds.

Question 6

phospholipid

Answer 6

A lipid made up of glycerol joined to two fatty acids and a phosphate group. The hydrocarbon chains of the fatty acids act as nonpolar, hydrophobic tails, while the rest of the molecule acts as a polar, hydrophilic head. Phospholipids form bilayers that function as biological membranes.

Question 7

steroid

Answer 7

A type of lipid characterized by a carbon skeleton consisting of four rings with various chemical groups attached.

Question 8

cholesterol

Answer 8

A steroid that forms an essential component of animal cell membranes and acts as a precursor molecule for the synthesis of other biologically important steroids, such as hormones.

Question 9

catalyst

Answer 9

A chemical agent that increases the rate of a reaction without being consumed by the reaction.

Question 10

polypeptide

Answer 10

A polymer (chain) of many amino acids linked together by peptide bonds.

Question 11

protein

Answer 11

A functional biological molecule consisting of one or more polypeptides folded and coiled into a specific three-dimensional structure.

Question 12

amino acid

Answer 12

An organic molecule possessing both carboxyl and amino groups. Amino acids serve as the monomers of polypeptides.

Question 13

polypeptide

Answer 13

The covalent bond between the carboxyl group on one amino acid and the amino group on another, formed by a dehydration reaction.

Question 14

primary structure

Answer 14

The level of protein structure referring to the specific sequence of amino acids.

Question 15

secondary structure

Answer 15

The localized, repetitive coiling or folding of the polypeptide backbone of a protein due to hydrogen bond formation between constituents of the backbone.

Question 16

a helix

Answer 16

A spiral shape constituting one form of the secondary structure of proteins, arising from a specific pattern of hydrogen bonding.

Question 17

B pleated sheet

Answer 17

One form of the secondary structure of proteins in which the polypeptide chain folds back and forth. Two regions of the chain lie parallel to each other and are held together by hydrogen bonds.

Question 18

tertiary structure

Answer 18

Irregular contortions of a protein molecule due to interactions of side chains involved in hydrophobic interactions, ionic bonds, hydrogen bonds, and disulfide bridges.

Question 19

disulphide bridges

Answer 19

A strong covalent bond formed when the sulfur of one cysteine monomer bonds to the sulfur of another cysteine monomer.

Question 20

quaternary structure

Answer 20

The particular shape of a complex, aggregate protein, defined by the characteristic three-dimensional arrangement of its constituent subunits, each a polypeptide.

Question 21

denaturation

Answer 21

In proteins, a process in which a protein unravels and loses its native shape, thereby becoming biologically inactive; in DNA, the separation of the two strands of the double helix. Denaturation occurs under extreme (noncellular) conditions of pH, salt concentration, and temperature.

Question 22

chaperonin

Answer 22

A protein molecule that assists in the proper folding of other proteins.

Question 23

X-ray crystallography

Answer 23

A technique that depends on the diffraction of an X-ray beam by the individual atoms of a crystallized molecule to study the three-dimensional structure of the molecule.