O-chem quiz 6

Biochemistry, the study of the chemical substances of living organisms, includes the study of

carbohydrates, lipids, proteins, and nucleic acids

Proteins are naturally occurring polymers in which

the monomer units are _____

amino acids

Amino acids are organic compounds that contain a _____ group and a _____ group and are found in proteins as _____.

amino; carboxyl;B-amino acids

ncomplete dietary proteins contain inadequate amounts of:

one or more essential amino acids.

With few exceptions, the amino acids found in nature and in proteins are _____ isomers

L

An amino acid with a positive charge on one atom and a negative charge on another atom with an overall charge of zero is known as a _____.

zwitterion

A _____ protein contains only amino acid residues, and a _____ protein contains one or more non-amino acids in the structures

simple; conjugated

The order in which amino acids are linked in a protein is known as the _____ structure.

Primary

The two most common types of secondary structures of proteins are the _____ and the _____

alpha helix; beta pleated sheet

What type of attractive interaction, that contributes to the tertiary structure of a protein, would be found buried in a nonaqueous environment within the protein?

Hydrophobic interactions

The structure of hemoglobin, with organization of its alpha and beta subunits, is an example of what type of protein structure?

Quaternary

Which of the following best describes what happens to a small peptide when placed in an acid solution and heated?

The small peptide undergoes hydrolysis to produce free amino acids

What is the consequence of protein denaturation?

All the above

Aqueous soluble proteins fold into a spherical or globular shape. Which of the following contains only soluble proteins?

Hemoglobin, insulin, immunoglobulin

Which of the following proteins plays the role of biochemical catalysts in the human body?

enzymes

An _____ is a glycoprotein produced by an organism in response to an invasion of a foreign substance known as a _____.

antibody; antigen

Which class of plasma lipoproteins is responsible for transporting cholesterol synthesized in the liver to cells throughout the body?

Low-density lipoproteins (LDLs)

The peptide met-gly-phe-ser-ala is known as a _____. The N-terminal amino acid is _____, and the C-terminal amino acid is _____. The IUPAC name of this peptide is _____

pentapeptide; methionine; alanine; methionylglycylphenylalanylserylalanine

Egg whites are made up of albumin, a single-chain protein. Why does the albumin solidify when placed in a hot skillet?

Heat causes denaturation of albumin destroying its secondary and tertiary structures.

What are enzymes?

Specialized catalysts of biochemical reactions

What is the difference between a simple enzyme and a conjugated enzyme?

Simple enzymes are composed only of protein chains while conjugated enzymes have a nonprotein part in addition to a protein part.

What function does the substrate perform in an enzyme-catalyzed reaction?

It is the substance upon which the enzyme acts

What is the area of an enzyme where catalysis of a substrate

occurs called?

Active site

Which of the following statements is true about an enzyme’s absolute specificity?

Enzyme will catalyze a particular reaction for only one

substrate

What factors affect enzyme activity?

All of the above

Identify the functions of carbohydrates in the human body

all the above

Carbohydrates are classified as

monosaccharides, disaccharides, oligosaccharides, and polysaccharides

A carbohydrate molecule whose mirror image is not superimposable is said to be a _____ molecule.

Chiral

What feature does a carbohydrate possess that generates stereoisomerism?

Presence of a chiral center

What formula is used to show the two-dimensional structure of groups around chiral centers in a molecule?

Fischer projection

How can you identify the D isomer of a carbohydrate by looking at the Fischer projection formula?

The –OH group on the chiral carbon farthest from the carbonyl group is pointing to the right.

What is meant when it is said that carbohydrates are optically active compounds?

A solution of carbohydrate will rotate the plane of polarized light

What structural feature distinguishes an aldose and a ketose?

An aldose possesses an aldehyde group, and a ketose possesses a ketone group

Which monosaccharide is the most important from a human nutritional standpoint?

D-Glucose

Monosaccharides in nature have cyclic forms because they can form:

internal hemiacetals that are stable.

Haworth projection formula for a monosaccharide is a formula showing:

a two-dimensional notation that specifies the three-

dimensional structure of a cyclic monosaccharide.

Which of the following sugars can be oxidized by Tollens and Benedict’s reagents in basic conditions?

all the above

What is the linkage that is formed when two monosaccharides react to form a disaccharide called?

Glycosidic linkage

Which disaccharide is a nonreducing sugar?

Sucrose

A _____ is a polysaccharide in which only one type of monosaccharide monomer is present.

homopolysaccharide