HEIN

What are the two primary functions of proteins?

structural materials and as enzymes

What substances do all proteins yield upon hydrolysis?

amino acids

What are proteins classified as if they yield only amino acids when hydrolyzed?

simple proteins

What is the classification for proteins that yield amino acids and one or more additional products?

conjugated proteins

What establishes the specific function of a protein?

the sequence of amino acids

What two functional groups are present in each amino acid?

an amino group (NH2) and a carboxyl group (-COOH)

What is the chemical formula given for the amino group in amino acids?

NH2

What is the chemical formula given for the carboxyl group in amino acids?

-COOH

What is the portion of the amino acid molecule designated as R commonly referred to?

amino acid side chain

Name one type of group that the side chain (-R) of an amino acid may contain?

Alkyl groups

Besides alkyl and aromatic groups, what is another group a side chain may contain?

Sulfur-containing groups

Ala

Alanine

Arg

Arginine

Which amino acid has the abbreviation Asn?

Asparagine

Aspartic acid?

Aspartic acid

Cys?

Cysteine

Glu

Glutamic acid

Gln

Glutamine

Which amino acid has the abbreviation Gly?

Glycine

His

Histidine

Ile

Isoleucine

Leu

Leucine

What is the abbreviation for Lysine?

Lys

Met

Methionine

Which amino acid is represented by the abbreviation Phe?

Phenylalanine

Pro

Proline

Ser

Serine

Thr

Threonine

Which amino acid has the abbreviation Trp?

Tryptophan

Tyr

Tyrrosine

Which amino acid has the abbreviation Val?

Valine

What are the 10 essential amino acids?

Phenylalanine, Valine, Tryptophan, Threonine, Isoleucine, Methionine, Histidine, Arginine, Leucine, and Lysine

What type of protein supplies all the essential amino acids?

complete protein

What is an incomplete protein deficient in?

one or more essential amino acids

Which amino acid is the only one that does not have at least one asymmetric carbon atom?

glycine

What term describes amino acids because they can react either as an acid or a base?

amphoteric

In what form do amino acids mainly exist even in neutral biological solutions?

zwitterions

What is the name for the pH at which there is no migration toward either electrode in an electrolytic cell?

isoelectric point

What is the isoelectric point of Arginine?

10.8

What is the isoelectric point of Lysine?

9.7

What is the isoelectric point of Alanine?

6.0

What is the isoelectric point of Glycine?

6.0

What is the isoelectric point of Serine?

5.7

What is the isoelectric point of Glutamic acid?

3.2

What is the isoelectric point of Aspartic acid?

2.9

Through what structures are amino acid units joined in proteins?

amide structures

What is formed when two amino acids combine and lose a molecule of water?

peptide

What is the name for a molecule containing three amino acid units?

tripeptide

What is the name for a molecule containing four amino acid units?

tetrapeptide

What term refers to the amino acid units making up a peptide minus the elements of water?

amino acid residues

In linear peptides, what is the amino-group end called?

N-terminal residue

In linear peptides, what is the carboxy-group end called?

C-terminal residue

How many different dipeptides can be formed from alanine and glycine?

two

What two characteristics give a polypeptide its biological effectiveness and specificity?

amino acid sequence and chain length

Which biological polypeptide is a pain-producing agent?

Substance P

Affects tissue inflammation and blood pressure

Bradykinin

Which biological polypeptide maintains water balance and blood pressure?

Angiotensin II

Relieves pain, produces sense of well-being

Leu-enkephalin and Met-enkephalin

Which polypeptide increases blood pressure and decreases kidney water excretion?

Vasopressin

Which biological polypeptide initiates childbirth labor?

Oxytocin

What are the four levels on which chemists typically describe large proteins?

Primary, Secondary, Tertiary, and Quaternary structure

the number, kind, and sequence of amino acid units structure of a protein?

primary structure

What determines the three-dimensional shape into which a protein folds?

the side-chain

a regular three-dimensional structure held together by hydrogen bonding

Secondary structure

Between which groups in the polypeptide chains does hydrogen bonding occur in secondary structures?

oxygen of the C=O and the hydrogen of the H-N groups

What are two examples of protein secondary structure?

alpha-helical and beta-pleated-sheet structures

distinctive and characteristic conformation, or shape

tertiary structure

Name one of the three interactions mentioned that hold the tertiary structure together?

Disulfide bonding

In what type of proteins is a quaternary structure found?

some complex proteins

What are complex proteins with quaternary structures made of?

two or more smaller protein subunits

By what type of bonds are subunits in a quaternary structure held together?

noncovalent bonds

Which proteins tend to function in support roles and contain a highly developed secondary structure?

fibrous proteins

What is the most abundant protein in the animal kingdom?

collagen

What fibrous protein makes up hair?

Keratin

What is the name of the fibrous protein found in silk?

Fibroin

Where is collagen found in the body?

Tendons, ligaments, and bone matrix

What protein shape is shared by myoglobin, hemoglobin, and immunoglobulin G?

globular proteins

Which globular protein functions as a binding protein carrying oxygen for muscle tissue?

Myoglobin

An enzyme that catalyzes protein digestion in the small intestine?

Carboxypeptidase A

Which proteins bind foreign molecules as a defense against disease?

immunoglobulin G

What protein has a spacefilling model where heme groups are visible in the subunits?

hemoglobin

What must happen to the hemoglobin to facilitate oxygen binding in the lungs?

conformation changes

What is the term for the process when a protein loses only its natural three-dimensional conformation?

denaturation

Which structural levels are altered or disrupted during denaturation?

secondary, tertiary, or quaternary

Which structural level is not altered during denaturation?

primary structure

A protein's function depends on its natural conformation, hence a denatured protein has?

lost all biological activity

What chemical reaction destroys the protein's primary sequence?

hydrolysis of the peptide bonds

Three tests listed to detect and distinguish proteins and amino acids?

Xanthoproteic, Biuret. and ninhydrin

Which test for proteins and amino acids starts with the letter B?

Biuret Test

Which test for proteins and amino acids starts with the letter N?

Ninhydrin Test