Proteins

Question 1

are by far the most important of all biological compounds.

Answer 1

Proteins

Question 2

The main structural material for plants is cellulose.
For animals, it is structural proteins, which are the chief constituents of skin, bones, hair, and nails.

Answer 2

Structure

Question 3

Two important structural proteins are

Answer 3

collagen and keratin

Question 4

Virtually all the reactions that take place in living organisms

Answer 4

Catalysis

Question 5

Every time we crook a finger, climb stairs, or blink an eye, we use our muscles.

Answer 5

Movement

Question 6

A large number of proteins perform transportation duties.

Answer 6

Transport

Question 7

Many hormones are proteins, including insulin, erythropoletin, and human growth hormone.

Answer 7

Hormones

Question 8

are fat-soluble molecules made from cholesterol.

Answer 8

Steroid hormones

Question 9

these are the three major sex hormones groups:

Answer 9

estrogens, androgens and progesterones.

Question 10

Some proteins store materials in the way that starch and glycogen store energy.

Answer 10

Storage

Question 11

Some proteins not only control the expression of genes, thereby regulating the kind of proteins synthesized in a particular cell, but also dictate when such manufacture takes place.

Answer 11

Regulation

Question 12

which are insoluble in water and are used mainly for structural purposes

Answer 12

fibrous proteins

Question 13

which are more or less soluble in water and are used mainly for nonstructural purposes.

Answer 13

globular proteins

Question 14

is an organic compound containing an amino group and a carboxyl group.

Answer 14

amino acid

Question 15

A pH at which a sample of amino acids or protein has an equal number of positive and negative charges.

Answer 15

Isoelectric point (pl)

Question 16

Compounds that have a positive charge on one atom and a negative charge on another are called

Answer 16

zwitterions

Question 17

zwitterions, from the German word

Answer 17

zwitter

Question 18

zwitterions, from the German word zwitter, meaning?

Answer 18

hybrid

Question 19

The very word “protein” is derived from the Greek

Answer 19

proteios

Question 20

The very word “protein” is derived from the Greek proteios, meaning?

Answer 20

of first importance

Question 21

the amino acid is still an lon, so it is still soluble in water. There is no pH at which an amino acid has no lonic character at all. If the amino acid is a positive ion at low pH and a negative lon at high pH, there must be some pH at which all the molecules have equal positive and negative charges. This pH is called the

Answer 21

isoelectric point (pt)

Question 22

can in turn be fairly easily reduced to give two molecules of cysteine.

Answer 22

cystine

Question 23

the presence of cystine has important consequences for the chemical structure and shape of the protein molecules of which it is part. The bond is also called a

Answer 23

disulfide bond

Question 24

Tryptophan is converted to serotonin, more properly called

Answer 24

5-hydroxytryptamine

Question 25

can be managed by controlling the levels of serotonin and Its further metabolites.

Answer 25

bipolar disorder

Question 26

Itself normally derived from phenylalanine, is converted to the neurotransmitter class called catecholamines

Answer 26

Tyrosine

Question 27

which includes epinephrine, commonly known by its proprietary name, adrenalin.

Answer 27

catecholamines

Question 28

is an intermediate in the conversion of tyrosine.

Answer 28

L-Dihydroxyphenylalanine (L-dopa)

Question 29

L-dopa are involved in

Answer 29

Parkinson's disease

Question 30

an amino acid that cannot be synthesized (from scratch) by the organism, and thus must be supplied in Its diet.

Answer 30

Essential amino acid

Question 31

uncommon amino acids are derived from the common amino acids and are produced by modification of the parent amino acid after the protein is synthesized by the organism in a process called

Answer 31

post-translational modification

Question 32

is unique among the proteinogenic amino acids. It is the only amino acid containing an essential dietary micronutrient (selenium) as a constitutive component, the only amino acid encoded by a UGA codon and the only one synthesized on its TRNA in all domains of life.

Answer 32

Selenocysteine

Question 33

is an a-amino acid that is used in the biosynthesis of proteins In some methanogenic archaea and bacteria

Answer 33

Pyrolysine

Question 34

an amide bond that links two amino acids.

Answer 34

Peptide bond

Question 35

The amino acids in a chain are often called

Answer 35

residues

Question 36

is the residue with the free a-COO^-group

Answer 36

C-terminal amino acid

Question 37

is the residue with the free a-NH3^+ group

Answer 37

N-terminal amino acid

Question 38

The amino acid at the end of a peptide that has a free a-carboxyl group.

Answer 38

C-terminus

Question 39

The amino acid at the end of a peptide that has a free a-amino group.

Answer 39

N-terminus

Question 40

consists of the sequence of amino acids that makes up the chain.

Answer 40

primary structure

Question 41

This change affects only two positions in a molecule containing 574 amino acid residues, yet it is enough to produce a very serious disease

Answer 41

sickle cell anemia

Question 42

differs from the normal type only in the beta chains and only in one position on these two chains: The glutamic acid in the sixth position of normal Hb Is replaced with a valine residue in HbS.

Answer 42

hemoglobin (called Hbs)

Question 43

a repetitive conformation of the protein backbone.

Answer 43

Secondary structure

Question 44

the orderly alignment of protein chains is maintained by intermolecular or intramolecular hydrogen bonds.

Answer 44

B-pleated sheet.

Question 45

a secondary structure where the protein folds into a coil held together by hydrogen bonds parallel to the axis of the coil.

Answer 45

Alpha (a)-helix

Question 46

a secondary protein structure in which the backbone of two protein chains in the same or different molecules is held together by hydrogen bonds

Answer 46

Beta (B) pleated sheet

Question 47

It is quite different from the a-helix. Collagen is the structural protein of connective tissues (bone, cartilage, tendon, blood vessels, skin), where it provides strength and elasticity.

Answer 47

extended helix of collagen

Question 48

of a protein is the three-dimensional arrangement of every atom in the molecule.

Answer 48

tertiary structure

Question 49

most often involved in stabilization of the tertiary structure of proteins is the disulfide bond.

Answer 49

Covalent Bonds

Question 50

We saw earlier that secondary structures are stabilized by hydrogen bonding between backbone - C=0 and —N-H groups.

Answer 50

Hydrogen Bonding

Question 51

also called electrostatic attractions, occur between two amino acids with lonized side chains-that is, between an acidic amino acid (—COO^-) and a basic amino acid (-NH,^+ or =NH,^*) side chain.

Answer 51

Salt Bridges

Question 52

in aqueous solution, globular proteins usually turn their polar groups outward, toward the aqueous solvent, and their nonpolar groups inward, from molecules.

Answer 52

Hydrophobie Interactions

Question 53

Two side chains with the same charge would normally repel each other, but they can also be linked via a metal ion.

Answer 53

Metal Ion Coordination

Question 54

a protein that helps other proteins to fold into the biologically active conformation and enables partially denatured proteins to regain their biologically active conformation.

Answer 54

Chaperone

Question 55

the spatial relationship and interactions between subunits in a protein that has more than one polypeptide chain.

Answer 55

quaternary structure

Question 56

in adult humans is made of four chains (called globins): two identical a chains of 141 amino acid residues each and two identical B chains of 146 residues each.

Answer 56

hemoglobin

Question 57

another example of quaternary structure and higher organizations of subunits can be seen In?

Answer 57

collagen

Question 58

partly or completely traverse a membrane bilayer.

Answer 58

Integral membrane proteins

Question 59

the loss of the secondary, tertiary, and quaternary structures of a protein by a chemical or physical agent that leaves the primary structure intact.

Answer 59

Denaturation -

Question 60

The main structural material for plants is

Answer 60

cellulose