polypeptides

Question 1

is amide linkage formed by the reaction between α-carboxyl group of one amino acid and α-amino group of another amino acid with the elimination of water molecule

Answer 1

Peptide (peptide bond)

Question 2

two amino acids are combined

Answer 2

Dipeptide

Question 3

3 to 10 amino acids combined

Answer 3

Oligopeptide

Question 4

> 10 amino acids combined

Answer 4

Polypeptide

Question 5

300-1000 amino acids combined

Answer 5

Proteins

Question 6

There are four levels of protein structure:

Answer 6

primary
secondary
tertiary
quarternary

Question 7

linear sequence of amino acids

Answer 7

primary

Question 8

regular patterns formed by primary structure folding

Answer 8

secondary

Question 9

completely folded polypeptide with one or more domains

Answer 9

tertiary

Question 10

association of multiple polypeptides; not found in all proteins

Answer 10

quaternary

Question 11

The simplest level of protein structure is simply the amino acid sequence within a polypeptide chain.

Answer 11

the primary structure

Question 12

Understanding the ??? is important because many genetic diseases results in protein with abnormal amino acid sequences

Answer 12

primary structure of proteins

Question 13

is local interactions between stretches of a polypeptide chain and includes α-helix and β-pleated sheets structures.

Answer 13

Secondary structure

Question 14

is primarily due to interactions between the R groups of amino acid which make up the protein.

Answer 14

The tertiary structure

Question 15

R group interactions (4)

Answer 15

§ hydrogen bonding
§ ionic bonding
§ dipole-dipole interactions
§ London dispersion forces

Question 16

are also important for the tertiary structure, in which amino acids with non-polar, hydrophobic R groups cluster together within the protein, leaving hydrophilic amino acids outside to interact with surrounding water molecules.

Answer 16

Hydrophobic interactions

Question 17

One specific form of covalent bond may contribute to tertiary structure: the

Answer 17

disulfide bond

Question 18

Many proteins however consist of several polypeptide chains, also known as ???

Answer 18

subunits

Question 19

They give the protein its quaternary form, as these subunits come together.

Answer 19

subunits

Question 20

One example of a ???
is hemoglobin.

Answer 20

quaternary-structured protein

Question 21

In general, the same types of interactions that lead to tertiary structure also hold the
subunits together to give ???

Answer 21

quaternary structure

Question 22

interactions that lead to tertiary structures are mostly ???

Answer 22

weak interactions,

such as hydrogen bonding and dispersion forces in London

Question 23

??? protein structure;

??? bonding of the peptide backbone causes amino acids to fold into a ??? pattern

Answer 23

secondary;

hydrogen;

repeating

Question 24

tertiary protein structure:

3-D folding pattern of a protein due to ??? interactions

Answer 24

side chain interactions

Question 25

quaternary protein structure: protein consisting of ?

Answer 25

more than one amino acid chain

Question 26

refers to any disruption in the secondary, tertiary and quaternary levels of protein structure.

Answer 26

denaturation

Question 27

in what protein structure does denaturation not occur?

Answer 27

primary protein structure

Question 28

denaturation does not cleave the peptide bonds, therefore the ??? of structure is not altered.

Answer 28

primary level

Question 29

The physical signs of protein denaturation are ??? and ???

Answer 29

precipitation and coagulation;

Question 30

the most significant consequence of denaturation is ???

Answer 30

the loss of biological activity.

Question 31

happens in many cases when denatured protein goes back to its native biologically active form.

Answer 31

Renaturation

Question 32

Heat and UV radiation this breaks the ??? bonds causing the folded structures of protein to ???

Answer 32

H-bonds; uncoil or unwind into random loops

Question 33

agent of denaturation: form intermolecular H- bonds with the protein

Answer 33

Organic solvents

Question 34

agent of denaturation: ??? and ??? break salt linkages by altering the pH causing a change in the ionization pf ??? and ??? groups

Answer 34

Acids and bases; -COOH and -NH2 groups.

Question 35

agent of denaturation: Prolonged contact with ??? and ??? will also cleave peptide bonds

Answer 35

acids and bases

Question 36

agent of denaturation: ??? like Hg+2, Ag+, Pb2+ and their salts form stronger bonds with ??? of acidic amino acids. It also cleaves the ??? bonds (ex. The use of egg albumin as antidote for heavy metal poisoning)

Answer 36

Heavy metals; carboxylate ions; -SH

Question 37

agent of denaturation: ??? precipitate proteins by combining with ??? and disrupting ??? (ex. Use of tannic acid for tanningleather; picric acid and tea for treating burns)

Answer 37

Alkaloid reagents; positively charged groups; salt linkages

Question 38

alkaloid reagents examples

Answer 38

picric acid and tannic acid