Topic 2. Amino acids peptides and protein

Question 1

Primary structure of a polypeptide chain

Answer 1

the sequence of amino acids in the polypeptide chain, termed the protein configuration

Question 2

Secondary structure of a polypeptide chain

Answer 2

how the chain is folded as a result of interaction of peptide bonds; such as helix or pleated sheet.

Question 3

Tertiary structure of a polypeptide chain

Answer 3

dealing with R group interactions, or large scale bends and folds of helix’s.

Question 4

Quaternarystructure of a polypeptide chain

Answer 4

how polypeptide chains interact if there are more than one in the single protein. 2 or more polypeptide chains.

Question 5

some general functions of proteins (8)

Answer 5

biological catalysts, Transport, Storage, contracting muscles, cell structure, defence, hormones/regulation, semi permeable membranes.

Question 6

The term prosthetic group is used to indicate

Answer 6

the non-protein part of a conjugated protein

Question 7

All amino acids have - the same skeleton of a central (or alpha) carbon atom, with attachments of: (4)

Answer 7

• an amino groupN2R
• a carboxy group COO
• a hydrogen atom H
• an R side-chain group.

Question 8

Aliphatic R groups

Answer 8

nonpolar and hydrophobic, Hydrophobicity increases with increasing number of C atoms in the hydrocarbon chain. Although these amino acids prefer to remain inside protein molecules,

Question 9

2 examples of Non-polar aliphatic R group amino acids

Answer 9

Alanine(CH), Glycine(H)

they tend to cluster together within proteins, stabilizing protein structure by means of hydrophobic interactions

Question 10

Aromatic R group amino acid example

Answer 10

Tyrosine (C-Benzene-OH
r aromatic side chains, are relatively
nonpolar (hydrophobic)

Question 11

Polar, uncharged R group amino acids

Answer 11

Serine (CHOH), cystein (CHSH)
these amino
acids are more soluble in water, or more hydrophilic,
than those of the non polar amino acids, because they
contain functional groups Lhat form hydrogen bonds

Question 12

Positively charged R group amino acid example

Answer 12

Lysine (CCCCNH3). The most hydrophilic

R groups are those that are either positively or negatively charged.

Question 13

Negatively charged R group amino acid

Answer 13

Aspartate (CCOO)

Question 14

chiral atom

Answer 14

the atom in a molecule that is bonded to four different chemical species.

Question 15

alpha carbon

Answer 15

is a carbon atom bonded to a functional group in an organic compound; the carbon atom next to the α carbon is the beta (symbol: β) carbon,

Question 16

Where to place the amino group when drawing structures of amino acids?

Answer 16

generally always on the left (L) unless drawing its stereoisomer (D)

Question 17

2 cysteins can become …….. after formation of a disulfide bond/bridge?

Answer 17

cystine

Question 18

amphoteric

Answer 18

of a compound, especially a metal oxide or hydroxide) able to react both as a base and as an acid.

Question 19

zwitterions

Answer 19

where the amino acid has an equal number of positive and negative charges

Question 20

pKa value?

Answer 20

The pKa value is one method used to indicate the strength of an acid

Question 21

Tryptophan is a precursor to

Answer 21

auxin

Question 22

Lignin is derived from what amino acid?

Answer 22

phenylalanine

Question 23

2 amino acids which help form tannins?

Answer 23

tyrosine and Phenlyalanine

Question 24

amino acids which are neurotransmitters in the brain

Answer 24

glycine, aspartate and glutamate

Question 25

Hormones, Dopamine

Noradrenaline and Adrenaline are all derrivitives of which amino acid?

Answer 25

tyrosine

Question 26

peptide bond

Answer 26

Two amino acid molecules can be covalently joined

through a substituted amide linkage called a peptide bond

Question 27

oligopeptide

Answer 27

are short chains of amino acid monomers linked via peptide bonds. The term oligopeptide is used to refer to a peptide with fewer members of amino acids as opposed to a polypeptide, which is a peptide comprised of several amino acid residues.

Question 28

Amphoteric molecule

Answer 28

has a both negative and positive charge

Question 29

5 different structure Categories of amino acids

Answer 29

1. non polar aliphatic
2. aromatic
3. polar uncharged
4. positively charged
5. negatively charged

Question 30

folding due to H bonds place proteins into two classes:

Answer 30

globular and fibrous
globulous: mainly coiled or folded (helix) are generally enzymatic. while fibrous proteins: elongated (pleated sheet) are generally structural.

Question 31

A protein with multiple polypeptide chains are called

Answer 31

oligomeric protein

Question 32

Denaturation of a protein is defined as

Answer 32

any change of shape of a protein associated with loss of function. Does not come about by cleaving covalent bonds, but by disrupting the weak forces that maintain the tertiary structure.

Question 33

The 5 forces maintaining protein structure

Answer 33

1. covalent bonding
2. ionic bonding
3. hydrogen bonding
4. hydrophobic interactions
5. Van der Waals interactions

Question 34

Collagen protein

Answer 34

is perhaps the most abundant protein in animals (constituting about 25% of all proteins) and is the major protein in extracellular matrix. Collagens are involved in cell adhesion and provision of elasticity in connective tissues.

Question 35

Myoglobin

Answer 35

is a conjugated protein with the iron-containing compound haem as its prosthetic group. It is the oxygen-storing protein of muscle. Its role is to accept oxygen from haemoglobin and carry it to the respiring cells.

Question 36

Haemoglobin

Answer 36

is the oxygen-carrying protein in blood. It carries oxygen from the lungs to the tissues. It consists of four chains,