Proteins

Question 1

From the Greek word proteios meaning

Answer 1

first of rank

Question 2

Most abundant biomolecule in the cell

Answer 2

Proteins

Question 3

A single linear chain of amino acids

Answer 3

POLYPEPTIDES

Question 4

May be made up of one or more polypeptide
chains folded in specific conformations

Answer 4

PROTEINS

MW ≥ 10,000 Da

Question 5

Expressed using ___, a unit of
mass that is nearly equal to that of a hydrogen
atom

Answer 5

Daltons (Da or D)

Question 6

Yield only amino acids upon hydrolysis

Answer 6

SIMPLE Proteins

Question 7

Simple proteins + non-protein substances

Answer 7

CONJUGATED Proteins

Question 8

Catalyze biological reactions

Answer 8

ENZYMES

Question 9

Bind or carry specific molecules or ions from one organ to another

Answer 9

TRANSPORT PROTEINS

Question 10

Mobilized by the body to derive building blocks or energy

Answer 10

NUTRIENT and STORAGE PROTEINS

Question 11

Defend organisms against invasion by foreign substances

Answer 11

DEFENSE PROTEINS

Question 12

Allow cells and organisms to contract, change shape or
move about

Answer 12

CONTRACTILE or MOTILE PROTEINS

Question 13

As supporting filaments, cables or sheets for strength and protection of biological structures

Answer 13

STRUCTURAL PROTEINS

Question 14

Regulate physical or cellular activities

Answer 14

REGULATORY PROTEINS

Question 15

Polypeptide chain coiled into
compact spherical shape
Soluble in water
Mobile within cells

• eg. amylase, hemoglobin

Answer 15

GLOBULAR PROTEINS

Question 16

Polypeptide chains arranged side-by-side in long filaments

Insoluble in water
Mechanically strong
Structural and protective function

• eg. collagen

Answer 16

FIBROUS PROTEINS

Question 17

Soluble in water and dilute aqueous solutions
• eg. egg albumin, lactalbumin of milk

Answer 17

ALBUMINS

Question 18

Soluble in dilute salt solutions but are
insoluble/sparingly soluble in water
• eg. ovoglobulin of egg, myosin of muscle

Answer 18

GLOBULINS

Question 19

• Soluble in dilute solutions of acids and bases
• eg. glutellin of wheat and oryzenin of rice

Answer 19

GLUTELLINS

Question 20

Insoluble in most ordinary solvents like water,
salt solutions, dilute acids, alkalis and alcohols
• eg. keratins of hair, collagen of bones

Answer 20

ALBUMINOIDS

Question 21

Soluble in 70-80% alcohol (others in 50-90%),
insoluble in water, neutral solvents or absolute
alcohol
• eg. zein of corn

Answer 21

PROLAMINS

Question 22

Sickle cell hemoglobin – Glu6 replaced by

Answer 22

Val

Question 23

Amino acid sequence and Linear order of amino acids from the Nterminus to the C-terminus

Answer 23

Primary Structure

Question 24

Dictates the structure and function of the protein

Answer 24

Primary Structure

Question 25

SPATIAL ARRANGEMENT of amino acid residues that are near one another in the linear sequence

Answer 25

Secondary Structure

Question 26

COMMON REGULAR FOLDING PATTERNS of the polypeptide backbone

Answer 26

Secondary Structure

Question 27

Main interaction: HYDROGEN BONDS between peptide bonds

Answer 27

Secondary Structure

Question 28

__ structures include: α-helix, β-pleated sheets, collagen helix

Answer 28

Secondary

Question 29

Polypeptide backbone is tightly wound around an imaginary axis that is drawn longitudinally in the middle of the helix

Answer 29

α-Helix

Question 30

Stabilized by H-BONDS BETWEEN —C=O AND N— H in the polypeptide backbone that are 3-4 RESIDUES APART.

Answer 30

α-Helix

Question 31

Usually found mostly in globular proteins

Answer 31

α-Helix

Question 32

R groups are protruding outward of the helical backbone • Bulky side chains are less commonly found in alpha-helices • Gly and Pro destabilizes the helical structure

Answer 32

α-Helix

Question 33

β-Pleated Sheet Backbone of the polypeptide chain is extended into a __ rather than a helix

Answer 33

zigzag

Question 34

lying side by side and held together by hydrogen bonds • “Pleated” due to alternating position of α-carbon

Answer 34

Zigzag polypeptide chains

Question 35

β-Pleated Sheet Can be

Answer 35

PARALLEL or ANTI-PARALLEL

Question 36

Three separate polypeptide chains are super-twisted about each other

Answer 36

Collagen Helix

Question 37

3 aa residues per turn • Superhelical twisting is righthanded • Repititive amino acid sequence: Gly-Pro-Hyp (hydroxyproline)

Answer 37

Collagen Helix

Question 38

Hinges, turns, coils, Gives flexibility, Connects secondary structures

Answer 38

Non-Helix and β-Sheet Regions

Question 39

Overall 3D arrangements of all atoms in the protein • Results from folding into specific 3D shapes and unique binding sites • Highest level of protein architecture common to all biologically active proteins

Answer 39

Tertiary Structure

Question 40

Tertiary Structure Stabilized by the following interactions: (4)

Answer 40

HYDROPHOBIC INTERACTIONS HYDROGEN BONDING ELECTROSTATIC INTERACTION DISULFIDE BONDS/BRIDGES

Question 41

Overall tendency of side chains of non-polar residues to collect in the interior of the protein

Answer 41

HYDROPHOBIC INTERACTIONS

Question 42

Between side groups or between peptide bonds

Answer 42

HYDROGEN BONDING

Question 43

Charged side chains (e.g. —COO― of aspartate and glutamate, and ε-NH3+ of lysine)

Answer 43

ELECTROSTATIC INTERACTION

Question 44

Formed by two cysteine residues. An actual covalent bond

Answer 44

DISULFIDE BONDS/BRIDGES

Question 45

Describes the organization of SUBUNITS (POLYPEPTIDE CHAINS WITH 3° STRUCTURE) in a protein with multiple subunits (multimeric) • Subunits are held together by NON-COVALENT INTERACTIONS

Answer 45

Quaternary Structure

Question 46

Can have homo-multimers or hetero-multimers • Multimeric/Oligomeric proteins are more stable than dissociated subunits

Answer 46

Quaternary Structure

Question 47

Oligomeric protein made up of __ polypeptide chains and a heme grp

Answer 47

4

Question 48

Folding of proteins can be stable or with the aid of

Answer 48

molecular chaperones

Question 49

Misfolded proteins must be targeted for

Answer 49

degradation

Question 50

Accumulation of misfolded proteins are the causes of some diseases:

Answer 50

• Alzheimer’s • Parkinson’s • Mad Cow • Senile dementia

Question 51

The primary structure of the protein is preserved – peptide bond is __ easily disrupted

Answer 51

not

Question 52

May result into reduction or complete loss of biological activity of the protein

Answer 52

Protein Denaturation

Question 53

Accomplished by the following agents of denaturation ✓ Physical agents:

Answer 53

heat, extremes of pH

Question 54

Accomplished by the following agents of denaturation ✓ Chemical agents: (4)

Answer 54

▪ strong acids and bases ▪ Heavy metal cations (Pb2+ Hg2+) ▪ Alkaloidal reagents (trichloroacetic acid) ▪ Organic solvents (ethanol, acetone)