Proteins & Enzymes

Question 1

These biomolecules contain many amide bonds, formed by joining amino acids.

Answer 1

Proteins

Question 2

Proteins account for _____ of the dry weight of the human body.

Answer 2

50%

Question 3

Unlike lipids and carbohydrates, proteins are ________ , so they must be ___________

Answer 3

not stored and must be consumed DAILY

Question 4

How many grams of proteins should adult daily intake?

Answer 4

0.8 grams of protein per kg of body weight

Question 5

Protein that stores O2 in tissues

Answer 5

Myoglobin

Question 6

Protein hormones synthesized in the pancreas and controls blood glucose levels

Answer 6

Insulin

Question 7

Transport protein that carries O2 in the blood

Answer 7

Hemoglobin

Question 8

Protein that stores iron in the liver

Answer 8

Ferritin

Question 9

Proteins that control muscle contractions

Answer 9

Actin and Myosin

Question 10

This contain two functional groups—an amino group (NH2) and a carboxyl group (COOH).

Answer 10

Amino acids

Question 11

The 20 amino acids that occur naturally in proteins differ in the identity of the R group bonded to the _________________.

Answer 11

alpha ( α) carbon

Question 12

What is the simplest amino acid?
(R=H)

Answer 12

Glycine

Question 13

The R group, called the ___________, determines the identity of the amino acid.

Answer 13

Side chain

Question 14

It is basic amino acid if ___________

Answer 14

R = a basic N atom

Question 15

If R = an additional COOH group, what amino acid is it?

Answer 15

Acidic amino acids

Question 16

Since amino acids contain a base (NH2) and an acid (COOH), a proton transfers from the acid to the base to form?

Answer 16

Zwitterion

Question 17

All amino acids (save glycine) have a ___________ on the α carbon.

Answer 17

Chiral center/chirality center

Question 18

An amino acid exists as a _______________ zwitterion at a certain pH, the isoelectric pH.

Answer 18

Neutrally charged

Question 19

When the pH _______ isoelectric pH, the carboxylate anion gains a proton, and the amino acid has a net positive charge.

Answer 19

less than

Question 20

When the pH is GREATER than the isoelectric pH, the ammonium cation loses a proton, and the amino acid has a ____________

Answer 20

net negative charge

Question 21

This and proteins are formed when amino acids are joined together by amide bonds.

Answer 21

Peptides

Question 22

This is pentapeptides made in the brain, act as pain killers and sedatives by binding to pain receptors.

Answer 22

Enkephalins

Question 23

Enkephalins belong to the family of polypeptides called ____________, which are known for their pain reducing and mood enhancing effects.

Answer 23

Endorphins

Question 24

____________ and____________ are cyclic nonapeptide hormones, which have identical sequences except for two amino acids.

Answer 24

Oxytocin and Vasopression

Question 25

This stimulates the contraction of uterine muscles, and signals for milk production; it is often used to induce labor.

Answer 25

Oxytocin

Question 26

It an antidiuretic hormone (ADH) targets the kidneys and helps to limit urine production to keep body fluids up during dehydration.

Answer 26

Vasopressin

Question 27

What is the primary structure of a protein?

Answer 27

Sequence of amino acids

Question 28

The secondary structure is the ______________________________________

Answer 28

3D arrangement of localized regions

Question 29

These regions arise due to ______________________ between the N—H group of one amide with the C═O group of another.

Answer 29

Hydrogen bonding

Question 30

The tertiary structure is the 3D shape adopted by _______________________

Answer 30

Peptide chain

Question 31

The nonpolar side chains are stabilized by _______________________ forces in the interior of the structure.

Answer 31

London dispersion

Question 32

Amino acids with charged side chains are attracted by?

Answer 32

Electrostatic interactions

Question 33

The quaternary structure of the protein is the shape adopted when ___________ folded polypeptide chains come together into one complex.

Answer 33

Two or more

Question 34

These are composed of long linear polypeptide chains that are bundled together to form rods or sheets.

Answer 34

Fibrous proteins

Question 35

Fibrous proteins are _________ in water

Answer 35

Insoluble

Question 36

These are coiled into compact shapes that are water SOLUBLE

Answer 36

Globular proteins

Question 37

What are the globular proteins?

Answer 37

Enzymes and transport proteins

Question 38

They are made of two mainly α-helix chains coiled around each other in a superhelix. They also found in hair, hooves, nails, skin, and wool.

Answer 38

α-Keratins

Question 39

What vitamin that helps in stabilizing the chains? and when missing, poorly formed collagen fibers results.

Answer 39

Vitamin C

Question 41

Myoglobin has ____ amino acids in 1 polypeptide chain

Answer 41

153

Question 42

Hemoglobin has ____ polypeptide chains, each carrying a heme unit

Answer 42

Four (4)

Question 43

Carbon monoxide (CO) is poisonous because it binds _______________ to the Fe2+ than does O2+

Answer 43

200 times more strongly

Question 44

This is a disease where a single amino acid is different in two of the subunits of hemoglobin.

Answer 44

Sickle cell anemia

Question 45

Protein hydrolysis involves ___________________ by treatment with aqueous acid, base, or certain enzymes.

Answer 45

breaking the peptide bonds

Question 46

In the intestines, enzymes ________ and ________________ hydrolyze the remainder of the amide bonds resulting in individual amino acids.

Answer 46

trypsin and chymotrypsin

Question 47

The process of altering the shape of a protein without breaking the amide bonds that form the primary structure.

Answer 47

Denaturation

Question 48

What are the factors that can disrupt the non-covalent interactions that hold a protein in a specific shape.

Answer 48

High temperature Acid Base Agitation

Question 49

These are proteins that serve as biological catalysts for reactions in all living organisms.

Answer 49

Enzymes

Question 50

NAD+ is the ___________ that oxidizes lactate to pyruvate with the aid of the enzyme lactate dehydrogenase

Answer 50

cofactor (coenzyme)

Question 51

An enzyme contains an ___________ that binds the substrate, forming an enzyme-substrate complex.

Answer 51

Active site

Question 52

The energy difference between reactants and the formation of products

Answer 52

Free energy of activation

Question 53

This model states that the active site is a RIGID CAVITY; to react, the substrate must exactly match the shape of the active site.

Answer 53

Lock-and-key model

Question 54

This model states that the active site has a FLEXIBLE SHAPE, which can adjust to fit a variety of substrate shapes.

Answer 54

Induced-fit model

Question 55

This bonds to the enzyme and alters or destroys the enzyme’s activity

Answer 55

Inhibitor

Question 56

A _________________ inhibitor has a shape and structure similar to the substrate, so it competes with the substrate for binding to the active site.

Answer 56

Competitive

Question 57

A ______________________ inhibitor bonds to the enzyme, but not to the active site.

Answer 57

Noncompetitive

Question 58

These are an inactive form of an enzyme that can be converted to the active form when needed.

Answer 58

Zymogens (proenzymes)

Question 59

This inhibits the enzyme that forms cell walls of bacteria, destroying the bacterium.

Answer 59

Penicillin

Question 60

ACE causes blood vessels to narrow, increasing blood pressure. What is ACE?

Answer 60

Angiotensin-converting enzyme

Question 61

These are given to those with high blood pressure to prevent ACE’s synthesis from it’s zymogen.

Answer 61

ACE inhibitors

Question 62

An essential enzyme that allows the virus to make copies of itself.

Answer 62

HIV protease

Question 63

HIV protease inhibitors interfere with this copying, ___________ the virus population in the patient.

Answer 63

Decreasing

Question 64

Factor affecting enzymes activity

Answer 64

Not limited to: - Temperature and pH - Enzyme and Substrate concentration - Cofactors - Inhibitors

Question 65

If the temperature exceeds the optimum temperature, the enzyme will be ______________

Answer 65

denatured

Question 66

The pH usually ranges between __ to __. Marked changes in pH produce conformational changes in protein structures that result in decreased activity

Answer 66

5 to 9

Question 67

The velocity of the reaction increases as the ENZYME concentration increases up to a certain point where the enzyme is saturated with substrate.

Answer 67

Enzyme concentration

Question 68

The velocity of the reaction increases as the SUBSTRATE concentration increases up to a point where the enzyme is saturated with the substrate.

Answer 68

Substrate concentration