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BIOCHEM LAB > Proteins & Enzymes > Flashcards

Proteins & Enzymes Flashcards

1
Q

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

A

Proteins

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2
Q

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

A

50%

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3
Q

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

A

not stored and must be consumed DAILY

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4
Q

How many grams of proteins should adult daily intake?

A

0.8 grams of protein per kg of body weight

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5
Q

Protein that stores O2 in tissues

A

Myoglobin

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6
Q

Protein hormones synthesized in the pancreas and controls blood glucose levels

A

Insulin

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7
Q

Transport protein that carries O2 in the blood

A

Hemoglobin

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8
Q

Protein that stores iron in the liver

A

Ferritin

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9
Q

Proteins that control muscle contractions

A

Actin and Myosin

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10
Q

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

A

Amino acids

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11
Q

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

A

alpha ( α) carbon

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12
Q

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

A

Glycine

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13
Q

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

A

Side chain

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14
Q

It is basic amino acid if ___________

A

R = a basic N atom

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15
Q

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

A

Acidic amino acids

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16
Q

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

A

Zwitterion

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17
Q

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

A

Chiral center/chirality center

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18
Q

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

A

Neutrally charged

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19
Q

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

A

less than

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20
Q

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

A

net negative charge

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21
Q

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

A

Peptides

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22
Q

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

A

Enkephalins

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23
Q

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

A

Endorphins

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24
Q

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

A

Oxytocin and Vasopression

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25
Q

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

A

Oxytocin

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26
Q

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

A

Vasopressin

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27
Q

What is the primary structure of a protein?

A

Sequence of amino acids

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28
Q

The secondary structure is the ______________________________________

A

3D arrangement of localized regions

29
Q

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

A

Hydrogen bonding

30
Q

The tertiary structure is the 3D shape adopted by _______________________

A

Peptide chain

31
Q

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

A

London dispersion

32
Q

Amino acids with charged side chains are
attracted by?

A

Electrostatic interactions

33
Q

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

A

Two or more

34
Q

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

A

Fibrous proteins

35
Q

Fibrous proteins are _________ in water

A

Insoluble

36
Q

These are coiled into compact shapes that are water SOLUBLE

A

Globular proteins

37
Q

What are the globular proteins?

A

Enzymes and transport proteins

38
Q

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.

A

α-Keratins

39
Q

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

A

Vitamin C

40
Q
A
41
Q

Myoglobin has ____ amino acids in 1 polypeptide
chain

A

153

42
Q

Hemoglobin has ____ polypeptide chains,
each carrying a heme unit

A

Four (4)

43
Q

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

A

200 times more strongly

44
Q

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

A

Sickle cell anemia

45
Q

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

A

breaking the peptide bonds

46
Q

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

A

trypsin and chymotrypsin

47
Q

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

A

Denaturation

48
Q

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

A

High temperature
Acid
Base
Agitation

49
Q

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

A

Enzymes

50
Q

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

A

cofactor (coenzyme)

51
Q

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

A

Active site

52
Q

The energy difference between reactants and
the formation of products

A

Free energy of activation

53
Q

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

A

Lock-and-key model

54
Q

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

A

Induced-fit model

55
Q

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

A

Inhibitor

56
Q

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

A

Competitive

57
Q

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

A

Noncompetitive

58
Q

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

A

Zymogens (proenzymes)

59
Q

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

A

Penicillin

60
Q

ACE causes blood vessels to narrow, increasing blood pressure.

What is ACE?

A

Angiotensin-converting enzyme

61
Q

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

A

ACE inhibitors

62
Q

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

A

HIV protease

63
Q

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

A

Decreasing

64
Q

Factor affecting enzymes activity

A

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

65
Q

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

A

denatured

66
Q

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

A

5 to 9

67
Q

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

A

Enzyme concentration

68
Q

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

A

Substrate concentration

BIOCHEM LAB (6 decks)

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