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[4] CHM110 | BIOCHEM > Proteins > Flashcards

Proteins Flashcards

1
Q

Function of protein where collagen and keratin are the chief constituents of skin, bone, hair, and nails.

A

Structure

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2
Q

Function of protein where virtually all reactions in living systems are catalyzed by proteins called enzymes.

A

Catalysis

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3
Q

Functions of proteins where muscles are made up of proteins called myosin and actin.

A
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4
Q

Functions of proteins where hemoglobin transports oxygen from the lungs to cells, other proteins transport molecules across cell membranes.

A

Transport

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5
Q

Functions of protein where __________ are proteins, among them insulin, oxytocin, and human growth hormone.

A

Hormones

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6
Q

Are the chief constituents of skin, bone, hair, and nails.

A

Collagen and Keratin

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7
Q

Virtually all reactions in living systems are catalyzed by proteins called __________

A

enzymes

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8
Q

Muscles are made up of proteins called __________ and __________

A

myosin; actin

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9
Q

Transports oxygen from the lungs to cells, other proteins transport molecules across cell membranes.

A

Hemoglobin

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10
Q

Function of protein where blood clotting involves the protein fibrinogen; the body used proteins called antibodies to fi ght disease.

A

Protection

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11
Q

Functions of protein where casein in milk and ovalbumin in eggs store nutrients for newborn infants and birds. Ferritin, a protein in the liver, stores iron.

A

Storage

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12
Q

Functions of proteins where certain proteins not only control the expression of genes, but also control when gene expression takes place.

A

Regulation

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13
Q

Proteins are divided into two types:

(1) __________
(2) __________

A

(1) Fibrous proteins
(2) Globular proteins

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14
Q

Blood clotting involves the protein __________; the body used proteins called antibodies to fight disease

A

fibrinogen

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15
Q

(1) __________ in milk and (2) __________ in eggs store nutrients for newborn infants and birds.

A

(1) Casein
(2) ovalbumin

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16
Q

__________, a protein in the liver, stores iron.

A

Ferritin

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17
Q

Certain proteins not only control the expression of (1) ______, but also control when (2) __________ takes place.

A

(1) genes
(2) gene expression

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18
Q

A compound that contains both an amino group and
a carboxyl group.

A

Amino Acid

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19
Q

An amino acid in which the amino group is on the carbon adjacent to the carboxyl group.

A

a-Amino Acid

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20
Q

Although a-amino acids are commonly written in the (1) __________ form, they are more properly written in the (2) __________ form.

A

(1) un-ionized
(2) zwitterion (internal salt)

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21
Q

With the exception of (1) __________, all protein-derived amino acids have at least (2) __________ and are (3) __________.

A

(1) glycine
(2) one stereocenter (the a-carbon)
(3) chiral

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22
Q

The vast majority of a-amino acids have the __________ at the a- carbon

A

L-configuration

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23
Q

Each ionizable group is shown in the form present in highest concentration at pH 7.0).

A

Nonpolar side chains

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24
Q

In nonpolar side chains, each ionizable group is shown in the form present in highest concentration at __________ .

A

pH 7.0

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25
Q

For 19 of the 20, the a-amino group is (1) __________; for proline, it is (2) __________

A

(1) primary
(2) secondary

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26
Q

Isoleucine and threonine contain a __________.

A

second stereocenter

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27
Q

The (1) __________ on an amino acid depends on the pH of the solution in which it is dissolved.

A

net charge

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28
Q

If we dissolve an amino acid in water, it is present in the aqueous solution as its __________.

A

zwitterion

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29
Q

If we add a strong acid such as HCl to bring the pH of the solution to pH 0, the strong acid donates a (1) ______ to the _______ of the zwitterion turning it into a (2) __________.

A

(1) proton; –COO–
(2) positive ion

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30
Q

If we add a strong base such as NaOH to the solution and bring its pH to 14, a (1) __________ is transferred from the __________ to the base turning the zwitterion into a (2) __________.

A

(1) proton; NH3+ group
(2) negative ion

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31
Q

A pH at which a sample of amino acids or protein has an equal number of positive and negative charges.

A

Isoelectric point (pI)

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32
Q

Proteins are long chains of (1) ______ joined by (2) ______.

A

(1) amino acids
(2) amide bonds

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33
Q

The special name given to the amide bond between the a-carboxyl group of one amino acid and the a-amino group of another.

A

Peptide bond (peptide linkage)

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34
Q

A short polymer of amino acids joined by peptide bonds; they are classified by the number of amino acids in the chain.

A

Peptide

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35
Q

A molecule containing two amino acids joined by a peptide bond.

A

Dipeptide

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36
Q

A molecule containing three amino acids joined by peptide bonds.

A

Tripeptide

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37
Q

A macromolecule containing many amino acids joined by peptide bonds.

A

Polypeptide

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38
Q

A biological macromolecule containing at least 30 to 50 amino acids joined by peptide bonds.

A

Protein

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39
Q

The individual amino acid units are often referred to as “__________.”

A

residues

40
Q

By convention, peptides are written from (1) ______, beginning with the free (2) __________ and ending with the free (3) __________.

A

(1) left to right
(2) –NH3+ group
(3) –COO– group

41
Q

The amino acid at the end of the chain having the free –COO– group.

A

C-terminal amino acid (C-terminus)

42
Q

The amino acid at the end of the chain having the free –NH3+ group.

A

N-terminal amino acid (N- terminus)

43
Q

The amino acids phenylalanine, tryptophan, and tyrosine have __________ on their side chains.

A

aromatic rings

44
Q

The precursor to the neurotransmitter serotonin.

A

Tryptophan

45
Q

Are precursors to norepinephrine and epinephrine, both of which are stimulatory neurotransmitters.

A

Phenylalanine and Tyrosine

46
Q

A peptide bond is typically written as a (1) __________ bonded to an (2) _________.

A

(1) carbonyl group
(2) N–H group

47
Q

Discovered that there is about 40% double bond character to the C–N bond and that a peptide bond between two amino acids is planar

A

Linus Pauling

48
Q

Linus Pauling discoveries:

• There is about (1) __________ character to the C–N bond.

• a peptide bond between two amino acids is (2) __________.

A

(1) 40% double bond
(2) planar

49
Q

Pauling explained her discoveries using this concept.

A

Resonance

50
Q

Proteins behave as __________.

A

zwitterions

51
Q

At its isoelectric point, the protein has __________.

A

no net charge

52
Q

At any pH above (more basic than) its pI, proteins have a __________

A

net negative charge.

53
Q

At any pH below (more acidic than) its pI, proteins have a __________.

A

net positive charge

54
Q

Has an almost equal number of acidic and basic side chains; its pI is 6.8.

A

Hemoglobin

55
Q

Has more acidic side chains; its pI is 4.9.

A

Serum Albumin

56
Q

Proteins are least soluble in (1) __________ at their isoelectric points and can be precipitated from solution when (2) __________.

A

(1) water
(2) pH = pI

57
Q

The sequence of amino acidsina polypeptide chain. Read from the N-terminal amino acid to the C-terminal amino acid.

A

Primary Structure

58
Q

Conformations of amino acids in localized regions of a polypeptide chain. Examples are a-helix, b-pleated sheet, and random coil.

A

Secondary Structure

59
Q

The complete three-dimensional arrangement of atoms of a polypeptide chain.

A

Tertiary Structure

60
Q

The spatial relationship and interactions between subunits in a protein that has more than one polypeptide chain.

A

Quaternary Structure

61
Q

The number peptides possible from the __________ amino acids is enormous.

A

20 protein-derived

62
Q

There are __________ dipeptides possible.

A

20 × 20 = 400

63
Q

There are ___________ tripetides possible.

A

20 × 20 × 20 = 8000

64
Q

The number of peptides possible for a chain of n amino acids is ______.

A

20n

65
Q

For a small protein of 60 amino acids, the number of proteins possible is __________

A

20^60 ≈ 10^78

66
Q

The hormone insulin consists of (1) __________, held together by (2) __________.

A

(1) two polypeptide chains (A and B)
(2) two disulfide bonds

67
Q

Amino acid sequence of Human Insulin:

• A chain positions 8-9-10 : (1) __________

• B chain position 30 : (2) __________

A

(1) -Thr-Ser-Ile
(2) -Thr

68
Q

Amino acid sequence of Cow Insulin :

• A chain positions 8-9-10 : (1) __________

• B chain position 30 : (2) __________

A

(1) -Ala-Ser-Val-
(2) -Ala

69
Q

Amino acid sequence of Hog Insulin :

• A chain positions 8-9-10 : (1) __________

• B chain position 30 : (2) __________

A

(1) -Thr-Ser-Ile-
(2) -Ala

70
Q

Amino acid sequence of Sheep Insulin :

• A chain positions 8-9-10 : (1) __________

• B chain position 30 : (2) __________

A

(1) -Ala-Gly-Val-
(2) -Ala

71
Q

Is a nonapeptide and an antidiuretic hormone.

A

Vasopressin

72
Q

A nonapeptide that affects contractions of the uterus in childbirth and the muscles of the breast that aid in the secretion of milk.

A

Oxytocin

73
Q

Conformations of amino acids in localized regions of a polypeptide chain.

A

Secondary Structure

74
Q

The most common types of secondary structure are (1) __________ and (2) __________.

A

(1) a-helix
(2) b-pleated sheet

75
Q

A type of secondary structure in which a section of polypeptide chain coils into a spiral, most commonly a right-handed spiral.

A

a-Helix

76
Q

A type of secondary structure in which two polypeptide chains or sections of the same polypeptide chain align parallel to each other; the chains may be parallel or antiparallel.

A

b-Pleated sheet

77
Q

In a section of a-helix
• The six atoms of each peptide bond lie in the (1) _________.
• The (2) __________ groups of peptide bonds point in the same direction, roughly parallel to the axis of the helix.
• The (3) __________ groups of peptide bonds point in the opposite direction, also roughly parallel to the axis of the helix.

A

(1) same plane
(2) N–H groups
(3) C=O groups

78
Q

In a section of a-helix
• The C=O group of each peptide bond is (1) __________ to the N–H group of the peptide bond __________ units away from it.
• All (2) __________ groups point outward from the helix.

A

(1) hydrogen bonded; four amino acid
(2) R–

79
Q

In a section of b-pleated sheet;
• The six atoms of each peptide bond of a b-pleated sheet lie in the (1) __________.
• The C=O and N–H groups of the peptide bonds from adjacent chains point (2) __________ each other and are in the same plane so that __________ is possible between them.
• All (3) __________ on any one chain alternate, first above, then below the plane of the sheet, etc.

A

(1) same plane
(2) toward
(3) R–groups

80
Q

Many __________ contain all three kinds of secondary structure in different parts of their molecules: a-helix, b-pleated sheet, and random coil.

A

globular proteins

81
Q

The overall conformation of an entire polypeptide
chain.

A

Tertiary Structure

82
Q

Tertiary structure is stabilized in four ways:
• (1) __________ as for example, the formation of disulfide bonds between cysteine side chains.

• (2) __________ between polar groups of side chains, as for example between the –OH groups of serine and threonine.

• (3) __________, as for example, the attraction of the –NH3+ group of lysine and the –COO– group of aspartic acid.

• (4) __________, as for example, between the nonpolar side chains of phenylalanine and isoleucine.

A

(1) Covalent bonds
(2) Hydrogen bonding
(3) Salt bridges
(4) Hydrophobic interactions

83
Q

The –SH (sulfhydryl) group of __________ is easily oxidized to an –S–S– (disulfide).

A

cysteine

84
Q

The (1) __________ group of cysteine is easily oxidized to an (2) __________.

A

(1) –SH (sulfhydryl)
(2) –S–S– (disulfide)

85
Q

The arrangement of polypeptide chains into a noncovalently bonded aggregation.

A

Quaternary Structure

86
Q

The individual chains of quaternary structures are held together by (1) __________, (2) __________, and (3) __________.

A

(1) hydrogen bonds
(2) salt bridges
(3) hydrophobic interactions

87
Q

Type of hemoglobin with two alpha chains of 141 amino acids each, and two beta chains of 146 amino acids each.

A

Adult Hemoglobin

88
Q

Type of hemoglobin with two alpha chains, two gamma chains, and has a greater affinity for oxygen.

A

Fetal Hemoglobin

89
Q

Form quaternary structures in which the outer surface is largely nonpolar (hydrophobic) and interacts with the lipid bilayer

A

Integral Membrane Proteins

90
Q

The process of destroying the native conformation of a protein by chemical or physical means.

A

Denaturation

91
Q

Some denaturations are (1) __________, while others (2) __________ the protein.

A

(1) reversible
(2) permanently damage

92
Q

Can disrupt hydrogen bonding; in globular proteins, it can cause unfolding of polypeptide chains with the result that coagulation and precipitation may take place.

A

Heat

93
Q

Disrupts hydrogen bonding.

A

6 M aqueous urea

94
Q

Detergents such as sodium dodecylbenzenesulfate (SDS) disrupt hydrogen bonding.

A

Surface-Active Agents

95
Q

2-Mercaptoethanol (HOCH2CH2SH) cleaves disulfide bonds by reducing –S–S– groups to –SH groups.

A

Reducing Agents

96
Q

Transition metal ions such as Pb2+, Hg2+, and Cd2+ form water-insoluble salts with –SH groups; Hg2+ for example forms –S–Hg–S–.

A

Heavy Metal Ions

97
Q

70% ethanol penetrates bacteria and kills them by coagulating their proteins. It is used to sterilize skin before injections.

A

Alcohols

[4] CHM110 | BIOCHEM (7 decks)

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