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BioChem 1st Shifting > Proteins > Flashcards

Proteins Flashcards

1
Q

The only amino acids with secondary a-amino group

A

Proline

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2
Q

Amino acid without stereocenter (not chiral)

A

Glycine

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3
Q

Two amino acids with two stereocenters

A

Isoleucine and threonine

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4
Q

Proposed that proteins are long chains of amino acids joined by amide bonds

A

Emil Fischer (1902)

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5
Q

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

A

Peptide

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6
Q

A molecule containing two amino acids joined by peptide bonds

A

Dipeptide

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7
Q

A molecule containing three amino acids joined by peptide bonds

A

Tripeptide

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8
Q

A macromolecule containing many amino acids joined by peptide bonds

A

Polypeptide

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9
Q

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

A

Protein

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10
Q

Individual amino acid units

A

Residues

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11
Q

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

A

Linus Pauling

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12
Q

Pauling explained the double-bonded character to the C-N bond through the concept of _____

A

Resonance

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13
Q

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

A

C-terminus

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14
Q

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

A

N-terminus

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15
Q

How do you read the amino acids?

A

Left-right (N-terminus to C-terminus)

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16
Q

The sequence of amino acids in a polypeptide chain

A

Primary structure

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17
Q

Conformations of amino acids in localized regions of a polypeptide chain

A

Secondary structure

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18
Q

Examples of secondary structure

A

a-helix, b-pleated sheet, random coil

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19
Q

Complete three-dimensional arrangement of atoms of a polypeptide chain

A

Tertiary structure

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20
Q

Spatial relationship and interactions between subunits in a protein that has more than one polypeptide chain

A

Quaternary structure

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21
Q

Antidiuretic hormone

A

Vasopressin

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22
Q

Affects the contractions of the uterus in childbirth and muscles of the breast in secretion of milk

A

Oxytocin

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23
Q

Differences in the structure of vasopressin and oxytocin

A

Vasopressin: Arg & Phe
Oxytocin: Leu & Ile

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24
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

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25
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

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26
Q

In a-helix, there are ____ amino acids per turn of the helix

A

3.6

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27
Q

The six atoms of each peptide bond in a-helix lie in the _____ plane

A

same

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28
Q

The N-H groups point in the _____ direction, roughly _____ to the axis of the helix (a-helix)

A

same, parallel

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29
Q

The C=O groups point in the _____ direction, roughly _____ to the axis of the helix (a-helix)

A

opposite, parallel

30
Q

All R-groups of a-helix point _____ from the helix

A

outward

31
Q

A polypeptide derived entirely from alanine, where the intrachain hydrogen bonds that stabilize the helix are visible as the interacting C-O and N-H bonds

A

polyalanine, a-helix

32
Q

In b-pleated sheet, the six atoms lie in the _____ plane

A

same

33
Q

The C=O and N-H groups of the peptide bonds (b-pleated sheet) from _____ chains point _____ each other and in the ____ plane

A

adjacent, toward, same

34
Q

All R-group (in b-pleated sheet) on any one chain ___ of the sheet

A

alternate (above, then below)

35
Q

The overall conformation of an entire polypeptide chain

A

tertiary structure

36
Q

Four ways of stabilization of tertiary structure

A

Covalent, hydrogen, salt bridges, hydrophobic interactions

37
Q

Example of tertiary structure stabilization: formation of disulfide bonds between cysteine side chains

A

Covalent bonds

38
Q

Example of tertiary structure stabilization: between the -OH groups of serine and threonine

A

Hydrogen bonding

39
Q

Example of tertiary structure stabilization: the attraction of the -NH3+ group of lysine and the COO- group of aspartic acid

A

Salt bridges

40
Q

Example of tertiary structure stabilization: nonpolar side chains of phenylalanine and isoleucine

A

Hydrophobic interactions

41
Q

The arrangement of polypeptide chains into noncovalently bonded aggregation

A

Quaternary structure

42
Q

Adult hemoglobin: two alpha chains of ____ amino acids each, and two beta chains of _____ amino acids each

A

141, 146

43
Q

Fetal hemoglobin: _____ alpha chains and _____ gamma chains

A

2, 2

44
Q

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

A

Denaturation

45
Q

Denaturating agent: can discrupt hydrogen bonding; in globular proteins, it can cause unfolding of polypeptide chains with the result that coagulation and precipiation may take place

A

Heat

46
Q

Denaturating agent: disrupts hyrdogen bonding

A

6M aqueous urea

47
Q

Denaturating agent: detergents such as sodium dodecylbenzenesulfate (SDS) disrupt hydrogen bonding

A

Surface-active agents

48
Q

Denaturating agent: 2-Mercaptoethanol cleaves disulfide bonds by reducing -S-S- groups to -SH groups

A

Reducing agents

49
Q

Denaturating agent: transition metal ions form water-insoluble salts with -SH groups

A

Heavy metal ions

50
Q

Denaturating agent: penetrates bacteria and kills them by coagulating their proteins

A

Alcohol

51
Q

Where will the equilibrium shift if pI>pH?

A

Left

52
Q

Where will the equilibrium shift if pI<pH

A

Right

53
Q

Net charge if pH>pI

A

Negative

54
Q

Net charge if pI>pH

A

Positive

55
Q

A sugar alternative that is 200x sweeter than sucrose

A

Aspartame

56
Q

Present amino acid in aspartame

A

Phenylalanine

57
Q

Effect of configuration in aspartame

A

D-configuration will lead to a bitter taste (it should be sweet)

58
Q

Three physiologically important amino acids especially as neurotransmitters

A

tyrosine, tryptophan, phenylalanine

59
Q

Low level of L-dopa will lead to ______

A

Parkinson’s disease

60
Q

Two amino acids associated with L-dopa

A

Tyrosine and phenylalanine

61
Q

Serotonin is converted from what amino acid?

A

Tryptophan

62
Q

Low levels of serotonin leads to ____

A

Depression

63
Q

Extremely high levels of serotonin leads to ______

A

Manic-depressive schizophrenia (Or bipolar disorder)

64
Q

Water insoluble complexes from heated test tube (from glycation process)

A

Advanced glycation end-products (GAE)

65
Q

pH of hemoglobin

A

6.8

66
Q

pI of albumin

A

4.9

67
Q

Difference between normal hemoglobin and sickle cell hemoglobin (HbS)

A

Valine replaces Glutamic Acid in the sixth position

68
Q

_____ prompts bone marrow to manufacture fetal hemoglobin for sickle cell anemia

A

Hydroxyurea

69
Q

True or false. Denaturation affects all structures of proteins

A

False. Primary structures are not affected, only to a small extent if ever, and it can be reversed

70
Q

Some denaturation caused by heat can be reversed by _____. They help a partially heat-denatured protein to regain its native secondary, tertiary, and quaternary structures

A

Chaperones

BioChem 1st Shifting (7 decks)

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