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lmao > Proteins > Flashcards

Proteins Flashcards

1
Q

What do you call the structural protein present in plants? The chief structural proteins in animals, which are constituents of hair, skin, nails, etc., are?

A
  • Cellulose
  • Collagen & Keratin
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2
Q

Two proteins that are responsible for our movement?

muscle expansion and contraction are involved in every mvmnt

A

actin & myosin

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3
Q

What do you call the protein that transports oxygen from lungs to other cells and CO2 from the cells to the lungs?

A

hemoglobin

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4
Q

what do you call the proteins from a foreing substance that enters the body? Similarly, what do you call the proteins that the body makes to counteract the foreing molecule?

A

Antigen; Antibody

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5
Q

what do you call the protein which has a protective function (blood clotting)?

A

Fibrinogen

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6
Q

what do you call the storage protein that stores nutrients in milk? what abt in eggs?

A

casein; albumin

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7
Q

what do you call the protein in liver that stores iron?

A

Ferritin

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8
Q

what are the two major types of proteins?

A
  • Fibrous
  • Globular
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9
Q

Among the two major types of proteins, which is used mainly for structural proteins and is generally insoluble? What about the one that has a functional (nonstructural) purpose and is more soluble in water?

A

Fibrous; Globular

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10
Q

The R groups of amino acids have four types of side chains based on polarity:
- Nonpolar
- Polar neutral
- Acidic
- Basic

Can you classify them based on hydrophobicity/hydrophilicity?

A
  • Nonpolar = hydrophobic
  • Polar, Acidic, Basic = hydrophilic
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11
Q

Looking at the general formula of amino acids, all but one are chiral with carbon stereocenters, ano yung isang iyon?

A

Glycine

Glycine = 2 H+ sa alpha carbon

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12
Q

what do you call the two possible configurations which is based on the enantiomers of amino acid given that it is a chiral molecule?

this configuration refers to the rotation of plane-polarized light

enantiomers = molecules that are non-superimposable mirror images of one another (do not overlap when placed on top of each other); inversion of the whole molecule

A

D and L configuration

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13
Q

Among the two isomers of amino acids, which of the two isomers does our body have?

A

L-isomer

D-amino acids are rare in nature (sometims nasa wall ng ibang bacteria)

when assigning D or L, remember that amine group is always on the left. You may also note that in line structure, follow CORN rule to see if counterclockwise ang priority grps (L)

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14
Q

can water be a strong enough base or acid to cause the dissociation COOH to COO- and protonation of NH2 to NH3+?

A

Yes.

An amino acid has COOH (can’t exist w/ presence of weak base) and NH2 (can’t exist w/ presence of weak acid) groups in the same molecule. Therefore, in water solution, the COOH donates a proton to the NH2

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15
Q

Compounds that have a positive charge on one atom and a negative charge on another are called what?

A

Zwitterions

German zwitter meaning “hybrid”

amino acids are zwitterions not only in H2O but also in solid state

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16
Q

When acids are added to amino acids, what happens to its zwitterion?

A

protonation (in COO- group)

from COO- to COOH; and NH3+ same lang din

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17
Q

When bases are added to amino acids, what happens to its zwitterion?

A

deprotonation (in NH3+ group)

from NH3+ to NH2; and COO- remains d same

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18
Q

What do you call the pH when a molecule have equal positive and negative charges?

A

Isoelectric point

3 basic = higher pI; 2 acidic = lower pI

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19
Q

At or near the isoelectric point, amino acids exist in aqueous solution largely or entirely as?

eto yung (+) on one atom & (-) on one atom

A

zwitterions

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20
Q

If amino acids can accept and donate protons, we call that compound as?

A

Amphoteric

Amino acids also are amphiprotic

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21
Q

Since amino acids in a solution can accept or donate protons, it can neutralize both acids and bases and their solutions are known as?

A

buffers

Amino acids are therefore amphiprotic compounds, and aqueous solutions of them are buffers (Bettelheim)

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22
Q

Why is it that amino acid is never found in this form: RCH(NH2)COOH?

(mahaba ans ko hehe)

A

Carboxylic acids are stronger acids than water. amines are stronger bases than water (weaker acids). Therefore, since COOH is more acidic, it should donate protons and then the amino group will accept that proton. It isnt possible to find this amino acid form because acids are technically proton donors and bases (weaker acids) are proton acceptors

The carboxyl has a hydrogen to donate, and the amino group can accept a hydrogen. In very un-scientific terms, the hydrogen is not going to be found on the
stronger acid and removed from the stronger base. That is why the zwitterion predominates

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23
Q

The combination of a carboxylic acid and an amine is called an?

A

Amide

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24
Q

The bond which is the product of the combination of COOH and NH3+ of amino acids is called?

A

peptide bond

2 amino acids = dipeptide

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25
Q

If there are more than 15 (30 sa book) amino acids in a protein, its chain is called?

A

polypeptide

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26
Q

What do you call the amino acids in a peptide chain?

A

residues

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27
Q

What do you call the amino acid at the end of a peptide that has a free alpha-carboxyl group?

A

C-terminus

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28
Q

What do you call the amino acid at the end of a peptide chain that has a free alpha-amino group?

A

N-terminus

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29
Q

Because of the presence of the carboxylate, the side chains of these two amino acids (D & E) are ____ charged at neutral pH.

A

negatively charged

There are two carboxylic acids present in D and E. Thus, at neutral pH, these two carboxylic acids (since stronger acids than water) donate their H+, making the overall charge of the amino acid negative

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30
Q

The side chains of lysine and arginine are ____ charged at or near neutral pH

A

positively

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31
Q

In lysine, the aliphatic hydrocarbon tail is bonded to a side-chain what group?

A

amino group

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32
Q

In arginine, the side-chain basic group, the ____ group, is more complex in structure than the amino group and also bonded to an aliphatic hydrocarbon tail.

A

guanidino

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33
Q

What functional group in histidine makes it basic?

A

Imidazole group

Histidine is also found in enzymes since its pH is around 6.0 which is not far from physiological pH

34
Q

What are the 3 amino acids that demonstrate aromaticity in their side chains?

A
  • Phe
  • Trp
  • Tyr
35
Q

Aromatic amino acids absorb UV light at ____ nm

A

280

36
Q

Considering that F, W, and Y are precursors to neurotransmitters, what is d descendant of W?

A

Serotonin

5-hydroxytryptamine

37
Q

Considering that F, W, and Y are precursors to neurotransmitters, what is d product of Y & F?

A

norepinephrine & epinephrine

38
Q

what do you call the process characterized by the modification of the parent amino acid after the protein is synthesized? This process is involved in the production of uncommon amino acids.

A

post-translational modification

39
Q

Identify the two uncommon amino acids characterized by their hydroxyl groups on their side chains?

A
  • Hydroxylysine
  • Hydroxyproline
40
Q

This uncommon amino acid has an extra iodine-containing aromatic group on its side-chain, what is it?

A

Thyroxine

41
Q

what do you call the horizontal line of atoms representing the repeating structure of proteins?

N-C-C-N-C-C

A

peptide backbone

42
Q

The pI of a protein is the pH where there is an equal number of positive and negative charges. If pH is above the isoelectric point, the overall charge of the protein is?

A

negative

43
Q

The pI of a protein is the pH where there is an equal number of positive and negative charges. If pH is below the isoelectric point, the overall charge of the protein is?

A

positive

44
Q

When pH is greater or lesser than the isoelectric point of a protein, charges will be present, these charges will cause the proteins too demonstrate what?

Attraction or Repulsion

A

Repulsion

repulse protein molecules when there is a difference between the pH and the isoelectric point

45
Q

When there are no repulsive forces, protein molecules clump together to form ____ of two or more molecules to reduce their solubility.

A

aggregates

thus, at isoelectric point, proteins are least soluble and can be precipitated from their solutions

46
Q

the primary structure of proteins describes the ____ of amino acids in the polypeptide chain.

A

linear sequence

47
Q

The secondary structure refers to certain ____, such as the a-helix conformation or the B-pleated sheet conformation or the absence of a repeating pattern, as with the random coil

A

repeating patterns

or repetitive conformations of the protein backbone

48
Q

The tertiary structure describes the overall ____ of the polypeptide chain.

A

3D conformation

49
Q

The ____ structure applies mainly to proteins containing more than one polypeptide chain (subunit) and deals with how the different chains are spatially related to one another

A

Quaternary

50
Q

As with naming peptides, the assignment of positions of the amino acids in the sequence starts at the ____ end.

A

N-terminal

51
Q

The primary structure of a protein determines to a large extend the ____ 2ndary and tert structures.

blank is also defined as “most frequently occurring”

A

native

52
Q

what structure pertains to the repetitive conformations of the protein backbone?

A

secondary structure

53
Q

what structure pertains to the overall 3D conformation of a polypeptide chain, including the interactions of the side chains and the position of every atom in the polypeptide?

A

Tertiary structure

54
Q

What structure determines the spatial relationship and interactions between subunits in a protein that has more than one polypeptide chain?

A

Quaternary structure

55
Q

what are the two most common secondary structures found in a protein? what do you call protein conformations that do not exhibit a repeated pattern?

A

a-helix & B-pleated sheet; random coils

56
Q

A secondary structure where the protein folds into a coil held together by hydrogen bonds parallel to the axis of the coil

A

a-Helix

57
Q

In the ____ form, a single protein chain twists in such a manner that its shape resembles a right-handed coiled spring.

A

alpha-helix

58
Q

what holds the shape of the helix and it exists between the backbone -C=O and NH groups?

A

hydrogen bonds

59
Q

In an alpha helix, a hydrogen bond between the oxygen of a carbonyl group and the hydrogen of an amine group is formed how many amino acids away? This cyclic pattern creates a helix of how many amino acids per turn?

A

4 amino acids away; 3.6 amino acids per turn

60
Q

In an alpha-helix, the amine group points where? what abt the carbonyl grp? the side chains point where?

upward or downward or inward or outward

A
  • upward
  • downward
  • outward from the helix
61
Q

what do you call the secondary structure that can occur between molecules when polypeptide chains run parallel or antiparallel from each other?

A

B-pleated sheet

62
Q

In all secondary structures, the hydrogen bonding is between backbone -C=O and H-N- groups, a characteristic that distinguishes between secondary and tertiary structures. In the latter, as we shall see, the hydrogen bonding can take place between ____.

A

R-groups

or interactions of side chains (not just the peptie backbone)

63
Q

What forms when a cysteine residues between two different chains meet?

A

formation of disulfide bond

which is a covalent bond

64
Q

What structures are stabilized by hydrogen bonding between polar groups on side chains or between side chains and the peptide backbone?

A

Tertiary structures

65
Q

Other term for salt bridges?

A

electrostatic attractions

66
Q

This occur between two amino acids with ionized side chains—that is, between an acidic amino acid (-COO-) and a basic amino acid (-NH3+ or =NH2+) side chain.

A

Salt bridges

or electrostatic attractions (held together by ion-ion attraction)

67
Q

In aqueous solutions, globular proteins usually turn their ____ groups outward, toward the aqueous solvent and their ____ groups inward, away from H2O molecules.

A

polar; nonpolar

68
Q

Two side chains with the same charge would normally repel each other, but they can also be linked via a what?

A

metal ion

For example, two glutamic acid side chains (-COO-) would both be attracted to a magnesium ion (Mg2+), forming a bridge.

69
Q

What do you call proteins that help other proteins to fold into the biologically active conformation and enable partially denatured proteins to regain their biologically active conformation?

A

chaperones

70
Q

As a result of noncovalent interactions in a quaternary structure, subtle changes in structure at one site on a protein molecule may cause drastic changes in properties at a distant site. Proteins that exhibit this property are called ____.

A

allosteric

71
Q

Protein conformations are stabilized in their native states by secondary and tertiary structures and through the aggregation of subunits in quaternary structure. Any physical or chemical agent that destroys these stabilizing structures changes the conformation of the protein and this process is called?

A

denaturation

72
Q

what cleaves hydrogen bonds, so boiling a protein solution destroys the a-helical and b-pleated sheet structure?

A

heat

73
Q

what denaturating agent causes the unfolding of the polypeptide chains wherein precipitation or coagulation then takes place?

A

heat

74
Q

what denaturating agent, besides heat, causes the breakage of H-bonds and cause the unfolding of globular proteins?

A

6M Urea

75
Q

____ change protein conformation by opening up the hydrophobic regions.

A

Surface-active agents (detergents)

76
Q

What denaturating agents are responsible for affecting (or breaking) the salt bridges and H-bonds?

A
  • Acids & Bases = salt bridges & H-bonds
  • Salts = salt bridges lng
77
Q

What denaturating agent is responsible for breaking the disulfide bonds that results to the reduction to -SH groups?

A

Reducing agents

78
Q

Heavy metal ions (for example, Pb2+, Hg2+, and Cd2+) also denature protein by attacking the ____. They form salt bridges, as in -S-Hg2+-S-

A

-SH groups

79
Q

____ changes secondary, tertiary, and quaternary structures. It does not affect primary structures

A

Denaturation

80
Q

When the amino group of one amino acid condenses with the carboxyl group of another amino acid, an ____ (peptide) bond is formed, with the elimination of water.

A

amide

lmao (14 decks)

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