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BIOCHEM LAB > EXERCISE 3 - 5 > Flashcards

EXERCISE 3 - 5 Flashcards

1
Q
  • Process of separating substances in a complex mixture by their different affinities to an adsorbent
  • One of the most useful methods of separating the components of minute amount of mixtures
  • Discovery with plant samples
  • Commonly used for analyzing mixtures of colored chemicals
A

CHROMATOGRAPHY

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2
Q

who invented chromatography

A

MIKHAIL SEMYONOVICH TSVET

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3
Q

chroma means

A

color

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4
Q

graphein means

A

to write

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5
Q
  • Either a liquid or solid that is fixed in place during the process
  • Usually a high-quality filter paper, or an adsorbent
A

STATIONARY PHASE

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6
Q
  • Either liquid or gas which moves the samples through the stationary phase during the process
  • Solvent or a mixture of solvents
A

MOBILE PHASE

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7
Q

CHROMATOGRAPHY

forces of attraction for non-polar

A

weak VAN DER WAALS

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8
Q

CHROMATOGRAPHY

forces of attraction for polar

A

dipole-dipole
hydrogen bonding

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9
Q

CHROMATOGRAPHY

Polar compounds adsorb strongly on what phase

A

STATIONARY PHASE

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10
Q

CHROMATOGRAPHY

Non-polar compounds have higher affinity with what phase

A

MOBILE PHASE

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11
Q

CHROMATOGRAPHY

The extent of separation is measured by

A

RETENTION FACTOR
Rf value

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12
Q

This value depends on the relative solubility and adsorptive properties of the components of the sample

A

RETENTION FACTOR
Rf value

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13
Q

Rf value formula

A

distance travelled by the substance / distance travelled by the solvent

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14
Q

Largely depends on adhesion and cohesion forces which allows the mobile phase to move along the stationary phase due to surface tension

A

PAPER CHROMATOGRAPHY

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15
Q

PAPER CHROMATOGRAPHY

It is important that the solvent level is ____ the spots with samples

A

BELOW

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16
Q

in paper chromatography, what should be the shape of the paper

A

COILED / FORMED INTO CYLINDER

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17
Q

why does the container needs to be covered during paper chromatography

A

to prevent volatilization

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18
Q

PAPER CHROMATOGRAPHY

solution used as spray to allow the visualization of spots

A

NINHYDRIN

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19
Q

ninhydrin solution reacts with amino acids giving colored compounds known as

A

RUHEMANN’S PURPLE

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20
Q

Building blocks of proteins

A

AMINO ACIDS

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21
Q

Amino acids may react as an acid or a base

A

AMPHOTERIC

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22
Q

The pH at which the amino acid exists in its zwitterionic form is called as

A

ISOELECTRIC pH

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23
Q
  • General test in nature
  • Used to detect the presence of peptide bond
  • Complexes turn the solution from blue to purple
  • The deeper the purple color, the higher is the number of the peptide-cupric ion
  • Negative for single amino acids
A

BIURET TEST

24
Q

BIURET TEST

In the presence of an ____ solution, the blue-colored cupric ions form complexes with peptide bonds

A

ALKALI

25
Q
  • The general test for amino acids
  • Used to detect the presence of amine group, which includes α-amino acids
  • Positive results are not exclusive to proteins or amino acids
  • Amino acid undergoes oxidative deamination
A

NINHYDRIN TEST

26
Q

in ninhydrin test, Amino acid undergoes ___

A

oxidative deamination

27
Q

NINHYDRIN TEST

Proline produces what complex

A

YELLOW

28
Q

NINHYDRIN TEST

Asparagine produces what complex

A

BROWN

29
Q
  • Used to detect the presence of aromatic amino acids—the presence of benzene (Tyr, Trp, and Phe)
  • Aromatic benzene undergoes nitration (+NO2) upon reacting with conc. Nitric acid produces yellow color in the solution
  • Upon addition of an alkali, these nitro derivative salts produce an orange color in solution due to ionization of the phenolic group
A

XANTHROPOTEIC TEST

30
Q

XANTHOPROTEIC TEST

Aromatic benzene undergoes ____ upon reacting with conc. Nitric acid

A

NITRATION

31
Q

XANTHORPOTEIC TEST

Aromatic benzene + conc. Nitric acid result

A

YELLOW SOLN

32
Q

XANTHOPROTEIC TEST

Aromatic benzene + conc. Nitric acid + alkali

A

ORANGE SOLN

33
Q
  • Used to detect the presence of phenolic amino acid—tyrosine
  • Tyrosine reacts with mercury and mercuric nitrate to form red-colored complex
A

MILLON’S TEST

34
Q

MILLON’S TEST

tyrosine + mercury & mercuric nitrate

A

RED-COLORED COMPLEX

35
Q
  • Used to detect the presence of the guanidino group found in the amino acid arginine
  • Arginine reacts with α-naphthol in ethanol and an oxidizing agent (e.g. sodium hypobromite, sodium hypochlorite) to give a red-colored product
A

SAKAGUCHI TEST

36
Q

SAKAGUCHI TEST

arginine + a-naphthol + oxidizing agent

A

RED COLORED PRODUCT

37
Q
  • Used to detect the presence of indole-containing amino acid—tryptophan
  • The indole group of tryptophan reacts with glyoxylic acid in the presence of sulfuric acid to give a purple-colored complex
A

HOPKIN’S-COLE TEST

38
Q

prepared from glacial acetic acid being exposed to sunlight

A

GLYOXYLIC ACID

39
Q
  • Used to detect sulfur-containing amino acid—cysteine
  • When cysteine is heated with sodium hydroxide, it will yield sodium sulfide, this chemical reaction converts organic sulfur into an inorganic one
  • Sodium sulfide is then reacted with Lead (II) Acetate, producing black precipitate in the solution
A

LEAD ACETATE TEST

40
Q

LEAD ACETATE TEST

cysteine heated w/ NaOH → NaS

NaS + Lead (II) acetate will produce

A

BLACK PPT

41
Q

are polymers of monomers of amino acids

A

PROTEINS

42
Q
  • Helper proteins that provide favorable conditions for protein folding to take place
  • Clump around the forming protein and prevent other polypeptide chains from aggregating
  • Once the target protein folds, these proteins disassociate
A

CHAPERONE PROTEINS

43
Q
  • Any process that temporarily or permanently changes the protein conformation which results in loss of protein activity and function
  • Destruction of the quaternary, tertiary, and secondary levels of the structure of proteins
A

PROTEIN DENATURATION

44
Q

PROTEIN DENATURATION

Destruction of the primary level of protein structure

A

HYDROLYSIS

45
Q

Denaturing a protein is occasionally ____

A

IIREVERSIBLE

46
Q

visualizes the process of protein denaturation

A

PAPER CLIP ANALOGY

47
Q

PROTEIN DENATURATION

  • Causes the atoms to vibrate more rapidly by kinetic energy
  • Disruption of relatively weak forces such as H-bonds and hydrophobic interactions
  • mostly employed technique in sterilization which destroys enzymes in bacteria
A

HEAT

48
Q

PROTEIN DENATURATION

are often charges and can form ionic bonds with a group of opposite charge

A

R GROUPS in amino acids

49
Q

PROTEIN DENATURATION

Chemicals like ethanol can form ____ with protein molecules which disrupts the intramolecular H-bonds of the protein itself

A

H BONDS

50
Q

used as a disinfectant because it denatures proteins of bacteria (can penetrate the bacterial cell wall)

A

70% ETHANOL

51
Q

coagulates proteins at the cell wall surface, forming a crust that prevents the alcohol from penetrating bacterial cell

A

95% ETHANOL

52
Q

PROTEIN DENATURATION

can form strong groups with disulfide groups of proteins

A

MERCURY II
LEAD II
SILVER

53
Q

PROTEIN DENATURATION

cause the protein to precipitate out of the solution as insoluble metal-protein salt

A

DISRUPTED DISULFIDE BRIDGES & SALT LINKAGES

54
Q

PROTEIN DENATURATION

are used as antidotes for heavy metal poisoning

A

HIGH PROTEIN SUBSTANCES

egg whites, milk

55
Q

EGG ALBUMIN

provides nourishment and binds digestive enzymes; approximately 54% of the protein content

A

OVALBUMIN

56
Q

EGG ALBUMIN

most heat-labile; approximately 12% of the protein content

A

OVOTRANSFERRIN

BIOCHEM LAB (11 decks)

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