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Analytical and Biochemistry Flashcards

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1
Q

What are the three main uses of Analytical techniques?

A

Determination of: Structure, Composition, and Purity

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2
Q

What are the three spectroscopic techniques?

A

IR, NMR, and Mass spectroscopy

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3
Q

Radiowaves do what to atoms?

A

NMR, change in orientation of nucleus relative to magnetic field

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4
Q

Microwaves di what to atoms?

A

Rotational transition

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5
Q

IR waves do what to atoms?

A

Vibrational transition

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6
Q

Visible light, UV light, and X-rays do what to atoms?

A

Electronic transitions in atoms and molecules (e- jump to new orbit)

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7
Q

What does every element have that is unique to it with regard to spectroscopy?

A

Idiosyncratic emission spectrum

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8
Q

What is IR Active?

A

A molecule is able to absorb IR radiation

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9
Q

What types of vibrations (IR) do diatomic molecules have?

A

Vibrations that increase bond length

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10
Q

If HCl is hit with IR radiation, what will happen?

A

The H-Cl bond will length, increasing the dipole moment of the molecule

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11
Q

What happens to non polar, diatomic molecules that absorb IR radiation, such as F2, Cl2, or Br2?

A

Their bond lengths increase, but there is no increase in dipole moment

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12
Q

What are I2, Cl2, Br2, etc considered to be in terms of IR spec? What does this mean

A

IR inactive: they can absorb IR radiation but it will not affect their polarity, only lengthen their bonds.

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13
Q

What types of vibrational modes do Triatomic molecules have (IR)?

A

Stretching and Bending

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14
Q

What are the two types of IR stretches?

A

Symmetrical and Asymmetrical

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15
Q

Which types of stretches are IR active?

A

Asymmetrical always active. Symmetrical active only in polar substances. Bend always active.

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16
Q

What types of stretches are active in CO2?

A

Non polar. Asymmetric stretch and bend are IR active.

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17
Q

How many absorptions does CO2 have on an IR spectrum?

A

Two, one for Asymmetric Stretch and one for Bend.

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18
Q

What is a methylene group

A

R1-CH2-R2

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19
Q

How many vibrational modes does CH2 have? What are they?

A

Six: Asymmetric Stretch, Symmetric Stretch, Bend, Rock, Wag, and Twist

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20
Q

What is always true of an IR spectrum containing -OH of an alcohol?

A

It must have a complimentary C-O peak

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21
Q

What is the fingerprint region? What is its use?

A

The region below 1500 Cm-1. Unique to each molecule, used for identification

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22
Q

What is C-O’s IR band?

A

1000-1300 cm-1

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23
Q

What is O-H’s (carb acid) IR band?

A

2400-3200 cm-1

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24
Q

What is C=O’s IR band?

A

1700-1750 cm-1

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25
Q

What is O-H’s (phenol, alcohol) IR band?

A

3200-3600 cm-1

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26
Q

Describe the setup of a Double Beam IR spectrophotometer

A
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27
Q

What is the principle behind Mass spectrometry?

A

High energy electrons are used to create Molecular ions, M+

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28
Q

What is always true of the parent molecular ion peak?

A

It always has the highest mass

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29
Q

In any fragmentation pattern reaction, how many resultant molecules have charge?

A

Only one.

e.g. C3H8+ –> C2H5+ + CH3

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30
Q

How many cuts do you get with the molecular scissors?

A

YOU GET ONE CUT WITH THE MOLECULAR SCISSORS (or chainsaw)!!!!!

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31
Q

What are the two ways to interpret fragmentation patterns?

A

Molecules are produced by addition of other parts; parent molecule is fragmented to smaller and smaller mass as functional groups are removed

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32
Q

What is the principle of NMR spec?

A

Radio waves are used to change the orientation of H+ spin with respect to a magnetic field.

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33
Q

How does the energy of the magnetic field determine the alignment of H+?

A

Higher energy = H+ aligned against

Lower Energy = H+ aligned with

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34
Q

How are H+ bonded to the same carbon described?

A

They are said to be chemically equivalent, occupying the same “environment”

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35
Q

What are the terms in which low resolution NMR specs display the number of H+ environments?

A

chemical shift/ppm

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36
Q

What is true of the vertical heights of peaks in an NMR spectra?

A

They are proportional to the number of H+ in that environment

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37
Q

What is the principle of an integration trace?

A

Measure the heights of all the peaks and divide by the smallest to obtain the ratio

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38
Q

What determines the H+ environment of a particular C atom?

A

The atoms attached to adjacent C atoms

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39
Q

What does the multiplicity of peaks on an NMR spec tell you?

A

The number of hydrogens on the adjacent carbon to that hydrogen environment

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40
Q

What is the formula for determining multiplicity in NMR?

A

n protons on adjacent C, n+1=multiplicity

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41
Q

Describe an Atomic Absorption Spec

A
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42
Q

What is the source of radiation in an atomic absorption spectrophotometer?

A

A cathode an anode spaced by a small distance in a chamber of inert gas. High voltage applied, gas between electrodes ionizes and the releases energy as light.

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43
Q

What is the purpose of the atomizer in an atomic absorption spec?

A

To mist a sample into a flame of either H2 or Ethyne

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44
Q

What are the purposes of the monochromator and detector in atomic absorption spec?

A

The monochromator filters all light except one frequency. The detector converts the electromagnetic energy from the monochromator into a digital signal

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45
Q

How is concentration determined from atomic absorption spec?

A

Calibration curve of abs vs. concentration. Measure abs and find conc.

46
Q

What are the uses of Atomic Absorption Spec?

A

Determination of concentrations of metals in: blood, water, food, and soil

47
Q

What is chromatography’s primary purpose?

A

Separation of mixtures

48
Q

What are the components of an industrial chromator?

A

Fine powder substance packed into column. Solvent poured into column

49
Q

What is the mobile phase in chromatography?

A

The movement of the solvent along the chromator

50
Q

What is the stationary phase of a chromator?

A

When the solution stops moving upward

51
Q

What is adsorption?

A

The attraction of a molecule in the solvent to the solid medium of the chromatographer. As the solvent flows by, the molecule remains attracted to the medium

52
Q

What is the relationship between polarity and adsorption?

A

The more polar a substance, the more likely it is to be adsorped

53
Q

How are amino acids located once in the stationary phase?

A

Addition of ninhydrin

54
Q

How are organic solutes located in the stationary phase?

A

H2SO4 or I2

55
Q

How are sugars located once in the stationary phase?

A

p-anisidine hydrochloride

56
Q

How is the retardation factor for paper chromatography calculated?

A

R(f) = Distance solute moves/distance solvent front moves

57
Q

What should always be true of the retardation factor?

A

It should ALWAYS be less than 1

58
Q

What does a high Rf value indicate?

A

It indicates an affinity for the mobile phase

59
Q

What does a low Rf value indicate?

A

It inidicates an affinity for the stationary phase

60
Q

How many naturally occurring amino acids are there?

A

20

61
Q

What word is used to describe the acid/base behavior of 2-amino acids?

A

amphoteric

62
Q

What is a zwitterion? What is the word to describe its key property?

A

The COOH group donates a proton, becoming COO-, while the NH3 group gains a proton, becoming NH4+. Their charges cancel. The molecule is therefore isoelectronic.

63
Q

What happens to the zwitterion at low pH?

A

The NH3 group is converted to NH4+ and all COO- groups are converted to COOH

64
Q

What happens to a zwitterion at high pH?

A

All COO- groups lose H+ and all NH4+ become NH3

65
Q

What are the neutral amino acids?

A

alanine and cysteine

66
Q

What is the primary structure of proteins?

A

A precise linear sequence of amino acids

67
Q

What type of reaction do amino acids undergo to be combined?

A

condensation

68
Q

What parts of two amino acids react in a condensation reaction?

A

The NH3 of one and the COOH of the other

69
Q

What bond does a condensation reaction produce? What is it called?

A

C=O(N)

Peptide linkage

70
Q

What is true of the formation of peptide bonds with regard to isomerism?

A

If alanine and cysteine are reacted, they can form two distinct compounds: ala-cys and cys-ala

71
Q

From what end of the amino acid chain are amino acids always named?

A

The amino end. Amino acid, like duh

72
Q

What is the secondary structure of a protein?

A

The alpha helix and beta pleated sheet

73
Q

What is the tertiary structure of a protein?

A

Specific three dimensional shape held in place by bonds

74
Q

What types of bonds hold the tertiary structure of a protein in place?

A

Ionic, Van der waals, disulfide linkages, hydrogen bonds

75
Q

What is the quarternary structure of proteins?

A

Polypeptide subunits (individual chains of amino acids) associate in a specific geometric manner

76
Q

What are the functions of proteins?

A

Structure, Biological catalysts, Hormones, Immunological proteins, Transport, Energy Source

77
Q

How are proteins analyzed using paper chromatography?

A

put in HCl and heated to break bonds. Difference in partition used to separate amino acids, paper sprayed with ninhydrin and Rf value calculated

78
Q

How are proteins analyzed using Electrophoresis?

A

Electric field applied to system. Polypeptide solution acidified, coated on polymer surface, and coated with buffer. Anions migrate to anode, cations migrate to cathode

79
Q

What are the functions of carbohydrates?

A

Energy source, energy store, precursor

80
Q

What is similar and different about glucose and fructose?

A

Glucose and fructose are both hexoses (6-carbon sugars). Glucose is an aldose (containing an aldehyde) while Fructose is a ketose (containing a ketone)

81
Q

What is the difference between alpha glucose and beta glucose?

A

Alpha glucose has H+ of the first C and the -CH2OH group of the 5th C on the same side of the molecule;

Beta glucose has these same two consituents on opposite sides of the molecule.

The -CH2OH is on the same side for both, the H+ is what changes sides

82
Q

What are the disaccharides?

A

Maltose, Sucrose, Galactose

83
Q

What are the primary monosaccharides?

A

Glucose, fructose, and lactose

84
Q

What are the primary polysaccharides?

A

Starch (alpha), Glycogen (alpha), and cellulose

85
Q

What are the two types of starch?

A

alpha amylose (unbranched), alpha amylopectin (branched)

86
Q

How does the extent of branching in glycogen compare with that of amylopectin?

A

Branching is more extensive in glycogen

87
Q

What type of linkage does cellulose have?

A

beta 1,4,-glycosidic

88
Q

What type of linkage does amylopectin have?

A

alpha 1,4-glycosidic and alpha 1,6-glycosidic

89
Q

What makes dietary fiber undigestable for some mammals?

A

Cellulose, hemicellulose, and lignin are all insoluble.

90
Q

What are triglycerides?

A

three fatty acids attached to a glycerol

91
Q

Where are fats found in the body?

A

Adipose tissue, composed of adipocytes

92
Q

How do carbohydrates and lipids compare in terms of energy storage capacity?

A

Fats release ~37kJ/g while carbs release ~16kJ/g

93
Q

What is the principle behind the Iodine number?

A

1 molecule of I2 reacts with 1 C=C bond, so the number of mols of I2 reacted can be used to determine the number of C=C bonds and thus the type of lipid

94
Q

What do saturated fatty acids have a higher melting point?

A

They are able to pack close together and apply stronger Van der waals forces on eachother

95
Q

What are unsaturated fatty acids typically liquids at room temp?

A

The kinks in the fatty acid chain caused by C=C bonds prevent close packing. The Van der waals forces are weaker than in saturated fatty acids

96
Q

What is an Omega-6 fatty acid?

A

A Linoleic fatty acid. Has two C=C bonds at the 6th and 9th carbons from the terminal carbon (i.e. COOH….C=C (9th carbon from end)…C=C (6th carbon from end)…CH3 (terminal carbon))

97
Q

What is an Omega-3 fatty acid?

A

A linolenic fatty acid. Three C=C bonds at the 3rd, 6th, and 9th carbons from the terminal Carbon (opposite end from the COOH)

98
Q

What is the difference between cis and trans fats?

A

Cis fats have the H+ attached to the C’s of C=C on the same side. This makes a kink in the fatty acid chain.

Trans fats have the H+ on opposite sides. This prevents a kink in the fatty acid chain.

99
Q

How are fats digested?

A

Lipases hydrolyze the bonds between glycerol and fatty acids. Lipoproteins transport poorly soluble fatty acids in the bloodstream.

100
Q

What is a phospholipid composed of?

A

Two fatty acids and a phosphate group attached to a glycerol molecule

101
Q

What are the two parts of a phospholipid?

A

The polar head (phosphate group with ester linkage to glycerol) and the non polar body (with ester linkage to glycerol)

102
Q

What are the characteristics of steroids?

A

Hydrophobic substance, common 4-ring carbon backbone

103
Q

What is the difference between LDL and HDL? Which is more healthy? Why?

A

Protein composition. HDL has about 33% protein whereas LDL has about 25% protein. HDL is more beneficial to human health because it removes cholesterol from the bloodstream and returns it to the liver

104
Q

What increases the incidence of LDL in the bloodstream?

A

Saturated fats and trans fats

105
Q

What increases the incidence of HDL in the bloodstream?

A

Poly and mono-unsaturated fats

106
Q

What are some of the macronutrients?

A

Carbohydrates, fats, proteins, sodium, magnesium, calcium

107
Q

What are some of the micronutrients?

A

Iron, copper, zinc, iodine, selenium, cobalt, manganese

108
Q

What are the two types of vitamins?

A

Lipid and Water soluble

109
Q

What are examples of water soluble vitamins?

A

C and B

110
Q

What are examples of lipid-soluble vitamins?

A

A, D, E, and K

Chemistry (10 decks)

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