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Chemistry IB > Option Flashcards > Flashcards

Option Flashcards

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1
Q

Do amino acids have a high or low melting point? Why?

A

High because the zwitterionic form is a solid so stronger electrostatic attractions between oppositely charged groups

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2
Q

What are amino acids normally soluble in and not soluble in?

A

Soluble in water not in organic solvents

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3
Q

What affects solubility of amino acids?

A

R group

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4
Q

Why are amino acids less soluble at the zwitterion isoelectric point?

A

No overall charge

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5
Q

Why are amino acids soluble in water?

A

Overall charge means they can be solvated by the polarity of water

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6
Q

Why are amino acids not very soluble in organic solvents?

A

Energy to break dipole forces or stronger electrostatic forces not paid back by formation of weak London forces

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7
Q

How are peptide chains named?

A

Starting with amino terminal at the end of a chain

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8
Q

How can a peptide be broken down without an enzyme?

A

6moldm3 hydrochloric acid

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9
Q

In which direction does an alpha helix turn?

A

Clockwise (right) from the carboxyl terminus

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10
Q

Where are there hydrogen bonds in alpha helices?

A

Between C=O and N-H above and vice versa

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11
Q

What intermolecular forces occur between hydrophobic/non-polar R groups?

A

London forces

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12
Q

Where do disulfide bridges occur?

A

Oxidation of sulfhydryl groups in two cysteine residues

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13
Q

How is Alzheimer’s linked to proteins?

A

Could be due to protein misfolding

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14
Q

How does a solvent move up chromatography paper?

A

Capillary action

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15
Q

What is the stationary and mobile phase of chromatography?

A

Stationary is interacting with water in chromatography paper

Mobile is interacting with solvent

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16
Q

What can we tell if a pigment does not travel very far up the chromatography paper?

A

More soluble in stationary phase than mobile phase

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17
Q

What is done after chromatography?

A

Dried to evaporate solvent and sprayed with locating agent (ninhydrin)

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18
Q

What is a common gel used in gel electrophoresis?

A

Polyacrylamide

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19
Q

What determines movement of protein through gel electrophoresis?

A

Mass:charge ratio

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20
Q

Which proteins move further in gel electrophoresis?

A

Higher charge or lower mass

Size and shape also affect

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21
Q

What dye is used in gel electrophoresis?

A

Coomassie brilliant blue

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22
Q

Why can heavy metal ions affect enzyme shape?

A

Strong affinity for sulfhydryl groups and replace the sulfur with hydrogen in cysteine residues that changes the tertiary structure and interactions of at groups

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23
Q

How do you calculate specific energy?

A

Energy released/ mass of substance consumed

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24
Q

Why do lipids release more energy than carbohydrates?

A

Less oxidised/ more reduced than carbohydrates or proteins so can undergo more oxidation to release more energy

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25
Q

What state do longer chain fatty acids tend to be?

A

Solids at room temperature

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26
Q

Why do melting points increase as fatty acids get longer?

A

London forces increase due to larger molecular mass

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27
Q

The more double bonds in a triglyceride…

A

The lower the melting point

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28
Q

What is iodine number?

A

A measure of the degree of unsaturation in a fat or oil. The number of grams of iodine that react with 100g fat or oil

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29
Q

The number of double bonds in a fatty acid is equal to…

A

The number of moles of iodine that will react with 1 mole of the fatty acid

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30
Q

What does the phosphate group lose to form a phospholipid?

A

OH

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31
Q

Where is the O- on a phospholipid?

A

At the bottom

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32
Q

Where is the double bond in the phosphate group in a phospholipid?

A

Above the phosphorous

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33
Q

What is the name of the group that forms from a phosphate and an alcohol?

A

Phosphodiester group

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34
Q

How can fats be hydrolysed?

A

Heat with acid or alkali like sodium hydroxide

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35
Q

Do triglycerides reform once absorbed?

A

Yes to be transported to their destination

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36
Q

How can you completely break apart a phospholipid?

A

Heat with concentrated acid

37
Q

What is formed under milder hydrolysis of a phospholipid?

A

Phosphodiester group and two fatty acid molecules

38
Q

What can cause rancidity?

A

Increased water content, enzymes, high pH, low pH, raised temperatures, deep fat frying, light intensity, availability of oxygen, metals present, water content

39
Q

What are products of oxidative rancidity?

A

Aldehydes, ketones and some alcohols

40
Q

What is the risk of hormone-replacement therapy?

A

Risk of breast cancer

41
Q

What are uses of hydrocortisone?

A

Reduce inflammation, eczema, asthma, rheumatoid arthritis

42
Q

What is an androgen?

A

Male sex hormone

43
Q

What are effects of anabolic steroids?

A

Breast growth in men, infertility, mood swings, aggressiveness, heart attack, stroke, liver disease, high blood pressure

44
Q

What type of sugar is glucose?

A

Aldose sugar

45
Q

What type of sugar is fructose?

A

Ketose sugar

46
Q

What do monosaccharides contain?

A

At least 2 OH groups

47
Q

What are the ring forms of carbohydrates called?

A

Haworth projections

48
Q

Name two water soluble vitamins

A

Vitamin B and C

49
Q

Name some fat soluble vitamins

A

A, D, E and K

50
Q

What does vitamin C do and where is it found?

A

Tissue growth and repair. Synthesis of collagen and antioxidant to protect body from harmful free radicals.
Found in fresh fruit and vegetables

51
Q

What is vitamin A used for?

A

Growth and development, skin repair, immune system, vision

52
Q

How has vitamin A tried to be fortified into foods?

A

Sugar, margarine, golden rice

53
Q

How has vitamin B content tried to be improved?

A

Cereal fortification

54
Q

What are calixarenes?

A 
A class used to remove heavy metal ions
Radioactive caesium ions and extract uranium ions from water
55
Q

Why does biomagnification occur?

A

Not broken down by environment or body and is stored in fatty tissue because fat soluble

56
Q

What is the equation of atom economy?

A

Molar mass of desired product / total molar mass of all reactant x 100

57
Q

What is the Michaelis constant?

A

The concentration of substrate when rate is equal to half of Vmax

58
Q

What does Km show?

A

Affinity of enzyme for substrate. Stability of enzyme-substrate complex
Low Km = high affinity

59
Q

What changes with competitive inhibition?

A

Km is higher

60
Q

Why can proteins absorb UV?

A

Aromatic rings in side chains

61
Q

How can visible spectroscopy be carried out?

A

Same as UV
Use Bradford reagent with coomassie briliant blue dye to bind to protein to give different colours
Measure absorbance at 595nm

62
Q

How is E calculated in the Beer-Lambert Law?

A

Gradient of graph of absorbance against concentration

63
Q

How do chromophores work?

A

Absorb radiation in UV-vis spectrum so contain a double bond, C=O or benzene ring
Promotes electrons from low energy level to higher energy level

64
Q

The longer the conjugated system…

A

The longer the wavelength of radiation absorbed

65
Q

What is the structure of anthocyanins?

A

Aromatic rings with lots of OH groups so soluble in water

66
Q

What affects the colour of anthocyanins? Give an example

A

The metal ions used

Al3+ and Fe3+ give vivid, deep coloured complexes

67
Q

What acts as ligands in complex ions?

A

Anthocyanin molecules

68
Q

What is the structure of carotenoids?

A

40-carbon polyene chain which may or may not have a cyclic group attached which may or may not have oxygen attached

69
Q

What are xanthophylls?

A

Carotenoids containing oxygen atoms

70
Q

What are the solubilities of carotenoids?

A

Insoluble in water

Soluble in lipids

71
Q

Give an example of a carotenoid?

A

Accessory pigments
Lycopene
B- carotene

72
Q

Which cation is most responsible for anthocyanin colour?

A

Flavylium

73
Q

At lower temperatures, what happens to the anthocyanin?

A

More red abundant

Flavylium less stable at higher temperatures

74
Q

What do anthocyanins do?

A

Dissociate into smaller molecules that do not absorb visible light as temperature increases

75
Q

What process are carotenoids susceptible to?

A

Oxidation

76
Q

In what pH are chlorophylls unstable?

A

Acidic (pH 3)

77
Q

When oxygen binds to hemoglobin, what ion change occurs?

A

Fe2+ to Fe3+

78
Q

What shape is the partial pressure oxygen hemoglobin graph?

A

Sigmoidal

79
Q

Oxygenation of hemoglobin is what sort of reaction?

A

Exothermic

80
Q

What binding occurs between hemoglobin and CO?

A

Lone pair on carbon binds to iron ion

81
Q

What sort of groups are in cytochromes?

A

Heme groups

82
Q

Which region of light do cytochromes absorb?

A

Visible

83
Q

How is TLC done?

A

A plate is coated with silica gel or alumina

84
Q

What is adsorption?

A

Stick to the surface

85
Q

What makes a pigment move slower in TLC?

A

Greater tendency to adsorb in stationary phase

86
Q

What is the difference between TLC and paper chromatography?

A

TLC is faster with a better resolution

87
Q

How does vision work?

A

Rhodopsin pigment made of opsin connected to cis-retinal. When light absorbed by retinal, changes to all-trans form which changes conformation of protein to trigger signal. After signal is sent, trans retinal dissociates from opsin and is replaced by a cis-retinal. Trans retinal converted back to cis-retinal by an enzyme

88
Q

How is retinal formed?

A

Oxidation of primary alcohol to aldehyde and then isomerisation converts one trans double bond to a cis double bond

Chemistry IB (3 decks)

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