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Option Flashcards

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
What state do longer chain fatty acids tend to be?
Solids at room temperature
26
Why do melting points increase as fatty acids get longer?
London forces increase due to larger molecular mass
27
The more double bonds in a triglyceride...
The lower the melting point
28
What is iodine number?
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
29
The number of double bonds in a fatty acid is equal to...
The number of moles of iodine that will react with 1 mole of the fatty acid
30
What does the phosphate group lose to form a phospholipid?
OH
31
Where is the O- on a phospholipid?
At the bottom
32
Where is the double bond in the phosphate group in a phospholipid?
Above the phosphorous
33
What is the name of the group that forms from a phosphate and an alcohol?
Phosphodiester group
34
How can fats be hydrolysed?
Heat with acid or alkali like sodium hydroxide
35
Do triglycerides reform once absorbed?
Yes to be transported to their destination
36
How can you completely break apart a phospholipid?
Heat with concentrated acid
37
What is formed under milder hydrolysis of a phospholipid?
Phosphodiester group and two fatty acid molecules
38
What can cause rancidity?
Increased water content, enzymes, high pH, low pH, raised temperatures, deep fat frying, light intensity, availability of oxygen, metals present, water content
39
What are products of oxidative rancidity?
Aldehydes, ketones and some alcohols
40
What is the risk of hormone-replacement therapy?
Risk of breast cancer
41
What are uses of hydrocortisone?
Reduce inflammation, eczema, asthma, rheumatoid arthritis
42
What is an androgen?
Male sex hormone
43
What are effects of anabolic steroids?
Breast growth in men, infertility, mood swings, aggressiveness, heart attack, stroke, liver disease, high blood pressure
44
What type of sugar is glucose?
Aldose sugar
45
What type of sugar is fructose?
Ketose sugar
46
What do monosaccharides contain?
At least 2 OH groups
47
What are the ring forms of carbohydrates called?
Haworth projections
48
Name two water soluble vitamins
Vitamin B and C
49
Name some fat soluble vitamins
A, D, E and K
50
What does vitamin C do and where is it found?
Tissue growth and repair. Synthesis of collagen and antioxidant to protect body from harmful free radicals. Found in fresh fruit and vegetables
51
What is vitamin A used for?
Growth and development, skin repair, immune system, vision
52
How has vitamin A tried to be fortified into foods?
Sugar, margarine, golden rice
53
How has vitamin B content tried to be improved?
Cereal fortification
54
What are calixarenes?
``` A class used to remove heavy metal ions Radioactive caesium ions and extract uranium ions from water ```
55
Why does biomagnification occur?
Not broken down by environment or body and is stored in fatty tissue because fat soluble
56
What is the equation of atom economy?
Molar mass of desired product / total molar mass of all reactant x 100
57
What is the Michaelis constant?
The concentration of substrate when rate is equal to half of Vmax
58
What does Km show?
Affinity of enzyme for substrate. Stability of enzyme-substrate complex Low Km = high affinity
59
What changes with competitive inhibition?
Km is higher
60
Why can proteins absorb UV?
Aromatic rings in side chains
61
How can visible spectroscopy be carried out?
Same as UV Use Bradford reagent with coomassie briliant blue dye to bind to protein to give different colours Measure absorbance at 595nm
62
How is E calculated in the Beer-Lambert Law?
Gradient of graph of absorbance against concentration
63
How do chromophores work?
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
The longer the conjugated system...
The longer the wavelength of radiation absorbed
65
What is the structure of anthocyanins?
Aromatic rings with lots of OH groups so soluble in water
66
What affects the colour of anthocyanins? Give an example
The metal ions used | Al3+ and Fe3+ give vivid, deep coloured complexes
67
What acts as ligands in complex ions?
Anthocyanin molecules
68
What is the structure of carotenoids?
40-carbon polyene chain which may or may not have a cyclic group attached which may or may not have oxygen attached
69
What are xanthophylls?
Carotenoids containing oxygen atoms
70
What are the solubilities of carotenoids?
Insoluble in water | Soluble in lipids
71
Give an example of a carotenoid?
Accessory pigments Lycopene B- carotene
72
Which cation is most responsible for anthocyanin colour?
Flavylium
73
At lower temperatures, what happens to the anthocyanin?
More red abundant Flavylium less stable at higher temperatures
74
What do anthocyanins do?
Dissociate into smaller molecules that do not absorb visible light as temperature increases
75
What process are carotenoids susceptible to?
Oxidation
76
In what pH are chlorophylls unstable?
Acidic (pH 3)
77
When oxygen binds to hemoglobin, what ion change occurs?
Fe2+ to Fe3+
78
What shape is the partial pressure oxygen hemoglobin graph?
Sigmoidal
79
Oxygenation of hemoglobin is what sort of reaction?
Exothermic
80
What binding occurs between hemoglobin and CO?
Lone pair on carbon binds to iron ion
81
What sort of groups are in cytochromes?
Heme groups
82
Which region of light do cytochromes absorb?
Visible
83
How is TLC done?
A plate is coated with silica gel or alumina
84
What is adsorption?
Stick to the surface
85
What makes a pigment move slower in TLC?
Greater tendency to adsorb in stationary phase
86
What is the difference between TLC and paper chromatography?
TLC is faster with a better resolution
87
How does vision work?
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
How is retinal formed?
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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