Biological Molecules Flashcards
1
Q
What is a monomer
A
The smaller units from which larger molecules are made
2
Q
What are polymers
A
A chain of lots of monomers joined together
3
Q
What is a condensation reaction
A
A reaction which joins two molecules together, which forms a chemical bond and involves the elimination of a water molecule
4
Q
What is a hydrolysis reaction
A
A reaction which breaks a chemical bond between two molecules and seperates them, this involves the use of a water molecule
5
Q
Are linear or ring monosaccharides more common?
A
Ring
6
Q
What are the 3 classes of carbohydrates and how many sugar units do they contain?
A
Monosaccharide - 1
Disaccharide - 2
Polysaccharide - Many
7
Q
What is the name of a monosaccharide with 3, 5 and 6 carbon atoms
A
3 - Triose
5 - Pentose
6 - Hexose
8
Q
What are the two functional groups found in monosaccharides
A
Ketone group (ketose sugar)
Aldehyde group (aldose sugar)
9
Q
what does the ketone group look like
A
Ketone has a carbonyl group
O
||
C - C - C
10
Q
What does the Aldehyde functional group look like
A
Aldehyde has a carbonyl group
O
||
C - H
11
Q
What does the carbonyl functional group look like?
A
O
||
C
12
Q
what does the hydroxyl group look like
A
O - H
13
Q
What does R represent in displayed formulas
A
Hydrocarbon chain
14
Q
What are monosaccharides
A
The monomers from which larger carbohydrates are made
15
Q
Why can’t monosaccharides be hydrolised?
A
They are already the most basic sugar unit
16
Q
What are 4 characteristics of monosaccharides
A
Colourless
Water soluble
Crystalline solids
Sweet taste
17
Q
What are the 3 monosaccharides
A
glucose
galactose
fructose
18
Q
what is the difference between fructose and glucose/galactose
A
fructose is a 5 membered ring, the other 2 are 6 membered rings
19
Q
What is the structure of galactose
A
C4 has OH on top and H below
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20
Q
Why are monosaccharides important (3)
A
- They are the major nutrients of cells which provide energy for cellular respiration
- They are the monomers for the synthesis of disaccharides and polysaccharides
- They are the raw material for the synthesis of other monomers like amino acids
21
Q
What does alpha and beta glucose look like?
A
- Both 6 membered rings that are 3D
- Beta glucose - C1 has OH projecting upwards the plane of the ring and H below
- In alpha glucose this is swapped
- MAKE SURE CARBONS BOND TO OXYGEN
https://www.google.com/search?client=firefox-b-d&sca_esv=9029f727d4831701&sxsrf=ADLYWIJBqG5mfsWfUdrzKVjKkT_YX5KLFw:1735031733791&q=alpha+and+beta+glucose+image&source=lnms&fbs=AEQNm0Aa4sjWe7Rqy32pFwRj0UkWd8nbOJfsBGGB5IQQO6L3J9LTkYkTMsFy3KExiuH6ofO9k4fklbg-dHv8qWa0fUb_IEpmKB_J5k3JZ4VHAi6k-J_thFZJG2-2F6xUFgCIEnWBSj_pmyEN9ji0rStsGqpfFchAyeHbU0WywiSnKP68Oet2MiyifXV50_DlPzhATeZVNIks&sa=X&ved=2ahUKEwjDqqrxiMCKAxW_Q0EAHbXNONAQ0pQJegQICBAB&biw=766&bih=776&dpr=1.25
22
Q
What type of bond does a condensation reaction between 2 monosaccharides form
A
Glycosidic bonds
23
Q
what are the 3 disaccharides
A
Maltose
Sucrose
Lactose
24
Q
what 2 monosaccharides form maltose
A
alpha glucose + alpha glucose
25
what 2 monosaccharides form sucrose
glucose + fructose
26
what 2 monosaccharides form lactose
beta glucose + galactose
27
What are the 3 characteristics of disaccharides
- Water soluble
- Can be crystallised
- Sweet taste
28
how do you name the bond formed in maltose
a - 1,4 glycosidic bond
(numbers come from the carbon number that forms the bond)
29
which of the disaccharides are reducing sugars? which are non reducing?
Reducing = maltose and lactose
Non reducing = sucrose
30
what are reducing sugars
Sugars that have a free aldehyde or ketone group (free carbonyl group)
31
What structure do you look for to determine if a sugar is reducing
HO - C - O - C
32
What are polysaccharides
molecules formed by the condensation of many glucose units which are joined by glycosidic bonds
33
what are the 3 polysaccharides
starch
glycogen
cellulose
34
which of the polysaccharides are formed by alpha glucose and which are made of beta
alpha - glyogen + starch
beta - cellulose
35
what are the 6 characteristics of polysaccharides
- insoluble in water
- compact
- easily hydrolised
- large molecules
- cannot be crystallised
- not sweet tasting
36
why is it important that polysaccharides are insoluble in water
so that they don't affect the osmotic pressure of the cell
37
why is it important that polysaccharides are compact
means lots of energy can be stored per unit volume
38
why is it important that polysaccharides are easily hydrolised
they can be broken down into glucose for respiration fast
39
why is it important that polysaccharides are large molecules
means they cannot cross the cell membrane
40
what is starch used for
the major storage form of carbohydrates in plants
41
what are the 2 forms of starch
amylose
amylopectin (more common)
42
which of the starch forms are branched and helical
amylopectin
43
which of the starch forms is unbranched and helical
amylose
44
what is the bond formed between monomers in amylose
a - 1,4 glycosidic bonds
45
why does amylose coil into helices
because of the angle of the bonds between glucose molecules
46
what are the bonds formed in amylopectin (branched and unbranched region)
branched: a - 1,6 glycosidic bonds
unbranched: a - 1,4 glycosidic bonds
47
what is glycogen used for
major storage form of carbohydrates in animals
48
where is glycogen mostly found
liver and muscles - where high metabolic activities take place
49
is glycogen branched?
yes, more than amylopectin
50
what are the bonds formed in glycogen (branched and unbranched)
branched: a - 1,6 glycosidic bonds
unbranched: a - 1,4 glycosidic bonds
51
why is it important for glycogen to be branched
more ends for faster hydrolysis
52
what is cellulose used for
an important structual material in plants
53
what bonds form in cellulose
b - 1, 4 glycosidic bonds
54
how is cellulose able to form b - 1,4 glycosidic bonds
CH2OH alternataes being above and below the plane of the ring
55
is cellulose branched?
no
56
is cellulose helical
no
57
what bonds hold parallel cellulose molecules together
hydrogen
58
what is a bundle of bonded cellulose molecules called
microfibrils
59
why is the bonding of parallel cellulose molecules important
provides strength
60
What is the food test for reducing sugars
benedicts test
61
what is the colour range produced from the benedicts test
starts as blue, turns to:
green, yellow, orange, brick red
62
what type of dilution is used to prepare the glucose concentrations in the benedicts test
serial dilution
63
how do you obtain quantative results for the benedict test
- use a colourimeter to find the absorbance of colour
- Draw a graph where x axis = glucose concentration and y axis = absorbance % and draw a line of best fit
- calibrate the curve down to the concentration
OR
Filter, dry and weigh the mass of the precipitate
64
How do you test for non reducing sugars
- heat with acid and neutralise
- heat with benedicts solution
- If a red precipitate is formed, its a non reducing sugar
65
why do non reducing sugars have to be heated with acid before benedicts solution
to break them down into monosaccharides
66
can reducing or non reducing sugars donate electrons
reducing
67
what are lipids soluble / insoluble in?
soluble in organic solvevnts like ether
insoluble in water
68
what type of relationship do lipids have with water
they're hydrophobic
69
are lipids polymers
no
70
what are the 2 main groups of lipids
triglycerides
phospholipids
71
what do trigylcerides form
fats and oils
72
what do phospholipids form
lecithin
73
what molecules form trigylcerides when a condensation reaction occurs
one glycerol
three fatty acids
74
what bonds form between glycerol and fatty acids
ester bonds
75
what is the formation of ester bonds called
esterification
76
what does a trigylercide look like
O
||
H - C - O - C - R
X 3
77
what breaks down trigylcerides through hydrolysis
enzyme lipase
78
what is glycerol
a chain of 3 carbons, with each carbon bonded to hydrogen and a hydroxyl group (OH)
79
what does glycerol look like
H
|
H - C - OH
|
H - C - OH
|
H - C - OH
|
H
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80
what is the structure of a fatty acid?
- long carbon skeleton (a hydrocarbon chain
- carbon at one end is a part of a
O
||
carboxyl functional group (C-O-H)
81
what type of bond does the carboxyl group form with the hydrocarbon chain
non polar C-H bonds
82
which part of the fatty acid is hydrophobic (polar) and which is hydrophylic (non-polar)
hydrophobic - hydrocarbon chain
hydrophylic - carboxyl group
83
what makes a fatty acid saturated
only single covalent bonds between carbon atoms (no double bonds)
84
what makes saturated lipids fat solid at room temperature
they lack double bonds so their flexibility allows the fat molecules to pack tightly together
85
what causes unsaturated fats to be liquid at room temp
the double bonds cause kinks iin the fatty acid hydrocarbon chains, so they cannot pack close together
86
define monosaturated
one double bond
87
define polyunsaturated
more than one double bond
88
what are saturated fatty acids usually found as? unsaturated?
saturated - animal fats
unsaturated - plant and fish oil
89
describe the structure of phospholipids
2 fatty acids bonded to one glycerol and a phosphate group
90
what type of charge does the phosphate group carry in phospholipids
negative
91
which parts of the phospholipid are hydrophobic (polar) and hydrophylic (non polar)
hydrophobic - hydrocarbon tails
hydrophylic - phosphate group heads
92
what are 5 roles of lipids
- energy storage (they store more energy than sugars)
- component of the cell membrane
- buoyancy
- insulation / protection
- they transport fat-soluble vitamins
93
what tests for fats
emulsion test
94
describe the emulsion test
- add ethanold then add water and mix
- if positive a milky emulsion will form
95
what is the structure of an amino acid
amino group
variable group
carboxyl group
H R O
| | ||
N - C - C
| | |
H H O - H
96
how many types of amino acids are there
20
97
what bond forms when a dipeptide is made
peptide bond
98
where does the peptide bond form in dipeptides
between the carboxyl group of 1 amino acid and the amino group of another amino acid
99
what is a polypeptide chain
a chain of amino acids.
100
what is a polypeptides backbond
the repeated N-C-C sequence
101
what dimension are proteins
3D
102
what are the four protein levels
primary, secondary, tertiary and quaternary
103
describe the primary structure of a protein
- a sequence of amino acids in 1 polypeptide chain
- determines the following structures due to the chemical nature of its backbond and side groups affecting bonding
- a slight change in the sequence can cause the whole protein to change (mutations)
- identifies all the amino acids present
104
what are the 2 types of secondary structures
alpha helix and beta pleated sheets
105
describe the secondary structure of a protein
- coiled / pleated structure of a polypeptide chain which is held together by hydrogen bonds between the polypeptide backbone
106
what causes hydrogen bonds to form in a secondary protein structure
within the backbone, the oxygen that is double bonded to carbon (C=O) has a partial negative charge and the hydrogen bonded to nitrogen (N-H) has a partial positive charge, causing hydrogen bonds to form
107
are the hydrogen bonds in proteins secondary structure strong
individually no, by lots of them allow the shape to be supported
108
describe the tertiary structure of a protein
- further folding and coiling of both forms of the secondary structures into a 3D shape (one polypeptide) due to the interactions between the variable groups.
109
what bonds form in the tertiary structure of a protein
hydrogen bonds
disulfide bonds
ionic bonds
110
how does a disulfide bond form in tertiary protein structures
a covalent bond between the sulphur atoms in 2 amino acid cysteine groups (S-S)
111
how do ionic bonds form in a proteins tertiary structure
between the carboxyl and amino grpips on the variable groups, these are ionised
112
why can proteins have the same number and type of amino acids but different tertiary structures
different amino acid sequence
Formation of ionic or hydrogen or disulfide bonds in different places
113
describe the quaternary structure of a protein
two or more polypeptide chains interacting
114
how do you test for proteins
add biuret reagent (blue)
a positive result will turn puprle
115
what are 4 functions of proteins
- Nutrition (they form digestive enzymes)
- Immunity
- Growth
- Support and movement
116
what is an enzyme
a protein that acts as a biological catalyst which increases the rate of reaction by lowing the activation energy. they are specific to the substrate
117
what causes enzymes to lower activation energys
They bend bonds which weakens them
118
describe an active site
- the location within an enzyme where a substrate is held during the chemical reaction
- formed by only a few of the enzymes amino acids
119
what is formed when an enzume and substrate bind
enzyme-substarte complex
120
what are the two theories regarding how enzymes work
lock and key
induced fit
121
what are the main ideas of the lock and key model
substrate is exactly complementary to the enzymes active sit and so the enzyme is rigid and does not change shape
122
what are the main ideas of the induced fit model
enzymes active site and substrate are not exactly complementary, so the active shape changes shape slightly so that it is exactly complementary to the substrate, then changes back to original conformation after
123
what are the 5 factors that affect the rate of enzyme reactions
- enzyme concentration
- substrate concentration
- temperature
- pH
- inhibitors
124
what causes enzyme reactions to meet its maximum if enzyme concentration is increasing
if substrate concentration is limited
125
why do high temps denature enzymes
they cause the weak hydrogen, ionic and disulfide bonds to break which changes the enzymes active site shape, so substrates can no longer bind
126
why are enzymes only functional over a narrow pH range
because the change in H+ ions dirsupts the ionic and hydrogen bonds in the enzyme
127
what is an example of an enzyme inside and outside the cell
inside - lysozyme
outside - amylase
128
what is an inhibitor
a substance that interacts with the enzyme to prevent it from working in its normal way, which stops or slows specific enzyme reactions
129
what are the 2 types of inhibition, are they reversible
competitive and non competitive, yes
130
name an irreversible inhibitor
cyanide
131
describe reversible inhibition
- occurs when an inhibitor forms weak chemical bonds with the enzyme
- temporary, no permanent damage to the enzyme
- removal of the inhibitor restores normal enzyme activity
- can be competitive or non competitive
132
describe competitive inhibition (4)
- inhibitor competes with the normal substrate to bind to the active site
- usually structurally similar to the normal substrate, so fits the active site
- prevents other substrates from binding to the active site, so decreases the rate of reaction
- increasing the substrate concentration reverses the effect of competetive inhibitors
133
what is the site where non competitive inhibitors bind to
the allosteric site
134
describe non competitive inhibition (4)
- inhibitor binds to the allosteric site
- alters the active sites shape, so it cannot bind with the substrate
- don't have a similar structure to the substrate
- effects cannot be reversed by increasing substrate concentration
135
where are non competitive inhibitors typically found
as metabolic substances that regulate enzyme activity
