2.2 Biological molecules Flashcards
1
Q
what is a condensation reaction
A
reaction that occurs when two molecules are joined together with the removal of water
2
Q
What is a hydrolysis reaction?
A
Reaction that occurs when a molecule is split into two smaller molecules with the addition of water
3
Q
What is a covalent bond?
A
when 2 non metals share a pair of electrons
4
Q
What is a monomer?
A
A small molecule which binds to many other identical molecules to form a polymer
5
Q
what is a polymer?
A
a large molecule made from many smaller molecules called monomers
6
Q
what are the 3 types of molecules?
A
carbohydrates, proteins, nucleic acids
7
Q
what is a monomer of a carbohydrate called
A
monosaccharide
8
Q
what is an example of a monosaccharide
A
glucose
9
Q
what is a polymer of a carbohydrate called
A
polysaccharide
10
Q
example of polysaccharide
A
starch, glycogen, cellulose
11
Q
what is a monomer of a protein called
A
amino acid
12
Q
what is a polymer of proteins called
A
polypeptide
13
Q
what is a monomer of a nucleic acid called
A
nucleotide
14
Q
what is a polymer of a nucleic acid called
A
DNA and RNA
15
Q
what are carbohydrates
A
a group of molecules containing C, H and O
16
Q
what are the three main groups of carbohydrates
A
monosaccharides, disaccharides, polysaccharides
17
Q
what are the properties of monosaccharides
A
sweet, soluble in water and insoluble in non-polar solvents
18
Q
what is alpha glucose and beta glucose
A
an energy source
19
Q
how is the displayed formula of alpha glucose different to beta glucose
A
In alpha glucose, on carbon 1 the hydroxyl group is below the ring structure and hydrogen is above. In beta glucose, on carbon 1 the hydroxyl group is above the ring structure and they hydrogen is below the ring structure
20
Q
how is ribose different to glucose
A
it is a pentose sugar rather than a hexose sugar. It found in RNA and is not an energy source
21
Q
when dissolved in a solution, how do triose and tetrose sugars exist
A
straight chains
22
Q
when dissolved in a solution, how do pentose and hexose sugars tend to exist
A
In a ring or cyclic structure
23
Q
What is an isomer?
A
molecules with the same molecular formula but different structures
24
Q
what are examples of dissacharides
A
maltose, sucrose, lactose
25
what are the properties of dissacharides
sweet and soluble in water and insoluble in non-polar solvents
26
What are the reducing sugars?
maltose and lactose
27
what are the non-reducing sugars
sucrose
28
What is a glycosidic bond?
A bond formed between two monosaccharides by a condensation reaction
29
How is a dissacharide formed?
Two monosaccharides join in condensation reaction forming a 1-4 glycosidic bond between the two hydroxyl groups and give off water
30
how is a disaccharide broken
hydrolysis of the glycosidic bond with addition of water
31
how are polysaccharides formed
a series of condensation reactions, water is given off each time a glycosidic bond is formed
32
what are polysaccharides made of one type of monosaccharide called
homopolysaccharide
33
where is starch found in plant cells
starch granules
34
what is amylose
a series of alpha glucose monomers joined by glycosidic bonds between carbons 1 and 4
35
what structure is amylose and what does it present
it forms a spiral shape and it presents a hydrophobic external surface
36
what is amylopectin
series of alpha glucose monomers which are joined by glycosidic bonds between carbon 1 and 4 as well as carbon 1 and 6
37
what is the structure of amylopectin
coils into a spiral shape with branches emerging from the spiral
38
what is the function of starch
energy store in plants
39
what are the two parts of starch
amylose and amylopectin
40
why is the branch structure of amylopectin important
it allows more alpha glucose molecules to be broken off when its needed for respiration
41
What is the structure of starch
coiled into double helix so its compact, held by hydrogen bonds, OH groups stored inside
42
why are OH groups stored on the inside of starch
so they aren't soluble and don't affect the water potential
43
what enzyme breaks 1-4 glycosidic bonds
amylase
44
what enzyme breaks 1-6 glycosidic bonds
glycosidase
45
where is glycogen found
glycogen granules in animals
46
structure of glycogen
similar to amylopectin but more branched. 1--4 and 1--6 glycosidic bonds. coiled
47
what is glycogen
energy store in animals
48
why is glycogen more branched than amylopectin
animals are more metabolically active and need more glucose for energy for respiration. As its more branched, easy access for enzymes to hydrolyse bonds to obtain alpha glucose
49
what is an advantage of a coiled structure
its more compact so more can be stored
50
what is starch and glycogen made of
alpha glucose
51
Where is cellulose found?
plant cell walls
52
what is cellulose made of
beta glucose
53
what are the bonds in cellulose
glycosidic bond on carbons 1-4. Every other beta glucose monomer, it rotates by 180* as on carbon 4 the OH group is below the ring structure and on carbon 1 the OH group is above the ring structure
54
what happens as a result of rotations
it causes hydrogen bonding between the oxygens which gives the chain additional strength and stops it from spiralling. OH group on carbon 2 sticks out which causes hydrogen bonding to form between chains
55
what forms microfibrils
60-70 chains of cellulose
56
what forms macrofibrils
up to 400 microfibrils
57
what do macrofibrils do
criss-cross for extra strength for the cell wall
58
function of cellulose
to have strength and support the whole plant
59
why is there space between macrofibrils
so water and mineral ions can pass in and out
60
advantage of cell wall being strong
prevents plant cells from bursting when they're turgid
61
what are the substances that make the cell wall waterproof
cutin and Suberin
62
what are some other structural polysaccharides
bacterial cell walls and exoskeletons
63
what is a hydrogen bond
the attraction between a hydrogen atom with a partial positive charge and another atom with a partial negative charge
64
benefit of having many hydrogen bonds
helps stabilise the structure of some biological molecules
65
why is water polar
the oxygen atom has a slight negative charge and the 2 hydrogen atoms have a slight positive charge
66
why can water flow easily
has a low viscosity
67
benefits of water being liquid at room temp
provide habitats for living things in bodies of water
form a major component of tissues in living organisms
provide an effective transport medium
68
why is ice less dense than water
because of its polar nature, water molecules align themselves in a structure which is less dense than water
69
benefits of water being less dense than ice
aquatic organisms have a stable environment through winter
bodies of water are insulated against extreme cold-ice reduces heat loss
70
benefits of water being good solvent
medium for reactions
allows ionic compounds to seperate
able to dilute toxic substances
organisms can absorb minerals
71
benefits of cohesion and surface tension on water
columns of water in plant vascular tissue are pulled up the xylem tissue
insects like pond skaters can walk on water
72
why is high specific heat capacity important for water
living things need a stable temperature for enzyme controlled reactions to work properly
aquatic organisms need a stable environment to live
73
Why is a high latent heat of vaporisation useful for living organisms?
cools living things and keeps their temperature stable
74
why is water being a reactant important
important for digestion and synthesis of large biological molecules
75
differences between cellulose and glycogen
glycogen branches cellulose isnt
monomer is alpha glucose is glycogen monomer in cellulose is beta glucose
cellulose glucose molecules rotate glycogen dont
cellulose molecules dont spiral glycogen does
glycogen has 1-4 and 1-6 bonds and cellulose only 1-4
76
components of a triglyceride
1 glycerol and 3 fatty acids
77
bonds in triglyceride
ester bonds, happens through condensation reaction
78
how many ester bonds are in a triglyceride
3
79
what does it mean if a fatty acid is monounsaturated
double bond which causes kink in tail
80
functions of triglycerides
Energy source- can be broken down in respiration to release energy
Energy store- they are insoluble in water so can be stored without affecting the water potential
Insulation-lipids in nerve cells act as an electrical insulator
Buoyancy-fat is less dense than water, aquatic mammals can stay afloat
Protection-humans have fat around delicate organs to act as a shock absorber
81
properties of triglycerides
insoluble in water
soluble in ethanol
larger molecule
not a polymer
82
why are triglycerides not polymers
1 glycerol and 3 fatty acids and you cannot keep adding more monomers as you would in a polysaccharide
83
what is saturated
when all single bonds
84
difference between monounsaturated fatty acid and polyunsaturated fatty acid
mono- one fatty w double bond
poly- two or more w double bond
85
what does having more double bonds do
lowers boiling point
86
components of triglycerides
C H O
87
components of phospholipid
glycerol, 2 fatty acids, and a phosphate group
88
bonds in phospholipid
2 ester bonds and 1 phosphate ester bond
89
how many lots of water does a condensation reaction in a phospholipid give off
3
90
define amphipathic
having both hydrophilic and hydrophobic regions
91
how do phospholipids arrange themselves in water
heads are in the water and the tails are sticking out or form tiny balls where the tails are inside and the heads are pointing outwards
92
why are phospholipids good in membranes
they arrange in a specific way that gives the membrane stability and as the membrane is selectively permeable, it lets it controls what goes in and out
93
components of cholesterol
4 carbon-bases rings
94
what is cholesterol
a steroid alcohol
95
what is cholesterol like
small and hydrophobic, sits in the middle part of the bilayer
96
what does cholesterol regulate
the fluidity of the membrane, preventing it from being too fluid or too stiff
97
examples of steroid hormones made of cholesterol
testosterone, oestrogen and vitamin D
98
difference between triglyceride and phospholipid
phospholipid has phosphate group, Tri doesnt
P has 2 fatty acids, Tri has 3
99
similarities of triglycerides and phospholipid
they have one glycerol and are joined by ester bonds
100
general structure of amino acid
amino group, R group, carboxyl group
101
what are components of amino acids
C, H, O, N and sometimes S
102
What differentiates one amino acid from another?
r group
103
what would the amino acid be if the R group was H
glycine
104
why can amino acids act as buffers
amino group can accept H+ ions (when PH too acidic) and carboxyl group can give off H+ ions (when PH is too high)
105
bonds in proteins
peptide bonds
106
different structures of proteins
primary, secondary, tertiary, quaternary
107
primary structure of protein
sequence of amino acids joined by peptide bonds
108
bonds and structure of secondary structure of protein
alpha helix or beta pleated sheet
peptide and hydrogen bonds
109
tertiary structure of protein and bonds
when coils and pleats fold
peptide, hydrogen , disulphide, ionic and hydrophilic and hydrophobic interactions
110
what are hydrogen bonds between
slightly positive hydrogen and slightly negative atoms
111
what are disulphide links between
r groups of 2 cysteines
112
what are ionic bonds between
carboxyl and amino group that are part of the R group
113
describe hydrophobic and hydrophilic interactions
hydrophobic parts of R groups avoid water, hydrophilic parts are near water. This causes the amino acid chain to twist which changes the shape of the protein
114
describe quaternary structure of a protein and bonds
more than 2 tertiary structures put together
peptide, hydrogen, ionic, disulfide, hydrophilic and hydrophobic
115
similarities of peptide and glycosidic bonds
form thru condensation break thru hydrolysis
116
differences of peptide and glycosidic bonds
peptide in proteins between C and N, glycosidic in carbohydrates between C-O-C
117
what are fibrous proteins
structural proteins which have regular repetitive sequences of amino acids and are insoluble in water
118
examples of fibrous proteins
collagen, keratin, elastin
119
What is every 3rd amino acid in collagen?
glycine
120
how does collagen provide mechanical strength
collagen in artery walls prevents them from bursting, tendons connect muscles to bones, bones, cartilage and connective tissue are made of collagen
121
structure of collagen
long and thin
122
what is keratin rich in
cysteine
123
what makes keratin strong
disulphide links and hydrogen bonding
124
what does keratin provide
mechanical protection and an impermeable barrier to infection
125
what does keratin prevent
entry of water-borne pollutants
126
what makes elastin strong
cross-linking and coiling of the structure
127
where is elastin found
In living things where they need to stretch or adapt their shape as part of life processes
128
what does elastin allow
skin to stretch around bones and muscle, lungs to inflate and deflate, bladder expand to hold urine, blood vessels to stretch and recoil as blood is pumped through
129
define globular proteins
proteins that are water soluble and have specific shapes so they can take up roles as enzymes
130
examples of globular proteins
haemoglobin, insulin, pepsin
131
what is haemoglobin made of
4 polypeptide chains (2 alpha and 2 beta chains)
132
what gives haemoglobin its specific shape
interactions between polypeptides
133
what does each chain of haemoglobin have
haem group (iron ion)
134
what does haemoglobin do
Binds to oxygen to transport it from the lungs to the tissues and cells
135
where does oxygen bind
iron in each of the 4 harm groups
136
what is insulin made of
2 polypeptide chains ( chain A begins with alpha helix, chain B ends w B pleat)
137
how does insulin assist with the movement of glucose into body cells
It binds to glycoprotein receptors on the outside of muscle and fat cells to increase their uptake of glucose from the blood and to increase their rate of consumption of glucose
138
why is insulin soluble
amino acids with hydrophilic r groups are on the outside
139
what is pepsin
protein digesting enzyme
140
what is pepsin made of
single polypeptide chain of 327 amino acids
141
what amino acids has pepsin got
4 with basic r groups, 43 with acidic r groups
142
where is pepsin stable
acidic environment in stomach
143
how is tertiary structure of pepsin held
hydrogen bonds and 2 disulphide bridges
144
how can scientists predict protein shapes
computer modelling
145
what can predicting the occurrence of biologically active binding sites help with
identifying new medicines
146
what are the 2 broad approaches of computer modelling
AB initio protein modelling
comparative protein modelling
147
food test for starch and positive result
iodine
colour change from yellow to blue/black
148
test for reducing sugars and positive result
heat sugar w Benedicts solution
colour change from blue to green to yellow to orange
149
test for non-reducing sugars and positive result
boil with hydrochloric acid to hydrolyse then cool it and use sodium hydrogen carbonate to neutralise and test for reducing sugar again
colour change from blue to green to yellow to orange
150
test for lipids and positive result
mix sample with ethanol, filter it then pour into water in a clean tube
solution turns cloudy white
151
test for proteins and positive result
biuret test
turns from light blue to lilac
152
define stationary phase
paper ( can be chromatography paper or thin layer chromatography)
153
define mobile phase
solvent
154
equation for RF value
Distance travelled by substance / distance travelled by solvent
155
aim of chromatography
to separate a mixture into its constituents
156
what do you do if you cannot see where a colourless molecule has finished
ultra violet light, spray ninhydrin, place in enclose container with iodine cristals
157
what can chromatography be used for
testing for drugs ,analysis of drugs for purity of components and analysis of foods to determine presence of contaminants
