biological molecules Flashcards
1
Q
is condensation reaction anabolic or catabolic?
A
anabolic
2
Q
describe the condensation reaction
A
requires energy to make polymers from monomers. a water is removed from 2 OH groups. Of both monomers. there is a new covalent bond formed between the remaining oxygen and both molecules
3
Q
is a hydrolysis reaction anabolic or catabolic?
A
catabolic
4
Q
why is water liquid at room temp?
A
in the liquid state, water molecules are constantly moving around breaking and reforming hydrogen bonds. many h bonds are very strong so this needs lots of energy to break and therefore prevents water evaporating at room temp
5
Q
describe a hydrolysis reaction?
A
requires the addition of water where polymers are broken down into monomers to release water. bonds are broken then reform with water to release energy
6
Q
name 6 properties of water?
A
liquid at room temp, ice has lower density than water, solvent, high surface tension, high specific heat capacity, high latent heat of vaporisation
7
Q
why is water being liquid at room temp a good thing?
A
provides a stable habitat, forms major components of living organisms, forms a reaction medium for reactions of life.
8
Q
how is ice less dense than water?
A
in liquid hydrogen bonds are constantly breaking and reforming so there is no set structure.
in solid ice, hydrogen bonds freeze and form an open crystaline structure, therefore molecules are further apart and there is empty space in the hexagonal structure
9
Q
how is water a solvent?
A
water is polar so the negative and positive parts of water is attracted to the negative and positive parts of the solute. these break the solute apart into their ions
10
Q
what is cohesion of water?
A
when a drop of water on a flat surface has a slight curvature like a dome, this is because of the hydrogen bonds pulling the molecules togerther at the sides
11
Q
why is water needed as a solvent?
A
so that ions and molecules can move around in the cell cytoplasm to react, in water
and so that molecules and ions can be transported around living organisms while dissolved in water
12
Q
why does water have a high surface tension?
A
Because, hydrogen bonds between water molecules pull them close at the surface and can withstand pressures applied
13
Q
what is the specific heat capacity of water?
A
4200j
14
Q
what is specific heat capacity? and units?
A
amount of energy needed to raise the temp of 1Kg of a substance by 1degree.
joules (J)
15
Q
why does water have a high specific heat capacity?
A
it takes a lot of energy to heat water because of the hydrogen bonds holding molecules in place.
16
Q
why is it important for water to have a high specific heat capacity?
A
most organisms have water in them and need a stable internal environment so by waters temp not fluctuating very much it keeps it stable.
aquatic organisms live in water and also need a stable external environment
17
Q
what is the latent heat of vaporisation?
A
it is the energy needed to change 1Kg of a substance from liquid to gas without changing its temperature
18
Q
why does water have a high latent heat of vaporisation?
A
when water changes from liquid to a gas, the hydrogen bond have to completely break in order for gas particals to spread out, so this requires a lot of energy
19
Q
why is water having a high latent heat of vaporisation an important property?
A
it can cool living things - when it evaporates off it will take a lot of energy with it from the skin and therefore cooling it down
20
Q
what are 3 functions of carbohydrates?
A
an energy source, energy store, structural support.
21
Q
what are 4 properties of monosaccharides?
A
taste sweet, crystaline white solid, soluble in water, form straight chains or rings
22
Q
draw a-glucose and b-glucose
A
a- oh group bottom
b- oH group top
23
Q
what is the structural difference between a and b-glucose?
A
alpha- the OH group on carbon 1 is on the bottom
beta- the OH group on carbon 1 is above
24
Q
what is the name of a monosaccharide with 3, 4, 5, 6 and 7 carbons?
A
triose, tetrose, pentose, hexose, heptose
25
what is the molecular formula of glucose, ribose and deoxyribose?
C6 H12 O6
C5 H10 O5
C5 H10 O4
26
a-glucose + a-glucose =?
maltose + water
27
a-glucose + fructose = ?
sucrose + water
28
a-glucose + galactose =?
lactose + water
29
B-glucose + B-glucose =?
cellubiose + water
30
describe the process which a disaccharide is broken down into 2 monosaccharides
it is a hydrolosis reaction (catabolic) it requires the addition of water to provide the hydroxyl groups and break the glycosidic bond
31
describe the bond made when producing a disaccharide
it is a glycosidic bond formed by a condensation reaction(anabolic) when the 2 hydroxyl groups on carbon 1 of one molecule and carbon 4 of the other come together. involves the removal of water
32
what are the 3 main polysaccharides?
starch, cellulose, gycogen
33
what 2 polymers is starch made from ?
amylose and amylopectin
34
what is the structure of amylose?
long chain of a-glucose, glycosidic bonds between carbon 1-4, it is an unbranched helix and coils into a spiral with hydrogen bonds holding it in place
35
Is amylose more or less soluble in water than glucose and why?
less soluble in water than glucose, because there are hydroxyl groups are tucked away on carbon 2( inside the coil) therefore making it less soluble because water cant bond to these groups and it allows hydrogen bonds to keep the structure stable
36
what is the function of starch and how does structure link to this?
it is an energy store in plants
The hydroxyl groups on carbon 2 allow it to be insolouble in water and therefore it not dissolve when being stored and can be used as an energy store but also not affect the water potential inside the cells.
the helix can compact to store a lot of glucose molecules in a small space
37
decribe the structure of amylopectin
long chain of a-glucose with glycosidic bonds between 1-4 it but it also has glycosidic bonds between 1-6 which creates a branched molecule. it also coils into a spiral with hydrogen bonds holding it in place
38
why are branched chains a good property of a polysaccharide that is an energy store?
branched chains are more compact and also offer the chance for lots of glucose molecules to be hydrolysed when lots of energy is required quickly
39
what is the structure of glycogen and what does this mean?
highly branched therefore more compact and glucose can be hydrolysed off easily.
the 1-4 bonds tend to be smaller so glycogen has less tendency to coil
40
why is it important that glycogen is more branched than starch?
glycogen is an animal energy store and animals move a lot more than plants do (wheere starch is stored) and movement requires a lot of energy so glycogen needs to be able to hydrolyse glucose of quicker than starch does
41
why do polysaccharides have to be insoluble in water?
if they dissolved in the cytoplasm, the water potential would reduce(the concentration of water would lower as the solute concentration (glucose) would increase.) and excess water would diffuse in wich would disrupt the reactions of the cell
42
what enzyme is responsible for hydrolysis 1-4 glycosidic bonds?
amylase
43
what enzyme is responsible for hydrolysing 1-6 glycosidic bonds?
glucosidase
44
How are polysaccharides insoluble in water ? give 2 reasons
1) they have a high molecular weight
2) the regions that the water could hydrogen bond to and therfore dissolve it are hidden on the inside of the molecule
45
Amylose can sometimes create a double coil and create insolubility, why?
this presents the hydrophobic external surface in contact with the solution around and repels the water so it cant hydrogen bond
46
what is the function of cellose?
founnd in plant cell walls for structural support
47
what is the structure of cellulose ?
made from long straight chains of b-glucose molecules (1-4 glycosidic bonds) that lie parralel to each other held vertically by hydrogen bonds.
Every other b-glucose is inverted which prevents it from spiralling.
hydroxyl groups on carbpon 2 sticks out to enable hydrogen bonds to from between chains.
48
how many cellulose chains make a microfibril and the diameter?
60-70 chains and 10-30nm
49
how many microfibrils make a macrofibril?
400 which are embedded in pectins (like glue) to form cell walls
50
why is cellulose a good material for plant cell walls?
the fibrils have high tensile strength because of the glycosidic bonds and the hydrogen bonds between chains.
macrofibrils criss criss to add extra strength
51
how to structrure relate to the function of the cell wall?
permeable, because there is space between the fibriles for solvents to pass through.
the criss crossing helps strengthen not only the cell but the whole plant as it does no have a skeleton.
the high tensile strength also prevents plant cells from bursting when turgid cells push on each other
52
what is the general structure of triglycerides?
one molecule of glycerol and 3 fatty acid molecules
53
what is meant by saturated?
ther are no c=c double bonds, tails fit closely, so more hydrogen bonds can form, more energy needed to break them, so it is solid at room temp therefore animal fats are saturated lipids
54
what is meant by an unsaturated lipid?
one(monounsaturated) or more than one (polyunsaturated) c=c double bond, molecules wont fit as well so less hydrogen bonds will form, less energy is needed to break these and therefore an unsaturated lipid is liquid at room temperature. plant oils are unsaturated
55
describe the structure of glycerol
a carbon chain of 3 and has 3 OH groups and it is an alcohol
56
decribe the structure of a fatty acid
has a carboxyl group at one end attached to a carbon chain of 2 to 20
57
what makes fatty acids an acid?
the carboxyl group will ionise into H+ and COO- this means it is an acid because it can produce free H+ ions.
58
How will a c=c double bond affect the carbon chain of a fatty acid?
it will add a kink to the chain and the kinks will push the molecules slightly further apart and cause the to be more fluid
59
what bond is formed between 2 lipids?
ester bond
60
how is an ester bond formed?
a condensation reaction (anabolic) between the COOH of the fatty acid and the OH group of the glycerol the fatty acid is attaching to
61
what are 6 functions of triglycerides?
energy store, energy source, electrical and therman insulation, buoyancy and protection
62
how is a triglyceride an energy source?
they can be broken down in respiration to release energy.
1)hydrolyse ester bonds
2)both glycerol and fatty acids are broken down to carbon dioxide and water
63
how is a triglyceride and energy store?
it is insoluble so can be stored in a cell without affecting the water potential
64
how does lipids act as bouyancy?
it is less dense than water so helos aquatic mammels float
65
how do lipids act as protection?
act as a shock absorber for delicate organs
66
what is meant by macromelecule?
a large, organic molecule
67
what is the structure of a phospholipid?
2 fatty acid tails which are attached to a glycerol but the 3rd fatty acid is replaced with phospate group
68
where and how does the ester bond form on a phospholipid?
it forms by a condensation reaction between a OH on the phosphate group and one of the 3 OH groups on the glycerol
69
how do the fatty acid tails of phospholipids behave in water?
they are hydrophobic because they are non-polar and so are repelled by water
70
how does the head of a phospholipids behave in water?
it is hydrophilic because the phosphate group being negative and therefore making it polar and attracted to water
71
why is a phospholipid amphipathic?
because the tail in hydrophobic and the head is hydrophillic
72
how does the amphipathic phospholipids act in water?
they form a layer on top of the water with the hydrophillic heads in the water and the hydrophobic tails sticking out of the water
73
what is a micelle?
a ball made up of phospholipids with their hydrophillic heads on the outside and the hydrophobic tails on the inside
74
what is the structure of cholesterol?
small hydrohobic molecule, not made from glycerol or fatty acid
75
what is the function of cholesterol ?
regulate fluidity of cell membrane
76
is cholesterol soluble in water?
no
77
what is a cation?
a positive ion
78
what is an anion?
a negative ion
79
what is the formula of a calcium ion?
Ca2+
80
what is the formula of a sodium ion?
Na+
81
what is the formula of a potassium ion?
K+
82
what is the formula of an ammonium ion?
NH4+
83
what is the formula of a nitrate ion?
NO3-
84
what is the formula of a hydrogen carbonate ion?
HCO3-
85
what is the formula of a chloride ion?
Cl-
86
what is the formula of a phosphate ion?
PO43-
87
what is the formula of a hydroxide ion?
OH-
88
what is 4 functions of hydrogen ions?
it regulates the blood ph
hydrogen bonding
ATP formation
transport of CO2 and O2 in the blood
89
what is the 5 functions of calcium ions ?
regulates the transmission of impulses at a synapse,
stimulates muscle contraction,
regulates protein channels of cell membranes, therefore increasing permeability,
activator of several enzymes,
formation of blood clots,
increases rigidity of bones, teeth and cartilage
90
how does calcium ions regulate muscle contraction?
When an impulse reaches a muscle fibre, Ca2+ is released from the sarcoplasmic reticulum
This Ca2+ binds to troponin, removing the tropomyosin from myosin-binding sites on actin
This allows actin-myosin cross-bridges to form when the muscle fibre contracts
91
what are 4 functions of sodium ions?
regulation of osmotic pressure and controls water levels of body fluid.
affects the absorbtion of carbohydrates in the intestine and water in the kidney.
required for nerve impulse transmission
constituent of vacuole which helps it maintain turgitdity
92
what are 8 functions of potassium ion?
generates healthy leaves and flowers
involved in the synthisis of glycogen and protein and the breakdown of glucose
assists in active transport across the cell membrane
constituent of the vacuole whichs helps maintain the rigidity
maintinence of ph levels
regulation of water in body fluids
important in muscle contraction
regulates transmissions of nerve impulses
93
what are 4 functions of ammonium ions?
component of amino acids, proteins, vitamins and chloraphill,
component of nucleic acids,
component in the nitrogen cycle,
maintinence of pH levels
94
what are the 3 functions of nitrate ions ?
component of amino acids, proteins, vitamins and chloraphill
component of nucleic acids
component of the nitrogen cycle
95
what are the 2 functions of the hydrogencarbonate?
maintainence of ph levels
involved in the transport of oxygen and carbon dioxide
96
what are the 3 functions of a chloride ion?
maintinence of pH levels in blood
used for production in hydrochloric acid in stomach
helps in the production of urine in the kidney and therefore balanceing water levels
97
what are 4 functions of phosphate ions?
helps roots grow
component of phospholipids, ATP, nucleic acids and some enzymes
increases rigidity of bones and teeth and cartalage
maintinence of pH levels of blood
98
what is 1 function of hydroxide?
maintinence of pH levels.
99
how does cyanide work?
KCN inhibits aerobic respiration and catalase.
it readlily disacosiates into H+ ions and CN- ions which bind irrevesibly and inhibit the final stage of respiration
100
draw an amino acid
R. O-H
| ||
NH2-C - C ---O
|
H
101
how does an amino acid act as a buffer?
resists changes in pH, the amino group accepts H+ and the carboxyl group donates a H+ COOH to COO-
102
when at low pHs will the amino acid gain or loose a H+ ion?
accept because low pH = lots of H+ ions
103
why is an amino acid amphoteric ?
has acidic and basic properties
104
how's a peptide bond formed ?
the H from the =OH and another O (but singlely bonded) from the same C, and a H from the NH2 from the other amino acid
105
describe the primary structure of a protein
sequence of amino acids bonded by peptide bonds
106
describe the secondary structure of a protein
consists of an alpha helix and a beta pleated sheet, coiling or folding of an amino acid chain as a result of h-bonds
107
what bonds are present at secondary structure?
peptide and hydrogen bonds
108
how does an alpha helix form?
h- bonds form between every fourth peptide bond
109
how does a beta pleated sheet form?
h- bonds form between an amino group and carboxyl group that is further down the strand so one chain will fold over on itself
110
describe the structure of the tertiary structure
same polypeptide chain but just further folded with more alpha helixes and beta sheets which twist to form a unique 3D structure
111
what bonding is present at tertiary level?
h-bonds, disulphide links, ionic bonds, hydrophobic interactions
112
where do hydrogen bonds form on a tertiary structure?
form between polar R groups
113
where do ionic bonds form on a tertiary structure?
between any positive and negatively charged R groups and there will be an electrostatic force present
114
where do disulphide links form on a tertiary structure ?
between any R groups that have sulphur in them
115
what is a hydrophobic interaction?
amino acids that have hydrophobic R groups will go to the middle of protein where it is away from water exterior- this helps form the protein
116
describe the quaternary structure of a protein
multiple different polypeptide chains and/or a prosthetic group present
117
what bonds are present in a quaternary structure?
same as tertiary but instead between R groups they are between polypeptide chains
118
what is a conjugated protein ?
mix of 2 or more polypeptide chains and a prosthetic group.
119
describe the properties of a globular protein
1) spherical all have specific shapes which help it have specific roles
2) hydrophobic R groups on inside and hydrophilic on outside
3)soluble in water
120
what is the structure of a fibrous protein ?
long polypeptide chain of repeating sequences
121
are fibrous proteins soluble in water? why?
no, because the amino acids have non-polar R groups
122
what type of role does a fibrous protein have?
structural
123
what are the 3 globular proteins ?
haemoglobin, insulin, pepsin
124
what are the 3 fibrous proteins ?
keratin, collagen, elastin
125
describe the structure of haemoglobin
4 polypeptide chains, 2 are alpha globes and 2 beta globin. quaternary structure, conjugated as it has 4 haem groups (fe2+)
126
what is the function of haemoglobin?
transport protein, transports o2 molecules round. maximises mass of 02 that can be carried round blood
127
what is the structure of insulin?
2 polypeptide chains, 1 alpha helix and 1 beta sheet. chains are joined by disulphide links
128
is insulin soluble in water? why?
yes, because it has hydrophilic R groups on outside so water can surround it. this is good because it can dissolve in the blood and travel to target organs
129
what is the function of insulin?
maintain blood glucose level
130
how does structure of insulin relate to its function?
hydrophilic R groups mean it can dissolve in blood stream, specific shape allows it to bind to receptors which lower blood glucose concentration
131
what is the structure of pepsin?
primary structure of basic R groups, tertiary structure held by H-bonds
132
what is the function of pepsin?
catalyses digestion of proteins in low pH
133
how does the structure of pepsin relate to its function?
basic R groups means it won't uptake many H+ ions which would give the molecule a positive charge which would disrupt H-bonds and ionic bonds therefore loos it shape and becoming denatured. so this allows it to not be affected by low pHs and still maintain its role
134
what is the structure of keratin?
can be alpha helix or beta sheet, lots of cysteine so lots of disulphide links between peptide chains, 2 polypeptide chains
135
what is the function of keratin?
found in places that need to be strong, impermeable and waterproof so provides a barrier from infection
136
what bonds occur in keratin? why?
disulphide links and h-bonds. these are strong and takes a lot of energy to break therefore can provide mechanical strength
137
what is the structure of collagen?
3 polypeptide chains wound together in a triple helix and insoluble
138
what are the functions of collagen?
provides mechanical strength, provides stability under high pressures
139
what bonding is found in collagen?
h- bonds, covalent between R groups to form cross links,
140
what is the structure of elastin?
lots of tropoelastin molecules connected by cross links which are covalent bonds from lysines in the molecule. when stretched molecules uncoil
141
what is the function of elastin?
found when tissues need to expand and recoil
142
Describe the hydrolysis reaction
Polymers are Brocken down to monomers to release energy, requires water input
143
What are the elements of a protein ?
C H O N S
144
What are the elements of a nucleic acid ?
C H O N P
