1.1 Flashcards
1
Q
What are the 5 molecules that make up living organisms?
A
Water, carbohydrates, protein, lipids, nucleic acids
2
Q
What are lipids?
A
Fat & oils
3
Q
What are nucleic acids?
A
DNA and RNA
4
Q
What elements make up 99% of the atoms in living organisms?
A
Hydrogen, carbon, oxygen, nitrogen
5
Q
What are micronutrients
A
Elements needed in trace amounts
6
Q
What can carbon atoms join to form?
A
Chain and ring structures, which are essential to life
7
Q
What are complex compounds of carbon called?
A
Organic compounds
8
Q
What do organic molecules have?
A
Carbon - hydrogen bonds. E.g CH4
9
Q
What are organic compounds?
A
Molecules of life, e.g carbohydrates, proteins and lipids. Complex compounds of carbon
10
Q
What are inorganic compounds?
A
Compounds which don’t have carbon-hydrogen bonds
11
Q
What is an ion?
A
An atom or group of atoms which has lost or gained 1 or more electrons
12
Q
What kind of elements present as inorganic ions?
A
Many key elements, essential for cell metabolism are present as inorganic ions.
13
Q
What is magnesium’s biological role?
A
Constituent of chlorophyll, so essential for photosynthesis.
14
Q
What is iron’s biological role?
A
Part of haemoglobin, which transports oxygen in red blood cells.
15
Q
What is nitrate’s biological role?
A
Nitrogen is derived from nitrate and it is needed for making nucleotides (ATP, DNA, RNA), and amino acid formation.
16
Q
What is phosphate’s biological role?
A
Making nucleotides like ATP, DNA, RNA. Constituent of phospholipids found in biological membranes. Hardens bones.
17
Q
What is calcium’s biological role?
A
A component of plant cell walls. Hardens bones and teeth. Is a chemical messenger.
18
Q
What is the most important biochemical?
A
Water. Without it, life wouldn’t exist on the planet.
19
Q
Is water polar or non polar?
A
A polar molecule
20
Q
What is a polar molecule?
A
Molecule where the oxygen end of the molecule has negative charge and hydrogen atoms have positive charge
21
Q
What is a dipole?
A
The uneven distribution of charge.
22
Q
How is a hydrogen bond formed?
A
When two water molecules are in close contact, the opposing charges attract each other, forming a hydrogen bond.
23
Q
What is the attraction between water molecules called?
A
Cohesion
24
Q
What do polar molecules dissolve.
A
Polar molecules can only dissolve polar molecules.
25
What bond is formed when 2 water molecules are in close contact and the opposing charges attract each other?
Hydrogen bond
26
What framework is formed by many hydrogen bonds?
Lattice-like framework (stronger than just one hydrogen bond)
27
Properties of water
Solvent, transport medium, chemical reaction site, high specific heat capacity, high latent heat of vaporization, cohesion, surface tension, density, transparent, metabolite.
28
What does it mean if water is a solvent?
Positive and negative parts of water molecule attract other charged particles.
Ion and polar molecules dissolve in water. Non polar molecules like lipids do not dissolve in water
29
What does it mean if water is a transport medium?
Lots of water in blood and it transports many dissolved substances around the body.
In plants, minerals dissolved in water transported from roots to leaves
30
What does it mean if chemical reactions take place in water?
Transport of ions and polar molecules allow chemical reactions to take place when particles or molecules meet
31
What does it mean if water has a high latent heat capacity
Lots of heat energy is needed to raise temp of water.
32
Why is high latent heat capacity important in water?
Keeps temperature of aquatic environments stable, and allows molecules to work effectively
33
What does it mean if water has a high latent heat of vaporisation?
Because of cohesion, large amounts of heat energy are needed to change water from liquid to vapour
34
What causes cooling in body?
Evaporation of water from our skin (a surface)
35
What is cohesion?
Attraction between water molecules. Allows water molecules to be transported up xylem of even the tallest trees.
36
Surface tension in water
At ordinary temperatures, water has the highest surface tension of other liquids. Cohesion of water molecules supports organisms to walk on water
37
Density of water
As ice, water is less dense.
38
Why is water less dense as ice?
Reduces tendency for lots of water to freeze completely, so organisms survive
39
Why is water transparent?
Allows light to pass through, so that aquatic plants and algae can photosynthesise.
40
What does it mean if water is a metabolite?
Takes place in many biochemical reactions. E.g photosynthesis and hydrolysis
41
What are carbohydrates?
Organic compounds containing carbon, hydrogen, and oxygen
42
What do carbohydrates do?
Source of energy in plants and animals. Some have structural role in plant cell walls (e.g. cellulose).
43
What are monosaccharides?
Small organic molecules called monomers .
Sugars that dissolve easily.
44
Structure of monosaccharides?
Can be straight chain or a ring structure
45
How are monosaccharides classified?
According to the number of carbon atoms in the molecule
46
Name of the monosaccharide with 3 carbons? And its function
Triose - important in metabolism
47
Name of the monosaccharide with 5 carbons? And its function
Pentose - nucleic acid formation
48
Name of the monosaccharide with 6 carbons? And its function
Hexose - Main energy source of the cell
49
What are isomers
Molecules that share the same number of atoms and same chemical formula, but the atoms are arranged differently. E.g. an alpha glucose ring has H above C1 while beta glucose has C1 above H
50
What are structural isomers?
Isomers with the same molecular formula but atoms are linked in different sequences. E.g glucose and fructose
51
What are optical isomers?
Isomers with the same molecular formula and are identical in every way except that they're mirror images of each other. E.g alpha glucose and beta glucose
52
What 2 isomers does glucose exist as?
Alpha and beta glucose. They share the same number of atoms but the atoms are arranged differently.
53
How are disaccharides formed?
By joining 2 monosaccharide units by condensation reactions
54
What bond joins 2 hexose units together to make a disaccharide?
Glycosidic bond
55
Steps of condensation reaction to form a disaccharide
1.) 2 hydroxyl (-OH) groups line up alongside each other.
2.) One -OH combines with the H atom of another, forming a water molecule (H2O)
3.) This allows a glycosidic bond/oxygen bridge to form.
56
How do you reverse the making of a disaccharide
Hydrolysis
57
What is hydrolysis?
The chemical addition of water to break a chemical bond.
58
What disaccharide do the monosaccharides glucose+glucose form?
Maltose, found in seeds
59
What disaccharide do the monosaccharides glucose+fructose form?
Sucrose, found in fruit
60
What disaccharide do the monosaccharides glucose+galactose form?
Lactose, found in milk
61
How to test for reducing sugars?
With Benedict's Reagent.
1. Heat up the solution with Benedict's.
2. If it's a reducing sugar it will turn the benedicts from blue to brick red.
62
How do reducing sugars turn benedicts from blue to brick red?
Because the sugar reduces the blue copper || sulphate to form copper | oxide, which is a brick red precipitate
63
How to test for non-reducing sugars with Benedict's?
Non-reducing sugars can't reduce cupper || sulphate so benedict's won't work.
1.) Sucrose must be hydrolysed by boiling in dilute hydrochloric acid.
2.) Glucose and fructose formed.
3.) Acid must be neutralised with sodium hydroxide before testing with benedict's reagent
4.) Should now give positive result because glucose and fructose are reducing sugars.
64
What are polysaccharides?
Polysaccharides are large molecules called polymers.
65
What are polysaccharides composed of?
Composed of many smaller monosaccharides.
66
How are polysaccharides made
Monosaccharides (simple sugars, like glucose) joined together by condensation reaction.
When special enzymes bind small monomers together, they create polysaccharides.
67
What is starch?
An alpha glucose monomer joined by 1-4 and 1-6 glycosidic bonds.
68
Function and properties of starch
For glucose storage in plants.
- found in plants.
- storage polysaccharide.
- compact, so good as energy stores.
- insoluble, so no osmotic effect.
69
What is glycogen?
An alpha glucose monomer joined by 1-4 and 1-6 glycosidic bonds.
70
Function and properties of glycogen
For glucose storage in animals.
- found in animals.
- storage polysaccharide.
- compact, so good as energy store.
- insoluble, so no osmotic effect.
- highly branched.
71
Why are polysaccharides branched?
Because of amylopectin (Alpha glucose monomers joined by 1-6 glycosidic bonds), which are branched
72
Why are polysaccharides coiled?
Because of amylose (Beta glucose monomers joined by 1-4 glycosidic bonds), which are branched.
73
What is cellulose?
A beta glucose monomer joined by 1-4 glycosidic bonds
74
Function and properties of cellulose
For structure of the cell wall.
- found in plant cell walls.
- gives high tensile strength to plant cell walls.
- Hydrogen bonding between cross linking of parallel chain gives structural stability.
- chains of cellulose grouped to form microfibrils.
- insoluble.
- adjacent glucose molecules rotates 180 degrees
75
Why are adjacent glucose molecules in cellulose rotates 180 degrees?
Allows hydrogen bonds to form between
-OH groups
76
What is chitin?
A beta glucose monomer joined by 1-4 glycosidic bonds
77
Function and properties of chitin
For the structure of fungal cell walls.
- found in fungal cell walls and exoskeletons.
- tough and insoluble.
- each glucose molecule has an amino group attached to it.
78
What is the test for starch?
Iodine.
A positive test turns iodine from brown to blue/black.
79
What are lipids?
Most common types are triglycerides (fats and oils). Like carbohydrates, they contain carbon, hydrogen and oxygen atoms. Very low oxygen content
80
How are triglycerides formed?
Formed by condensation reaction between glycerol and fatty acids.
(3 fatty acid chains bond with glycerol by condensation reaction)
81
What bond is formed between glycerol and fatty acids when a triglyceride is made?
ester bond
82
What is a fatty acid?
organic molecules which have a -COOH group attached to a hydrocarbon tail
83
What forms the backbone of a triglyceride?
glycerol (an alcohol)
84
Properties of triglycerides
- non-polar (doesn't dissolve in water but does in alcohol).
- hydrophobic
- no repeating subunits, just glycerol and fatty acids
85
What is an r-group
Variable group of atoms on an amino acid. Bonds form between them
86
What is the test for lipids? And how does it work?
Emulsion test for lipids.
1. shake equal volumes of ethanol and water with solution.
2. If lipids present it would form cloudy emulsion.
Because ethanol dissolves lipids so lipids come out of solution and make it cloudy
87
Functions of triglycerides
- energy reserve in plants and animals
- thermal insulator
-protection of delicate organs.
- metabolic water source
- waterproofing
- low density and buoyancy
- nerve transmission
- steroids and cholesterol.
88
Why/how are triglycerides good energy reserves in plants and animals
In animals, fat (a triglyceride) is stored under skin and around organs. In plants, triglycerides stored as oils in seeds.
Also is better than carbs because has twice as much energy
89
Why/how are triglycerides good thermal insulators
When stored under the skin, it reduces heat loss
90
Why/how are triglycerides good protection?
Around delicate organs like kidneys
91
Why/how are triglycerides good metabolic water sources?
Produce lots of metabolic water when oxidised. essential for desert animals who don't drink water and survive on metabolic water from fat intake
92
Why/how are triglycerides low density and buoyancy
Fat has low density so that animals float in water. Seeds with oils can be easily dispensed since they're light
93
Why/how are triglycerides good nerve transmissions
Form myelin sheath which seeps up nerve transmission
94
Why/how are triglycerides steroids and cholesterol
Steroids (include sex hormones) are lipids. Ring structure, not long chain structure
95
What are unsaturated fatty acids?
Fatty acids which have double bonds between neighbouring carbon atoms. Don't carry maximum possible number of hydrogen atoms.
96
Why do unsaturated fatty acids have a lower melting point?
Each double bond causes a kink in the fatty acid chain so it can't be packed together closely, so it has a lower melting point as it's easier to change it's state. E.g. Oils
97
What is it called when unsaturated fatty acids only have one double bond?
Monounsaturated
98
What is it called when unsaturated fatty acids have more than one double bond?
Polyunsaturated
99
What are saturated fatty acids?
Fatty acids which have no double bonds between carbon atoms
100
Why are saturated fatty acids solid?
Fatty acids are packed closely together.
E.g. animal lipids like lard.
101
What would multiple fatty acids linked together form?
Polymer
102
How is heart disease caused?
Caused by build up of fatty deposits in coronary arteries, and high blood pressure
103
Risk factors of heart disease?
- a diet high in saturated fatty acids
- lack of regular exercise
- high salt diet
- age, gender, genetics
- smoking
104
How are lipoproteins formed?
Food is absorbed into bloodstream and lipids & proteins combine to form lipoproteins.
105
Why are low density lipoproteins (LDL's) produced?
If diet is high in saturated fatty acids, they're produced
106
Why do LDL's cause harm?
They're deposited on the inner endothelial lining of coronary arteries and build up to form an atheroma
107
What do atheromas do?
Narrow coronary arteries and slow blood flow. Reduces oxygen and glucose delivery to the cardiac muscle, which causes angina. Large blood clots can form and block the artery which starves heart muscle of oxygen and glucose. This causes heart attack
108
What forms from a diet rich in unsaturated fatty acids?
Forms high density lipoproteins (HDLs) in bloodstream
109
What do HDL's do?
Carry harmful fats to the liver for disposal
110
Higher ratio of HDL:LDL means?
Lower risk of cardiovascular and coronary heart disease
111
What are phospholipids?
Special types of lipids where 1/3 of the 3 fatty acids are replaced by a phosphate group.
112
Are phosphate groups polar or non polar?
Polar so soluble in water
113
Explain the heads and tails of phospholipids
Hydrophilic head with a phosphate group, and 2 hydrophobic fatty acid tails
114
How is a micelle formed?
In water, the hydrophobic fatty acid tails of phospholipids turn inwards to form a micelle
115
If there is enough phospholipid molecules, what is formed?
A bilayer.
Polar/hydrophilic phosphate heads point outwards (in water), hydrophobic fatty acid tails point inwards (away from water)
116
Phospholipid bilayer forms...
basis of all cell membranes
117
Compare triglycerides with phospholipids
- T have 3 fatty acid tails, P only have 2 fatty acid tails.
- T have no phosphate group, P have phosphate group.
- T are nonpolar, P have polar head and non polar tail.
- T are completely hydrophobic, P have hydrophilic head and hydrophobic tails.
118
What are proteins
Polymers of amino acids that are incredibly important biological molecules. Have many essential and varied functions.
119
What are proteins made up of?
Carbon, hydrogen and oxygen atoms (like carbohydrates and lipids)
120
What do all and some proteins contain?
Always contain Nitrogen (N). Some contain Sulphur (S) and Phosphorus (P)
121
What is key for a protein to be functional?
shape of the protein
122
Functions of proteins?
- build and repair muscles and bones with the amino acids they're made of.
- wound healing and tissue regeneration.
- form structure of tissues and organs for them to work correctly.
- provide energy when carbohydrates and fat intake are inadequate
- make antibodies
- homeostasis
- muscle contraction and movement
123
Structure of proteins
All proteins made up of linear sequences of amino acids. Around 20 different amino acids with different -R groups
124
What does DNA do on an amino acid?
DNA decides what goes where/positions the amino acids
125
General amino acid structure
All amino acids have a central carbon atom with amino group (-NH2) and carboxyl group (-COOH) on either side. The 3rd bond is Hydrogen and the 4th bond is an r-group
126
What is the simplest amino acid
Glycine.
The r group is just a hydrogen atom
127
What are essential amino acids
Amino acids that can only be obtained from our diet
128
What are non essential amino acids
Amino acids that can be synthesised by our bodies
129
What do peptide bonds do?
Link amino acids together to form dipeptides and polypeptides
130
How do you turn polypeptides into proteins
Polypeptides can be folded to make proteins
131
How are peptide bonds formed?
Caused by a condensation reaction between (-COOH) carboxyl group and (-NH2) amino group. Water is produced
132
How is a dipeptide molecule formed?
2 amino acids being joined with a peptide bond
133
How are polypeptides formed?
Many amino acids joined together through polymerisation
134
What are polymers?
Long molecules made of repeating subunits (monomers)
135
How are polymers formed?
Monomers added 1 at a time by condensation reaction to form a long molecule
136
What is primary structure?
The order and sequence of amino acids in a polypeptide chain
137
What determines the sequence of amino acids
DNA determines the sequence of amino acids. 1 gene codes for 1 polypeptide
138
What is secondary structure?
The folding of a primary structure to form an alpha helix shape
139
How is secondary structure alpha helix formed?
Formed due to hydrogen bonding between R-groups. Hydrogen bonds twist and fold polypeptides, forming alpha helix shape or beta pleated sheet,
140
What is tertiary structure?
The further folding of secondary structure to create a 3D globular shape.
141
How is shape of tertiary structure maintained?
Maintained by disulphide, ionic, covalent hydrophobic, and hydrogen bonds formed between R-groups
142
What structure do enzymes have and why?
Tertiary structure. The bonds maintain the shape of the active site
143
144
What is quaternary structure?
Combination of 2 or more polypeptide chains in secondary or tertiary form
145
146
How are large complex molecules formed with quaternary structures
Some are associated with non protein groups which form large complex molecules. E.g haemoglobin
146
Structure of haemoglobin
4 polypeptide chains associated with non protein haem groups
147
Functions of globular proteins (tertiary and quaternary)
Enzymes, antibodies, hormones
148
Structure of globular proteins
Compact and folded into spherical molecules
149
Are globular proteins soluble or insoluble
Soluble in water,
150
What do fibrous proteins (secondary) do?
Perform structural functions
151
Structure of fibrous proteins?
Consist of polypeptides in parallel chains/sheets with numerous cross linkages to form long fibres
152
Properties of fibrous proteins?
Insoluble in water,
strong,
tough
153
Structure of a single fibre?
3 identical polypeptide chains twisted together. Linked by hydrogen cross-bridges
154
What do hydrogen cross bridges do?
Make structure very stable
155
What is collagen and what does it do?
Fibrous protein/single fibre. Provides properties needed in tendons
156
What is the test for peptide bonds? (between amino acids of polypeptides/proteins)
Biuret test.
If protein is present, biuret turns from blue to violet/purple. Intensity of the colour directly proportional to the protein concentration/number of peptide bonds
157
Why does biuret change from blue to purple?
Copper || ion forms the violet/purple coloured complex in alkaline solution
158
What is used to measure change in colour and why?
Colorimeter. Because at low concentrations, colour change may not be obvious so colorimeter is used to measure change.
