Biochemistry🧪 Flashcards
(69 cards)
1
Q
Magnesium function
A
- Used to form chlorophyll
* Present bone and teeth
2
Q
Iron function
A
Component of haemoglobin
3
Q
Calcium function
A
- Used to strengthen bones and teeth
- Used to strength cell walls in plants - major part of middle lamellae
- Important role in blood clotting and muscle contraction
4
Q
Phosphate function
A
- Used to form phospholipids
- In many biological compounds such as ATP and nucleic acid
- Needed for root growth
5
Q
Why is water polar?💧
A
The hydrogen atoms are slightly positive and the oxygen atom is slightly negative
6
Q
What does the polar nature of water allow to form?💧
A
Hydrogen bonds form between a hydrogen atom of one water molecule and the oxygen atom of another - this creates cohesion
7
Q
What is water cohesion?💧
A
- Hydrogen bonds between water molecules creates cohesion
* Molecules stick together in a strong lattice structure - long water columns don’t break, e.g. transpiration stream
8
Q
What is surface tension of water?💧
A
- At the air/water interface, cohesion produces surface tension
- Some insects can exploit this property - body is supported by surface tension
9
Q
Why is water’s solvent properties important?💧
A
- Known as a universal solvent
- Chemical reactions can occur in a solution - chemicals are free to move about
- Makes transport easier - solutes are able to dissolve, e.g. in the blood, and then be carried around the organism
10
Q
Why is water a metabolite?💧
A
Used up in many reactions
11
Q
Why is water a good transport medium?💧
A
- Good solvent
- Viscous
- Lubricant
12
Q
Why is water’s high specific heat capacity important?💧
A
- Takes large amount of energy to raise the temperature of a body of water
- Important to cells - large amount of energy to raise a cell’s temperature, so cell can maintain stable internal temperature which is important for actions of enzymes
- Important In bodies of water - provides a relatively stable environment for aquatic animals
13
Q
Water’s high latent heat of evaporation💧
A
- Relatively large amount of energy required to turn water from a liquid to a gas
- Important for organisms as evaporation of water takes energy away from skin, causing a cooling effect
14
Q
Density changes in water💧
A
- Solid water has a lower density than liquid water - ice floats
- Important as ice provides an insulating layer on top of a body of water - liquid below ice has higher temperature than air above it - organisms survive
15
Q
Water’s transparency💧
A
Light can travel through water, meaning organisms such as plants and algae are able to photosynthesise underwater
16
Q
Water as a buoyancy aid💧
A
Water provides support and buoyancy for aquatic organisms
17
Q
What is a polymer?
A
Large molecules made up of repeating units of monomers
18
Q
What is a condensation reaction?
A
A chemical reaction involving the joining together of two molecules and the removal of a molecule of water
19
Q
What is a hydrolysis reaction?
A
The splitting of a large molecule into smaller molecules by the addition of water
20
Q
What are carbohydrates?🍞
A
- Source of energy in all living organisms
* All contain carbon - forms 4 bonds, hydrogen - forms 1 bond and oxygen - forms 2 bonds
21
Q
What is a monosaccharide?🍞
A
- CnH2nOn
- Classified by number of carbon atoms: triose (3), pentose (5), hexose (6)
- Provides building blocks for larger carbohydrate molecules
- Act as a respiratory substrate
22
Q
Glucose🍞 (monosaccharide)
A
- Used in respiration to produce ATP
- Monomer for many different polysaccharides
- Has two isomers: alpha and beta - differ in arrangement of H and OH on carbon 1
23
Q
What is an isomer?
A
Molecules with the same chemical formula but different structure
24
Q
What is a disaccharide?🍞
A
- Two monosaccharides joined by a glycosidic bond - condensation reaction (produces a molecule of water)
- Can be broken back into monosaccharides (hydrolysis)
- Small and water soluble - suitable for transport
25
What are reducing sugars?🍞 (disaccharide)
* Monosaccharides and some disaccharides
* Have carbonyl groups which can be oxidised to carboxylic acids
* Reduce other compounds, forming a precipitate
26
What is a polysaccharide?🍞
* Three or more monosaccharides joined by condensation reactions
* Either have a structural or storage function
* Large size - insoluble
* Osmotically inactive - stored without being affected by osmosis
27
What is starch? (Storage polysaccharide)🍞
* Store of glucose - made up of many alpha glucose molecules
* Two components - amylose and amylopectin
28
What is amylose?🍞(Starch)
Chain of glucose monomers joined by 1,4 glycosidic bonds and formed into a helix - unbranched
29
What is amylopectin?🍞(starch)
Has 1,4 and 1,6 glycosidic bonds, giving it a branched structure
30
What makes starch a good good store?🍞(Storage polysaccharide)
* Compact - pack lots of energy into a smaller space than glucose
* Insoluble - has little effect on osmotic pressure, doesn’t get transported from storage areas by water
* Readily converted to sugars -easily converted into transportable molecules
31
What is glycogen?🍞(storage polysaccharide)
* Polymer made up of many alpha glucose monomers
* Similar to amylopectin - 1,4 and 1,6 glycosidic bonds - branched structure
* Store glucose in animals
32
Why does glucose’s structure indicate animals’ higher metabolic requirements?🍞
More branched structure - broken down more rapidly
33
What is cellulose?(structural polysaccharide)🍞
* Polysaccharide made up of beta glucose monomers joined by 1,4 glycosidic bonds - forms long straight (unbranched) chains - strength
* Each beta glucose molecule is rotated 180’ from the previous molecule - enables hydrogen bonds to form between OH groups in adjacent chains
* Many cellulose chains form a microfibril, many microfibrils form a cellulose fibre, cellulose fibres make up cell walls of plants
34
What gives cellulose its strength?🍞(structural polysaccharide)
Many hydrogen bonds and unbranched structure
35
What is chitin?(structural polysaccharide)🍞
* Made up of chains of beta glucose monomers, rotated 180’ from previous monomer, with hydrogen bonds between chains forming microfibrils
* Amino acids added to form a mucopolysaccharide
* Contains nitrogen
* Strong and lightweight
* Forms exoskeletons of insects and cell walls of fungi
36
What is used to test starch?🍞
* Several drops of iodine added to sample
| * If present, sample turns blue/black
37
What is used to test for reducing sugar?🍞
* Benedict’s reagent is added to sample
* Solution is boiled
* If present, change from blue to brick red precipitate
38
What is used to test for non-reducing sugar?🍞
* If reducing sugar test shows a negative result, this test can be carried out
* Hydrolysing glycosidic bond by heating with hydrochloric acid - forms two monosaccharides
* Neutralised by adding sodium hydrogen carbonate
* Boiled with Benedict’s reagent
* If present, brick red precipitate
39
What are lipids?🍔
* Made up of carbon, hydrogen and oxygen
* Made up of glycerol and fatty acids
* Non-polar, insoluble
40
What are fatty acids?🍔
* Consist of a methyl group, a variable length hydrocarbon chain and a carboxyl group
* Hydrocarbon chains contain an even number of carbon atoms - between 14 and 22
* Either saturated or unsaturated
* Vary - length of hydrocarbon tail or how saturated the molecule is
* Fatty acids affect the lipids’ properties
41
Difference between saturated and unsaturated fatty acids🍔
* Saturated - no carbon-carbon double bonds in the hydrocarbon chain
* Unsaturated - carbon-carbon double bonds in the hydrocarbon chain
42
Difference between monounsaturated fatty acids and polyunsaturated fatty acids🍔
* Monounsaturated - one carbon-carbon double bond
| * Polyunsaturated - two or more carbon-carbon double bonds
43
What are triglycerides?🍔
* 1 glycerol and 3 fatty acids
* 3 condensation reactions which form 3 ester bonds
* When oxidised, releases more energy than carbohydrates and produces metabolic water
44
What are phospholipids?🍔
•2 fatty acids and a phosphate group combine with a glycerol molecule
45
Functions of lipids in living organisms🍔
* Energy storage - 2x more than same mass of carbohydrate
* Protection of delicate organs
* Thermal insulation
* Buoyancy
* Source of metabolic water for organisms such as camels
* Waterproofing
46
Why is a high intake of saturated fats a contributory factor in heart disease?🍔
Raises LDL cholesterol level, increasing the risk of atheroma in coronary and other arteries
47
What are waxes?🍔
* Long chained fatty acids linked to a long chained alcohol
| * Insoluble and form a waterproof layer
48
What are steroids?🍔
* Four-ring structure with various side chains
* Insoluble in water but soluble in organic solvents
* Important as hormones
* Synthesised from cholesterol
49
What is cholesterol?🍔
* Important constituent of body cells, especially cell membrane
* Too much cholesterol and saturated fat can produce atheroma deposits - reduce blood flow in arteries
50
What are proteins?🥩
Polypeptides made up of carbon, hydrogen, oxygen, nitrogen and sometimes sulphur
51
What is a polypeptide?🥩
* A polymer consisting of a chain of amino acid molecules
* Joined by peptide bonds formed by condensation
* One or more polypeptides form a protein
52
What is used to test for lipids?🍔
* Emulsion test
* Ethanol added to sample and shaken thoroughly
* Distilled water is added
* If present, a layer of cloudy white suspension will form
53
Roles of proteins🥩
* Enzymes
* Carrier proteins
* Antibodies
* Structural proteins
* Hormones
* Transport - haemoglobin
* Contractile proteins
54
What are amino acids?🥩
* Made up of a amino group (NH2) and a carboxyl group (COOH) and a variable residual (R) group
* Amino end - base - positive amino acid ion
* Carboxyl end - acid - negative amino acid ion
* They are amphoteric - act as base and acid, so can act as a pH buffer
55
How many R groups are there?🥩
20 different R groups, so 20 different amino acids
56
How is a dipeptide Formed?🥩
* Two amino acids combine in a condensation reaction to form a dipeptide - a molecule of water is also formed
* Peptide bond forms between carboxyl group of one amino acid and the amino group of the other amino acid
57
What is a protein’s primary structure?🥩
The type, number and sequence of amino acids in a protein
| Peptide bonds
58
What is a protein’s secondary structure?🥩
* Polypeptide can twist to form either an alpha helix or a beta pleated sheet
* Shape is held together by hydrogen bonds between the peptide bonds
59
What is a protein’s tertiary structure?🥩
* Polypeptide helix twists and folds into specific complex 3D shapes
* Specific structure is maintained by hydrogen bonds, ionic bonds and disulphide bonds between the R groups of the amino acids
60
What is a protein’s quaternary structure?🥩
* Only some proteins have a quaternary structure
| * Two or more polypeptides with a tertiary structure can combine to form a quaternary structure
61
What is the hydrophobic effect?🥩
* Helps some proteins maintain their structure
* When globular proteins are in solution, the hydrophobic groups point inwards, away from the water
* Allows molecule to be soluble in water
62
Stability of proteins🥩
* Increases in temperature/changes in pH or presence of heavy metal ions or organic solvents cause the atoms to vibrate
* Bonds break - 3D structure changes
* Affects tertiary and quaternary structure - denatures
63
Globular proteins🥩
* Tertiary and quaternary structure
* Compact molecules
* Highly twisted polypeptide chains roll up into a ball - specific in shape
* Hydrophobic R groups point out - water soluble
* Tend to be less stable and are involved in metabolic reactions
* Includes enzymes, antibodies and hormones
64
What is haemoglobin?🥩(globular)
* Globular protein
* Consists of 4 polypeptide chains - disulphide bridges hold them together
* At the centre of each polypeptide is a haem group
65
Fibrous proteins🥩
* Secondary structure
* Insoluble, strong, stable and flexible
* Polypeptides Laos sown in parallel chains, linked together to form long fibres or sheets
* E.g. keratin or collagen
66
What is collagen?🥩(fibrous)
* Fibrous protein
* Provides the tough properties needed in tendons and bones
* Consists of 3 alpha helix chains formed into long strands - wind around each other held together by hydrogen bonds
67
What is used to test for proteins?🥩
* Biuret test
* Biruet reagent is added to sample
* If present, change from blue to lilac/purple
68
Number of bonds formed by Carbon, oxygen and hydrogen🍞🍔
* Carbon - 4
* Oxygen - 2
* Hydrogen - 1
69
Monosaccharides and the disaccharides they form🍞
* Glucose + glucose = maltose
* Glucose + fructose = sucrose
* Glucose + galactose = lactose
