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185 Cards in this Set
- Front
- Back
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What elements are carbohydrates made of? |
Carbon, hydrogen, oxygen |
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What elements are lipids made of? |
Carbon, hydrogen, oxygen |
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What elements are proteins made of? |
Carbon, hydrogen, oxygen, nitrogen |
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What elements are nucleic acids made of? |
Carbon, hydrogen, oxygen, nitrogen, phosphorus |
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What process makes polymers from monomers? |
Polymerisation |
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What are carbohydrate monomers?
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Sugars - monosaccharides or disaccharides
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What are carbohydrate polymers?
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Polysaccharides - starch, cellulose, glycogen
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What are lipid monomers?
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Glycerol & fatty acids
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What are lipid polymers?
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Triglycerides (fats + oils) & phospholipids
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What are protein monomers?
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Amino acids
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What are protein polymers? |
Proteins - enzymes, hormones, antibodies |
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What are nucleic acid monomers? |
Nucleotides |
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What are nucleic acid polymers? |
DNA & RNA |
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What are inorganic ions? |
Essential macro & micronutrients that make up 1% of an organisms weight |
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What are magnesium ions used for? |
To make chlorophyll |
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What are iron ions used for? |
To make haemoglobin |
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What are phosphate ions used for? |
To make cell membranes |
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What are calcium ions used for? |
To strengthen teeth & bones
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Discuss water's abudancy in cells |
It is the most abundant molecule in cells
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Discuss water's polarity |
Dipole - 2 H+, 1 O- |
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What does water's charge distribution mean? |
It is uneven
Adjacent water molecules are attracted + bonded So weak hydrogen bonds between molecules - which are collectively stable |
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Discuss water cohesion & its importance [3] |
Molecules attract and stick together |
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Discuss water as a solvent & its importance [4] |
It is an effective solvent |
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Discuss water density & its importance [2] |
Ice is less dense than water |
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Discuss water's specific heat capacity & its importance [2] |
High - lots of energy to heat up, releases lots of energy when cooling down |
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Discuss water's latent heat of evaporation & its importance [2] |
High - lots of energy to evaporate |
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Discuss water's transparency & its importance [2] |
Allows light to pass through |
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When is water needed for reactions? [2] |
- Photosynthesis as a reactant |
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When is water released from a reaction? [2] |
- Condensation reactions to make polysaccharides, lipids + proteins |
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What are the 3 main types of carbohydrate? |
Monosaccharide, disaccharide, polysaccharide |
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What are the properties of monosaccharides? [4] |
- Sweet |
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What is the general formula for monosaccharides? |
(CH2O)n - n = number of carbons |
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What are the 3 main monosaccharides and how many carbons do they have? |
- Trioses (3) |
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What do monosaccharides display and what is it? |
Structural isomerism |
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What is the formula for trioses? |
C3H6O3 |
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What are the 2 subtypes of trioses and give an example |
Aldotriose - glyceraldehyde |
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What is the formula for hexoses? |
C6H12O6 |
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Why are hexoses important? |
They are the building blocks for disaccharides |
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What are the 2 isomers of hexoses and give examples |
Aldohexose - glucose + galactose |
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What is the usual form hexoses take + when does this occur? |
A stable ring when dissolved in water |
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What form does an aldohexose take? |
A 6 sided ring (pyranose) |
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What form does a ketohexose take? |
A 5 sided ring (furanose) |
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What do isomers provide? |
A greater chemical variety |
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What is an alpha isomer of glucose? |
The hydroxyl group on carbon one is below the plane of the ring |
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What is a beta isomer of glucose? |
The hydroxyl group on carbon one is above the plane of the ring |
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What are pentoses used for and give examples [2] |
Nucleic acid synthesis |
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What are the properties of disaccharides? [4] |
- Sweet |
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How are disaccharides formed? |
From a condensation reaction between 2 monosaccharides |
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What is a condensation reaction? |
The chemical removal of a molecule of water to form a glycosidic bond and join two compounds |
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Where is the glycosidic bond formed in a condensation reaction between 2 monosaccharides? |
Between carbon 1 + carbon 4 |
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How do you reverse a condensation reaction? |
Add water + hydrolase |
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What is a hydrolysis reaction? |
The chemical addition of a molecule of water to break a glycosidic bond |
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What is maltose? |
A disaccharide formed from 2 alpha-glucose |
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Where is maltose found? [2] |
- Germinating seeds |
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What is sucrose? |
A disaccharide formed from 1 alpha-gluocse + fructose |
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What is sucrose used for? |
- The form that sugar is transported as in phloem |
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Where can sucrose be extracted from and why? |
Sugar cane + sugar beet to make common white sugar |
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What is lactose? |
A disaccharide formed from 1 alpha-glucose + galactose |
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Where is lactose found? |
It's the sugar in milk |
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What is a use of polysaccharides and why? |
Glucose storage or structural molecules |
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Why are polysaccharides good storage molecules? [2] |
- Easily reconverted into glucose by hydrolysis when energy is needed |
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What is starch? |
The excess glucose made from photosynthesis |
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Where is starch found in abundance and why? |
Seeds, as it's the food supply for germination |
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Discuss starch as a food source |
Important for animals indirectly + directly - potatoes, rice, cereal |
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What is starch made of? |
A mixture of 2 polysaccharides - amylose + amylopectin |
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What is amylose? |
alpha-glucose with 1,4 bonds |
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Describe the structure of amylose |
Folds up into spiral shape because no side branches |
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What is amylopectin made of? |
alpha-glucose |
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Describe the structure of amylopectin |
Side branches with 1,4 + 1,6 bonds - branches every 12th molecule |
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What does amylopectin's highly branched structure mean? |
It can be hydrolysed more quickly |
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What is glycogen and how is it formed? |
Excess glucose is converted to glycogen in the liver using the hormone insulin |
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Describe the structure of glycogen [2] |
- Similar to amylopectin - alpha-glucose |
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Compare the branched structure of starch to glycogen - why is this significant? |
Glycogen can be hydrolysed faster than starch because animals need glucose faster |
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Where is glycogen stored? |
Liver + muscles |
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What is percentage of carbon in plants is cellulose? |
50% |
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What is cellulose used for? [2] |
- Fabric manufacture (cotton) |
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Describe the structure of cellulose [2] |
- Straight, unbranched beta-glucose chains |
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What is significant about the arrangement of beta-glucose in cellulose? |
Adjacent molecules are rotated 180 so hydrogen bonds are cross-linked, forming tough microfibrils |
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What is the importance of cellulose's strength? |
It can withstand osmotic pressure + prevent bursting (lysis) |
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Describe the structure of chitin |
Similar to cellulose but some of the -OH groups repleaced with amino acids containing nitrogen |
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What are the funtions of chitin? [2] |
- Forms tough exoskeletons of arthropods |
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What is a food test for starch + the positive result? |
- Add yellow/brown Iodine solution |
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What is a food test for reducing sugars + the positive result? |
- Boil at 70-90C for 5 min with blue Benedict's solution |
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What is a non-reducing sugar? Give an example |
- A sugar without an aldehyde group |
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How do you a 'treat' a non-reducing sugar for testing? [2]
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- Boil with hydrochloric acid to break the glycosidic bond - forming glucose + fructose |
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How does the proportion of elements in lipids vary to carbohydates? |
More hydrogen, less oxygen |
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What is the definition of lipids? [2] |
- No precise definition due to variable chemistry |
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Give 5 examples of lipids |
- Triglycerides |
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What do fatty acids contain? |
A carboxylic acid group that can ionise to release H+ ions, so the O is left with a negative charge |
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What is the general formula for fatty acids? |
RCOOH (where R = alkyl group) |
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Describe the tail of a fatty acid |
- Hydrocarbon tail |
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What is the main property of the fatty acid tail and why? |
Tail cannot ionise so is non-polar, insoluble, hydrophobic |
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Describe the structure of a saturated fatty acid + relate it to the melting point [3] |
- No C=C double bonds in hydrocarbon tail as it is fully saturated with hydrogen |
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Describe the structure of a unsaturated fatty acid + relate it to the melting point [3] |
- C=C double bonds in hydrocarbon tail are not fully saturated with hydrogen |
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What alcohol is in lipids? |
Glycerol |
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Describe the structure of triglycerides |
Glycerol backbone, 3 hydroxyl groups joined with fatty acid via condesation reaction to form ester bond |
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What are triglycerides further classified into? |
Solid (fats) & liquid (oils) at 20C |
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Relate saturation of fatty acid to melting point |
The more unsaturated the fatty acid, the lower the melting point |
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Why aren't triglycerides classed as polymers? |
A polymer is the same monomer linked, triglycerides are glycerol + fatty acids |
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Do plants have more saturated or unsaturated fats? |
More unsaturated |
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Name 4 commerical oil sources |
Coconut, soya bean, olive, linseed |
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What does the formation of triglycerides produce? |
3 H2O |
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Why are triglycerides insoluble? |
The polar fatty acid + polar glycerol are 'used up' |
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Why are triglycerides good energy storage molecules and why is this important? [3] |
- Oxidation of 1g triglycerides yields nearly 2.5x as much as 1g of carbohydrates |
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Discuss the function of triglycerides as sources of metabolic water [3] |
- During oxidation of triglycerides, over 2x as much metabolic water is produced |
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Why aren't triglycerides used as main respiratory substrate? |
Carbohydrates require less oxygen than triglycerides to release energy |
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How are triglycerides used for thermal insulation and why is this important? [2] |
- Stored as subcutaneous fat |
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Why are triglycerides used for mechanical protection? |
They protect internal organs (e.g. kidneys) from physical damage
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How do triglycerides provide use regarding buoyancy? |
Fat is less dense than water so buoyancy is provided for aquatic organisms |
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How are triglycerides used for waterproofing? |
They form a waxy cuticle which waterproofs leaves & waterproof skin + fur |
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What are saturated fats linked with? Name 3 places this affects [5] |
- Heart disease |
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What 2 things encourage fatty deposit formation? |
Nicotine + high blood cholesterol |
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Why are high animal fat diets bad? |
Surplus fat is converted into cholesterol, making you more susceptible to heart disease |
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What are phospholipids made of? |
Glycerol, 2 fatty acids, polar phosphate group |
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How are phospholipids formed? |
Condensation reaction |
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Discuss polarity of phospholipids |
Polar phosphate head, 2 non-polar fatty acid tails |
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What happens if you put a thin layer of phospholipids on a water surface? [3] |
- They arrange in a single monomolecular layers |
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What happens if you put a large amount of phospholipids in water + shake? [3] |
- Micelle is formed |
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What is the cell plasma membrane? |
A phospholipid bilayer where they spontaneously arrange with tails inwards + heads outwards |
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What happened regarding plasma membranes in 1930? |
Davson & Danielli produced a theory that the phospholipid bilayer was coated with a protein layer |
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What happened regarding plasma membranes in the 1950s? [2] |
- Plant + animal cells were studied using an electron microscope |
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What theory was developed in 1972 and by who? |
The Fluid Mosaic Model developed by Singer & Nicholson |
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What is the fluid mosaic model? |
A mosaic of proteiin floats in fluid phospholipid bilayer |
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Discuss the properties of membrane proteins [3] |
- Protein's penetration depends on the size of its hydrophobic portions |
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What are the functions of membrane proteins? [5] |
- Formation of hydrophilic pores |
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Describe extrinsic proteins [3] |
- Charged
- Attach to outside - Associate with phosphate heads |
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What are the functions of extrinsic proteins? [2] |
- Hormone receptors |
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Describe intrinsic proteins [4] |
- Large portions that aren't charged |
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What are the functions of intrinsic proteins? [2] |
- Act as carrier proteins |
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What are hydrophilic pores? |
- Pores perforating membrane at regular intervals |
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Name 3 functions of proteins |
- Enzymes (amylase, catalase) |
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How many different amino acids are there? |
20 |
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What is the basic structure of an amino acid? [4] |
- Carboxyl group (-COOH) - Basic amino group (-NH2) |
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What is the significance of the basic amino group and the acidic group in an amino acid? |
They cancel each other out |
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What do the properties + shape of the protein depend on? |
The R group
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How do you link amino acids? [2] |
- Condensation reaction between the amino group on the 1st acid + the carboxylic acid group on the 2nd acid |
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What does linking amino acids require? |
Enzyme activity + energy input |
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What is the link formed when amino acids are joined? |
A peptide bond (carbon-nitrogen) |
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What happens if you join an amino acid to a dipeptide? |
You form a tripeptide |
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What happens if you join many amino acids? |
You form a polypeptide |
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What does the structure + function of a protein depend on? |
The type + order of amino acids |
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Why do carbohydrates and fats have a smaller range of functions than proteins? |
They are only 1 sub-unit repeated, proteins are different amino acids |
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What is a gene? |
"It determines the order of amino acids in 1 polypeptide chain" |
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What can alter the structure + function of a protein? [3] |
Substitution, addition or deletion of amino acids |
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What is sickle cell anaemia? |
1 amino acids in the beta polypeptide chains is different to normal |
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What is the primary structure of a protein? |
"The sequence of amino acids in the polypeptide chain" |
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Discuss the primary structure of a protein [3] |
- It is assembled at the ribosomes |
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What is the secondary structure of a protein? |
"The predictable shape (e.g. a helix/b sheet) that the polypeptide chain forms due to hydrogen bonding between amino acids in the chain" |
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Discuss the alpha-helix secondary structure of a protein |
- Most common |
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Discuss the beta-sheet secondary structure of a protein |
- Single polypeptide chain folds back on itself |
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What is the tertiary structure of a protein? |
"The specific 3D shape the polypeptide chains folds up into, due to hydrogen, ionic + dusulphide bonds between amino acids in the chain" |
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Discuss hydrogen bonds in the tertiary structure of a protein [2] |
- Very weak |
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Discuss ionic bonds in the tertiary structure of a protein [3] |
- Weak |
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Discuss disulphide bonds in the tertiary structure of a protein [2] |
- Very strong covalent bonds |
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Why is the tertiary structure of a protein not random? |
It is detemrined by the primary structure |
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What depends on the tertiary shape of a protein? |
Functions of enzymes, hormones + receptors |
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Describe globular proteins in 3 words |
Compact, coiled + folded |
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Describe the amino acid sequence in globular proteins? |
Highly irregular |
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What is significant about the groups on amino acids in globular proteins? [2] |
- They interfere with hydrogen bonds + disrupt any a helixes/b sheets |
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Describe fibrous proteins in 5 words, giving an example of their role |
Non-compact, tough, long, rope-like |
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What is the amino acid sequence like in fibrous proteins? |
Regularly repeating |
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Discuss disruptive groups in fibrous proteins |
Few/none |
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What is keratin made of? |
Many a-helix polypeptide chains closely bound + held by hydrogen bonds (crosslinks) |
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Name 5 places where keratin is found |
Wool, hair, nails, claws, beaks |
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What does the hardness of keratin depend on? [3] |
- The number of a-helix chains |
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What is collagen made of? |
3 a-helix polypeptide chains, closely bound + held by hydrogen bonds |
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What is collagen + where is it found? |
It is the structural protein found in tendons |
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What is protein denaturation? |
A change in specific 3D shape due to disruption of hydrogen, ionic or disulphide bonds |
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What causes protein denaturation in terms of energy? |
Kinetic energy gained, moves, bonds break |
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Discuss protein denaturation in terms of amino acid sequence/3D shape |
Amino acid sequence is unaltered but 3D shape is changed |
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Give 2 examples of what happens as a result of protein denaturation? |
- Substrates no longer fit active sites (enzymes) / receptor sites (hormones) |
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Name 2 agents that cause denaturation |
- Heat |
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What is the quaternary structure of a protein? |
"The association of 2 or more polypeptide chains in tertiary form, to create a functional protein" |
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Describe the structure of haemoglobin [2] |
- 4 polypeptide chains, 2 alpha + 2 beta, each folded into specific 3D shape |
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Discuss the hydrogen in OH + NH groups |
Has a tendency to donate electrons + become electropostive + unstable |
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Discuss the oxygen in C=O groups |
Has a tendency to accept electrons + become electronegative + unstable |
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How do hydrogen bonds form? |
An electropositive hydrogen donates an electron to an electronegative oxygen |
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Why are hydrogen bonds weak? |
The hydrogen and oxygen are unstable as they don't have the right quota of electrons, so break, then reform etc |
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Describe hydrogen bonds in 3 phrases |
- Weak |
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Describe a test for proteins and the positive result |
Add blue Biruet solution |
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How is the protien test semi-quantitative? |
It turns a deeper violet if more peptide bonds (so more protein) |
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How would you assess the percentage concentration of a reducing sugar? |
Compare the colour to a standard solution using a colorimeter |
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Describe a test for fats/oils and the positive result? |
Mix with absolute alcohol + shake, then pour into boiling tube half full with cold water |
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What is a hazard, risk + control measure of the protein test? |
- Hazard: Biuret is an irritant |
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What is a hazard, risk + control measure of the fats/oils test? |
- Hazard: ethanol is flammable |
