Biological molecules summary

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What provides evidence for evolution?
The biochemical basis of life, it is similar fr all living things
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What are polymers?
Big molecules made from large numbers of smaller units called monomers
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What are examples of monomers?
Monosaccrides, amino acids and nucleotides
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What is a condensation reaction?
Joins two molecules together with the formation of a chemical bond and releases a molecule of water
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What is a hydrolysis reaction?
Breaks a chemical bond between two molecules and uses a water molecule
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What are the monomers of carbohydrates?
They are monosaccharides e.g glucose, galactose and fructose
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What is the structure of a and b glucose?
A glucose: H on top, OH bottom. B glucose: OH top, H bottom
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How are disaccharides formed?
From The condensation reaction of two monosaccharides (forming glycosidic bonds)
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Which monosaccharides make up which disaccharides?
MALTOSE: Glucoe + glucose SUCROSE: glucose + fructose. LACTOSE: glucose + galactose
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How do you do the Benedictus test for reducing sugars?
Add Benedictus reagent (blue) to a sample nd heat it in a water bath brought to boil. Red means reducing sugar present.
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How to test for non reducing sugars?
If stays blue could be non reducing sugar, so have to break down into monosaccharides by getting a new sample of solution, Add dilute hydrochloride acid and heat in water bath at boil. Neutralise it adding sodium hydrogencarbonate and then do b test
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How are polysaccrides formed?
From the condensation of more than two monosacs
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How are starch and glycogen formed>
By the condensation of a glucose units
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How is cellulose formed?`
By the condensation of b glucose units
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How is the structure of starch related to its function?
PLANTS store excess glucose as starch. It is a mixture of a glucose - amylose: angles of glycosidic bonds give coiled structure, makes it compact n good for storage. Amylopectin: glucose can be realised quickly
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How is the structure of glycogen related to its structure?
ANIMALS store excess glucose as glycogen. Lots of side branches means stored glucose can be realised quickly, also good for storage
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How is the structure of cellulose related to its structure?
Long chains of b glucose which forms straight cellulose chains linked by hydrogen bonds that form microfibrils which provides structural support for cells
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How do you do the iodine test for starch?
Add iodine dissolved in potassium iodide solution. There is starch if it goes blue-black
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What are two groups of lipids?
Triglycerides and phospholipids
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What is the basic structure of triglycerides?
They have one molecule of glycerol with three fatty acids attached with long tails which are hydrophobic (repel water) this makes lipids insoluble in water
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How are triglycerides formed?
By condensation reactions. An ester bond forms between the two molecules, realising a water molecule. This happens twice more to form it
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What is the basic structure of fatty acids
Same basic structure but hydrocarbon tail varies. Saturated don’t have double bonds between carbon atoms, unsaturated do and cause a kink
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What forms an ester bond?
A condensation reaction between glycerol and a fatty acid
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What is the basic structure of a phospholipid ?
Similar to triglyceride but only two fatty acids and one phosphate group in its place which is hydrophilic, and th fatty acid tails are hydrophobic
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How does the properties of triglycerides relate to their function?
Long hydrocarbon tails contain lots of chemical energy which realise lots of energy hen they’re broken down. They’re insoluble in water and dont affect water potential so osmosis doesn’t happen.
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How does the properties of phospholipids relate to their function?
Their heads are hydrophilic and tails phobic so form a double layer ith heads facing out. Water soluble substances cant easily pass through, membrane is a barrier
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How do you do an emulsion test?
For lipids. Shake sample with ethanol, add to water, if its milky colour there is a lipid present
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What are proteins made from?
The monomers of proteins are amino acids. DIpeptides are formed when 2 aminos join together. Polypeptides formed when MORE than 2 aminos join. Proteins made of 1 or more polypeps
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What is the general structure of an amino acid?
A carboxyl group, an amino group and an r group attached to a carbon atom. R group generally contain carbon apart from glycine with just one hydrogen atom
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How do condensation reactions link amino acids?
A molecule of water is realised. Bonds form between amino acids called peptide bonds. This forms dipeptides and polypeptides
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What is the structure of protein?
PRIMARY: the sequence of amino acids in the polypep chain. 2ND: h bonds form coiling chain into a helix or folding into b sheet 3RD: h bonds n ionic bonds, forms 3D structure, 4TH: the way the polypep chains are assembled
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What bonds form in the tertiary structure?
H bonds, ionic bonds and disulphate bridges
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How are proteins shape specific for its functions?
ENZYMES: roughly spherical due to tight folding of pep chains, soluble so have roles in metabolism. TRANSPORT PROTEINS: e.g. channel proteins in membranes, has hydrophilic n phobic aminos so protein folds up forming a channel. This transports molecu
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How do you carry out a biuret test?
Test solution needs to be alkaline, so add sodium hydroxide, then copper(II) sulphate solution. If protein turns purple
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What do enzymes catalyse?
A wide range of intercellular and extra cellular reactions that determine structure and functions from cellular to whole organism level
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How do enzymes catalyse reactions?
They act as a biological catalyst. They lower the amount of activation energy needed with an enzyme substrate complex
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What is the new theory evolved of the lock and key model?
Realised enzyme changed shape slightly to complete fit. The induced fit model introduced. Substrate doesn’t only ave to be right shape to fit, but make active site change to fit it in
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How are enzymes very specific?
Usually only catalyse one reaction bc only 1 complementary substrate will fit active site. Determined by tertiary stuructre
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How are enzyme properties related to its tertiary structure?
Each enzyme has different tertiary structure so different shaped active site. If 3 structure of proteins changes, active site will change shape, substrate wont fit anymore
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What factors affect enzyme activity?
Temperature, pH, substrate concentration, enzyme concentration, competitive and non competitive inhibitors
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How does temperature affect enzyme activity?
Reaction increases with temp. Substrate molecules more likely to collide with enzymes active site. If temp too high reaction stops as bonds can break ad active site changes shape.
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How can pH affect enzyme activity?
Optimum pH 7. Pepsin, in stomach, optimum 2. Above and below optimum h and OH ions in acids n alkalis can disrupt ionic n h bonds holding enzyme tertiary structure so enzyme can become denatured
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How can substrate concentration affect enzyme activity?
Higher sub conc faster reaction. More molecules - more collisions - more occupied enzymes. Up until a saturation point, have as many substrate molecules as they can handle
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How can enzyme concentration affect enzyme activity?
More enzyme molecules increases rate of reaction. If substrate becomes limited, they’ll be more than enough enzymes and adding more has no further effect
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What are enzyme competitive inhibitors ?
Prevents enzyme activity. They have a similar shape to substrate and block active site. Increasing conc of substrate minimises chances of inhibitor so increases ate of reaction
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What are non competitive inhibators?
Bind to the enzymes away from its active site and active site changes shape so substrate no longer fit. Increasing substrate conc makes no difference as it doesn’t compete.
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Other cards in this set

Card 2

Front

What are polymers?

Back

Big molecules made from large numbers of smaller units called monomers

Card 3

Front

What are examples of monomers?

Back

Preview of the front of card 3

Card 4

Front

What is a condensation reaction?

Back

Preview of the front of card 4

Card 5

Front

What is a hydrolysis reaction?

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