Unit 1 Flashcards
Name 3 monosaccharides
Glucose
Galactose
Fructose
Name 3 disaccharides and the monosaccharides that form them
Glucose + glucose = maltose
Glucose + galactose = lactose
Glucose + fructose = sucrose
What Bond is formed between monosaccharides?
How is this bond formed?
How is this bond broken?
Glycosidic bond
Condensation reaction in which water is released
Hydrolyses reaction where an enzyme brings H20
Define polysaccharide
Name 3 polysaccharides
Polymers which are formed when more than 2 monosaccharides join together
Cellulose, starch, glycogen
What is the use of starch?
Excess glucose if stored as starch in plants - when energy is needed starch is broken down
What is starch made of?
What are the properties of these chains?
Mixture of two polysaccharides of alpha glucose called amylose and amylopectin
Amylose: long unbranched chain of alpha glucose. Coiled structure which is good for storage because it can fit a lot in a small space
Amylopectin: long branched chain of alpha glucose. Side branches allow enzymes to break bonds easily so glucose can be released easily
Why is starch good for storage
It is insoluble in water and doesn’t affect water potential so water cannot enter in via osmosis preventing turgidity so it is good for storage
What is glycogen used for?
What are the properties of glycogen?
Excess glucose stored as glycogen in animals
Polysaccharide of alpha glucose
Similar structure to amylopectin + more side branches so glucose can be released quickly
Very compact - good for storage
What is cellulose used for?
What are the properties of cellulose?
Structural support in plant cell walls
Long unbranched chains of beta glucose bonded together to form straight cellulose chains
Cellulose chains are linked together by H bonds which form strong microfibrils
Test for reducing sugars
Sample + benedicts reagent
Heat
Brick red precipitate
Remains blue if not present
Test for starch
Sample + iodine
Dark blue
Test for non reducing sugar
Sample + HCl Heat Sodium bicarbonate Benedicts reagent Reheat Green, orange to brick red
Remains blue if not present
What is the name of the lipid structure?
Describe this structure
What is the name of the bond
Triglyceride
Glycerol head bonded to 3 fatty acid hydrocarbon chain tails via condensation reactions
Ester bond
What are the properties of the glycerol head and fatty acid tail
Glycerol is polar - charged and attracted to water
Fatty acid tail is non polar
Define saturated fatty acid
Define unsaturated fatty acid
Why would a fatty acid be unsaturated?
Single bonds between carbon atoms
Double bonds between carbon atoms causing chains to kink
There is less number of hydrogens
Why is a triglyceride not considered a polysaccharide?
It is not made of repeating units
Emulsion test
Sample + ethanol
Shake
Add water + shake
Cloudy if lipid present
Structure of amino acid
H
|
|
NH2 ---- C ---- COOH
|
|
R
Amino group
Carboxyl group
R group - range of chemical groups different in each amino acidWhat is the bond between 2 amino acids?
What is it caused by?
What is the resulting molecule called when more than two amino acids are bonded together
Peptide bond
Condensation reactions
Polypeptide
Describe the formation of protein - primary structure
Polymerization occurs between amino acids to form polypeptide
Triplet sequence in base sequence in DNA codes for each amino acid - determines structure of polypeptide
Describe the formation of protein - secondary structure
Hydrogen bonds form due to attraction via slight negative charge in primary structure
Causes structure to coil into alpha helix or pleat in beta pleated sheet
Describe the formation of protein - tertiary structure
Chain is coiled or folded further
Hydrogen, ionic and disulfide bonds form
Biuret test
Sample + sodium hydroxide
Copper sulphate solution
Purple layer forms
Remains blue if not present
Explain is a change in the primary structure may result in a different 3D structure
Sequence of amino acid changes
Bonds form in different places
The structure will cool of fold into a different 3D tertiary structure
Describe and explain how an enzyme forms a product
The substrate has a complimentary shape to the active site
The substrate binds to active site, forming an enzyme substrate complex
Why does the enzyme lower the activation energy of the reaction it catalyses?
Reduces repulsion between molecules so they can be bonded easily
If catalysing, fitting into the active site puts a strain on the bonds in the substrate m, thus it breaks down more easily
Describe the lock and key model of the enzyme
Why is it discredited?
Substrate fits exactly to active site supported by observations that enzymes are specific in reactions
Because bonds in tertiary structure of the protein are not strong enough to hold a rigid structure
Describe the induced fit model of the enzyme
Initially the substrate is not complimentary to the active site
The active site changes shape and moulds itself around the substrate and thus becomes complimentary
After product is produced, enzyme returns to original shape
What type of sugar is glucose?
What are the two types of glucose ?
Hexose sugar
Alpha and beta
