Biological Molecules Flashcards
What are monosaccharides?
Simple sugars
What is an example of a monosaccharide?
Glucose
What is the general formula for monosaccharides?
Cn(H20)n
What is a disaccharide?
A sugar formed from two monosaccharides
How are disaccharides joined?
By a 1-4 glycosidic bond
What is lactose made from?
Glucose + galactose
What is sucrose made from?
Glucose + fructose
What is maltose made from?
Glucose + glucose
What is removed in a condensation reaction?
H2O
How do you test for non- reducing sugars?
Reducing sugar test If no colour change get fresh sample Add 2cm3 of HCl Place in water bath for 3mins Add 1/2 spatula of sodium hydrogen carbonate to neutralise Add Benedict's to hydrolysed sample If now positive is a reducing sugar
Why is sucrose not a reducing sugar?
Cannot become linear so no free aldehyde group to react with
Why are most disaccharides reducing sugars?
Able to reduce oxidising agents
Ring opens to reveal aldehyde group
What are the reducing sugars?
Glucose
Fructose
Galactose
Which monomer is starch made from?
Alpha glucose
What is starch’s structure?
Chains branched + unbranched
What is the branched structure called in starch?
Amylopectin
What is the unbranched structure called in starch?
Amylase
Where is starch found?
Form of a small grain
Never in animals
What is starch’s function?
Energy store
What is starch’s structure related to its function?
Large so can’t diffuse out
Insoluble so doesn’t effect water potential
Compact so can be stored in small place]
What is good about starch having a branched structure?
Enzymes simultaneously act on it to produce glucose monomers rapidly
Which monomer is glycogen made from?
Alpha glucose
What is glycogen’s structure?
Similar to starch but shorter chains + highly branched
Where is glycogen found?
Animals + bacterial cells
Stored as small granules in muscles + liver
What is glycogen’s function?
Main carbohydrate storage product of animals
What is glycogen’s structure related to its function?
Insoluble so won’t effect water potential
Large so won’t diffuse out
What is good about glycogen having a highly branched structure?
Enzymes act on it simultaneously so it is rapidly broken down into glucose
Which monomer is cellulose made from?
Beta glucose
What is cellulose’s structure?
Straightened, unbranched chains
That run parallel to allow H bods to form cross links
Where is cellulose found?
Plant cell walls
What is cellulose’s function?
Provides rigidity to the cell
Exerts inward pressure to stop cell from bursting
What is cellulose’s structure related to its function?
Every 2nd beta glucose is rotated 180 degrees to create linear chain
Cross linked by H to provide strength
How is the H bonds in cellulose grouped to provide strength?
Grouped to form microfibilis, which are grouped to form fibres
What are the lipids?
Triglycerides
Phospholipids
Cholesterol
Steroids
What are the functions of lipids?
Waterproofing Substrate for respiration Store of energy Insulation Protection of organs Cell membranes Buoyancy + streamlining Hormones
What does hydrophobic mean?
Molecules that are not polar so do not dissolve/mix with water
What does hydrophilic mean?
Molecules that are polar so dissolve/mix with water
What does saturated mean?
A hydrocarbon chain that doesn’t contain a double carbon bond
What does unsaturated mean?
A hydrocarbon chain that does contain a double carbon bond
What do double bonds do to a lipids structure and what does this mean?
It bends the structure so it cannot pack tightly together so is a liquid at room temperature
Are lipids soluble?
They aren’t in water but are in organic solutions
What solutions are lipids soluble in?
Alcohol and acetone
What is the difference between fats and oils?
Fats= solids at room temperature Oils= liquids at room temperature
How do lipids arrange themselves in water?
Hydrophilic heads are at the surface of the water and hydrophobic tails are above the water
Why is a triglyceride a good energy store?
High ratio of energy storing C-H bonds to C atoms
Can store a large amount in small place
Why does the storage of a triglyceride not effect osmosis?
Because it is insoluble
Why does a triglyceride release water when oxidised?
High hydrogen to oxygen atoms ratio
How does a phospholipid structure allow them to form glycolipids?
By combining carbohydrates with cell surface membrane
What are glycolipids important for?
Cell recognition
What happens when a phospholipids are in aqueous environment?
Form a bi layer with cell-surface membranes so a hydrophobic barrier is formed between the inside + outside of cell
What do amino acids form?
Polymers that form polypeptide chains that form proteins
How many amino acids occur naturally?
20
What does that fact that the sane 20 amino acids occur i each organism prove?
Evolution
What is the structure of an amino acid?
1 central carbon atom Amino acid group (NH2) Carboxyl group (COOH) Hydrogen atom R(side) group
What varies with each amino acid?
R group
How many different side chain is there?
20
What do side chains contain?
H, C and O atoms
What do some R groups contain?
Sulphur/nitrogen atoms
How are dipeptides formed?
Condensation reaction
What is removed during the formation of dipeptides?
H2O
What is the bond between the nitrogen and carbon in a dipeptide?
Peptide bond
What are the functions of proteins?
Enzymes eg amylase Structure eg. keratin Membrane transport Antibodies Hormones eg. insulin Receptors Cell recognition Mass transport eg. haemoglobin
What is the structure of a triglyceride?
Glycerol with 3 fatty acid chains joined with an ester bond
What is the structure of a phospholipid?
Hydrophobic tail Hydrophilic head One glycerol molecule 2 fatty acids Third fatty acid is a polar phosphate group Ester bond
What is a tertiary structure?
Secondary structure is folded more giving the protein a 3D shape, maintained by bonds
What is a quaternary structure?
Complex molecules containing many polypeptide chains and contain non-protein molecules
What is the function of haemoglobin?
Transport oxygen
Associate with oxygen at gas exchange and disociate at tissues
What is the structure of haemoglobin?
Quaternary- all 4 polypeptide chains linked to form a spherical group
Each associated with a haem group
What is haemoglobin’s structure related to its function?
Changes affinity for oxygne under different conditions
Shape changes in presence of CO2
New shape binds more loosely to O2
Is haemoglobin globular or fibrous?
Globular
What is the function of collagen
Found in tendons which join to muscles
Muscles contract and bone is pulled in direction of contraction
What is the structure of collagen?
Quaternary- made up of 3 poltpeptide chains wound together in the same way
What is collagen’s structure related to its function?
Individual polypeptide chains held together by crosslinks
Between amino acids of other chains
Is collagen globular or fibrous?
Fibrous