Biological molecules Flashcards
Describe the structure of glycogen
Alpha glucose
1,4 and 1,6 glycosidic bonds
Very branched
Storage polysaccharide
shorter branches than starch
How does extreme changes in pH affect enzyme activity
Extreme changes in pH change the charges of the amino acids holding the enzyme active site together which in turn affects the ionic bonding of the enzyme which causes the tertiary structure and active site to change shape so no E-S complexes can be formed
What is a condensation reaction?
A reaction that removes a H2O molecule and creates a chemical bond
How do you perform a reducing sugar test?
4 steps
- Add 2cm of reducing sugar (glucose fructose galactose lactose maltose) to a test tube
- Add 2-3 drops of Benedicts reagent
- Heat test tube in water bath to above 80 degrees
- Positive result = colour change from blue –> red
Describe the role of enzymes in the digestion of proteins in a mammal
Proteins are digested by hydrolysis of peptide bonds
First endopeptidase hydrolyses peptide bonds in the middle of polypeptide chains producing smaller polypeptides
Secondly exopeptidase hydrolyses peptide bonds at the end of polypeptides which produces either dipeptides or amino acids
Lastly dipeptidase hydrolyses peptide bonds in dipeptides which produce amino acids
What can ATP be used for?
Muscle contraction
Cell division
Active transport
Describe the structure of ATP
ATP = adenine tri phosphate
ATP = an adenine group + 3 phosphate + ribose
How does substrate concentration affect enzyme activity
Increased sub-concentration results in faster ROR because of more frequent collisions between enzymes and substrates so more E-S complexes are formed
However it gets to a point where all enzyme active sites are saturated and can no longer hold any more substrates so ROR can no longer be increased
How do you perform a non-reducing sugar test?
- Add 2cm of sucrose to a test tube
- Add 2cm of any acid and boil for 5-10 minutes which hydrolyses the glycosidic bond
- Let it cool down and then add an alkali to neutralise the solution
- Heat solution in a water bath to above 80 degrees
- Positive result = colour change from orange —> red
What does maltose, sucrose and lactose contain?
Maltose - 2 alpha glucose
Sucrose - Glucose and Fructose
Lactose - Glucose and Galactose
How do competitive inhibitors work
Substrate and inhibitor both compete for enzyme active site as both are complementary, if inhibitor binds to the active site then no E-S complexes can be formed and this overall slows down ROR not completely stopping it. This can be overcome by adding more substrate
What is a triglyceride and phospholipid made up of?
1 glycerol molecule + 3 fatty acids = triglyceride
1 glycerol molecule + 2 fatty acids + phosphate group = phospholipid
Describe the structure of a protein
Primary structure - sequence of amino acids in a polypeptide linked by peptide bonds
Secondary structure - Coiling of the polypeptide chain forming a helix which is held together by hydrogen bonds between C=O- and NH+
Tertiary structure - Folding and twisting of the polypeptide chain to form a specific 3D shape held together by hydrogen bonds between R groups containing OH. Ionic bonds between R groups that have charges and disulphide bonds between R groups that have sulphur
Quaternary structure - 2 or more polypeptides linked together
How do non competitive inhibitors work
Not complementary to the same active site as substrate but will bind to another site called the allosteric site which changes the tertiary structure and active site of the enzyme which completely stops ROR as no E-S complexes can be formed
How does temperature affect enzyme activity
Increased temp means more kinetic energy so more collisions between enzyme and substrate so more E-S complexes formed resulting in higher ROR
However most enzymes denature above 40C because the heat breaks the bonds holding the enzyme together resulting in a lower ROR
Describe the structure of starch
Alpha glucose
Coiled
Storage polysaccharide
1,4 and 1,6 glycosidic bonds
Insoluble
Branched
What is a monomer?
Small molecules that can link together to form larger molecules
Write an equation for the formation and hydrolysis of ATP
ATP synthase
ADP + Pi ——————> ATP + H2O = ATP formation
ATP hydrolase
ATP + H2O —————–> ADP + Pi = ATP hydrolysis
Explain how the structure of starch is beneficial
Coiled -Makes it compact so it can store as much glucose as possible in a small area
Branched - Branch ends can be hydrolysed into glucose which can be then used in aerobic respiration
Large molecule - cant be diffused across cell membrane
Insoluble - does not affect water potential therefore no osmosis occurs and less risk of cell rupture and damage
Describe the structure of cellulose
Beta glucose
1,4 glycosidic bonds
Structural polysaccharide
Each alternate B glucose is inverted
Forms long straight chains
Describe the steps in starch digestion
- Starch chewed in mouth and exposed to amylase secreted by salivary glands which hydrolyses starch down to maltose
- Maltose travels down to the Ileum (in the small intestine) and is exposed to maltase which hydrolyses it into 2 alpha glucose
- Alpha glucose is then absorbed into blood stream
How is a peptide bond formed
Condensation reaction between a carboxyl group and amine group
What is a polymer?
A long molecule made up of the same repeating units
Explain 5 properties of water that make it important for organisms
Its a metabolite meaning its required for reactions like photosynthesis and hydrolysis reactions
Its a solvent allowing substances to dissolve in it and allow reactions to occur
High specific heat capacity so it can resist changes in temperature
High latent heat of evaporation meaning it exerts a cooling effect on organisms
Cohesive forces between water molecules support water columns
