Moduel 1 : Biological Molecules Flashcards
What is a Monomer?
One of many small molecules that combine together to form a polymer.
What is a polymer?
Molecules made of lots of repeating units (monomers) joined together.
What are some examples of Monomers?
Amino Acids, Monosaccharides and nucleotides.
What is a condensation reaction?
A reaction which joins two molecules together with the formation of a covalent bond and involves the elimination of a a molecule of water.
What is a Hydrolysis reaction?
A reaction which breaks the covalent bond between two monomers and involves the use of a water molecule.
What are the elements which make up the molecules of life?
The molecules of life all contain Carbon, Hydrogen and Oxygen. These are all organic.
What four categories can all molecules of life be grouped into?
Carbohydrates, Lipids, Proteins and Nucleic Acids.
What is an organic molecule?
Molecules containing carbon that can be found in living things: four classes are carbohydrates, proteins (chains of amino acids), lipids and nucleic acids.
What is a Monosaccharide?
These are individual sugar molecules that make up disaccharides and polysaccharides.
What are three examples of a monosaccharide?
Glucose, fructose and galactose.
What type of sugar glucose?
A hexose sugar that can form two isomers: alpha-glucose and beta-glucose.
What is the difference between the structure of an alpha and a beta glucose molecule?
In alpha glucose the OH on carbon 1 and 4 are on the same side. Whereas in beta glucose the OH on carbon 1 and 4 are on opposite sides.
What is a disaccharide?
Disaccharides are formed when two monosaccharides join through a condensation reaction forming a glycosidic bond between the OH groups.
What are some examples of disaccharides?
Maltose = glucose + glucose (reducing)
Lactose = glucose + galactose (reducing)
Sucrose = glucose + fructose (non-reducing)
What are reducing sugars?
They can lose ore donate an electron to other compounds. All monosaccharides and some disaccharides are reducing sugars.
What is a glycosidic bond?
Bonds between sugar molecules in disaccharides and monosaccharides.
What is a polysaccharide?
A polysaccharide is formed when more than two monosaccharides are joined together by condensation reactions. Polysaccharides can be Broken down by hydrolysis back into t here monomers.
What are three examples polysaccharides?
Starch, Glycogen and Cellulose
What monosaccharide is starch made of?
Alpha glucose
What monosaccharide makes up glycogen?
Alpha glucose
What monosaccharide makes up cellulose?
Beta glucose
What is the structure of starch?
Mixture of two polysaccharides: amylose and amylopectin.
Amylose = long unbranched forms coiled/spring shape.
Amylopectin = long branched chain due to 1-6 glycosidic bonds.
What is the structure of glycogen?
A long, branched chain with lost of branches (more than amylopectin). The glycosidic bonds at branches are 1-6.
what is the structure of cellulose?
Long unbranched straight chains. The glycosidic bonds are 1-4. The cellulose chains are then linked together by hydrogen bonds between the glucose molecules in each chain to from thicker fibres called microfibrills.
What are the properties of amylose?
Coiling makes it compact and stores more in a smaller space.
What are the properties of amylopectin?
Branches increase surface area for enzymes to hydrolyse glycosidic bonds allowing glucose to be released quickly.
What are the properties of glycogen?
Lost of branches increase surface area for enzymes to hydrolyse glycosidic bonds allowing glycogen to be released quickly. It is also a compact molecule so it is good for storage.
What re properties of cellulose?
the hydrogen bonds between the cellulose chains make the microfibrils very strong but still flexible allowing them to provide support.
What are the uses of starch?
Plants use starch as a way of storing excess glucose as it is to large to leave cells and insoluble. Starch can be hydrolysed to release glucose for respiration.
what are the uses of glycogen?
Animals store excess glucose as glycogen in muscles and in the liver. Glycogen is therefor an energy store as it can be hydrolysed to release glucose quickly when needed for respiration.
What are the uses of cellulose?
Cellulose is a major structural component in the cell walls or plants, it provides support and allows cells to become turgid.
Are lipids polymers?
No
What are lipids used for?
Lipids can provide a source of energy, help to insulate organisms, act as waterproofing, form membranes and hormones.
What is a glycerol?
A molecule which combines with three fatty acids to form triglycerides. It is a 3 carbon chain with three hydroxyl groups.
What does hydrophilic mean?
Section of a molecule which is attracted to water.
What does hydrophobic mean?
Section of a molecule which is repulsed by water.
What is a lipid?
A class of organic molecule that are fatty acids are their derivatives and are insolvable in water but solvable in organic solvents. They include triglycerides, phospholipids, waxes and steroids.
What are mono-unsaturated fatty acids?
Fatty acid which possesses a carbon chain with a singe double bond between carbon atoms.
What is a phospholipid?
Triglyceride which one of the three fatty acid molecules are replaced by a phosphate molecule. Phospholipids are important in the structure of a functioning of plasma membranes.
Hat is an poly-unsaturated fatty acid?
Fatty acid which is possesses a carbon chain with many double bonds between carbon atoms.
What is a saturated fatty acid?
A fatty acid in which there are no double bonds between carbon atoms.
What is a triglyceride?
A individual lipid molecule made up of a glycerol molecule and three fatty acids. Contains ester bonds.
What are the components of a triglyceride?
A glycerol molecule and three fatty acid chains.
What a re the components of a phospholipid?
A glycerol molecule, a phosphate group and two fatty acid chains.
What bond are involved in triglycerides?
Ester bond formed by condensation reaction between each of the three OH groups on the glycerol and the OH group of each fatty acid chain. They are non-polar.
What bonds are involved in phospholipids?
Ester bonds formed by condensation reaction between two OH groups on the glycerol and the OH group of each fatty acid chain.
What are the properties of a triglyceride?
The fatty acid chains are hydrophobic which makes lipids insolvable in water. They bundle together as insolvable droplets because the tails face inwards, and the glycerol heads shield them from the water. The hydrocarbon fatty acid chains can be saturated or unsaturated.
What are the properties of phospholipids?
The phosphate group is hydrophilic and the fatty acid chains are hydrophobic. This allows phospholipid to form bilayers which make up membranes in and around the cell.
How are triglycerides used?
Used as an energy store as there is a lot of energy released when the fatty acid chains are broken down.
How are phospholipids used?
Membranes, hormones
How does an unsaturated fatty acid effect the shape of a lipid?
The double bond causes the chain to bend or kink.
How do phospholipids form a bilayer?
Phospholipid heads are hydrophilic and their tails are hydrophobic so when placed in water they form a double layer with the heads facing outwards towards the water and their tails facing inwards away form the water.
What are the properties of a phospholipid bilayer?
The centre of the bilayer is therefor hydrophobic so water solvable substances cannot easily pass through. This creates a barrier and allows speciation of solutions and can create different conditions either side of the membrane.
What is an amino acid?
A monomer which makes up proteins. Has a central carbon atom which is bonded t a Carboxylic acid group, an amino group a hydrogen atom and an R group.
What is an amine group?
The -NH2 group of an amino acid.
What is a Carboxylic acid group?
The -COOH of an amino acid.
What is a disulphide bridge?
Bond formed between sulphur atoms in R groups of amino acids.
What is a hydrogen bond?
Chemical bond formed between the positive charge on a hydrogen atom and the negative charge on another atom of an adjacent molecule. Often between negative oxygen and positive hydrogen atoms.
What is an ionic bond?
A bond between a positive ion which has lost an electron and a negative electron which has gained and electron.
What is a peptide bond?
The type of bond that is formed between two amino acids.
What is a polypeptide?
Many amino acids joined together by peptide bonds.
What is a protein?
A polymer which is made up of amino acids linked by peptide bonds. May also contain prosthetic groups as part of its quaternary structure.
What is the R group?
Each of the 20 amino acids has a different R group - determines the bonding that the amino acid can carry out.
How do amino acids join to for a protein?
When two amino acids join via a condensation reaction a peptide bu=one is formed and a water molecule is released
What is a dipeptide?
When two amino acids bond together by a condensation reaction it is known as a dipeptide.
How can dipeptide and polypeptides broken down?
A hydrolysis reaction.
What is the primary structure of a protein?
The number and sequence of amino acids in the polypeptide chain. This can determine the 3D shape or tertiary structure and can therefor effect the shape of the active site of an enzyme.
What is the secondary structure of a protein?
Hydrogen bonds from between amino acids in the chain, this causes it to coil into an alpha-helix or fold into beta-pleated sheets. The many hydrogen bonds make these structures stable. Most channel proteins and made of alpha helices.
What is the tertiary structure of a protein?
This is the 3D shape of the polypeptide chain. It creates a specific shape due to the sequence of amino acids in the chain as hydrogen bonds, ionic bonds, disulphide bridges and hydrophobic interactions between the R groups. A change of the sequence of amino acids would affect the secondary structure as these bonds would form in different places. All enzymes, antibodies and some hormones have tertiary structures.
What is the quaternary structure in a protein?
If proteins are made of more than one polypeptide chain, then they are joined together to create quaternary structure. Antibodies and haemoglobin are examples of these. Other non-protein groups may also be associated. Like the heamo group in haemoglobin.
What are globular proteins?
They have a spherical shape when folding into there tertiary structure. They are compact, roughly spherical and are soluble in water.
What is a fibrous protein?
Long strands of polypeptide chains with cross linkages due to hydrogen bonds and have little to no tertiary structure.
What is activation energy?
Energy required to bring about a reaction.
What is the active site?
A group of amino acids that makes up the region of an enzyme into which the substrate fits to catalyse a reaction. It is made by the tertiary structure of the protein.
What does it mean if a enzyme is complimentary?
Describes the relationship between the active site of an enzyme and the substrate molecule - the way in which they fit together.
What is an enzyme?
A protein that acts as a catalyst and so lowers the activation energy needed for a reaction.
What is an inhibitor?
A substance which reduces the activity of an enzyme.
What is metabolism?
All the chemical processes that take place in living organisms.
What is the pH?
A figure expressing the acidity or alkalinity of a solution on a logarithmic scale on which 7 is neutral, lower values are more acidic and higher values are more alkali.
What is the rate of reaction?
The speed of a chemical reaction - can be worked out by looking at the decrease in concentration of a reactant over time or increase in concentration of a product over time.
Why are enzymes specific?
Each enzyme only catalyses a certain reaction.
What is a substrate?
A substance that is cited on or used by another substrate or process. Fits into the active site of an enzyme.
What is an enzyme substrate complex?
The intermediate forms when a substrate molecule interacts with the active site of an enzyme.
What is the lock and key model?
The original model which explained how enzymes worked. It stated that the shape of an active site is exactly complimentary (like a lock) to a specific substrate molecule (the key) and the substrate fits in exactly when they collide forming an enzyme substrate complex.
What is the enduced fit model?
New molecular evidence suggests that the shape of the active site of an enzyme is not exactly complimentary to the substrate molecule. When t he substrate collides with the enzyme, the active site can change shape slightly to fit around the substrate and form an enzyme substrate complex.
How does enzyme concentration effect the rate of the enzyme reaction?
Increasing enzyme concentration increases the number of active sites available for the substrate to collide with. More ES-complexes can form as enzyme concentration increases. The rebate of reaction will increase until the amount of substrate becomes the limiting factor as there are more enzymes than substrate so increasing the enzyme concentration will have no more effect on the rate. The gradient can be used to calculate how fast the rate is changing.
How does substrate concentration effect the rate of reaction?
Increasing the substrate concentration will increase the rate of reaction is there are more substrate molecules. More collisions so more ES-complexes will form. The rate of reaction will slow as the enzyme concentration becomes a limiting factor. When all the enzyme active sites are occupied increasing the substrate concentration will have no further effect on the rate.
How does temperature effect the rate of reaction?
As temperature increases so does the rate of reaction as there is more kinetic energy so the molecules move faster increasing the number of collisions and therefore the number of ES-complexes formed. Each enzyme has an optimum temperature. Once this has been reached increasing the temperature further decreases the rate of reaction. At high temperatures the enzyme molecules vibrate too much, and bonds are broken which maintain the tertiary structure. The active site changes shape and no more ES-complexes can be formed as the substrate no longer fits. The enzyme is permanently denatured, the reaction stops.
How does pH effect the rate of reaction?
All enzymes also have an optimum pH as well as temperature. Most wot best at pH 7 but some work best at pH 2 (e.g pepsin in the stomach). Above and below the optimum pH for each enzyme the H+ ions and OH disrupt the ionic and hydrogen bonds holding the enzyme’s tertiary structure in place. At extremes of ph the active site changes shape and no more ES-compleme can be formed as the substrate no longer fits. The enzyme is permanently denatured, the reaction stops.
What is a competitive inhibitor?
Have a similar shape to that of substrate molecules. Compete with the substrate to bind to the active site of the enzyme. They block the active site so the substrate cannot bind, and no ES complexes are formed.
What is a non-competitive inhibitor?
Do not bind to the active site as they have different shape to the substrate so don not compete. Bind to a site away from the actives site known as the allosteric site. Causes the active site of the enzyme to no longer be complimentary to the substrate so no ES complexes can be formed.
How will increasing the substrate concentration effect the rate of reaction with a competitive inhibitor?
Increasing the substrate concentration still increases the rate of reaction. Increasing the concentration of substrate will reverse the effects of a competitive inhibitor as the substrate will out-compete the inhibitor of the active site.
How does increasing the substrate concentration effect the rate of reaction with non competitive inhibitors?
Increasing the concentration of the substrate will not effect the rate of reaction. Increasing the concentration of the substrate will not have any effect on the rate of reaction as they cannot bind to the active site.
What is Benedict’s reagent?
Blue solution which is used to test for reducing and non-reducing sugars.
What is the Biuret test?
A simple biochemical reaction to detect the presence of protein, if the Biuret’s solution (blue) turnes purple when protein is present.
What is an emulsion test?
Test for lipids. Mix your sample with ethanol and then add water. If a white collude emulsion forms, then lipids are present.
What is a non-reducing sugar?
A sugar which cannot serve as a reducing agent. An example is sucrose.
What is the test for non reducing sugar?
Following a negative reducing sugar test. Heat the solution with HCl to hydrolyse the non reducing sugar into its monosaccharides. Then perform the Benedict’s test again. If you get a positive result after hydrolysis, then a non reducing sugar is present.
What is the test for a reducing sugar?
Heat a solution with Benedict’s reagent to test for reducing sugars. It it goes brick read, then a reducing sugar is present.
What is a reducing sugar?
A sugar that serves as a reducing agent. All monosaccharides are reducing sugars along with some disaccharides.
