1A: Biological Molecules Flashcards
The Theory of Evolution
All organisms on Earth are descended from one or a few common ancestors and that they have changed and diversified over time
Evidence for the Theory of Evolution
Universal DNA, same base sequences code for the same Amino Acids
Examples of Monomers
Monosaccharides, Amino Acids, Nucleotides
Examples of Polymers
Carbohydrates, Proteins, Nucleic Acids
Reaction to form Polymers from Monomers
Condensation Reaction
Reaction to break Polymers into Monomers
Hydrolysis
The elements in Monosaccharides
C, H, O
3 Examples of Monosaccharides
Glucose, Fructose, Galactose
Structure of Glucose
Hexose Sugar
Drawn Structure of Glucose
Alpha is same side for OH
Beta is opposite
3 Examples of Disaccharides
Sucrose, Lactose, Maltose
What Maltose is formed of
2 a-Glucose Molecules
What Lactose is formed of
Glucose and Galactose
What Sucrose is formed of
Glucose and Fructose
The name for the test for Sugars
Benedict’s Test
Steps to test for a Reducing Sugar
- Add Benedict’s Reagent and heat gently
- Positive result = Brick Red Precipitate. Negative result + Remain Blue
Steps to test for a Non-reducing Sugar
- Add Benedict’s Reagent and heat gently
- Negative result = remain blue
- Heat a new sample with dilute HCl
- Neutralise by adding Sodium Hydrogencarbonate
- Retest with step 1
Structure of Starch
Amylose- long, unbranched chain of a-Glucose coiled together compactly
Amylopectin- long, branched chain of a-Glucose, side chains are easily accessed by enzymes to help release Glucose quickly
Structure of Glycogen
Very branched chain of a-Glucose found in animals
Structure of Cellulose
long, unbranched chain of B-Glucose, chains held together by Hydrogen Bonds forming Microfibril Structure
Steps to test for Starch
Add Iodine dissolved in Potassium Iodide Solution. Positive result is orange to blue/black
Structure of a Triglyceride
1 Glycerol (hydrophilic) with 3 Fatty Acid Chains (hydrophobic)
Difference between Saturated and Unsaturated fatty Acid
Unsaturated has a C=C double bond
How Triglycerides are formed
Condensation Reactions to for Ester Bonds
Structure of a Phospholipid
1 Glycerol (hydrophilic), 2 Fatty Acid Chains (hydrophobic), and a Phosphate Group
Properties of Triglycerides
Used as energy storage molecules, long hydrocarbon tails can store lots of chemical energy
Insoluble in water, won’t affect water potential
Bundle into droplets
Properties of Phospholipids
Can form a Bilayer, that is the cell membrane
Test for Lipids
Emulsion Test
1. Shake substance with Ethanol
2. add water
Milky emulsion will form
The monomer of Proteins
Amino Acids
Structure of a Dipeptide
2 Amino Acids with Peptide Bond
Structure of a Polypeptide
More than 2 Amino Acids joined together by Peptide Bonds
Amino Acid Structure
A Carboxyl Group, an Amine Group, and an R Group
Reaction to form Dipeptides and Polypeptides from Amino Acids
Condensation
Structure of Proteins
Primary Structure- the sequence of Amino Acids in a Polypeptide Chain
Secondary Structure- Hydrogen Bonds form between Amino Acids in the chain and an Alpha Helix or beta Pleated Sheet is formed
Tertiary Structure- Hydrogen Bonds, Ionic Bonds, and Disulfide Bridges (between Cystines) form further folding the structure
Quaternary Structure- Multiple polypeptide chains held together by bonds
Enzyme Structure
Roughly Spherical due to tight folding polypeptide chains
Soluble and often have roles in Metabolic Reactions
Antibody Structure
Made of 2 light Polypeptide Chains
Have Variable Regions where the Amino Acid Sequence varies
Transport Protein Structure
Contain Hydrophobic and Hydrophilic amino acids, which cause the proteins to fold up and form channels
Structural proteins Structure
Physically Strong
Consist of long peptide chains lying parallel to each other with cross-links between them
eg. Keratin, collagen
Steps to test for proteins
- add a few drops of Sodium Hydroxide Solution
- add some Copper (II) Sulfate solution
- positive result = Blue to Purple
Definition of an Enzyme
Biological Catalyst
How enzymes speed up reactions
Provide an alternate reaction pathway with lower activation energy
When a substrate fits into an enzyme’s active site
Enzyme-Substrate Complex
The Lock and Key Model
Enzyme is the lock, Substrate is the Key (wrong)
The Induced Fit Model
Helps explain why Enzymes are so specific and only bond to one particular substrate
The active site changes shape to fit the substrate
The factors affecting Enzyme Activity
Temperature, pH, Substrate Concentration, Enzyme Concentration
Ways to measure enzyme activity
- How fast the product is made
- How fast the product is broken down
How temperature affects enzyme activity
More heat = more kinetic energy = molecules move faster
This makes the substrate molecules more likely to collide with enzyme’s active site
If the temperature gets too high, the enzyme’s molecules vibrate more and this can break the bonds that hold the enzyme’s shape and cause it to denature
How pH affects enzyme activity
al enzymes have an optimum pH
any pH other than this then the H+ and OH- ions in acids and alkalis disrupt the ionic bonds in the enzyme’s structure and cause it to denature
How Substrate Concentration affects enzyme activity
the higher the substrate concentration, the faster the reaction (more successful collisions)
increases until saturation is reached
How Enzyme Concentration affects enzyme activity
the higher the enzyme concentration, the faster the reaction (more successful collisions)
increases until saturation is reached
Definition of Competitive Inhibitor
Has a similar shape to substrate molecule so takes its place, preventing other substrate molecules from bonding
Definition of Non-competitive Inhibitor
Binds to allosteric site and changes shape of enzyme’s active site
RP1- investigating enzyme-controlled reactions
Measuring rate of product production
- Set up boiling tubes containing the same volume and concentration of hydrogen peroxide
- To keep pH constant, add equal volumes of a suitable buffer solution to each boiling tube
- Set up the rest of the apparatus as shown in the diagram
- Put each boiling tube in a water bath set to a different temperature (10, 20, 30, 40) along with anopther tube containing catalase. Leave them for 5 minutes to get them to the correct temperature
- Use a pipette to add the same volume and concentration of catalase to each boiling tube. Then quickly attach the bung and delivery tube
- Record how much oxygen is produced in the first minute of the reaction
- Repeat the experiment at each temperature and use the results to find the mean volume of oxygen produced
- Calculate the mean rate of reaction at each temperature by dividing the volumes of oxygen produced by the time taken
Measuring the rate of substrate usage
- Put a drop of iodine in potassium iodide solution into each well on a spotting tile. Label the wells to help read the results
- Mix together a known concentration and volume of amylase and starch in a test tube
- Using a dropping pipette, put a drop of this mixture into one of the well containing iodine solution at regular intervals
- Observe the resulting colour change
- Record how long it takes for the iodine solution to no longer turn blue/black when the starch/amylase mixture is added
- Repeat the experiment using different concentrations of amylase
- Repeat 3x each time to calculate a mean time taken
