Biological Molecules Flashcards
What are the 4 main Biological Molecules?
- Carbohydrates
- Proteins
- Lipids
- Nucleic Acids
What are the major elements of Biological Molecules?
- Carbon
- Hydrogen
- Oxygen
- Nitrogen
What bonds are used in Biological Molecules?
- Covalent bonding
- Ionic bonding
- Hydrogen bonding
What is Covalent bonding?
When the 2 atoms share a pair of electrons in their outer shells. As a result, the outer shell of both atoms is filled and a more stable compound is made
What is Ionic bonding?
The attraction of ions with opposite charges
What is Hydrogen bonding?
An attraction between a Hydrogen atom and an atom with a negative charge eg. oxygen
What are large Biological molecules called?
Polymers
What are Polymers made up of?
Monomers which join together in a condensation reaction
How are Polymers broken down?
In a hydrolysis reaction
What is a Molar Solution?
A solution that contains one Mole of solute in each litre of the solution
What is a Mole?
One Mole contains the same number of particles as there are in 12g of Carbon-12 atoms
What are Carbohydrates made up of?
- Carbon
- Hydrogen
- Oxygen
What are the uses of Carbohydrates?
- Sources of energy in all organisms
- Structural materials used in cell walls and cell membranes
What are Monosaccharides?
The simplest form of sugars. They cannot be hydrolyzed into a simpler sugar
What is the general formula for Monosaccharides?
(CH2 O)n
(the n can be between 3-7)
What is the most common Monosaccharide?
Glucose (C6 H12 O6)
What are the 4 main Monosaccharides?
- Glucose
- Fructose
- Galactose
- Ribose
What are the 2 types of Glucose?
- Alpha Glucose (a)
- Beta Glucose (b)
What is Alpha Glucose used for?
It is used to make Starch and Glycogen
What is Beta Glucose used for?
It is used to make Cellulose
What are Disaccharides?
They are 2 Monosaccharides joined together by a Glycosidic Bond
How are Disaccharides formed?
Formed in a Condensation reaction involving water
How is the Disaccharide Maltose formed?
From 2 Glucose molecules
How is the Disaccharide Sucrose formed?
From 1 Glucose molecule and 1 Fructose molecule
How is the Disaccharide Lactose formed?
From 1 Galactose molecule and 1 Glucose molecule
What are Reducing Sugars?
Reducing sugars are sugars that can act as reducing agents by donating electrons to other substances. Which include all monosaccharides and some disaccharides,
What is the Benedict’s test?
When a Reducing Sugar reacts with Benedict’s solution and reduces the copper(II) ions to copper(I) ions, changing the colour from blue to orange.
What do you do when the Disaccharide cannot reduce the copper(II) ions?
The Disaccharide must be hydrolyzed into into Monosaccharides, which are all Reducing Sugars, so they can reduce the copper(II) ions
What are Polysaccharides?
They are long chains of Monosaccharides joined together by Glycosidic bonds via Condensation reactions
What are the 3 main Polysaccharides?
- Starch
- Glycogen
- Cellulose
What are the functions of Starch?
- Storage for plants
- Insoluble
- Forms starch grains inside many plant cells
- Can be broken down into Glucose and used as an energy source
What is Starch made out of?
Many Alpha Glucose molecules joined together in a Condensation reaction
How is starch good for storage?
Insoluble: Doesn’t affect water potential
Large: Doesn’t diffuse out of cells
Compact: Stored in small spaces
Hydrolysis: Forms Alpha Glucose, easily transported and used in respiration
Branched: High surface area for quick and easy hydrolysis
What is the difference between Glycogen and Starch?
Glycogen has shorter chains and is more highly branched
Where is glycogen mainly stored?
Small granules in in the muscles and liver
Why does glycogens’ structure suit it for storage?
Insoluble - doesn’t draw water from osmosis and it can’t diffuse out of cells
Compact - so lots can be stored in a small space
More branched than starch - so can be hydrolysed quicker than starch
What is cellulose made out of?
Beta glucose
What is different about cellulose’s structure to starch’s or glycogen’s
Cellulose has straight unbranched chains which allows lots of hydrogen bonds to form, making cellulose very strong
What is cellulose a major component of?
Plant cell walls. Cellulose provides rigidity to the plant cell and prevents it from bursting as water enters it by osmosis
What is the structure of triglycerides?
1 glycerol + 3 fatty acids joined by an ester bond
What are the roles of lipids?
Source of energy
Waterproofing
Insulation
Protection
What is the structure of phospholipids?
Two fatty acids, a phosphate group, and a glycerol molecule
What is the test for lipids?
The emulsion test
Add 5cm^3 of ethanol to 2cm^3 of the solution you want to test. Shake thoroughly to dissolve any lipid in the sample. Add 5cm^3 of water and shake again, A cloudy white colour indicates the presence of a lipid
What is the primary structure of proteins?
Polypeptides
How are amino acids linked to form polypeptides?
Through polymerization, which is a series of condensation reactions.
What is the secondary structure of proteins?
Alpha helix
What is the tertiary structure of proteins?
Alpha helices twisted and folded together and held together with disulfide bridges, ionic bonds and hydrogen bonds
What is the quaternary structure of proteins?
A complex molecule containing a number of individual polypeptide chains that are linked in various ways
What is the test for proteins?
The Biuret test
Place a sample of the solution in a test tube and add equal volume of room temperature sodium hydroxide solution
add a few drops of very dilute copper(II) sulfate and mix gently
A purple colour indicates the presence of peptide bonds and therefore a protein
How do enzymes speed up chemical reactions?
They lower the activation energy required for the chemical reaction to start.
Explain the lock and key model of enzyme action
Enzymes work like a lock and key. The substrate will only fit the active site of one particular enzyme.
Explain the induced fit model of enzyme action
The active site forms as the enzyme and substrate interact. The proximity of the substrate leads to a change in the enzyme that forms the functional active site.
What is a catalyst?
An enzyme that alters the rate of a chemical reaction without undergoing permanent changes themselves
