chap 4- biological molecules Flashcards
What are the chemical components of organic molecules (including carbohydrates and lipids)?
- Carbon
- Hydrogen
- Oxygen
- Proteins also contain Nitrogen and Sulphur
- Nucleic acids also contain Phosphorous and Nitrogen
What is a carbohydrate?
- Made of simple sugar molecules
- Monosaccharides e.g. Glucose – one sugar
- Polysaccharides e.g. starch, glycogen, cellulose- many sugars
What is a lipid?
- Made up of fatty acids and glycerol
- 3 fatty acids to 1 glycerol molecule
- Fats are solid at room temp, oils are liquid
What is a protein?
- Chains of amino acids
- Sequence is coded for by genes
- Sequence of amino acids determines protein shape
- Protein shape and structure gives the protein its function
How does the shape of an enzyme determine its function?
- Enzyme has active site
- Active site has specific shape
- Only target molecule can fit in the active site
How does the structure of an antibody allow it to work?
- Antibodies have a binding site
- Binding site has specific shape
- Can therefore recognise specific antigens
What is the food test for starch?
take a few drops of the sample on a white tile. add a drop of iodine solution. observe the color change from orange-brown to blue-black confirming the presence of starch
What is the test for glucose?/ reducing sugar
take a known volume of sample, and add an equal volume of benedicts solution. Heat using a thermostatically controlled digital water bath at 80°C. observe the color change from
a) blue to green ( traces )
b) blue to yellow ( low concentration)
c) blue to orange ( mild concentration)
d) from blue to brick red ( high concentration)
What is the test for protein?
take a known volume of sample, add a few drops of biuret solution, observe the color change
a) blue to lilac ( low concentration)
b) blue to purple ( mild concentration)
c) blue to violet ( high concentration
Fat test
take a sample in a test tube, add ethanol until you get a clear solution. add a few drops of distilled water. if the solution turns cloudy or milky it confirm the presence of starch
What is the test for Vitamin C?
add 1cm³ of DCPIP solution in a test tube, add small amount of sample. observe the color of blue color disappearing
Catalyst
Substances that increase the rate of chemical reaction without being changed by the reaction
Enzymes
proteins that are biological catalyst that speed up chemical reactions
Describe the structure of DNA
Describe the structure of DNA
* Two strands coiled in a double helix
* Strands contain bases
* Cross-links formed by base pairs
* Adenine (A) with Thymine (T)
* Cytosine (C) with Guanine (G)
What is the role of water in organisms?
Important as a solvent for digestion, excretion and transport
