Lab 3: Biomolcules Flashcards
What are the four major classes of organic molecules produced by living organisms?
Proteins
Nucleic Acid
Carbohydrates
Lipids
What is a monosaccharide?
Monosaccharides are the simplest unit of carbohydrates, often referred to as simple sugars.
Why are all monosaccharides and most disaccharides reducing sugars?
Because they contain a free aldehyde or ketone functional group that can undergo oxidation-reduction reactions.
What is meant by the term reduction? What is a reducing agent?
Reduction is when an atom or molecule gains one or more electrons. The substance that donates/loses the
electron is called a reducing agent.
What is meant by the term oxidation? What is an oxidizing agent?
Oxidation is when an atom or molecule loses one or more electrons. The substance that accepts the electrons is called an oxidizing agent.
Suppose you have performed Benedict’s assay with glucose. Which molecule/ion has become oxidized?
Which one has become reduced?
Glucose loses electrons and becomes oxidized (reducing agent).
Cu2+ gains electrons and is reduced (oxidizing agent).
Why is sucrose not a reducing disaccharide?
Because it lacks a free anomeric carbon atom. As a result, sucrose cannot open and close its ring structure and therefore cannot act as a reducing sugar.
List the monosaccharides and reducing disaccharides that were assayed in the lab.
Monosaccharides: Glucose, fructose, galactose
Reducing Disaccharides: Lactose, maltose
What is the difference between reducing disaccharides and non-reducing disaccharides?
Reducing disaccharides have a free anomeric carbon atom that allows it to open and close its ring structure.
Non-reducing
disaccharides do not have this feature.
Name three polysaccharides and their function in cells.
- Starch stores energy in the form of glucose
- Glycogen releases energy in the form of glucose
- Cellulose provides structure rigidity and strength.
If you completely hydrolyze a starch molecule, what would you produce?
Individual glucose molecules.
All monosaccharides (are/are not) reducing sugars.
are
Benedict’s Assay turns positive to indicate…
reducing sugars
Barfoed’s Assay turns positive to indicate…
monosaccharides
Iodine Assay turns positive to indicate…
Starches
