Biology Lab 2 Flashcards
4 main macromolecules
Carbohydrates (sugars),
Lipids (fats),
Proteins,
Nucleic Acids
Reducing sugar
Has an Aldehyde group on it.
Can reduce copper ions (at proper pH)
Copper ions react with glucose to form a precipitate of ?
Copper oxide
Which precipitate has more sugar? Green or brownish red?
Brownish red
Benedict’s solution is used to test for ?
Presence of simple sugars (in food, blood, urine)
Reducing sugars are either monosaccharides or?
Disaccharides
If Benedict’s reagent is added to a solution and it turns blue, is there a reducing sugar?
No
If Benedict’s reagent is added to a solution and it turns orangish brown, is reducing sugar present?
Yes
A single or simple sugar is called a
Monosaccharide (mono=1) (saccharine=sugar)
2 or more monosaccharides bonded together are called?
Oligosaccharides (oligo=few)
Barfoed’s reagent is used to
Distinguish between monosaccharides and oligosaccharides.
Benedict’s reagent and Barfoed’s reagent both contain?
Copper ions
Which reagent is more acidic? Benedict’s or Barfoed’s?
Barfoed’s
If Barfoed’s reagent is added to a solution and a reddish precipitate forms at the bottom of the test tube, are monosaccharides present?
Yes
List 3 monosaccharides.
Glucose, Fructose, Sprite
________is a polysaccharide used for storing energy in plants
Starch
Starch reacts w/ Lugol’s iodine (IKI) to produce what color?
Dark blue/black
List 2 characteristics of LIPIDS (oils, fats, waxes, steroids)
Do not dissolve well in water
Do not all have similar chemical structures (like carbohydrates do)
Name 2 types of tests for lipids
Brown paper test
Sudan IV test
Sudan IV is a ______________ that dissolves in_____________ but not in water.
Red powder
Lipids
Biuret is prepared from?
Urea
Biuret contains 2?
Peptide bonds
When Biuret reacts with copper sulfate, what color forms?
Purple
A reaction between copper ions and peptide bonds causes what color?
Purple
Proteins give a strong reaction to Biuret because?
Proteins contain many peptide bonds, which link individual amino acids in the polypeptide chain.
Name something that reacted with Biuret.
Albumin solution.
If a sample tests positive with Benedict’s reagent but not with Barfoed’s reagent, what can you tell about that sample?
That it contains a reducing sugar, but it is not a monosaccharide, it is an oligosaccharide.
Benedict’s reagent and Barfoed’s reagent are both blue because?
They both contain copper ions
Draw 2 different isomers of the chemical C2H6O
Draw
List 2 foods that would react with Benedict’s reagent but not with IKI
Soda (Sprite), Apple?
Macromolecules
Latin -> macro = large
Large molecules that make up important parts of the cell
