Lab Practical 2: Carbohydrates Part 1

Give an example of a Monosaccharide, draw the chemical structure (straight-chain or cyclic when applicable) and describe its function as it pertains to animal nutrition.

Glucose (C6H12O6) - provides both energy & structure. Can be broken down in glycolysis, providing energy & precursors for cellular respiration.

What type of carbohydrates do you identify through the use of a Benedict's test?

Reducing/Non-reducing sugar

Sodium carbonate acts as an enediol. What does this mean?

Sodium carbonate makes the reducing sugar become a stronger reducing agent i.e., enediol.

The Iodine test, using potassium iodine, identifies the presence of ________.

Starch

Give an example of a Disaccharide, draw the chemical structure (straight-chain or cyclic when applicable) and describe its function as it pertains to animal nutrition.

Sucrose (C12H22O11) - provides the body with the energy required to perform physical & mental functions.

What is the ratio of hydrogen to oxygen atoms present in a carbohydrate?

2H : 1O

Name two monosaccharides and the chemical formula for each.

1) 3C Tritose: C3H6O3 2) 5C Pentose: C5H10O6

During the Benedict's test, If a reducing sugar is present, the solution will reduce ____1____ to ____2____.

1) Copper sulfate 2) Copper oxide

What is a disaccharide? Give an example.

2 monomers joined by covalent bonds ex: table sugar (Sucrose)

What is a carbohydrate?

A molecule of hydrated carbon atoms.

What type of chemical reaction takes place in a Barfoed's Test?

A reduction reaction takes place.

What identifies an alpha versus a beta bond? Draw an example of each.

Alpha - •where the C1 OH that is formed ends up BELOW the C1 hydrogen Beta - where the C1 OH that is formed ends up ABOVE the C1 hydrogen

Which of the following would be identified using a Barfoed's test? A) Lipids B) Disaccharides C) Polysaccharides D) Amino Acids

B) Disaccharide

What three atoms come together to form carbohydrates?

Carbon, hydrogen, & oxygen

Give an example of a Polysaccharide, draw the chemical structure (straight-chain or cyclic when applicable) and describe its function as it pertains to animal nutrition.

Cellulose (C14H26O11) - helps maintain normal digestive function & also slows digestive processes.

Which of the following molecules listed above cannot be hydrolyzed in the digestive system of most animals? Why?

Cellulose, b/c they have a smaller GI system that lack digestive enzymes that can digest cellulose.

What is the simplest form of carbohydrates?

Monosaccharides

What type of carbohydrates would indicate a positive Barfoed's reaction?

Monosaccharides

Glycogen is an example of what form of carbohydrate?

Polysaccharide

How does the number of hydrogen atoms and the number of oxygen atoms compare in a carbohydrate?

The number of hydrogen atoms is higher

You are conducting a Barfoed's test on a carbohydrate sample. A red/brown precipitate appears by 12 minutes after adding the solution to the sample. What have you identified about your carbohydrate?

The sample is a disaccharide.

Is a chain of α (alpha) 1-4 glucose molecules more readily available than a chain of β (beta) 1-4 glucose molecules? Explain.

Yes, b/c α 1-4 chains are formed w/the help of glycogen synthase enzyme. These enzymes help in catalysis & synthesis of α 1-4 glyosidic linkage whereas chains β 1-4 glucose molecules are mainly present in cellulose.

What would be the resulting end product(s) if the following molecules are hydrolyzed? a) Sucrose - b) Cellulose - c.) Glycogen -

a) Glucose & Fructose b) Glucose c) Glucose