Unit 5 BIOL 1406 LAB REVIEW

Define a catalyst and give an example

Catalysts are substances that increase the rates of chemical reactions by lowering the amount of energy required for the reaction. An example would be enzymes

Define the following enzymatic terms: substrate, product, and active site.

1. The substrate fits into a specific site on the enzyme called the active site

2. The active site is where the activity, or catalysis of the reaction takes place

3. The enzyme can only work on substrates that fit into the active site. If a molecule cannot fit into the active site, it will not be converted into products

Describe the function of monosaccharides in the cell.

Cells cannot directly use the large starch molecules and first need to break down polysaccharides into individual glucose monosaccharides

Define a monomer and recall the monomer of many polysaccharides.

1. A monomer is a small, basic molecular unit that can chemically bond with other similar units to form a polymer.

2. Glucose is to the monomer of many polysaccharides

Recall the type of bond that forms between carbohydrate monomers

Glycosidic linkage

Describe what cells need to do to starch in order to obtain ATP/energy.

Once starch is broken down to glucose, the glucose functions as the intitial substrate for cellular respiration. Through a series of reactions in cellular respiration, glucose is further catabolized. The energy harvested from glucose is used to make adenosine triphosphate (ATP) which supplies energy to drive most forms of cellular work

Explain what an enzyme does to the activation energy of a reaction

An enzyme acts as a biological catalyst that speeds up chemical reactions by lowering the activation energy required for the reaction to proceed.

Recall the characteristics of the structure of carbohydrates (monosaccharide, polysacchardies, and disaccharide.)

1. Monosaccharide is glucose

2. Polysaccharide is starch

3. Disaccharide is maltose

Differentiate between monosaccharides, disaccharides and polysaccharides.

1. Monosaccharide means “one” so single monomer

2. Polysaccharide means “many” so many carbohydrate polymers

3. Disaccharide means “two”

Describe the structural difference between starch and cellulose

They have different linkages and cellulose cannot be digested by amylase whereas starch can.

Describe what is meant by the term substrate specificity

Substrate specificity refers to the ability of an enzyme to recognize and bind to a specific substrate (reactant) and catalyze its reaction. This is due to the unique shape and chemical properties of both the enzyme’s active site and the substrate.

Recall where in the body humans produce amylase

Salivary glands and the pancreas

Explain the effect of amylase on starch. Describe why this is useful in the human body and in industry.

In industry, using amylase to break down starch is a cheap and effective method used to produce simple carbohydrates (sugars) from plants.

The sugars produced can be used as food products or fermented to biofuel. If companies desire to generate simple sugars using amylase, they must generate substantial quantities of amylase

To produce massive amounts of the enzyme, food and biofuel industries have created amylase-producing bacteria.

Describe two different ways to detect amylase activity

1. The decrease in the amount of starch (can be detected using iodine)

2. The increase in the amount of product of the amylase reaction (maltose)

Describe what color iodine turns in the presence of starch. Describe the color of iodine when there is no starch present.

1. Deep blue black (presence of starch)

2. Yellow (no starch present)

Describe what color DNS reagent turns in the presence of maltose (reducing sugar). Describe the color of DNS when there is no maltose.

1. Dark amber/brown color (maltose)

2. Yellow (no maltose)

Differentiate between negative and positive controls.

Positive control has active amylase whereas negative control has no active amylase

Differentiate between quantitative and qualitative data

1. Quantitative involves numbers

2. Qualitative involves descriptions of observations (ex: color, shape, size)

Describe why you used human saliva in these experiments. Describe what you expected to be present in the saliva you were testing.

1. It was used because human saliva contains salivary amylase which is responsible for breaking down starch into maltose

2. What was expected to be present in the saliva, was salivary amylase, water, and mucus

If you add iodine directly to a starch plate, describe the color the plate will turn

Blue-black

If you add iodine directly to a starch plate and you get no coloration, or a clear section, describe what this means. Explain what happened to the starch in the clear zone. Explain what a clear zone indicates regarding amylase activity

It means that starch area has been broken down by an enzyme, likely amylase. The clear zone means that the amylase activity is breaking down the starch.

Predict what will happen in each condition. (Will there be any maltose/DNS reaction?)

1. 2% starch + amylase buffer =

2. 2% starch + saliva =

3. 2% starch + 2% maltose=

4. 2% starch + commercial amylase =

1. maltose/dns reaction

2. maltose/dns reaction

3. maltose/dns reaction

4. maltose/dns reaction

Explain which of the conditions from the previous question is the

1. positive control for sugar production?

2. Negative control for sugar production?

3. Positive control for the DNS reagent?

1. Commercial amylase

2. Water

3. Maltose

Explain why the samples needed to incubate at 37°C for 10 min

For the amylase enzyme’s optimal temperature

Describe what has to happen to the DNS before a color change can be observed.

Maltose must reduce DNS since it is a reducing sugar