Lab: Biological macromolecules and scientific method

Steps of the Scientific Method

1. Make observations

2. Ask a question based on observations

3. Formulate hypothesis

4. Design methods for conducting experiments

5. Record results

6. Discuss results

7. Publish results

Standard format for scientific report

1. Title of authors

2. Abstract (one paragraph overview of paper, including results and conclusion)

3. Introduction (background information, research question, hypothesis)

4. Methods ( how experiment was done, and materials used

5. Results (state the facts)

6. Discussion (interpret and explain results

7. References ( citations, articles used in paper)

This format is IMRaD format

Biomolecules

carbohydrates, lipids, proteins, nucleic acids

What makes an "organic chemical"

Any chemical containing carbon and hydrogen arranged in rings or chains

Testing for carbon - organic/inorganic test

Test by: burning substance. If substance leaves a black or dark brown residue, then substance is positive for carbon, therefore it is organic.

-organic substances contain carbon

-inorganic substances are those without carbon

Monosaccharides or simple sugars

A single ring or chain or hydrated carbons.

These monosaccharides have the ability to donate electrons to other compounds, earning them the name "reducing sugars"

Monosaccharides are joined

By dehydration synthesis (the removal of water during glycosidic bond formation)

How to determine the presence of reducing sugars

Benedicts test

Benedict's test

Benedicts reagent is a copper containing solution that is blue-green in color. When heated in the presence of a reducing agent, forms a reddish/brown copper precipitate.

- amount of reducing agent present changes color of solution from blue to green, brick red , or brown

How to test for complex carbohydrates

Iodine test

Iodine test

Starch (polysaccharide), can be detected using iodine as an indicator.

- iodine is normally orange in solution, starch is normally colorless

-when solutions are mixes, a blue-black complex is formed, giving confirmation of the presence of starch

-iodine is a small molecule, able to pass through many cell membranes

Test for lipids

Emulsion test

Presence of lipids will be determined using a lipid a Sudan stain ( a red, fat soluble molecule that adheres to lipids.

-an emulsifier has both polar and non polar ends in its molecule. When added to oil and water, the polar ends of the emulsifying agent binds to water, and the non polar end binds to the oil.

How to test for proteins

Biuret test

When amino acids are joined together by means of a peptide bond, the result is what?

Polypeptide

How many amino acids do proteins use

20

How to tell if proteins are present via Biuret test

If there is a lavender color in the solution, then the test is positive for proteins

nucleic acids

made up of five separate building blocks known as nucleotides. Each nucleotide consists of three molecular subunits: phosphate group, a 5-carbon sugar and one of five nitrogen containing bases

how to isolate DNA out of a solution

using salt and an organic liquid called ethanol