Biology lab toucan manual topic 2

Biomolecules

Macromolecules found in living systems containing five or more carbon atoms linked together to form a ring or chain

The four key biomolecules

Carbohydrates, lipids, proteins, and nucleic acids

Organic compounds

Contain carbon, hydrogen, and oxygen

Basic structural unit of nucleic acids

Nucleotide

Indicators

Chemicals that change color in the presence of a specific chemical substance

Color change indicates

Positive test result

No color change indicates

Negative test result

What is used as the control in all chemical analyses?

Distilled water

Carbohydrates

Provide substrates for cellular respiration and lead to energy production

Basic building blocks for carbohydrates

Monsaccharides (sugars)

Disaccharide

Two monosaccharides joined together by a condensation reaction

Polysaccharide

Monosaccharide molecules are often linked together to form a medium length chain

Example of polysaccharides

Starch, cellulose, and glycogen

Benedict’s test

Detects the presence of reducing sugars

Positive Benedict’s test result

Yellow, orange, or red-orange

Negative Benedict’s test result

Blue

Lugol’s test

A carbohydrate test that identifies the presence of starch

Polymers of glucose

Starch molecules

Positive Lugol’s test result

Dark blue-black

Negative Lugol’s test result

Brown/yellow

Compounds insoluble in water

Lipids

Lipids include

Fats, oils, phospholipids, waxes, and steroids

Most common form of lipids

Polymer triglyceride

Polymer triglyceride consists of

A glycerol molecule combined with three fatty acids

Why does Sudan IV associate with lipids?

Fat-soluble dye that is hydrophobic

Sudan IV test

Tests for the presence of fats

Positive Sudan IV test result

Orange colored spot

Negative Sudan IV test restul

Red particles or colorless spot

The basic unit of a protein molecule

Amino acid

Peptide bond

The bond between two amino acids

Dipeptides or polypeptide

Short protein chains

Ninhydrin reagent test

Test for alpha amino acids and proteins containing free amino and acid groups

Free amino acid

One that is not joined to another amino acid in a chain or ring

Positive ninhydrin test result

Purple or violet

Negative ninhydrin test result

Yellow

Why isn’t the amino acid group in proline free?

It is a part of the 5-membered ring structure of a molecule

Serine

Proline

The Biuret test

Detects the presence of proteins and short peptide chains of amino acids

Positive Biuret test result

Violet

Negative Biuret test result

Blue

Why is there a color change in the Biuret test?

The amine groups in the amino acids react with the copper ions