CHAPTER 4_Biological molecules

What are the three main categories of biological molecules in living organisms?

Carbohydrates, proteins, and lipids.

What elements are carbohydrates primarily composed of?

Carbon, oxygen, and hydrogen.

What is a molecule formed by a single glucose unit called?

a monosacharide

What is a molecule formed by 2 glucose units called?

a disaccharide)

What is a molecule formed by lots of glucose called

a polysaccharide

What are most fats (lipids) made made up of

triglycerides

What are the basic units that make-up fats/ triglycerides?

1 glycerol molecule and 3 fatty acid chains.

in what two categories are lipids divided into

• oils (liquid at room temperature)

• fats (solid at room temperature)

What are proteins formed by

long chains of amino acids

What do all amino acids have in common except for one thing

• common: structure

• different: R (variable) group

Is it true that when amino acids are joined, protein is formed

yes

How many different amino acids are there?

About 20 different amino acids.

What color change indicates a positive test for glucose using Benedict's solution?

A color change from blue to orange or brick red.

What solution do you use to find out if something contains glucose

Benedict's solution.

What are the steps to conduct an experiment for glucose

1. dissolve benedict’s solution in water.

2. Heat mixture in a 60°-70° water bath for about 5 minutes.

3. Take test tube out of water

4. a positive test result would show the change from blue to orange or brick red

What color indicates a positive test for proteins using Biuret solution?

A color change from blue to violet/purple.

What solution do we use to find out if something contains proteins

Biuret solution.

What are the steps to conduct an experiment for proteins

1. Add Biuret solution to the sample.

2. If test is positive the color will change to violet/purple.

What indicates a positive test for lipids when mixed with ethanol and cold water?

Formation of a cloudy emulsion.

What solution do we use to test for lipids

ethanol

What are the steps to conduct an experiment for lipids

1. Mix the sample with 2cm³ of ethanol, then add water and shake.

2. If positive, a cloudy emulsion will form.

What solution do we use to find out if something contains starch

Iodine solution.

What is the result of adding iodine to a food sample containing starch?

A color change to blue-black.

What are the steps to conduct an experiment for starch

1. Add iodine solution to the sample.

2. positive test would show change to blue-black.

What solution do we use to test for Vitamin C

DCPIP solution

What indicates a positive test for vitamin C with DCPIP?

The blue color of the dye disappearing.

What are the steps to conduct an experiment for Vitamin C

1. Add 1cm³ DCPIP solution to the test tube + small amount of food

2. If positive, blue colour of the dye will disappear.

What is the structure that contains the instructions for growth and development in organisms?

DNA

What instruction does DNA have

growth and development of the organisms

What does an organism consist of

2 strands of DNA in a double helix formation

What is a nucleotide composed of?

• A backbone: phosphate, a deoxyribose sugar,

• A base: (A, T, C, or G).

Which bases pair together in a DNA strand?

• Adenine pairs with Thymine (A-T)

• Cytosine pairs with Guanine (C-G).

What forms the 'backbone' of a DNA strand?

The phosphate and sugar sections of the nucleotides.

What is a gene?

A sequence of bases in DNA

What is the importance of the sequence of bases in DNA?

It holds the code for the formation of proteins.

What is COOC referred to

Carboxylic Acid

What is NH² referred to

Amino