Bio biological molecules chapter 3

Carbohydrates

carbohydrates are organic molecules made up of the elements carbon, hydrogen and oxygen. the hydrogen and oxygen atoms are present in the ratio two to one

-substrate for respiration

-form supporting structures like cell wall

-formation of lubricants like mucus

nutrients

nutrients are chemical substances in food that provide energy and materials needed by the body

Benedict's test

1. 2cm3 of food = 2cm3 of Benedict's solution

2. shake the mixture

3. please test you in a boiling water bath for 5 min

4. blue black = starch present

brown = absent

iodine test

1. place food substances (chop up if necessary) on a white tile

2. add 2-3 drops of dilute iodine solution to the substance to be tested

3. blue black = reducing sugar present, brown = absent

Lipids

-heat insulator for animals like blubber

-important component of cell membrane

-energy storage

ethanol emulsion test

0. chop food up into small pieces

1. 2cm3 of ethanol to the substance in a test tube

2. shake mixture thoroughly

2.5 allow solid particles to settle

3. add 2cm3 of water to mixture

clear = absent

cloudy white emulsion = fats present

proteins

-form enzymes to speed up chemical reactions

-produce hormones like insulin

-formation of antibodies

biuret test

1. 2cm3 biuret solution to 2cm3 of food sample in a clean test tube

2. shake well, allow the mixture to stand for 5 min

3. violet = proteins present, blue = absent