LC BIOLOGY - FOOD AND FOOD TESTS

Food definition

• provides the nutrients needed for organisms

• to, get their energy

• and, the materials they require to live

Most Common Elements in Food

carbon

hydrogen
nitrogen

oxygen

phosphorus

sulfur

Elements in Dissolved Salts

Ca
Cl
K

Mg
Na

Trace Elements

iron (Fe)

copper (Cu)

zinc (Zn)

Biomolecules

chemicals that are made inside a living thing

Elements in Carbohydrates

carbon, hydrogen, and oxygen

Carbohydrate Ratio

Cx(H2O)y, where x=y

Monosaccharides

carbohydrates composed of a single sugar unit

e.g glucose and fructose

Disaccharides

carbohydrates composed of two sugar units joined together

e.g. maltose and sucrose

Polysaccharides

carbohydrates composed of many sugar units

e.g starch, cellulose

Carbohydrate Sources

• bread

• rice

• pasta

• sugars

Structural Role of Carbohydrates

cellulose is used to form plant cell walls

Metabolic Roles of Carbohydrates

• glucose made in photosynthesis

• glucose releases energy in respiration

Benedict’s Reagent

used to test for reducing sugars

blue to brick red

Iodine

used to test for starch

orange to blue/black

Lipids

made of C, H, and O

(in no specific ratio)

Fats

solid at room temperature

Oils

liquid at room temperature

Triglyceride

glycerol and 3 fatty acids

Phospholipids

fat-like substances in which one of the fatty acids is replaced by a phosphate group or has a phosphate group added to it

Lipid Sources

butter, creams, oils, fried foods

Structural Role of LIpids

• store energy

• insulate the body

• form membranes

Metabolic Role of Lipids

release energy in respiration

Brown Paper

test for lipids

Proteins

made of C, H, O, and N (S,P)

Protein Structure

amino acids peptides polypeptides protein

Protein Sources

meat, fish, eggs, milk

Structural Role of Proteins

form structures such as skin, hair, nails, and muscle

Metabolic Role of Proteins

• enzymes

• some hormones

• antibodies

Fibrous Protein

keratin

Globular Proteins

• egg whites (albumen)

• enzymes

Biuret Solution

used to test for proteins

(sodium hydroxide, then copper sulfate)

(blue to purple)

Vitamin C chemical example

ascorbic acid

Vitamin C Sources

vegetables, and fresh fruit

Metabolic Roles of Vitamin C (3p)

• forms connective tissue

• growth and maintenance of bones and teeth

• promotes a healthy immune system

Vitamin C Deficiency

scurvy (poor skin, bleeding, bad teeth and gums)

Vitamin D (chemical)

calciferol

Vitamin D Sources

liver, fish oils, made in the skin by ultraviolet rays

Metabolic Role of Vitamin D

helps absorb calcium for bones and teeth

Vitamin D Deficiencies

rickets in children, osteomalacia in adults

(weak, deformed, brittle bones)

Calcium

(absorbed from the soil)

needed by plants to hold cell walls together

Magnesium

needed by plants for chlorophyll

Calcium

needed in animals for bones and teeth

(found in milk and cheese)

Iron

needed for haemoglobin

(found in liver and green vegetables)

Water

• good absorber of heat

• good solvent

• participates in chemical reactions

• moves in and out of cells, giving them the correct shape

Fat Soluble Vitamins

• vitamin A

• vitamin D

• vitamin E

• vitamin K

Water Soluble Vitamins

• vitamin B

• vitamin C

Metabolism

sum of all chemical reactions in an organism

Anabolic Reaction

energy is taken in and used to convert small molecules to larger ones

e.g photosynthesis

Catabolic Reaction

larger molecules are broken down to smaller ones and energy is released

e.g. respiration

Necessity of Food

• source of energy

• make chemicals needed for metabolic reactions

• provides raw materials needed for growth and repair in organism