LC Biology- Food + Human Nutrition

Nutrition

the way in which an organism obtains and uses food

Role of nutrients in organisms

-Source of energy

-To make chemicals needed for metabolic reactions

-The raw materials for growth and repair of structures

6 common elements found in food

Carbon (C), Hydrogen (H), Oxygen (O), Nitrogen (N), Phosphorus (P), Sulfur (S)

5 elements present in dissolved salts

Sodium (Na), Magnesium (Mg), Chlorine (Cl), Potassium (K), Calcium (Ca)

3 trace elements

Iron (Fe), Copper (Cu), Zinc (Zu)

Biomolecules

chemicals that are made inside a living thing

Elements in carbohydrates & their ratio

Carbon (C), Hydrogen (H), Oxygen (O)

Cx(H20)y

Properties of Monosaccharide

-Composed of a single sugar unit (1 ring of carbon atoms)

-Sweet to taste

-Soluble in water

Examples of Monosaccharides

-Glucose:

Made by plant in photosynthesis

Main molecule from which living things get energy

Found in sweets & fruit

Disaccharides

-composed of 2 sugar units joined together

-sweet tasting

-soluable in water

Examples of disaccharides

-Maltose:

-Sucrose:

Polysaccharides

-Composed of many sugar units

-Insoluble or slightly soluble in water

-Not sweet tasting

3 Examples of polysaccharides

starch, cellulose, glycogen

Starch

-Made up of many glucose molecules

-Stored by plants

e.g. Bread, pasta

Cellulose

It is very strong (why it is used in structure of cell wall and difficult to digest

Glycogen

-Complex polysaccharide

-Animals store glycogen in their liver and muscles

Sources of carbohydrates

bread, potatoes, rice, pasta, sugars, fruits, sweets, cakes

Metabolic role of carbohydrates

Glucose is broken down in respiration to release energy.

Elements in Lipids

-Carbon ,Hydrogen, Oxygen- no simple ratio

Triglyceride

Smallest lipids.

One molecule of glycerol linked to 3 fatty acids

Phospholipid

Fat-like substances

One of the fatty acids are replaced with phosphate group

Sources of lipids

butter, oils, margarine, cream, fat on meat, fried food

Structural role of lipids

-Heat insulation

-Protection of organisms

Metabolic role of lipids

Lipids can be broken down in respiration to release energy

Elements in Protein

Carbon ,Hydrogen, Oxygen, Nitrogen.

Some contain small amounts of Sulfur or Phosphorus

No ratio

Sources of proteins

Fish, meat, eggs, beans

Sources of proteins

meat, fish, eggs, nuts, milk, peas, beans

Structural role of proteins

-Fibrous protein such as keratin is found in skin and hair

-Myosin is found in muscle

Metabolic role of proteins

-Proteins are used in enzymes to control reactions

-Proteins form antibodies to fight infection

Vitamins

-Complex carbon-based substances that the body cannot make

-Needed in tiny amounts

Vitamin C

Ascorbic acid

Soluble in water

Found in citrus fruits

Metabolic role of vitamin C

-Formation of connective tissues

-Growth and maintenance of bones and teeth

-Helps wounds to heal

-Helps immune system to function properly

Deficiency of vitamin C

Scurvy : poor healing of skin, bleeding under the skin, bleeding gums with loose teeth

Vitamin D

Most common form is calciferol

Soluble in fat

Sources are liver, fish oils, milk, egg yolk

Can be made by the action of ultraviolet rays on chemicals in the skin

Metabolic role of Vitamin D

-helps absorb calcium from the intestines

-needed for healthy bones and tooth formation

Deficiency of vitamin D

Rickets/Osteomalacia:

weak, brittle, deformed bones

2 Plant minerals, their source and use

-Magnesium:

Found in salts in the soil

Help form chlorophyll

-Calcium:

Found in salts in soils

Helps cell walls attach to each other

2 Animal minerals, their source and use

-Iron:

Found in liver, meat, green vegetables

Helps form haemoglobin

-Calcium:

Found in dairy products

Helps form bones and teeth

Water is essential to life for 3 main reasons:

-It is the liquid in which all metabolic reactions take place

-It provides the basis for transport systems in organisms

-It is the environment in which many organisms live

Metabolism

the sum of all the reactions in an organism

Anabolic reactions

use energy to convert smaller molecules into larger ones

e.g protein synthesis, photosynthesis, the formation of cellulose from glucose

Catabolic reactions

release energy when a complex molecule is broken down to a simpler form

e.g respiration, digestion, decay of dead organisms