Food - storage, structure and role

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Nutrition is the way in which an organism obtains its food

A nutrient is any substance that is important in sustaining life (the major nutrients are proteins, carbohydrates, lipids, vitamins, minerals, and water). They are chemical substances present in food that are use by organisms to maintain metabolism and the continuity of life.

Nutrients are used

as a source of energy

to make chemicals needed for cell or metabolic reactions

as the raw materials for the growth and repair of stuructures in an organism.

ELEMENTS

Common elements

Carbon

Hydrogen

Oxygen

Nitrogen

Phosphorous

Sulfur

Dissolved salts

Sodium

Magnesium

Chlorine

Potassium

Calcium

Trace elements

Iron

Copper

Zinc

*with the exception of C, H, O, the above elements are referred to as minerals

Compounds made from carbon are said to be organic compounds

Biomolecules / biochemicals are substances made by living things that have important metabolic roles. They are organic compounds that contain carbon, hydrogen, and other elements.

Carbohydrates

Lipids (fats and oils)

Proteins

Vitamins

ELEMENTS: C,H,O

FORMULA: Cx(H2O)y

(where x and y are the same number i.e. there is always twice as much hydrogen as oxygen in a carbohydrate e.g. C6H12O6 (glucose)

SOURCES: bread, rice, potatoes, pasta

monosaccharides

disaccharides

polysaccharides

MONOSACCHARIDES

Single sugar units (ring of carbon atoms)

Sweet & soluble in water

Energy providers

5 carbon sugars- pentoses (e.g.ribose, deoxyribose)

6 carbon sugars - hexoses (e.g. glucose --> main molecule from which organisms get their energy - fruit,sweets), fructose (sweeter than glucose - fruit) and galactose.

DISACCHARIDES

Two monosaccharides joined together

Sweet & soluble in water

Energy providers

e.g. sucrose (table sugar - glucose + fructose)

maltose (found in germinating seeds - glucose + glucose)

lactose (found in milk - glucose + galactose)

POLYSACCHARIDES

Many monosaccharides linked together

Not sweet & insoluble in water

Food storage / structural support

e.g. starch (amylose)--> carbohydrate stored by plants

composed of branched and unbranched chains of glucose molecules

food storage in plants

easily digested (glucose molecules arranged in a line)

rice, potatoes, flour, bread, pasta

cellulose --> structural carbohydrate in plants (cell wall)

composed of long chains of glucose molecules bonded together

more cross bonding between chains than starch as it is not readily broken down it acts as a source of fibre in animal diets.

chitin --> strong polysaccharide in the exoskeleton of arthropods (crabs, beetles, lobsters, and the cell walls of fungi

offers structural support

glycogen--> polysaccharide stored by animals

many glucose molecules, more branched than starch

stored predominantly in muscle and liver cells

Food - storage, structure and role

ELEMENTS: C,H,O

RATIO: No set ratio (very little oxygen)

e.g. C200H4O11

FAT: Lipids that are solid at room temperature (20 degrees)

OIL: Lipids that are liquid at room temperature (20 degrees)

Triglyceride: A lipid with 3 fatty acids linked to a glycerol, acts as the fat and oil energy reserves of plants and animals. (smallest lipid)

Food - storage, structure and role

Phospholipid: Fat-like substances where one of the fatty acids is replaced by a phosphate group or has a phosphate group attached to it. (major component of cell membranes).

Food - storage, structure and role

SOURCES: meat, milk, butter, chesse, plant oils, margarine.

STRUCTURAL ROLE

phospholipids --> cell membranes

under the skin --> heat insulation and energy store (adipose tissue)

protective layer around the internal organs e.g. kidneys

protective wax cuticle on the outside of plants e.g. holly

METABOLIC ROLE

energy storage --> contains more than 2x energy for the same mass of carbohydrate or protein.

energy source --> realeased during respiration

storage of fat soluble vitamins e.g. vitamin D

some lipids function as hormones e.g. oestrogen

ELEMENTS: C, H, O, N (P/S sometimes)

COMPOSED OF: Amino acids, linked in chains folds and branches. The bond between amino acids is called a peptide bond.

Food - storage, structure and role

A peptide has a small number of amino acids

A polypeptide has more than 20 amino acids

A protein is a long polypeptide (at least 200 amino acids)

Each protein has a specific 3 dimensional, functional shape.

The

The arrangement and sequence of amino acids determines the type of protein produced.

Fibrous proteins

Long chains in parellel form (little/ no folding) strong and tough e.g. collagen, myosin, keratin.

Globular proteins

Tightly folded amino acid chains giving a spherical shape e.g. enzymes

Protein synthesis takes place within the ribosomes of the cell.

Structural role

Keratin --> protein found in hair, finger nails, toenails, and the outer dead layer of skin.

Myosin --> major protein involved in the contraction of skeletal and cardiac muscle.

Collagen --> Major protein in cnonective tissue (elasticity of skin).

Metabolic role

Many proteins function as enzymes (biological catalysts).

Many proteins act as hormones, they are chemical messengers in th blood that help regulate many metabolic activities.

Food - storage, structure and role

Vitamins are organic compunds needed in small quantities in the diet to ensure a good standard of health. They are complex, carbon-based substances that the body cannot make.

VITAMIN C (WATER SOLUBLE --> ASCORBIC ACID)

Common sources: vegetables, fruit (espcially citrus fruits such as ornages and lemons)

Required by the body to assist with the absorption of iron from the gut and also to maintain strong connective tissue and for the growth and maintenance of bones and teeth.

Deficiency of vitamin C can result in scurvy.

Symptoms of scurvy include: internal bleeding, easy bruising, bleeding gums, loose teeth, poor healing.

Food - storage, structure and role

VITAMIN D (FAT SOLUBLE --> CALCIFEROL)

Good sources: milk, eggs, liver, fish liver oils, produced by the skin when exposed to U.V. light

Required by the body for the absorption of calcium and phosphorous from the gut and also to ensure healthy bone formation and maintenance.

Deficiency of Vitamin D can result in a disease called rickets (in children) and osteomalacia (in adults)

Symptoms include: late teething and walking, deformed legs and arms, and weak bones.

Food - storage, structure and role

ENERGY TRANSFER REACTIONS

All the reactions in an organism can be referred to as its matabolism. Metabolism can be divided into anabolism, and catabolism.

ANABOLISM

Smaller molecules are converted into larger ones (requires energy) e.g. protein synthesis/ photosynthesis

CATABOLISM

Complex molecules are broken down into simpler ones (release of energy) e.g. digestion/respiration.

Minerals are soluble inorganic salts that contain elements essential for a healthy metabolism. They are neeed in minute quantities by the body to maintain a healthy body.

Plants obtain their minerals by abosorbing them from soil water.

Animals obtain their minerals through their diet.

Plant mineral requirements

CALCIUM --> required for the formation of the middle lamella, located between the cells to 'glue' them together.

MAGNESIUM --> required for the production of chlorophyll

Animal mineral requirements

CALCIUM --> required for the healthy formation of teeth and bones.

IRON --> required for the formation of haemoglobin

WATER

Component of the cell's cytoplasm and also of the body's fluids.

Universal solvent --> an ideal transport medium for many soluble substances

Plays a role in a number of metabolic processes e.g. photosynthesis and respiration.

Enables dissolved substances to move through cell membranes.

Controls the shape of the cell, the red blood cells are biconcave in shape and as such is extremely efficient at carrying oxygen, its shape is determined by the correct level of water in the cell.

Good absorber of heat energy. A great deal of heat is required to increase temperature. As water is a temperature-stable medium it is ideally suited for metabolism and for homeostasis.

Participates in chemical reactions:

Condensation reactions: where smaller molecules join to form larger molecules with the loss of a water molecule

Food - storage, structure and role