Nutrition

• Nutrients - refers to any substance required for the growth and maintenance of an organism
• Autotrophs: organisms that obtain energy from sunlight and chemicals to produce their own food. Example: plants
• Heterotrophs - organisms that cannot make their own food and obtain their energy from other organisms
• Apoplastic Route - uptake of soil solution by the hydrophilic walls of root hairs provide access to the apoplast.
• Symplastic Route - minerals and water that cross the plasma membrane of root hairs can enter the symplast.
• Root hairs - slender extensions of specialized epidermal cells that greatly increase the surface area available for absorption.
• Root nodules - localized swellings in roots of certain plants where bacterial cells exist symbiotically with the plant.
• mycorrhizae - a symbiotic interaction between a young root and a fungus.
• Calorie - unit of energy that indicates the amount of energy contained in food.
• Carbohydrates - serve as a major energy source for the cells in the body. These are usually obtained from grains, cereals, breads, fruits and vegetables. On average, carbohydrates contain 4 Calories per gram
• Proteins - can also be used as an energy source but the body mainly uses these as building materials for cell structures and as enzymes, hormones, parts of muscles, and bones. Proteins come from dairy products, poultry, fish, meat, and grains. Like carbohydrates, proteins also contain 4 Calories per gram.
• Fats - are used to build cell membranes, steroid hormones, and other cellular structures. They contain a higher amount of energy per gram than carbohydrates and proteins, about 9 Calories per gram
• Essential Nutrients - include substances that animals can only get from the foods they eat because they could not be synthesized inside the body.
• Essential amino acids: needed for synthesis of proteins and enzymes
• Essential fatty acids: used for making special membrane lipids; an example is linoleic acid in humans.
• Vitamins: organic molecules required in small amounts for normal metabolism
• Trace elements or minerals: inorganic nutrients needed by the body in minute amounts