Comprehensive lecture notes for lecture 2

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26 Sep 2010

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BIO204 Lecture 2 t Animal Nutrition: Benefits and Problems of Complex Molecules
- A nutrient is a substance that an organism requires to remain alive. Nutrients may be sources of
energy or raw materials required to synthesize compounds for growth and maintenance of cell
functions. Water is an essential nutrient to nearly every organism.
- Animals may be classified based on the method by which they acquire carbon compounds and
energy. Carbon compounds that have high potential energy are oxidized to ATP to form a more
readily available store of energy.
- Carbohydrates, fats, and proteins supply organisms with energy. Fat is more saturated than
carbohydrates and proteins and thus contains a far greater amount of energy per unit mass
(aprox. 2X the amount of E per gram)
- The average human adult male is composed primarily of water (aprox. 60%). Protein is the
second-most abundant molecule category in the body (18%), while fats account for 14% and
carbohydrates for about 2%.
- Water is a crucial nutrient as it is necessary for nearly all biological functions. Water is a solvent
for biological reactions, facilitates heat exchange, lubricates tissues and facilitates passage of food
through the digestive tract.
- Carbohydrates are the primary energy source for most organisms. Although they provide less
energy than fats, nervous tissues can only be supplied with energy by carbohydrates. Sugars are
also very important in cell-cell signaling and adhesion.
- Lipids are the ultimate energy source for most organisms; they provide twice the amount of
energy per gram as sugars. In addition, fats have high satiation values, making organisms feel full
more quickly, thus preventing overconsumption. Additionally, fats are major components of cell
PM, are solvents for steroids and vitamins, and are excellent insulators of heat.
- Proteins are found in all tissues, but occur in large amounts in muscle tissues. Proteins catalyze
biological reactions, are necessary for growth and metabolism, and may even be used as energy
sources when all other sources have been depleted.
- Inorganic salts are crucial for the smooth operation of metabolic and biological processes. Salts
are used in virtually all body functions, since they allow regulation of osmolarity and hydrostatic
forces in the body[µ}µvÀ]}vuvX^}uv}]µuv(}]}v
potentials, calcium is needed for muscle contraction, phosphorous is used in the production of
bone (hydroxyapatite), iron is used in hemoglobin, and iodine is necessary to maintain proper
thyroid gland function.
- Vitamins (both fat and water soluble) are essential for survival, although only small quantities are
required. Vitamin C is essential for collagen synthesis, Vit. D is necessary for proper bone
formation and nutrient absorption, and other vitamins are needed for various biological reactions.
- Caloric intake describes the amount of energy that is taken in by an organism; undernourishment
refers to when the body must catabolize its own energy reserves in order to compensate for
deficits in caloric intake
- Malnutrition results when an organism lacks essential nutrients; this state may result in diseases
such as Rickets, Scurvy, and Goiter.
- Animals can be divided into two categories:
- Autotrophs: can produce organic compounds
- Heterotrophs: must absorb organic compounds
- Heterotrophs can be further divided into:
- Herbivores: eat only plants
- Carnivores: eat only animals
- Omnivores: eat plants and animals
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