Nutrition and Biological Macromolecules: Essential Concepts in General Biology

Nutrition

Interaction of Food with the Organism

Nutrition is the process by which organisms obtain and utilize food for maintenance, growth, reproduction, and survival. This involves several steps, including the acquisition, digestion, absorption, metabolism, and elimination of nutrients.

• Nutrients are required for maintenance, growth, and reproduction.

• Processes include finding/catching (foraging or predation), eating, digestion, absorption, metabolism, and elimination.

Essential Nutrients

Essential nutrients are substances that organisms cannot synthesize themselves and must obtain from their environment.

• Amino acids (some are essential)

• Fatty acids (some are essential)

• Vitamins (most are essential)

• Minerals (nearly all are essential)

These nutrients provide the essential components for cellular processes required for maintenance, growth, and survival.

Molecular Diversity from Carbon Skeleton Variation

Organic molecules are built from carbon skeletons, which vary in length and shape, leading to a diversity of biological molecules and activities.

• Carbon chains form the skeletons of most organic molecules.

• Variation in carbon chain length and shape changes biological activity.

Hydrocarbons and Chemical Groups

Hydrocarbons

Hydrocarbons are organic molecules consisting only of carbon and hydrogen. They are found in substances like oil and gasoline, and also as components of biological molecules such as fats.

• Hydrocarbons can undergo reactions that release large amounts of energy.

Chemical Groups

Certain chemical groups are key to the structure and function of biological molecules:

• Hydroxyl group: –OH

• Carboxyl group: –COOH

• Carbonyl group: >C=O

• Amino group: –NH2

• Sulfhydryl group: –SH

• Methyl group: –CH3

• Phosphate group: –PO42–

Minerals

Role and Importance

Minerals are inorganic nutrients required in small quantities for normal function and are essential for the formation of body structures and physiological processes.

• Iron: Found in blood (hemoglobin)

• Calcium: Bones, teeth

• Sodium: Nerve function

• Potassium: Nerve function

• Copper: Involved in enzymes; excess is toxic to sheep

• Iodine: Required for thyroid hormones

Most minerals have a 'sweet spot'—too high or too low levels can be harmful.

Vitamins

Definition and Function

Vitamins are organic nutrients required in small quantities for normal physiological function. Most cannot be synthesized by the organism and must be obtained from the diet.

• Some vitamins require minerals to function.

• Vitamin D can be synthesized from cholesterol in the skin with sunlight.

• Vitamins are classified as water-soluble (B's and C) or fat-soluble (A, D, E, K).

• Vitamin E requires selenium to be effective; without selenium, vitamin E is mostly useless.

Vitamin	Solubility	Main Functions	Deficiency Effects
B vitamins	Water	Coenzymes in metabolism	Fatigue, anemia, nervous system disorders
Vitamin C	Water	Antioxidant, collagen synthesis	Scurvy
Vitamin A	Fat	Vision, immune function	Night blindness
Vitamin D	Fat	Calcium absorption, bone health	Rickets, osteomalacia
Vitamin E	Fat	Antioxidant	Neurological problems
Vitamin K	Fat	Blood clotting	Bleeding disorders

Additional info: Table inferred from standard vitamin functions and deficiencies.

Carbohydrates

Definition and Types

Carbohydrates are organic molecules composed of carbon, hydrogen, and oxygen. They serve as a primary energy source for organisms.

• General formula: $C_n(H_2O)_n$

• Monosaccharides: Simple sugars (e.g., glucose, galactose, fructose)

• Disaccharides: Two monosaccharides joined by a covalent bond (e.g., maltose = glucose + glucose; sucrose = glucose + fructose)

• Polysaccharides: Many monosaccharides linked together (e.g., starch, glycogen, cellulose, chitin)

Storage Polysaccharides

• Starch: Plant storage polysaccharide (found in potatoes, grains)

• Glycogen: Animal storage polysaccharide (found in muscle, liver)

Structural Polysaccharides

• Cellulose: Major component of plant cell walls; indigestible by most animals without microbial help

• Chitin: Found in arthropod exoskeletons; provides structural support

Lipids

Fats

Lipids are hydrophobic molecules that include fats, phospholipids, and steroids. Fats are composed of glycerol and three fatty acids.

• Saturated fatty acids: No double bonds, saturated with hydrogen; typically found in animal fats

• Unsaturated fatty acids: One or more double bonds, fewer hydrogens; found in plant and fish fats

• Omega-3 fatty acids are essential for humans

Phospholipids

• Major component of cell membranes in animals

• Structure: two fatty acids + glycerol + phosphate group

Steroids

• Characterized by a carbon skeleton in four fused rings

• Precursor for hormone synthesis

• Cholesterol is a key example