Biological Organization and Nutrition Fundamentals

Levels of Organization: These correspond to degrees of complexity in organized matter. The levels are: subatomic, atomic, molecular, cellular, tissue, system, organelle, and body.

Cell Structure: Eukaryotic cells possess several key elements:

• Plasma Membrane: A thin layer surrounding the cell, composed of proteins and lipids.
• Cytoplasm: An aqueous solution containing organelles.
• Nucleus: A spherical structure containing genetic material, formed by the nuclear membrane, nucleoplasm, chromatin, and the nucleolus.

The major organelles of eukaryotic cells include: mitochondria, endoplasmic reticulum, ribosomes, Golgi complex, vacuoles, lysosomes, and the centrosome.

Tissues: A tissue is a collection of similar cells with a very similar structure that perform the same functions. Types of tissues include:

• Lining and glandular tissues.
• Connective tissue: connective tissue proper, adipose, cartilaginous, and bony.
• Muscle tissue: smooth, cardiac, and skeletal.
• Nervous tissue.

Organs: Organs are structures formed by several different tissues that perform specific functions.

Systems and Organelles: Systems and organelles are made of organs of the same type that perform similar functions. Systems include: muscular, skeletal, nervous, and endocrine. Organelles include: digestive, respiratory, reproductive, circulatory, excretory, and locomotive.

Nutrient Composition: Foods are made of nutrients, which are substances that provide energy and matter. Nutrients are classified as organic (carbohydrates, lipids, and proteins) and inorganic (water and mineral salts).

Classification and Function: Energy released from food is measured in Calories, kilocalories, and kilojoules. A calorie is the amount of heat required to raise the temperature of one gram of liquid water by one degree Celsius. The energy value of food is expressed as the number of kilocalories provided by 100g of that food. Foods are classified into three groups:

• Energy Foods: Serve as a source of energy, rich in carbohydrates and lipids.
• Plastic Foods: Necessary for forming cells, tissues, and organs; rich in proteins.
• Regulator Foods: Essential for proper bodily functions and utilization of other foods; provide vitamins and minerals.

Diet: A diet is complete, varied, and balanced when it provides all types of foods in adequate amounts of nutrients and energy to meet the body's daily energy expenditure.

Food Conservation: Conservation techniques aim to protect food and its components from microorganisms. Methods include:

• Cold storage: refrigeration and freezing.
• Heat conservation: pasteurization and sterilization.
• Dehydration.
• Preservation by chemical addition.