Proteins

Proteins are complex biomolecules essential for numerous biological functions. This page focuses on the structure and properties of proteins, particularly their building blocks, amino acids.

Definition: Proteins are large, complex molecules composed of chains of amino acids, which perform a wide variety of functions in living organisms.

Amino acids, the monomers of proteins, have a general structure consisting of:

• An amino group (-NH2)
• A carboxyl group (-COOH)
• A variable R group (side chain)

Vocabulary: The R group in an amino acid determines its unique properties and influences the overall structure and function of the protein.

Proteins are formed through the linking of amino acids via peptide bonds:

Definition: A peptide bond is a covalent bond formed between the carboxyl group of one amino acid and the amino group of another, releasing a water molecule in the process.

The structure of proteins can be described at four levels:

1. Primary structure: The sequence of amino acids
2. Secondary structure: Local folded structures (e.g., alpha helices, beta sheets)
3. Tertiary structure: Overall three-dimensional shape of a single protein molecule
4. Quaternary structure: Arrangement of multiple protein subunits

Highlight: The three-dimensional structure of a protein is crucial for its function, and any disruption to this structure can lead to a loss of functionality.

Denaturation is a process that can disrupt protein structure:

Definition: Denaturation is the process by which proteins lose their shape and, consequently, their function due to external factors such as high temperature or changes in pH.

Understanding protein structure and function is essential for comprehending their roles in biological processes, including enzymatic reactions, cellular signaling, and structural support.

Comparison of Carbohydrates and Lipids

This page provides a comparative analysis of carbohydrates and lipids, two essential classes of biomolecules, highlighting their distinct characteristics and roles in biological systems.

Carbohydrates:

• Serve as a short-term energy storage
• Have a more significant effect on osmotic pressure
• Are easier to digest
• Can be used in both anaerobic and aerobic respiration
• Store half as much ATP per gram compared to lipids
• Are water-soluble

Lipids:

• Function as long-term energy storage
• Have less effect on osmotic pressure
• Are harder to digest
• Can only be used in aerobic respiration
• Store twice as much ATP per gram compared to carbohydrates
• Are not water-soluble

Highlight: The water solubility of carbohydrates and the insolubility of lipids significantly influence their roles in biological systems and their storage and transport within organisms.

The page also introduces the concept of Body Mass Index (BMI), a measure used to assess body composition:

Definition: Body Mass Index (BMI) is calculated by dividing an individual's mass in kilograms by the square of their height in meters.

BMI Categories:

• Underweight: <18.5
• Normal weight: 18.5-24.9
• Overweight: 25-29.9
• Obese: 30-34.9
• Severely obese: 35-39.9
• Morbidly obese: >40

Vocabulary: Obesity is a medical condition characterized by excessive body fat accumulation that can have negative effects on health.

Understanding the differences between carbohydrates and lipids is crucial for comprehending their roles in energy storage, metabolism, and overall health.