Biology Chapter on Macronutrients and Micronutrients

Basic Concepts of Life - Module 1

• Life, at the molecular level, is characterized by organization, not by disorganisation.
• Molecules are the smallest particles of a substance retaining its properties; they can be composed of one or more atoms
• Common examples include water (1 oxygen, 2 hydrogens)
• Life forms share common molecular characteristics: obeying thermodynamics, using ATP as energy currency, being formed of similar small and large biomolecules.
• Seemingly different organisms share similar molecular characteristics. They can all use glucose for energy, store their information in DNA, and convert food energy into ATP. This shows a remarkable similarity.

What is Life?

• A typical conventional definition of "life" includes several main characteristics.

Conventional Definitions of Life

• Organization: Life is composed of one or more cells—the basic units of life—which are organized into a whole organism (e.g., Homo sapiens). Tissues are made up of cells, and organs are made up of tissues, and so on. Biomolecules (carbohydrates, fats, proteins, nucleic acids) form even the cell itself.
• Reproduction: Life has the ability to produce new organisms. Reproduction involves either mitosis (one cell forming two new identical cells) or meiosis (processes to produce new organisms).
• Metabolism: Life undergoes chemical processes necessary for maintenance of life. Metabolism is the sum of catabolism (breakdown of substances to release energy) and anabolism (synthesis of substances that use energy). The study of biochemistry centers around metabolism.
• Growth: Life grows and maintains a higher rate of building up than breaking down. It increases in size and progresses from a simpler to a more complex form. The balance of catabolism and anabolism is important for growth.
• Homeostasis: Life maintains a constant internal state. This involves regulating internal conditions to maintain balance (e.g., sweating to cool down, shivering to warm up).
• Response to Stimuli: Life has the ability to respond to stimuli in the short term (e.g., microorganisms moving toward food or away from poison, plant leaves turning toward the sun, animals chasing prey).
• Adaptation: Life can respond to its environment over a long period of time. This is determined by genes and environment. Adaptations can include things like melanin pigment in the skin to protect against UV rays or giraffes developing long necks to reach leaves high in trees.

Other Proposed Features of Life

• Carbon-containing: Carbon is the fundamental element forming the basis of life on Earth.
• Reliance on water: Water is essential for the survival of all life forms.
• Genetic information: DNA and RNA store the blueprint of an organism.

What is a Molecule?

• A molecule is the smallest particle of a substance that retains its properties.
• A molecule can be composed of one or more atoms.

Biological Molecules

• Biological molecules can contain a few, or up to many thousands of atoms, and have nearly infinite possibilities.
• Examples include amino acids like serine and complex proteins such as alcohol dehydrogenase.

What elements (atoms) are in biomolecules?

• Biomolecules contain various elements, as indicated in the Periodic Table of Elements. Many are common elements on the Earth, and other elements are possible.

What elements form biomolecules in nature?

• Common elements form into molecules in various forms in nature, including gases, solids, and liquids.

Shared Molecular Characteristics of Life

• Life obeys the laws of thermodynamics.
• ATP is the common energy currency of life.
• Life is composed of similar biomolecules.

The 3 Molecular Characteristics of Life

• Life obeys the laws of thermodynamics (first and second laws).
• ATP (adenosine triphosphate) is the common energy currency of life.
• Life is composed of similar biomolecules, both small and large (carbohydrates, lipids, proteins, and nucleic acids).

1st Law of Thermodynamics

• Energy is neither created nor destroyed; it can only change from one form to another.
• In living organisms, the energy from food molecules is transformed (changed) into a usable form of chemical energy (ATP).

2nd Law of Thermodynamics

• All processes increase entropy (disorder).
• In living organisms, large food molecules (low entropy) are broken down into smaller molecules (high entropy) producing energy. This process is called catabolism. In contrast anabolism, the opposite process of increasing order, requires energy to occur
• The process of using energy to decrease entropy is an important aspect of maintaining order and performing essential functions in living organisms.

ATP - What is it?

• ATP is the common "energy currency" transferring energy in cells.
• ATP is produced during photosynthesis (plants) and cellular respiration (animals).

3rd Molecular Characteristic: Biomolecules

• Life is composed of very similar small and large biomolecules (carbohydrates, proteins, lipids, and nucleic acids).
• These biomolecules can be categorized into "small" (monomers, dimers, trimers, oligomers) and "large" (polymers, with hundreds or thousands of monomers).
• The nutrients in food are examples of biomolecules.

What is a Nutrient?

• A nutrient is any substance with nutritional value to an organism.
• Nutrients can provide energy or building blocks for maintaining, growing, and repairing the organism.
• Some nutrients can be made by the body ("non-essential"), while others must be obtained from food ("essential").

Micronutrients vs Macronutrients

• Micronutrients are required in small amounts (vitamins and microminerals).
• Macronutrients are required in large amounts (carbohydrates, proteins, lipids, and some minerals).

What do vitamins and minerals actually do?

• Vitamins act as co-factors for enzymes.
• Microminerals are important for the function of various proteins (e.g., iron is necessary for hemoglobin function).

Macronutrients: Energy Source

• Macronutrients (carbohydrates, lipids, and proteins) are primarily energy sources for organisms.
• However, they also have other functions (e.g., structural formation for organisms).

What about Nucleic Acids?

• Nucleic acids (DNA and RNA) are nutrients because they are crucial for maintaining, growing, and repairing the organism by containing genetic information.
• However, nucleic acids themselves might not be considered a crucial source of chemical energy (like carbohydrates, proteins, and lipids).

Nucleic Acid monomer: Nucleotide

• Nucleotides are the monomers of nucleic acids.

Nucleic Acid polymer: DNA

• DNA, the genetic material, is organized into chromosomes.
• DNA is double-stranded, and its bases are paired (A with T, G with C).
• Deoxyribose sugar and phosphates form the DNA backbone.

Nucleic Acid polymer: RNA

• RNA carries instructions from DNA for protein synthesis. This is complementary to DNA.
• RNA is single-stranded and uses uracil instead of thymine, in its base pairing. Ribose sugars form the RNA backbone.

Textbook Readings for the Next Module

• Textbook readings for next module include general chemistry topics such as nomenclature of chemical compounds, the structure and properties of hydrocarbons, chemical bonds, electronegativity and polarity, and isomers for the Biochemistry Module 2.