Energy

Kinetic vs. Potential Energy

Energy is the capacity to do work. In physiology, energy is crucial for cellular processes.

• Kinetic Energy: Energy of motion.

• Potential Energy: Stored energy due to position or structure.

• Example: ATP stores potential energy, which is released as kinetic energy during muscle contraction.

Composition of Matter

Atomic Structure and Properties

Matter is composed of atoms, which are the smallest units of chemical elements.

• Atom Structure: Nucleus (protons and neutrons) and electrons in orbitals.

• Atomic Number: Number of protons in the nucleus.

• Mass Number: Sum of protons and neutrons.

• Atomic Weight: Average mass of all isotopes of an element.

• Formula:

Chemical Bonds

Bond Types and Stability

Chemical bonds hold atoms together in molecules and compounds.

• Stable Atom: Atoms are stable when their outer electron shell is full.

• Types of Chemical Bonds:

  • Ionic Bonds: Transfer of electrons between atoms.

  • Covalent Bonds: Sharing of electrons between atoms.

  • Hydrogen Bonds: Weak attraction between a hydrogen atom and another electronegative atom.

• Comparison: Ionic bonds are stronger than hydrogen bonds but can be weaker than covalent bonds.

Biochemistry

Organic Compounds, Electrolytes, Acids, and Bases

Biochemistry explores the chemical processes within living organisms.

• Organic Compound: Molecules containing carbon, such as carbohydrates, lipids, proteins, and nucleic acids.

• Electrolyte: Substances that dissociate into ions in solution and conduct electricity.

• Acid: Substance that releases hydrogen ions () in solution. Example: Hydrochloric acid ().

• Base: Substance that accepts hydrogen ions or releases hydroxide ions (). Example: Sodium hydroxide ().

• Buffers: Maintain homeostasis of acids and bases in the body, especially in blood.

Carbohydrates

Carbohydrates are organic molecules that provide energy.

• Building Blocks: Monosaccharides (simple sugars).

• Formation: Monosaccharides combine via dehydration synthesis to form disaccharides and polysaccharides.

• Example: Glucose is a monosaccharide; starch is a polysaccharide.

Lipids

Lipids are hydrophobic molecules important for energy storage and cell membranes.

• Triglyceride: Composed of glycerol and three fatty acids.

• Saturated Fatty Acid: No double bonds; solid at room temperature.

• Unsaturated Fatty Acid: One or more double bonds; liquid at room temperature.

• Fatty Acid: Long hydrocarbon chain with a carboxyl group.

• Phospholipid: Contains a phosphate group; major component of cell membranes.

Steroids

Steroids are lipids with a characteristic four-ring structure.

• Most Important Steroid: Cholesterol; found in cell membranes and precursor to hormones.

Proteins

Proteins are polymers of amino acids and perform diverse functions in the body.

• Building Blocks: Amino acids.

• Protein Formation: Amino acids join via peptide bonds (dehydration synthesis).

• Bond in Protein: Peptide bond.

• Structural Levels:

  • Primary: Sequence of amino acids

  • Secondary: Alpha helix or beta sheet

  • Tertiary: 3D folding

  • Quaternary: Multiple polypeptides

• Fibrous vs. Globular Proteins:

  • Fibrous: Structural (e.g., collagen)

  • Globular: Functional (e.g., enzymes)

Nucleic Acids

Nucleic acids store and transmit genetic information.

• Classes: DNA and RNA.

• Nucleotide: Building block of nucleic acids; consists of a sugar, phosphate, and nitrogenous base.

• Nitrogenous Bases: Adenine, thymine, cytosine, guanine, uracil (RNA only).

• Base Pairing: Adenine pairs with thymine (DNA) or uracil (RNA); cytosine pairs with guanine.

• Structure of DNA: Double helix.

ATP (Adenosine Triphosphate)

ATP is the primary energy carrier in cells.

• Structure: Adenine, ribose, and three phosphate groups.

• Function: Stores and releases energy for cellular processes.

• Equation:

Chemical Reactions

Chemical reactions are essential for metabolism and other physiological processes.

• Synthesis Reaction: Two or more substances combine to form a new compound.

• Decomposition Reaction: A compound breaks down into simpler substances.

• Exchange Reaction: Parts of molecules are exchanged to form new compounds.

• Rate Influencers: Temperature, concentration, particle size, catalysts (enzymes).

Table: Comparison of Major Biomolecules

Additional info: Some content was expanded for clarity and completeness, including definitions, examples, and academic context for each topic.