Lecture Notes: Journey from Rocks to Life and Beyond

Origin of Earth

• Earth formed about 4.5 billion years ago as a flaming mass of rocks.
• Bombarded by rocks containing water, which turned into steam.
• Earth began cooling down, leading to rain and oceans.
• Hydrothermal vents at the ocean floor containing chemicals conducive for life.

Introduction to Biology

• Biology studies life but is fundamentally chemistry.
• Living beings as molecular structures performing chemical reactions.

Chemical Composition of Life

• Carbohydrates: Quick energy.
• Lipids: Long-term energy storage and membrane formation.
• Proteins: Tissue formation and enzymatic functions.
• Nucleic Acids: DNA and genetic information.

Enzymes

• Proteins that catalyze and speed up chemical reactions.
• Example: Lactase breaks down lactose.

Characteristics of Life

• Ability to produce energy, grow, develop, reproduce, and respond to the environment.
• All living things are made of cells: Eukaryotes (complex) and Prokaryotes (simple).

Cells

• Eukaryotes: Have organelles, including a membrane-bound nucleus.
• Prokaryotes: No organelles, DNA freely floats.

Taxonomy and Classification

• "Kingdoms" classify organisms: Protists, Fungi, Plants, Animals.
• Scientific names use genus and species for clarity.

Homeostasis

• Maintaining internal stability (e.g., body temperature).
• Enzymes require specific conditions (e.g., pH) to function.

Cell Membrane

• Semipermeable phospholipid bilayer.
• Allows selective movement of molecules through passive (diffusion) and active transport.
• Importance of ATP for active transport.

Energy Conversion and Photosynthesis

• Cellular Respiration: Converts glucose and oxygen into water, CO2, and ATP.
• Photosynthesis: Plants use light to convert water and CO2 into glucose and oxygen.
• ATP and its structure: Key energy molecule and nucleotide.

DNA and Genetic Information

• DNA structure: Double helix of nucleotides (Adenine, Thymine, Cytosine, Guanine).
• Genes and protein synthesis: DNA to RNA to protein (transcription and translation).

RNA

• Carries genetic information from DNA to ribosomes.
• Difference from DNA: Single-stranded, ribose sugar, Uracil instead of Thymine.

Genetic Variation and Inheritance

• Alleles: Different versions of a gene, can be dominant or recessive.
• Example: Eye color inheritance and variations (codominance, incomplete dominance).

Chromosomes

• DNA coiled into chromosomes; humans have 23 pairs.
• Homologous chromosomes carry the same genes.
• X-linked genes and sex chromosomes differences.

Cell Division

• Mitosis: Produces identical body cells.
• Meiosis: Produces gametes (sperm and eggs) through genetic recombination.

Mutations and Evolution

• Mutations can be harmful, neutral, or beneficial.
• Natural selection leads to evolution.

Bacteria vs. Viruses

• Bacteria: Prokaryotic, single cell, treated with antibiotics.
• Viruses: Not cellular, reproduce in hosts, not treatable with antibiotics.

Human Body Systems

• Nervous System: Neurons conduct electrical signals for body functions.
• Action potentials and neurotransmitter roles.

Additional Information

• Promotion for Brilliant for learning more about biology and other sciences. Offers interactive lessons and problem-solving skills.

This summary provides a high-level overview of the material covered in the lecture, focusing on the key concepts and ideas discussed.