Lecture Notes: Biology and Life Processes
Formation of Earth and Early Development
- Earth formed about 4.5 billion years ago
- Initially a hot, fiery mass, bombarded by rocks
- Cooling of Earth led to water accumulation and formation of hydrothermal vents
Chemistry of Life
- Biology is essentially chemistry
- Life consists of:
- Carbohydrates: Provide quick energy
- Lipids: Store long-term energy, form membranes
- Proteins: Form tissues
- Nucleic Acids: Form DNA
- Enzymes are catalysts in chemical reactions (e.g., lactase breaks down lactose)
Definition and Characteristics of Life
- Life vs. non-life (e.g., cats vs. rocks)
- Living organisms: metabolize, grow, reproduce, respond to environment
- All living things are made of cells:
- Eukaryotes: Have membrane-bound organelles
- Prokaryotes: No membrane-bound organelles, DNA free-floating
Cell Structure and Function
- Cells have semi-permeable membranes with phospholipid bilayers
- Diffusion: Movement with gradient
- Osmosis: Water movement towards solute concentration
- ATP: Energy molecule used for active transport and cellular respiration
- Photosynthesis: Plants convert light energy to glucose
DNA and Genetic Information
- DNA structure: Two strands of nucleotides (adenine, thymine, cytosine, guanine)
- Genes: Sections of DNA coding for traits
- RNA: Transcribes DNA to transport to ribosomes for protein synthesis
- Transcription and Translation: Process of making proteins from DNA
Genetic Variation and Inheritance
- Genetic code: Based on alleles (dominant or recessive)
- Phenotype: Physical trait expressed
- Genotype: Genetic makeup
- Intermediate Inheritance and Co-dominance
- Sex Chromosomes: X and Y; X-linked traits affect males
Cell Division
- Mitosis: Produces identical body cells
- Meiosis: Produces genetically varied gametes
- Important for genetic diversity and proper chromosome number in offspring
Mutations and Evolution
- Gene mutations: Changes in base sequences (can be harmful/beneficial)
- Natural Selection: Survival of the fittest
- Genetic Drift: Random survival and reproduction
- Concerns with antibiotic resistance
Bacteria vs. Viruses
- Bacteria: Single-cell organisms, can be beneficial
- Viruses: Not made of cells, require a host to reproduce
- Antibiotics treat bacterial infections, not viral infections
Nervous System and Brain Function
- Nervous system: Conducts electrical signals via neurons
- Action Potentials: Electrical signals transmitting information
- Myelin Sheath: Insulates axons, speeds up signal transmission
- Neurotransmitters: Chemicals facilitating signal transmission across synapses
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These notes summarize the major points and concepts discussed in the lecture on biology, life processes, genetic information, and the nervous system.