Biology for Medical Students I – Comprehensive Study Notes (Transcript)

Course Overview

  • The Biology for Medical Students I course focuses on the fundamental principles of molecular biology, cell biology, biochemistry and evolution.
    • Principles are introduced at the molecular level: structure and function of biological macromolecules; how these molecules are integrated into the cell; basics of cellular metabolism; gene replication, expression, and evolution.
  • Provides a foundation to understand basic mechanisms of life on a cellular level with implications for health/disease and biotechnology.
  • Includes a research laboratory component where practical skills of modern molecular biology techniques are taught.
  • Biology for Medical Students I is a prerequisite for Biology for Medical Students II.

Course Leader and Teaching Staff

  • Course Leader: Larisa Lezina (also spelled Larissa Lezina in some materials)
  • Co-Leader & Instructor: Jeannette Kunz
  • Teaching Assistants: Agata Burska; Assem Zhakupova; Kamila Raziyeva; Kamilya Kokabi

Course Outline (Session-by-Session)

  • Session 1 (Week of Aug 18) – Topics: Course Introduction; Cells, Genomes, and the Diversity of Life. Essential Cell Biology (ECB) Ch. 1; Molecular Biology of the Cell (MBC) Ch. 1. Labs: Introduction / Safety / Basic equipment use.
  • Session 2 (Week of Aug 25) – Topics: Chemical Components of Cells. ECB Ch. 2; MBC Ch. 2. Labs: Lab notebook & Mastering pipetting & calculations.
  • Session 3 (Week of Sept 1) – Topics: Energy, Catalysis, and Biosynthesis. ECB Ch. 3; MBC Ch. 2. Labs: Preparation of solutions & Making dilutions.
  • Session 4 (Week of Sept 8) – Quiz 1; Topics: Proteins. ECB Ch. 4; MBC Ch. 3. Labs: DNA extraction, quantification & analysis.
  • Session 5 (Week of Sept 15) – Topics: Proteins; Enzymes. ECB Ch. 4; MBC Ch. 3. Labs: Basic quantification methods (nucleic acids). Lab Quiz 1.
  • Session 6 (Week of Sept 22) – Topics: DNA, Chromosomes, and Genomes. ECB Ch. 5; MBC Ch. 4. Labs: Introduction to data analysis and basic bioinformatics; 1) Restriction maps, 2) ORFs, 3) PCR primer design.
  • Session 7 (Week of Sept 29) – Topics: DNA Recombination; Recombinant DNA Technology. Midterm. ECB Ch. 6; MBC Ch. 5. Labs: Introduction to PCR amplification 1.
  • Session 8 (Week of Oct 13) – Topics: DNA Replication, Repair, and Recombination. ECB Ch. 6; MBC Ch. 5. Labs: Introduction to PCR amplification 2.
  • Session 9 (Week of Oct 20) – Topics: Transcription; Translation. ECB Ch. 7; MBC Ch. 6. Labs: DNA analysis (Restriction analysis and gel electrophoresis) 1. Lab Quiz 2.
  • Session 10 (Week of Oct 27) – Quiz 2; Topics: Transcription; Translation. ECB Ch. 7; MBC Ch. 6. Labs: DNA analysis (Restriction analysis and gel electrophoresis) 2.
  • Session 11 (Week of Nov 3) – Topics: Control of Gene Expression. ECB Ch. 8; MBC Ch. 7. Labs: pGLO-Library transformation.
  • Session 12 (Week of Nov 10) – Topics: How Genes and Genomes Evolve. ECB Ch. 9; MBC Ch. 4. Labs: pGLO-Expression & Protein purification.
  • Session 13 (Week of Nov 17) – Topics: Modern Recombinant DNA Technology. ECB Ch. 10; MBC Ch. 8. Labs: pGLO-Expression & Protein purification cont. Lab Quiz 3.
  • Session 14 (Week of Nov 24) – Topics: Visualizing Cells and Their Molecules. ECB Ch. 1; MBC Ch. 9. Labs: DNA extraction and precipitation (DNA isolation).

Summative Assessments and Weighting

  • Quiz 1: 9% (9 September 2025)
  • Case studies (3): 9% (TBA)
  • Mid-term: 18% (30 September 2025)
  • Quiz 2: 9% (28 October 2025)
  • Labs (Notebook, 3 Quizzes): 25% (Notebook 10%, Quizzes 15% of final grade)
  • Final exam: 30% (TBA)

Classroom Conduct

  • In order to facilitate learning and minimize distractions, students are expected to:
    • Turn cell phones and pagers to non-audible during classes and laboratories.
    • Report to class on time.
    • Be alert and attentive in class.
    • Refrain from individual conversation during class unless instructed otherwise.
    • Show respect for fellow students and faculty.

Attendance Policy

  • Attendance is mandatory for all activities (lectures, laboratories).
  • Absence includes missing the entire class, arriving >15 minutes late, or leaving early.
  • Any single absence must be discussed with Course Leads.
  • Being late by <15 minutes 2 times is considered 1 unexcused absence.
  • Excused absences require documentation (medical) or discussion with Course Lead for family emergencies.
  • If absent for other reasons, a Leave of Absence form must be obtained and signed by Course Lead, Program Director, and Dean of NUSOM; otherwise, absence is unexcused and affects final grade.

Missed Quizzes and Assignments

  • If a quiz is missed without an appropriate excuse, it is graded 0%.
  • If an appropriate excuse is provided, the missed quiz can be resat; only one quiz may be missed with an excuse.
  • Late submissions incur grade penalties: 5% deduction within 1 hour after deadline; 10% within 2 hours; 0% thereafter (on Moodle).

Statement on Classroom Recording

  • To ensure free and open discussion, students may not record classroom lectures, discussions, or activities without advance written permission of the instructor.
  • Any approved recording must be used solely for the student’s private use.

What is Biology? (Definition)

  • Biology is a branch of natural science that studies living organisms and their vital processes.
  • The word biology derives from the Greek words "bios" (life) and "logos" (study).

What is Life? Philosophical Perspectives

  • Democritus (460 BC): essential characteristic of life was having a soul (psyche); the soul, like everything else, was composed of fiery atoms.
  • Aristotle (322 BC): everything in the material universe has both matter and form; the form of a living thing is its soul (psyche/anima).
  • Three kinds of souls:
    • Vegetative soul: nourishment, growth, and self-maintenance in plants; no motion or sensation.
    • Animal soul: movement and sensation in animals.
    • Rational soul: consciousness and reasoning.

Main Traits of Life

  • Homeostasis: regulation of the internal environment to maintain a constant state (e.g., sweating to reduce temperature).
  • Organisation: composed of one or more cells—the basic units of life.
  • Metabolism: transformation of energy to synthesize cellular components (anabolism) and to decompose organic matter (catabolism); energy is required for homeostasis and activity.
  • Growth: higher rate of anabolism than catabolism; organisms increase in size/structure.
  • Adaptation: evolutionary process by which organisms become better suited to their habitat.
  • Response to stimuli: e.g., chemotaxis in unicellular organisms; complex sense responses in multicellular organisms; phototropism in plants.
  • Reproduction: production of new individuals (asexual or sexual).
  • Heredity (inheritance): passing traits from parents to offspring.

Examples of Living Organisms

  • Examples shown include Escherichia coli (bacteria), mouse, sea urchin, seaweed (Fucus).
  • Image captions reference magnifications and scale bars (e.g., 3.0 μm to 6836x; 5 μm). These illustrate diverse cell sizes across life.

Viruses: The Edge of Life

  • Viruses are often considered as gene-coding replicators rather than fully living organisms.
  • Described as "Organisms at the edge of life" because they:
    • possess genes,
    • evolve by natural selection,
    • replicate by self-assembly.
  • However, viruses do not metabolize and require a host cell to produce new viral products.

Cells: The Fundamental Units of Life

  • Core idea: All life is cellular; cells are the basic units that carry out life’s processes.

Unity and Diversity of Cells

  • Cells vary enormously in appearance and function (examples A–E in the figures). Sizes span broad ranges from micrometers to tens of micrometers, illustrating diversity in form and function.
  • Example: some algae (Valonia ventricosa) can reach diameters of 1–4 cm as single cells, illustrating extreme cell size diversity.
  • Notation: 1 micrometer (µm) = 1e-6 meters.

The Universal Features of Life on Earth

  • All Cells Store Hereditary Information in double-stranded DNA.
    • DNA is composed of four monomer types (nucleotides): A, G, C, T.
    • Sugar-phosphate backbone uses deoxyribose sugar.
  • All Cells Replicate Hereditary Information by templated polymerization.
    • New DNA strand synthesized based on a template strand.
    • Complementary base pairing: A pairs with T; G pairs with C.
  • All Cells Transcribe Portions of DNA into RNA.
    • RNA monomers: A, G, C, U (uracil).
    • Sugar in RNA backbone is ribose.
  • All Cells Use Proteins as Catalysts.
    • Amino acids: 20 common types.
    • Proteins are polypeptides; enzymes act as biological catalysts to speed up biochemical reactions.
  • All Cells Translate RNA into Protein by a conserved mechanism.
    • Codons: triplets of nucleotides code for specific amino acids.
    • tRNAs (with anticodons) deliver amino acids to the ribosome for incorporation into protein.
  • Genes encode proteins; Gene expression is the process by which information in a gene yields a functional product (usually a protein).
  • Life Requires a Continual Input of Free Energy.
    • Energy sources: primarily the sun (photosynthesis) or consumption of other organisms; animals obtain energy from chemical bonds in food molecules.
    • Energy metabolism aims to generate ATP from nutrients.
  • All Cells Are Biochemical Factories.
    • Cells use a common set of small molecules: simple sugars, nucleotides, amino acids, ATP, etc.
  • All Cells Are Enclosed by a Plasma Membrane (selective barrier).
    • Membrane composed of amphiphilic molecules (phospholipids) with hydrophilic heads and hydrophobic tails; forms a bilayer.
    • Membrane transport proteins regulate movement of nutrients and wastes across the membrane.
  • Minimal Genome Concept.
    • A living cell can exist with fewer than 500 genes.
    • Humans have approximately 100000100000 genes, including about 2000020000 protein-coding genes.
    • Mycoplasma genitalium: ~530530 genes, ~400400 essential.
    • Carsonella ruddii: ~224224 genes, ~182182 protein-coding; relies on other organisms via symbiosis to survive.
  • Summary: All Cells share core principles (DNA storage, replication, transcription, translation, metabolism, energy use, membrane enclosure) but vary in size, complexity, and gene content.

Central Dogma and Flow of Genetic Information

  • Central flow: DNA -> RNA -> Protein (DNA replication precedes inheritance; transcription produces RNA; translation builds proteins).
  • DNA synthesis and replication are templated, ensuring fidelity and heredity across generations.
  • RNA (mRNA) serves as a guide for protein synthesis, with tRNA bringing amino acids to ribosomes for translation.
  • The same basic machinery (DNA, RNA, ribosomes, tRNAs, amino acids) underpins all cellular life.

Protein Synthesis and Enzymatic Catalysis

  • Proteins serve as catalysts (enzymes) to accelerate biochemical reactions.
  • Amino acids (20 standard types) assemble into polypeptides; sequence determines structure and function.
  • Example: Lysozyme as a catalytic protein (illustrated in the figure set) demonstrating enzyme–substrate interaction at a catalytic site.

Energy Metabolism and ATP

  • Energy metabolism focuses on generating ATP from nutrients.
  • ATP is the primary energy currency of the cell; production is the ultimate goal of energy metabolism.
  • Energy input from the environment (sunlight or chemical energy in food) drives cellular processes and maintains order (anti-entropy).

Cell Structure and Membrane Architecture

  • Plasma membrane: selective barrier that regulates the passage of nutrients and wastes.
  • Membrane composition: amphiphilic phospholipids creating a bilayer with hydrophilic heads and hydrophobic tails.
  • Membrane proteins facilitate selective transport and communication with the environment.

Minimal Genome and Gene Content

  • Concept: Some organisms function with a small number of genes; complexity does not always require large genomes.
  • Examples: Mycoplasma genitalium, Carsonella ruddii—and the idea that many essential functions may be provided by host organisms or by reduced gene sets.

Recap: Interconnected Themes for Health and Biotechnology

  • Understanding DNA structure, replication, transcription, translation provides a foundation for understanding genetic engineering, biotechnology, and disease mechanisms.
  • The universal features of life underpin approaches to diagnostics, therapeutics, and synthetic biology.
  • Safety, ethics, and policy considerations (e.g., recording policy, attendance, and academic integrity) support responsible scientific practice.

Connections to Foundational Principles and Real-World Relevance

  • Foundational Principles:
    • Structure–function relationships in macromolecules drive cellular processes.
    • Central dogma governs how information flows from DNA to phenotype.
    • Evolution shapes genomes, gene content, and metabolic capabilities.
  • Real-World Relevance:
    • Biotechnology applications rely on recombinant DNA technology, PCR, and protein purification.
    • Medical biology uses understanding of gene regulation and protein function to develop therapies.
  • Ethical and Practical Implications:
    • Lab safety, data integrity, and responsible conduct in experiments.
    • Intellectual property considerations in biotechnology and bioengineering.
    • Respect for privacy and consent in health-related genetic information.

Key Formulas and Notation (LaTeX)

  • Nucleotide building block for DNA: extnucleotide=extsugar+extphosphate+extbaseext{nucleotide} = ext{sugar} + ext{phosphate} + ext{base} where base ∈ \{A, T, C, G\}.
  • DNA nucleotide pairing: A↔TandG↔C.A \leftrightarrow T \quad\text{and}\quad G \leftrightarrow C.
  • RNA nucleotide: replace T with U, i.e., base set ∈ \{A, U, C, G\}.
  • Codon definition: ext{codon} \in {A,U,G,C\}^3 (triplet of nucleotides coding for one amino acid).
  • Central dogma schematic (flow): DNA→RNA→Protein\text{DNA} \rightarrow \text{RNA} \rightarrow \text{Protein} (with replication, transcription, translation steps).
  • Energy currency: ATP\text{ATP} as primary energy carrier (conceptual focus rather than numeric value in these slides).
  • Scale and sizes: examples include numbers such as 100 μm100\,\mu\text{m}, 25 μm25\,\mu\text{m}, 5 μm5\,\mu\text{m}, 3 μm3\,\mu\text{m}, etc. (for cell sizes).

References to Ancient Concepts (Philosophical) – Quick Recall

  • Democritus (460 BC): life’s essence tied to a soul composed of fiery atoms.
  • Aristotle (322 BC): form (soul/anima) as the living principle; three kinds of souls defined: vegetative, animal, rational.

Quick Study Tips Based on Transcript Structure

  • Review the session topics and associated ECB/MBC chapters to map lectures to textbook material.
  • Practice explaining the central dogma in your own words and sketching the flow from DNA to RNA to protein.
  • Memorize the four DNA bases and the replacement base in RNA (T → U).
  • Be able to describe the structural basis of the plasma membrane and the role of transport proteins.
  • Remember key gene-content examples and the minimal genome concept to discuss genome size versus organism complexity.
  • Understand how energy metabolism connects to ATP production and cellular work.
  • Be prepared to discuss ethical and practical implications of lab safety, recording policies, and attendance.

Endnotes

  • This set of notes captures the major and minor points from the transcript, including session topics, assessment structure, policies, core biological concepts, and philosophical context. They are designed to serve as a comprehensive study companion for Biology for Medical Students I.