MCAT Biology Syllabus

Biology syllabus — full chapter and topic list

Expand any chapter to see its topics and sub-topics. This is the whole examinable outline for Biology in MCAT, not a summary of it.

1. 1

   Cell Biology

   7 topics

   • Cell Theory
     • Basic Tenets of Cell Theory
     • Historical Experiments Supporting Cell Theory
   • Prokaryotic vs. Eukaryotic Cells
     • Structural Differences
     • Functional Differences
     • Examples and Roles in the Environment
   • Cell Membrane Structure and Function
     • Phospholipid Bilayer
     • Membrane Proteins
     • Membrane Transport Mechanisms (Passive Transport, Active Transport, Facilitated Diffusion, Osmosis)
   • Transport Across Cell Membranes
     • Endocytosis and Exocytosis
     • Ion Channels and Membrane Potential
   • Cell Organelles and Their Functions
     • Nucleus
     • Mitochondria
     • Endoplasmic Reticulum (Rough and Smooth)
     • Golgi Apparatus
     • Lysosomes and Peroxisomes
     • Cytoskeleton (Microtubules, Microfilaments, Intermediate Filaments)
   • Cell Cycle and Mitosis
     • Phases of the Cell Cycle (Interphase, Mitotic Phase)
     • Regulation of the Cell Cycle
     • Checkpoints and Apoptosis
   • Meiosis and Gametogenesis
     • Stages of Meiosis
     • Differences Between Meiosis and Mitosis
     • Formation of Sperm and Ova
2. 2

   Molecular Biology

   5 topics

   • DNA Structure and Function
     • Double Helix Model
     • Complementary Base Pairing
     • DNA Replication
   • RNA Structure and Function
     • Types of RNA (mRNA, tRNA, rRNA)
     • RNA Synthesis (Transcription)
   • DNA Replication
     • Enzymes Involved (Helicase, DNA Polymerase, Ligase)
     • Leading and Lagging Strands
   • Transcription and RNA Processing
     • Transcription Mechanism
     • RNA Splicing, Capping, and Polyadenylation
   • Translation and Protein Synthesis
     • Ribosome Structure and Function
     • tRNA and Codon-Anticodon Interaction
     • Steps of Translation (Initiation, Elongation, Termination)
3. 3

   Genetics and Evolution

   5 topics

   • Mendelian Genetics
     • Laws of Segregation and Independent Assortment
     • Punnett Squares and Predicting Offspring Ratios
   • Non-Mendelian Inheritance
     • Incomplete Dominance
     • Codominance
     • Multiple Alleles
     • Polygenic Inheritance
   • Genetic Linkage and Mapping
     • Linkage and Recombination
     • Genetic Maps and Distance Calculation
   • Population Genetics
     • Hardy-Weinberg Equilibrium
     • Factors Affecting Allele Frequencies (Genetic Drift, Gene Flow, Mutation, Natural Selection)
   • Evolutionary Concepts
     • Natural Selection
     • Speciation
     • Adaptive Radiation
     • Phylogenetics
4. 4

   Microbiology

   5 topics

   • Bacterial Structure and Function
     • Cell Wall Structure
     • Reproduction
     • Genetic Variation
   • Viral Structure and Life Cycles
     • Virus Structure
     • Life Cycles
   • Fungi and Parasites
     • Basic Characteristics and Life Cycles
     • Pathogenicity and Human Disease
   • Microbial Growth and Control
     • Lag Phase
     • Log Phase
     • Stationary Phase
     • Death Phase
     • Methods of Control
   • Host-Microbe Interactions
     • Normal Flora
     • Pathogenesis and Immune Evasion
5. 5

   Immunology

   5 topics

   • Innate Immune System
     • Physical and Chemical Barriers
     • Phagocytic Cells
     • Inflammatory Response
   • Adaptive Immune System
     • Lymphocytes
     • Antigen Presentation and Recognition
     • Clonal Selection and Expansion
   • Antibodies and Antigens
     • Structure and Function of Antibodies
     • Types of Antibodies
     • Antigen-Antibody Interactions
   • Vaccination and Immune Memory
     • Principles of Vaccination
     • Types of Vaccines
     • Long-term Immunity
   • Immune System Disorders
     • Autoimmune Diseases
     • Allergies
     • Immunodeficiency
6. 6

   Physiology

   8 topics

   • Nervous System
     • Neuron Structure and Function
     • Action Potential and Synaptic Transmission
     • Central Nervous System (Brain, Spinal Cord)
     • Peripheral Nervous System (Somatic, Autonomic)
   • Endocrine System
     • Hormone Types and Mechanisms of Action
     • Major Glands and Hormones (Hypothalamus, Pituitary, Thyroid, Adrenal, Pancreas, Gonads)
     • Feedback Mechanisms
   • Cardiovascular System
     • Heart Anatomy and Physiology
     • Blood Vessels and Circulation
     • Blood Composition and Function
   • Respiratory System
     • Anatomy of the Respiratory System
     • Mechanisms of Breathing
     • Gas Exchange and Transport
   • Digestive System
     • Anatomy of the Digestive Tract
     • Digestive Enzymes and Their Functions
     • Nutrient Absorption
   • Renal System
     • Kidney Structure and Function
     • Nephron and Urine Formation
     • Regulation of Water and Electrolyte Balance
   • Musculoskeletal System
     • Muscle Structure and Contraction Mechanisms
     • Bone Structure and Function
     • Joint Types and Movement
   • Reproductive System
     • Male and Female Reproductive Anatomy
     • Hormonal Regulation of Reproduction
     • Gametogenesis and Fertilization
7. 7

   Developmental Biology

   4 topics

   • Embryogenesis
     • Stages of Early Development (Fertilization, Cleavage, Blastulation, Gastrulation)
     • Germ Layer Formation
     • Organogenesis
   • Stem Cells and Differentiation
     • Types of Stem Cells (Totipotent, Pluripotent, Multipotent)
     • Mechanisms of Differentiation
   • Organ Development
     • Major Organ Systems Development
     • Critical Periods and Teratogens
   • Developmental Disorders
     • Genetic Disorders
     • Congenital Malformations

Biology flashcards for MCAT

22 of 51 cards from the Biology deck — real questions with worked answers.

1. What are the three main tenets of the classical Cell Theory?

   (1) All living organisms are composed of one or more cells; (2) The cell is the basic structural and functional unit of life; (3) All cells arise from pre-existing cells (Virchow's "omnis cellula e cellula").

2. List the four key structural differences between prokaryotic and eukaryotic cells.

   Prokaryotes lack a membrane-bound nucleus (DNA in nucleoid), lack membrane-bound organelles, have a single circular chromosome, and have 70S ribosomes. Eukaryotes have a true nucleus, membrane-bound organelles, linear chromosomes, and 80S ribosomes.

3. Compare the ribosome sedimentation coefficients of prokaryotes and eukaryotes.

   Prokaryotes have 70S ribosomes (50S + 30S subunits). Eukaryotes have 80S cytoplasmic ribosomes (60S + 40S subunits). Note the Svedberg unit ($S$) is not additive because it reflects sedimentation rate.

4. According to the fluid mosaic model, what are the primary components of the cell membrane?

   A phospholipid bilayer (amphipathic, with hydrophilic heads outward and hydrophobic tails inward) interspersed with cholesterol, integral (transmembrane) and peripheral proteins, and carbohydrates attached as glycoproteins and glycolipids.

5. What role does cholesterol play in the fluidity of the animal cell membrane?

   Cholesterol acts as a fluidity buffer: at high temperatures it restrains phospholipid movement (decreasing fluidity), and at low temperatures it prevents tight packing (increasing fluidity), maintaining optimal membrane fluidity across temperatures.

6. Distinguish passive diffusion, facilitated diffusion, and active transport with respect to gradient and energy.

   Passive (simple) diffusion moves solutes down their gradient without protein or energy. Facilitated diffusion moves solutes down their gradient via a carrier/channel protein, no energy. Active transport moves solutes against their gradient and requires energy (ATP).

7. Describe the ion movements and stoichiometry of the $\ce{Na+/K+}$-ATPase.

   Per ATP hydrolyzed, it pumps 3 $\ce{Na+}$ out of the cell and 2 $\ce{K+}$ into the cell, both against their gradients. This is primary active transport that maintains the resting membrane potential and is electrogenic.

8. Define osmosis and predict water movement for hypertonic, hypotonic, and isotonic external solutions.

   Osmosis is diffusion of water across a semipermeable membrane from low to high solute concentration. In a hypertonic solution the cell shrinks (water leaves); in a hypotonic solution it swells/lyses (water enters); in an isotonic solution there is no net water movement.

9. Differentiate primary and secondary active transport.

   Primary active transport uses ATP directly to move a solute against its gradient (e.g., $\ce{Na+/K+}$-ATPase). Secondary active transport (co-transport) uses the electrochemical gradient established by primary transport to drive another solute against its gradient, via symport or antiport.

10. What is the function of the mitochondrion and why is it considered semi-autonomous?

    The mitochondrion is the site of the citric acid cycle, oxidative phosphorylation, and ATP production. It is semi-autonomous because it has its own circular DNA, 70S ribosomes, and double membrane, consistent with the endosymbiotic theory.

11. Contrast the functions of rough and smooth endoplasmic reticulum.

    Rough ER is studded with ribosomes and synthesizes/modifies secretory and membrane proteins. Smooth ER lacks ribosomes and functions in lipid/steroid synthesis, detoxification, and (in muscle) calcium storage.

12. What is the role of the Golgi apparatus, and name its cis and trans faces.

    The Golgi modifies, sorts, packages, and ships proteins and lipids into vesicles. The cis face (near the ER) receives vesicles; the trans face (near the membrane) ships them to their destinations.

13. Compare the enzymatic roles of lysosomes and peroxisomes.

    Lysosomes contain acid hydrolases that digest macromolecules and cellular debris via autophagy at low pH (~5). Peroxisomes break down very-long-chain fatty acids via $\beta$-oxidation and detoxify, producing and degrading $\ce{H2O2}$ using catalase.

14. Name the phases of interphase and what occurs in each.

    $G_1$ (cell growth, organelle synthesis), $S$ (DNA replication, chromosomes duplicated), and $G_2$ (further growth, preparation for mitosis). $G_0$ is a non-dividing resting state.

15. List the four stages of mitosis in order and one key event in each.

    Prophase (chromatin condenses, spindle forms, nuclear envelope breaks down), Metaphase (chromosomes align at the metaphase plate), Anaphase (sister chromatids separate to opposite poles), Telophase (nuclear envelopes reform, chromosomes decondense), followed by cytokinesis.

16. What occurs at the $G_2/M$ checkpoint and which molecule drives it?

    The $G_2/M$ checkpoint verifies that DNA has been correctly and completely replicated and there is no DNA damage before mitosis. It is driven by MPF (maturation-promoting factor), a complex of cyclin B and cyclin-dependent kinase 1 (CDK1).

17. How does meiosis differ from mitosis in outcome (ploidy and number of daughter cells)?

    Mitosis produces 2 genetically identical diploid ($2n$) daughter cells. Meiosis produces 4 genetically unique haploid ($n$) daughter cells through two divisions (meiosis I and II).

18. What are synapsis and crossing over, and when do they occur?

    Synapsis is the pairing of homologous chromosomes to form tetrads (bivalents), and crossing over is the exchange of genetic material between homologs at chiasmata. Both occur in prophase I of meiosis, generating genetic recombination.

19. When do homologous chromosomes separate versus sister chromatids in meiosis?

    Homologous chromosomes separate during anaphase I (reductional division, $2n \to n$). Sister chromatids separate during anaphase II (equational division), analogous to mitosis.

20. Compare spermatogenesis and oogenesis in terms of number and size of functional gametes.

    Spermatogenesis produces 4 functional, equal-sized sperm per primary spermatocyte. Oogenesis produces 1 large functional ovum plus 2-3 polar bodies per primary oocyte, due to unequal cytoplasmic division.

21. Describe the double-helix structure of DNA including strand orientation and helix type.

    DNA is a right-handed double helix of two antiparallel strands (one $5'\to 3'$, the other $3'\to 5'$) with a sugar-phosphate backbone and nitrogenous bases pairing in the interior; standard B-DNA.

22. State Chargaff's rules and the base-pairing / hydrogen-bond details in DNA.

    Chargaff's rules: %A = %T and %G = %C, so purines = pyrimidines. Adenine pairs with thymine via 2 hydrogen bonds; guanine pairs with cytosine via 3 hydrogen bonds.

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