Molecular biology

Follow DNA copying and repair, RNA processing, translation, regulation, and molecular evidence. Separate sequence consequences from cellular function.

Prerequisite: High-school biology, chemistry, and arithmetic. Sequence notation is introduced within the course. Thirteen lessons and 26 illustrated exercises connect molecular structure to copying, expression, regulation, turnover, and evidence. Short sequence readers, isotope predictions, splicing comparisons, and bounded quantitative models keep assumptions visible. The course is not a laboratory protocol or a clinical interpretation service.

Lessons

1. 1

   Separate sequence, molecule, and cellular function

   DNA, RNA, and proteins are physical molecules with different jobs. A sequence describes only part of their behavior.

2. 2

   Read complementary strands in the correct direction

   Base pairing and strand orientation are separate constraints. Reversing a sequence is not complementing it.

3. 3

   Copy DNA while preserving strand direction

   Each old strand guides a new partner. Isotope-label predictions distinguish competing copying mechanisms.

4. 4

   Distinguish damage, mismatch, and inherited change

   An abnormal base pair is not yet the same thing as a stable sequence variant in all descendants.

5. 5

   Make RNA from a specified DNA template

   RNA resembles the coding strand, but the polymerase reads the other strand.

6. 6

   Build a mature message from a longer transcript

   Splicing changes which sequence reaches the ribosome without necessarily changing the underlying DNA.

7. 7

   Read codons and assemble an amino-acid chain

   The ribosome reads an RNA frame. Charged transfer RNAs connect codons to amino acids, and release factors respond to stop codons.

8. 8

   Connect a peptide to function without assuming identity

   Amino-acid order constrains structure, but function also depends on folding, partners, modifications, and location.

9. 9

   Control expression through binding and accessibility

   Cells with similar DNA can make different products because regulatory conditions differ.

10. 10

    Balance synthesis and removal over time

    Abundance is a changing pool. Its size depends on both production and loss.

11. 11

    Trace sequence changes without predicting a phenotype too soon

    Substitution, insertion, and deletion affect codons in different ways. Sequence consequences are only one stage of interpretation.

12. 12

    Ask what a molecular assay actually measures

    Sequence, RNA, protein, and activity assays answer different questions. Controls determine which comparisons are interpretable.

13. 13

    Audit a claim from DNA to cellular activity

    Use the complete chain to distinguish what is observed, what follows from a model, and what remains a hypothesis.