Week 14 — Gene Expression

Why this matters

A nursing student explaining a sickle cell result and a lab technician reading a sequence at a bench both follow one gene from message to protein.

In plain language

Every cell in your body carries the same DNA, but the DNA itself never leaves the nucleus. This week you follow one gene as the cell copies it into a working message and then reads that message to build a protein. The copying step is transcription (writing a gene's letters into a matching RNA message), and the reading step is translation (turning that message into a chain of amino acids). Francis Crick named this flow the central dogma in 1958, and its message is read three letters at a time, in a code nearly every living thing shares. By the end of the week you can take a short gene, write its message, and name the protein it makes.

• Already covered: Week 13 built DNA's double helix and its pairing rule.
• This week: transcription, the genetic code, translation, and the sickle-cell codon.
• How they connect: the same pairing rule writes the message, with U for T.
• Where we're going next: Week 15 asks how cells switch genes on and off.

Focus

How does a string of DNA letters become a working protein?

By the end of this module, you should be able to:

• [ ] state the central dogma in order, with places
• [ ] transcribe a template strand into mRNA
• [ ] translate an mRNA from AUG with a codon table
• [ ] explain why one changed letter may or may not alter a protein

To-do

Plan your week

1. Read Chapter 14 (about 45 minutes), then the lecture and slides.
2. Work the lecture tutorial (60–90 minutes) and the practice set (20 minutes).
3. Run the Biology Lab & Inquiry (2 hours), then the discussion and assignment.
4. Take the quiz.

This week's checkpoint: carry a short gene from template to protein and scan the mRNA for T.

You've got this

Take it in order; ask your instructor if a step snags.

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