Week 13 · Readings & resources

Week 13 — Readings & Resources

Introduction to Biology Free sample edition

Your primary reading is Chapter 13 (in this module). Everything below is the optional, go-deeper layer — pick what helps, skip the rest.

How to use this page

This page has 11 items (5 readings and 6 videos). Allow 48–59 minutes for everything. Each group points back to the matching chapter section and class-session segment, so use the full menu when you want more, or take the quick path below.

Every video here has captions: turn them on with the CC button in the player. The chapter covers the same ideas in text.

Pick-one quick path (20–22 min total)

① The twisted ladder and its pairing rule

Chapter 13, Section “Picture the double helix: rails and rungs” · Session 1, Segment 1, “The double helix: rails and rungs” · Remember: the rails are sugar and phosphate, and the rungs pair A with T and G with C.

DNA Structure and Replication: Crash Course Biology #10 — CrashCourse — a fast, joking episode that builds the double helix and then copies it; it names more replication enzymes and strand details than this course asks for, so hold on to the ladder, the pairing rule, and helicase, polymerase, and ligase, and let the extras go by. (video, 13 min) (captions: creator)
DNA Structure — Teacher's Pet — a short, labeled walk around one nucleotide and then the whole ladder: sugar, phosphate, and base, and how the bases pair across the middle; pause it and name each part before the narrator does. (video, 4 min) (captions: creator)
The DNA molecule is shaped like a twisted ladder — DNA from the Beginning — a one-screen concept page on the sugar-phosphate uprights and the paired rungs, with tabs for an animation and short biographies; read the concept text and check that its rungs match the chapter's A–T and G–C rule. (reading, 3–5 min)
Deoxyribonucleic Acid (DNA) Fact Sheet — genome.gov — a plain-language question-and-answer sheet on what DNA is made of and how its bases pair into a double helix; this builds on Week 9's work with the S phase, when a cell copies its DNA. Stop at the questions about how DNA makes proteins; next week takes that up. (reading, 5–8 min)

② The history, in order

Chapter 13, Section “Place the history in order: from transformation to the double helix” · Session 1, Segment 5, “The history, in order” · Remember: each discovery handed a clue to the next, and no quotation from these scientists is needed to tell the story.

Rosalind Franklin: Great Minds — SciShow — a short portrait of Franklin and her X-ray images of DNA, and of how those images fed the double-helix model; as you watch, place her work between Chargaff's ratios and Watson and Crick's model on the chapter's timeline. (video, 4 min) (captions: creator)

③ Copying the ladder: semiconservative replication

Chapter 13, Section “Compare three copying models” · Session 2, Segment 6, “Three ways to copy” · Remember: each new double helix keeps one old strand and builds one new one, half old and half new.

Meselson-Stahl Experiment — Bozeman Science — a steady walk through the heavy-nitrogen and light-nitrogen experiment, round by round; before each round's result appears, predict the bands each of the three models would give. Notice that the video says the experiment proved the model, where this course says the evidence supports it. (video, 4 min) (captions: creator)
A half DNA ladder is a template for copying the whole — DNA from the Beginning — a one-screen concept page on why one strand can serve as the pattern for its partner, and on the two lines of evidence, DNA polymerase and the nitrogen experiment, that backed the idea; use it while working through the Week-13 module overview. (reading, 3–5 min)
DNA replication - 3D — yourgenome — a short animation of the copying machinery at work; it shows the two new strands built in different ways, a detail beyond this course, so watch for the unzipping, the adding of new bases, and the sealing of the pieces. (video, 4 min) (captions: creator)

④ The strawberry lab

Chapter 13, Section “Run the strawberry extraction” · Session 2, Segment 10, “The strawberry, explained” · Remember: soap opens the membranes, salt helps the DNA clump, and cold alcohol brings it out of the liquid.

Extracting DNA from fruit — yourgenome — a short demonstration of the kitchen extraction from mashed fruit to white strands; watch it before your own lab and note the job of each ingredient as it goes in. (video, 2 min) (captions: creator)
How To Extract DNA From Anything Living — Learn.Genetics — a step-by-step home procedure, written for split peas but naming strawberries as another source, with a short answer under each step on why it works; compare its detergent, salt, and alcohol steps with the chapter's, and treat its extra enzyme step as optional. (reading, 5–8 min)

Optional one-stop reference (free online reference)

DNA Replication — Talking Glossary of Genomic and Genetic Terms — the course's free glossary of genetic terms, open at its entry on DNA replication; read the short definition and skip any detail on the two strands being copied differently, which reaches past this week. (reading, 1–2 min)

Heads-up (links rot): these point to outside sites that occasionally move or rename pages. If a link ever fails, tell your instructor and use the reference above in the meantime.

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