Week 9 — Readings & Resources · The Cell Cycle & Mitosis

Course: Introduction to Biology — General Biology I (BIOL 101) · Silver Oak University (fictional sample) · Prof. Castellano
Objective covered: Objective 5 — Explain how cells divide: the cell cycle, the phases of mitosis, the purpose of division, cell-cycle control, and the mitotic index.

How to use this page

Everything here is a link to an external resource — open it in your browser, the same way you'd open a YouTube link. Nothing needs to be downloaded.

This week's load is deliberately light: 2 short videos + 2 short readings, grouped by the ideas from the lecture, plus a couple of optional free references. Watch or read one item per group and you're ready for the quiz; do all of them and you'll be very comfortable. Total time is roughly 35–45 minutes if you do everything, far less if you pick one per group.

Order that matches the lecture: ① the cell cycle → ② the phases of mitosis (PMAT) & cytokinesis → ③ cell-cycle control & cancer → ④ the mitotic index (the lab connection).

A habit to start now: before you trust any biology claim — in these resources or anywhere — ask the questions from class: Is this mitosis or meiosis? Are the phases in the right order? Does the chromosome count stay the same?

① The Cell Cycle · and ② The Phases of Mitosis (PMAT)

Maps to Lecture Segments 2–4. A cell spends most of its life in interphase (G1 → S → G2, with DNA copied in S), then divides in the M phase. Mitosis runs in a fixed order — Prophase → Metaphase → Anaphase → Telophase — followed by cytokinesis, producing two identical diploid cells.

Video — "Mitosis: The Amazing Cell Process that Uses Division to Multiply!" (Amoeba Sisters)
🔗 https://www.youtube.com/watch?v=f-ldPgEfAHI
Why it earns the click: a friendly ~8-minute tour of exactly what we built on the board — why mitosis matters, interphase, chromosome replication, the PMAT phases, and cytokinesis — with the same mnemonics. It makes the same point we did: mitosis makes two identical cells.
⏱ ~8 min

Reading — "The Cell Cycle" (OpenStax Biology 2e, §10.2)
🔗 https://openstax.org/books/biology-2e/pages/10-2-the-cell-cycle
Why it's assigned: the cleanest plain-language version of interphase (G1, S, G2), the phases of mitosis, and cytokinesis we walked through in class — and it ends with the very whitefish-blastula counting exercise that mirrors this week's lab (count cells, find the percentage in each phase, estimate the time spent). Free to read online, no account needed.
⏱ ~12 min

③ Cell-Cycle Control & Cancer

Maps to Lecture Segment 5 & 7. The cycle has checkpoints that stop a damaged or incomplete cell from dividing. Cancer is what happens when that control fails — mitosis with the brakes cut — which is why chemo drugs that target dividing cells also hit fast-dividing healthy tissues (hair, gut, marrow).

Video — "The Cell Cycle (and cancer)" (Amoeba Sisters)
🔗 https://www.youtube.com/watch?v=QVCjdNxJreE
Why it earns the click: walks through the cell cycle (G1, S, G2, G0), the checkpoints, cell-cycle regulation, and how losing control leads to cancer — exactly the framing for this week's discussion. About 9 minutes.
⏱ ~9 min

④ The Mitotic Index — the Lab Connection · and the Big Picture

Maps to Lecture Segment 6 and Lab 9. The mitotic index = (cells in mitosis ÷ total cells) × 100. In a fast-growing onion root tip, most cells are in interphase and a minority are dividing — counting them gives you a real number for how fast division is happening.

Reading — "The Cell Cycle" interactive overview (Learn.Genetics, University of Utah)
🔗 https://learn.genetics.utah.edu/content/basics/cellcycle
Why it's assigned: a clear, visual walkthrough of the phases of the cell cycle and what happens in each — a good companion before you start the onion-root-tip lab and have to identify each phase by eye.
⏱ ~8 min

Optional one-stop references (free online)

• Khan Academy — Mitosis. A free unit with short articles and videos on the phases of mitosis and the cell cycle. A good place to return to all term.
  🔗 https://www.khanacademy.org/science/biology/cellular-molecular-biology/mitosis
• Khan Academy — "Cancer" (video). An optional, plain-language explanation of cancer as cells that have lost normal cell-cycle control and divide uncontrollably — the science behind this week's discussion.
  🔗 https://www.khanacademy.org/science/biology/cellular-molecular-biology/stem-cells-and-cancer/v/cancer

Pick-one quick path (≈17 min total)

In a hurry? Do exactly these two and you'll be ready for the quiz:
1. Watch "Mitosis: The Amazing Cell Process…" (groups ①–②) — it covers interphase, PMAT, and cytokinesis.
2. Watch "The Cell Cycle (and cancer)" (group ③), and skim the OpenStax §10.2 "Determine the Time Spent in Cell-Cycle Stages" box (group ④) so the mitotic-index lab feels familiar.

Heads-up (links rot): these point to outside sites that occasionally move or rename pages. If a link ever fails, tell Prof. Castellano and use the OpenStax or Khan Academy references above in the meantime.