Week 6 — Readings & Resources · Cellular Respiration

Course: Introduction to Biology — General Biology I (BIOL 101) · Silver Oak University (fictional sample) · Prof. Castellano
Objective covered: Objective 4 — Trace how cells harvest energy from glucose: the three stages in order, their locations, the role of oxygen, and fermentation.

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 optional free online 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 big picture + the three stages in order → ② zoom into the stages (glycolysis, Krebs, ETC) → ③ fermentation, when oxygen runs out.

A habit to start now: before you trust any biology claim — in these resources, from a chatbot, or anywhere — ask the questions from class: Are the three stages in the right order? Where does each one happen? Which stage makes the most ATP, and where is oxygen actually used?

① The Big Picture · the three stages in order

Maps to Lecture Segments 2–3. Cellular respiration "burns" glucose in a controlled way to make ATP, in three stages — glycolysis → Krebs cycle → electron transport chain — and the order and locations are the whole game this week.

Video — "ATP & Respiration: Crash Course Biology #7" (CrashCourse)
🔗 https://www.youtube.com/watch?v=00jbG_cfGuQ
Why it earns the click: Hank Green does push-ups to power the explanation and walks the same three stages in order — glycolysis, then the Krebs cycle, then the electron transport chain — with ATP, pyruvate, and oxygen showing up exactly where we put them in class.
⏱ ~13 min

Reading — "Glycolysis" (OpenStax Biology 2e, §7.2)
🔗 https://openstax.org/books/biology-2e/pages/7-2-glycolysis
Why it's assigned: the cleanest plain-language version of stage one — glucose split into two pyruvate in the cytoplasm for a net 2 ATP, with no oxygen required. Free to read online, no account needed. (The "Outcomes of Glycolysis" section is the part to anchor on.)
⏱ ~10 min

② Zoom In · the Krebs cycle and the electron transport chain

Maps to Lecture Segments 3 & 5. Where the pyruvate goes next: the Krebs cycle in the mitochondrial matrix (which releases CO₂) and the electron transport chain on the inner membrane (which makes the most ATP, with O₂ as the final electron acceptor).

Reading — "Oxidation of Pyruvate and the Citric Acid Cycle" (OpenStax Biology 2e, §7.3)
🔗 https://openstax.org/books/biology-2e/pages/7-3-oxidation-of-pyruvate-and-the-citric-acid-cycle
Why it's assigned: shows the Krebs (citric-acid) cycle running in the matrix of the mitochondria, releasing carbon dioxide, and producing the NADH and FADH₂ that feed the next stage — exactly the role we gave it in class. (Read for the big picture, not the eight individual steps.)
⏱ ~10 min

Reading (optional) — "Oxidative Phosphorylation" (OpenStax Biology 2e, §7.4)
🔗 https://openstax.org/books/biology-2e/pages/7-4-oxidative-phosphorylation
Why it's here: the electron transport chain "is the last component of aerobic respiration and is the only part of glucose metabolism that uses atmospheric oxygen," sitting in the inner mitochondrial membrane and making most of the ATP — the source for "the chain makes the most" and "O₂ is the final electron acceptor." Skim the intro and the "ATP Yield" paragraph.
⏱ ~8 min

③ When Oxygen Runs Out · Fermentation

Maps to Lecture Segment 6 and your lab. With no oxygen, cells fall back on glycolysis + fermentation — lactic-acid in your muscles, alcohol + CO₂ in yeast (the CO₂ you'll measure in the lab).

Video — "Fermentation" (Amoeba Sisters)
🔗 https://www.youtube.com/watch?v=YbdkbCU20_M
Why it earns the click: a friendly ~8.5-minute tour of what happens when oxygen isn't available — both alcoholic fermentation (yeast → ethanol + CO₂) and lactic-acid fermentation (your muscles) — the exact backup process behind the sprint discussion and the yeast lab.
⏱ ~9 min

Reading — "Metabolism without Oxygen" (OpenStax Biology 2e, §7.5)
🔗 https://openstax.org/books/biology-2e/pages/7-5-metabolism-without-oxygen
Why it's assigned: explains fermentation as the way cells keep glycolysis going without oxygen, and covers both lactic-acid fermentation (muscle cells, red blood cells) and alcohol fermentation (yeast → ethanol + CO₂, which makes bread rise and wine bubble). The clearest source for the lab's biology.
⏱ ~10 min

Optional one-stop references (free online)

• Khan Academy — "Intro to cellular respiration: the big picture." A free article that lays out the whole pathway and the three stages in order — a clean place to review before the quiz.
  🔗 https://www.khanacademy.org/science/ap-biology/cellular-energetics/cellular-respiration-ap/a/intro-to-cellular-respiration-the-big-picture
• Khan Academy — Cellular respiration and fermentation (unit). A free unit with short articles and videos on glycolysis, the citric-acid cycle, oxidative phosphorylation, and fermentation. A good place to return to all term.
  🔗 https://www.khanacademy.org/science/biology/cellular-respiration-and-fermentation

Pick-one quick path (≈22 min total)

In a hurry? Do exactly these two and you'll be ready for the quiz:
1. Watch "ATP & Respiration: Crash Course Biology #7" (groups ①–②) — it gets you the three stages, in order, with locations.
2. Watch "Fermentation" (group ③) for the no-oxygen backup behind the sprint discussion and the yeast lab.

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.