Unit 3: How Cells Obtain Energy: Cellular Respiration
Reading
BJU Biology: Ch. 4, part 'A' (the first half of the chapter)
AP: OpenStax Biology: Ch. 6 "Metabolism" and Ch. 7 "Cellular Respiration"
Topics
Homework
Various handouts and instructions are posted near the bottom.
Lab options for this Unit
BJU Biology: Ch. 4, part 'A' (the first half of the chapter)
AP: OpenStax Biology: Ch. 6 "Metabolism" and Ch. 7 "Cellular Respiration"
Topics
- Activation energy
- Enzymes
- ATP
- Cellular Respiration
Homework
Various handouts and instructions are posted near the bottom.
Lab options for this Unit
- Bio-Rad Photosynthesis and Cellular Respiration lab ("Algae Beads" lab). This is an excellent lab covering both Cell Respiration AND Photosynthesis, and fulfills the AP "dirty dozen labs" # 5 and #6. There are lab reports for both regular and AP levels.
- Ethanol Biofuels lab (instructions in the next Unit)
| cellular_respiration_-_glycolysis_krebs_cycle___electron_transport_chain |
Below: Cells require energy to run, including powering their motor proteins (left). The ATP Synthase rotary turbine in the Mitochondria is responsible for charging up ATP 'batteries'.
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Lecture outline
At this point in the course, we are beginning to see that every cell is like a complex factory - full of nanomachines, walking motor-proteins, and spinning turbo-generators - and that's what makes Biology and Biotechnology incredibly fascinating.
Cells require energy to do all this work (that's why you eat!). Animal cells get their energy and raw-materials by breaking down glucose (blood sugar) in a process called cellular respiration (covered in this Unit), while plant cells get their energy and raw materials from sunlight and atmospheric carbon dioxide (CO2) in a process called photosynthesis (covered in the next Unit).
At this point in the course, we are beginning to see that every cell is like a complex factory - full of nanomachines, walking motor-proteins, and spinning turbo-generators - and that's what makes Biology and Biotechnology incredibly fascinating.
Cells require energy to do all this work (that's why you eat!). Animal cells get their energy and raw-materials by breaking down glucose (blood sugar) in a process called cellular respiration (covered in this Unit), while plant cells get their energy and raw materials from sunlight and atmospheric carbon dioxide (CO2) in a process called photosynthesis (covered in the next Unit).
A simple explanation of cellular respiration:
- Your food is digested and broken down into glucose. Glucose is a 6-carbon sugar. A way to think of glucose is old-fashioned corn syrup.
- The glucose molecules are transported from your small intestine into your blood stream. It is now referred to as blood sugar.
- The glucose is transported from your bloodstream across your cell membranes (active transport) so the cells can use it as fuel. The insulin produced by your pancreas tells your cells to uptake the glucose. We learned this in our Diagnosing Diabetes lab.
- Once in the cell, the 6-carbon glucose molecules are broken down into 3-carbon molecules known as pyruvate, in the process generating 2 ATP molecules for energy use. This step is called glycolysis. ATP = adenosine triphosphate.
- Then, in the mitochondria, the pyruvate molecules are broken all the way down to CO2, in the process generating 2 more ATPs ... plus a bunch of NADH and FADH2 energy molecules. The CO2 produced in this step is the CO2 you breathe out in your breath.
- In the final step, the NADH and FADH2 molecular trucks deliver their stored-up energy to high-speed molecular turbines called ATP Synthase, also in your mitochondria. ATP Synthase is a fascinating, proton-powered, molecular-sized, turbine generator - which is assembled from dozens of protein parts. The ATP Synthase spins rapidly and generates 34 additional ATPs - a lot of energy!
The 3 steps of cellular respiration
Step 1: Glycolysis ("Gimme a Break")
Step 1: Glycolysis ("Gimme a Break")
- Glucose enters the cell's cytoplasm, where the 6-carbon molecule is broken down into two, 3-carbon molecules called pyruvate. This generates 2 ATP's for energy use.
- ATP is called the 'battery' or 'energy currency' of the cell. If one molecule of glucose represents a $10 bill, then a molecule of ATP represents 25 cents. The cell can't burn a molecule of glucose all at once - it's too big; that's why it needs a smaller unit such as ATP.
- The 3-carbon pyruvate molecules are then broken down all the way to CO2 molecules in the Krebs Cycle (also called Citric Acid Cycle).
- This occurs in the mitochondria, the "power plant" of the cell
- 2 more ATP's are made available, but more importantly the electron carriers NADH and FADH2 are loaded with electrons and ready to enter the 'electron transport chain'.
- The loaded electron trucks NADH and FADH2 then transfer their electron cargo to the Electron Transport Chain
- The energy from the electrons is used to run high-speed turbines called ATP-Synthase. The turbines are mounted in the inner membrane of the mitochondria. (refer to video clip)
- The turbines spin very fast (7,000 RPM) and are connected by a driveshaft to a generator which very quickly charges up new ATP 'batteries'
- In this manner, ADP (discharged batteries) are transformed to ATP (newly charged batteries). About 34 additional ATP's are produced in this step. This is highly productive!
Below: 'ATP Synthase' is a molecular rotary turbine which recharges ATP in your cells. It is literally a proton-powered turbine-generator. These amazing nanomachines are in the mitochondria within your cells, and within chloroplasts in plants.
Watch the videos below. They will give you a mental picture of what is going on.
Below: Cellular Respiration explained really well (4 min).... watch this one
Below: The Electron Transport Chain explained in some detail (7 min). I would highly recommend watching this...
Below: ATP Synthase rotary turbine in all its Glory (4 min). This is a detailed look at its structure.
Homework
The video goes with the cell respiration homework questions. It explains the process of cellular respiration.
The video goes with the cell respiration homework questions. It explains the process of cellular respiration.
| cellular_respiration_homework_questions_2022__taken_from_bju_chapter_.docx |
| bugs_with_gears_assignment_.docx |
Algae-Beads lab (Bio-Rad Photosynthesis and Cellular Respiration lab)
This lab allows students to measure Photosynthesis and Cellular Respiration first-hand by using the fresh-water algae "Scenedesmus obliquus". The lab handout below is for Regular and AP students. PRINT THIS AND BRING TO THE LAB!
Instructions:
This lab allows students to measure Photosynthesis and Cellular Respiration first-hand by using the fresh-water algae "Scenedesmus obliquus". The lab handout below is for Regular and AP students. PRINT THIS AND BRING TO THE LAB!
Instructions:
- All students are responsible for completing the work in "Investigation #2" including tables, charts, and graphs, as well as Focus Questions #2.1, 2.3 - 2.6, and 2.8 (6 questions).
- In addition, AP students are also responsible for completing the 3 case studies at the end: "Brown Shrimp", "The Dead Zone", and "Brown Kelp in the Indian Ocean".
- 2020: use the time lapse photos below to complete the lab report
| 5._algae_beads_lab_handout_for_regular_and_ap_students__21pp_.pdf |
| algae_beads_lab_time_lapse_photos.docx |
Bacterial Flagellum research assgmt
| bacterial_flagellum_research_assgmt.docx |