Ch. 4A: Cell Energy
Reading
BJU Biology: Ch. 4A - "Cellular Energy"
AP Princeton Review Ch. 6 - Cellular Energetics
Topics
Metabolism, Respiration, Photosynthesis
Lab
The best lab for illustrating cell energetics is the ethanol biofuels lab - "Biosynthesis and distillation of ethanol". In the fermentation step, we study cell respiration, and in the distillation and combustion steps we learn thermodynamics. This has been a favorite lab for several years. Lab handouts and instructions are down below, near the bottom.
Biofuels Video Presentations
Fun project if time allows
BJU Biology: Ch. 4A - "Cellular Energy"
AP Princeton Review Ch. 6 - Cellular Energetics
Topics
Metabolism, Respiration, Photosynthesis
Lab
The best lab for illustrating cell energetics is the ethanol biofuels lab - "Biosynthesis and distillation of ethanol". In the fermentation step, we study cell respiration, and in the distillation and combustion steps we learn thermodynamics. This has been a favorite lab for several years. Lab handouts and instructions are down below, near the bottom.
Biofuels Video Presentations
Fun project if time allows
| 3._cellular_respiration_ppt_lecture_.pptx |
| Photosynthesis lecture slides |
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Below: Motor Proteins (below left) and ATP Synthase (below right) need energy to run on!
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What are we learning here?
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, while plant cells get their energy and raw materials from sunlight and atmospheric carbon dioxide (CO2) in a process called photosynthesis.
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, while plant cells get their energy and raw materials from sunlight and atmospheric carbon dioxide (CO2) in a process called photosynthesis.
Cellular Respiration
Step 1: Glycolysis ("Gimme a Break")
Photosynthesis
In photosynthesis, the plant captures photons of light on chlorophyll, which in turn converts the electromagnetic energy of light into electrical energy (just like an antenna and amplifier do), and then sends the electricity down the line on a series of protein transport molecules which also function as proton pumps, eventually reaching a rotating, proton-powered turbine called ATP Synthase, which charges-up new ATP energy molecules using a rotating camshaft - just like cellular respiration does. The newly-charged ATP energy molecules then power a complex chemical factory within the leaf - with the ATP functioning just like a battery - wherein the plant manufactures all its starch, cellulose, and other molecules from carbon (C) it obtains from atmospheric CO2. Putting it another way, the plant literally 'builds itself' from the CO2 contained in the atmosphere - using ATP batteries which have been charged by a rotary turbine, which is powered by a stream of protons, which were pumped using electricity, which was obtained from an antenna (chlorophyll molecule), which originally had captured a bit of sunlight. When you stand back and realize the beauty-of-design and complex engineering contained within that process, Biology starts to get very, very interesting.
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!
Photosynthesis
In photosynthesis, the plant captures photons of light on chlorophyll, which in turn converts the electromagnetic energy of light into electrical energy (just like an antenna and amplifier do), and then sends the electricity down the line on a series of protein transport molecules which also function as proton pumps, eventually reaching a rotating, proton-powered turbine called ATP Synthase, which charges-up new ATP energy molecules using a rotating camshaft - just like cellular respiration does. The newly-charged ATP energy molecules then power a complex chemical factory within the leaf - with the ATP functioning just like a battery - wherein the plant manufactures all its starch, cellulose, and other molecules from carbon (C) it obtains from atmospheric CO2. Putting it another way, the plant literally 'builds itself' from the CO2 contained in the atmosphere - using ATP batteries which have been charged by a rotary turbine, which is powered by a stream of protons, which were pumped using electricity, which was obtained from an antenna (chlorophyll molecule), which originally had captured a bit of sunlight. When you stand back and realize the beauty-of-design and complex engineering contained within that process, Biology starts to get very, very interesting.
The videos 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 handouts
See Canvas for due dates.
See Canvas for due dates.
| cellular_respiration_video_questions.docx |
| bugs_with_gears_assignment_.docx |
| 4.1._photosynthesis_MCQs_PDF handout.pdf |
Ethanol Biofuels lab: "Biosynthesis and distillation of ethanol"
| 0._biofuels_lab_handout_ |
| 5._biofuels_video_project.docx |
| biofuels_lab_report_part_2_student_examples DO YOUR OWN WORK.pdf |
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In this lab, we will make ethanol using fermentation, concentrate it using distillation, and demonstrate its capability as a fuel by running a Sterling Engine. This project is an excellent platform for learning about 1) cellular respiration and 2) modern biotechnology.
Learning objectives:
- (optional if time allows) Break-down carbohydrates into sugars using amylase enzyme. This is called "conversion".
- (optional if time allows) Detect sugars and carbohydrates using the Benedicts Reagent test and the Iodine test.
- (to save time, we may start here) Fermentation of sucrose to ethanol
- Prove that fermentation produces CO2 as a waste byproduct. Bubble CO2 through lime water to create Calcium Carbonate precipitate, and observe the accompanying pH reduction.
- Concentrate the ethanol from 10% up to 90%+ using distillation
- Use the ethanol biofuel to run a Sterling Engine
Learning objectives:
- Fermentation is an anaerobic (without oxygen) process which converts glucose into energy for the cells.
- Yeast (and your muscle cells) can use fermentation to generate energy quickly in the absence of oxygen.
- Fermentation represents only the first stage of Respiration. Your body's cells will normally go further to Kreb's Cycle and to Oxidative Phosphorylation - yielding much more energy.
- Fermentation starts with Glucose (6-carbon molecule) and ends at Pyruvate (3-carbon molecule). Complete cellular respiration, by comparison, converts the Glucose (6-carbons) all the way to Carbon Dioxide and water.
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