Biology Chapter 7—The Working Cell: Energy from Food



Biology Chapter 7—The Working Cell: Energy from Food

Objectives: 7.3

➢ Describe the structure of ATP and how it stores energy.

➢ Give examples of work that cells perform.

➢ Summarize the ATP Cycle

ATP Structure – see figure 7.9

Adenosine triphosphate = ____

Adenosine diphosphate =____+

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The ATP Cycle

The Cycle is shown in figure 7-11. This shows how the ATP cycle is continuous and is constantly being replenished by energy from food and the energy that is converted to ATP is stored energy that can be used to complete cell work.

Cell Work

There are 3 basic types of cell work:

Chemical Work-

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Mechanical Work-

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Transport Work –

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Objectives: 7.4

➢ Relate breathing and cellular respiration.

➢ Summarize the cellular respiration equation.

➢ Tell how “falling” electrons area source of energy

➢ Explain the role of electron transport chains.

Cellular Respiration and breathing – the connection

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Glucose is broken down in our cells to carry on the process of producing ATP which not part of breathing but is part of cellular respiration.

Cellular Respiration Equation

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The process of cellular respiration can make up to 38 ATP from one glucose molecule.

Falling Electrons

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Instead of burning as in the food lab our cells release energy in small increments.

Electron Transport Chains

Since electron carriers like NADH and FADH2 pass electrons down the chain, the final stage of cellular respiration produces the largest amount of ATP. Each carrier is stronger than the one before and at the end combines the final carrier molecule(oxygen final electron acceptor) and joins them with hydrogen ions, forming water. Small amounts of energy are released a little at a time and this energy is trapped to eventually make ATP

Objectives: 7.5

➢ Describe the structure of a mitochondrion

➢ Summarize the three stages of cellular respiration and identify where ATP is made

Mitochondria(singular, mitochondrion)

There is an __________________________________ and a space between. The _______________is the thick fluid enclosed by the inner membrane.

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Cellular Respiration in review

Stage I: Glycolysis –This stage takes place in the ________________________ and doesn’t require Oxygen __________________________________________________.

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Each 3-carbon molecule transfers electrons(2) and one hydrogen ion – see diagram

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Stage 2- The Krebs Cycle- This stage takes place in matrix of the inner membrane of the mitochondria- This stage only occurs in aerobic respiration

Starting with the __________ from glycolysis – the pyruvic acid is converted to _______________ (Acetyl CoA), a 2-carbon compound and a _____________________ is released, but since

there are 2 pyruvic acid molecules there will be ____ carbon dioxide molecules. As the Krebs Cycle begins, please remember that there will be ________ of the cycle for each glucose

molecule. Two more carbon dioxide are released as molecules are converted into other carbon compounds. ____________________________________________________ (another energy

carrier) These numbers are all doubled due to the two turns of the Kreb’s Cycle per one glucose.

Stage 3- Electron Transport Chain and ATP Synthase Action- This stage takes place in the inner membranes of the mitochondria.

Now the energy carrier molecules come into play, each carrier pulls the electrons more strongly until the end when they are pulled to oxygen and combine with Hydrogen to form water. Since some energy is released at each transfer of electrons between carriers H+ ions are pumped across the membrane against the concentration gradient. So they are moving to a more concentrated area, which builds up and since ATP synthase is a located in the membrane and spins, H+ ions can be pushed back into a less concentrated area producing large amounts of ATP from ADP + P and the enzyme embedded in the membrane, ATP synthase.

End Result of Cellular Respiration

Glycolysis Krebs Cycle Electron Transport Chain Totals

2 - ATP 2 - ATP 32 – 34 ATP ___________

2 NADH 8 NADH 0 NADH ___________

0 FADH2 2 FADH2 0 FADH2 ___________

Objectives – 7.6

➢ Explain how fermentation in muscle cells is different from cellular respiration.

➢ Give examples of products that depend on fermentation in microorganisms.

When a person expends a lot of energy they may not be able to take in enough oxygen to complete the cellular work of exercise. In these instances your body will make ATP without oxygen, called ______________. Since this process only goes through glycolysis only 2 ATP are made, but this will make it possible for your body to catch up. In the meantime your body will produce lactic acid as waste of fermentation, which causes muscle cramps. Your body will regain it ability to go through all the steps of cellular respiration after a few minutes of heavy breathing or stopping the activity. The body then converts the lactic acid back to pyruvic acid and the cells can now continue with aerobic respiration. Some organisms also use ______________________ to produce some foods, for example yogurt, cheese, sauerkraut and soy sauce.

Alcoholic fermentation occurs in yeast and some microorganisms. In this situation when oxygen is not available the organisms produce ethyl alcohol as a waste product instead of lactic acid in our muscle cells. Carbon dioxide is also released and this is the bubbles you see in rising bread dough or soft drinks or beer.

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