Notes: Cellular Respiration Chapter 4 section 4.4; 4.5 and 4.6.

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Notes: Cellular RespirationChapter 4 section 4.4; 4.5 and 4.6

Chemical energy and food

• How much energy is in food?– When 1 gram of glucose (C6H12O6) is burned

in the presence of oxygen, 3811 calories are released.

• What is a calorie? – A calorie is the amount of energy needed to

raise the temperature of 1 gram of water 1 degree Celsius.

– On a food label Calories (with a capital “C”) represent kilocalories. 1 kilocalorie = 1000 calories.

– Cells use the energy in glucose by slowly releasing it.

• How many calories are in 2 crackers?

• How many calories are in 6 crackers?

60,000

180,000

• Cellular Respiration is the SLOW release of energy from glucose.

4.4 Overview of Cellular Respiration TEKS 4B, 9B

Cellular respiration makes ATP by breaking down sugars.

• Cellular respiration is aerobic, or requires oxygen.• Aerobic stages take place in mitochondria.

mitochondrion

animal cell

Overview of Cellular Respiration

• Is the process that releases energy by breaking down glucose and other food molecules in the presence of oxygen within the mitochondria.

Oxygen + glucose carbon dioxide + water + energy

O2 + C6H12O6 CO2 + H2O + ATP

Glycolysis (part 1)• Glycolysis is the process by which one molecule

of glucose is broken in half to produce two 3-carbon molecules of pyruvate (sometimes called pyruvic acid). • Occurs within the cytoplasm.

4.5 Cellular Respiration in Detail TEKS 4B, 9B

Glycolysis is needed for cellular respiration.

• The products of glycolysis enter cellular respiration when oxygen is available.– two ATP molecules are used to split glucose– four ATP molecules are produced– two molecules of NADH produced– two molecules of pyruvate produced

• Glycolysis must take place first.

– anaerobic process (does not require oxygen)– takes place in cytoplasm– splits glucose into two three-carbon molecules– produces two ATP molecules and 2 NADH (NET)

Aerobic Cellular RespirationIf Oxygen is present

• The remaining 90% of the energy from the glucose molecule that was not used in glycolysis is used in the part of cellular respiration that requires oxygen (aerobic). • Cell Respiration occurs within the

mitochondria when oxygen is present. • Also named aerobic respiration. • There are two parts after glycolysis: the Krebs

Cycle and the Electron Transport Chain.

Cellular respiration is like a mirror image of photosynthesis.

• The Krebs cycle transfers energy to an electron transport chain.– takes place in

mitochondrial matrix– breaks down three-carbon

molecules from glycolysis– makes a small amount of

ATP– releases carbon dioxide– transfers energy-carrying

molecules

mitochondrionmitochondrion

matrix (area enclosedby inner membrane)

inner membrane

energy

energy from glycolysis

Krebs Cycle

The Krebs Cycle

o Krebs Cycle (Citric Acid Cycle)- Pyruvate is broken down into carbon dioxide molecules in a series of steps that also form ATP, NADH, and FADH2 for use in the Electron Transport Chain. oOccurs within the matrix

Play until 1:20

The Krebs cycle is the first main part of cellular respiration.

• Pyruvate is broken down before the Krebs cycle.– carbon dioxide

released– NADH produced– coenzyme A (CoA)

bonds to two-carbon molecule

• The Krebs cycle produces energy-carrying molecules.

– NADH and FADH2 are made

– intermediate molecule withCoA enters Krebs cycle

– citric acid(six-carbon molecule)is formed

– citric acid is broken down,carbon dioxide is released,and NADH is made

– five-carbon molecule is broken down, carbon dioxide is released, NADH and ATP are made

– four-carbon molecule is rearranged

• The Krebs cycle produces energy-carrying molecules.

mitochondrionmitochondrion

matrix (area enclosedby inner membrane)

inner membrane

energy

energy from glycolysis

• The electron transport chain produces a large amount of ATP.

– takes place in inner membrane

– energy transferred to electron transport chain

– oxygen enters process

– ATP produced

– water released as awaste product

Electron Transport

In the Electron Transport Chain,

o Electron Transport Chain- Uses high energy electrons from NADH and FADH2 from Krebs cycle to build up H+ ions in the Intermembrane space making it positive and the matrix negative.

The electron transport chain is the second main part of cellular respiration.

• The electron transport chain uses NADH and FADH2 to

make ATP.– high-energy electrons enter electron transport chain– energy is used to transport hydrogen ions across the

inner membrane– hydrogen ions

flow through achannel in themembrane

The electron transport chain is the second main part of cellular respiration.

• The breakdown of one glucose molecule produces up to38 molecules of ATP.

– ATP synthase produces ATP

– oxygen picks up electrons and hydrogen ions

– water is released as a waste product

• The electron transport chain uses NADH and FADH2 to

make ATP.

• The equation for the overall process is:

C6H12O6 + 6O2 6CO2 + 6H2O

• The reactants in photosynthesis are the same as the products of cellular respiration.

In the Electron Transport Chain,

o The H+ ions will then move through the ATP synthase to the negative side causing the ATP synthase to turn. Each turn brings ADP and a phosphate (Pi) together to form high energy ATP.

• The Krebs Cycle and Electron Transport Chain occur in the mitochondria.

Fermentationif no oxygen is present

• Fermentation occurs when no oxygen is present.

• Also called anaerobic respiration - meaning without oxygen.

• It turns NADH back into NAD+ so that it can be recycled and glycolysis can continue.

4.6 Fermentation TEKS 4B

Fermentation allows glycolysis to continue.

• Fermentation is an anaerobic process.– occurs when oxygen is not available for cellular

respiration– does not produce ATP

• Fermentation allows glycolysis to continue making ATP when oxygen is unavailable.

• Lactic acid fermentation occurs in muscle cells.– glycolysis splits glucose into two pyruvate molecules– pyruvate and NADH enter fermentation– energy from NADH converts pyruvate into lactic acid– NADH is changed back into NAD+

• NAD+ is recycled to glycolysis

Lactic Acid fermentation- in a shortage of oxygen in your muscle cells, it regenerates NAD+ so glycolysis can continue.

• Lactic acid builds up in your muscles which causes pain and soreness.

pyruvic acid + NADH lactic acid + NAD+

• Lactic acid fermentation also occurs with certain microorganisms to produce certain foods; Ex. yogurt, sour cream and pickles

yogurt

Sauerkraut

Fermentation and its products are important in several ways.

• Alcoholic fermentation is similar to lactic acid fermentation. Occurs in YEAST CELLS– glycolysis splits glucose and the products enter

fermentation– energy from NADH is used to split pyruvate into an

alcohol and carbon dioxide– NADH is changed back into NAD+

– NAD+ is recycled to glycolysis

Two Types of Fermentation:

Alcoholic fermentation- Performed by yeast and other microorganisms

pyruvic acid + NADH alcohol + CO2 + NAD+

• We can use this to help us make things such as bread and wine

The Totals

• Cellular respiration produces 36 ATP molecules.• More ATP is produced with oxygen than without.

Cellular respiration is more efficient using oxygen.

2 2 32

The Totals

• Glycolysis: 2 ATP

• Fermentation: None! but regenerates electron carriers for glycolysis

• Krebs Cycle: 2 ATPs

• Electron Transport Chain: 32 ATPs

Total Number of ATP produced:

• Anaerobic respiration: 2 ATP (From glycolysis)

• Aerobic respiration: 36 ATP (From glycolysis, kreb’s cycle and electron transport chain)

Energy and Exercise: Quick Energy

• Running a short race, you use ATP in your muscles, and produce new ATP by lactic acid fermentation and cellular respiration.

• When sprinting, you produce most of your ATP using lactic acid fermentation because you have run out of oxygen for the Krebs cycle.

• You breathe heavily after you finish a race to rebuild your ATP supply.

Energy and Exercise: Long-term Energy

• When running a long race, you use carbohydrate energy stored as glycogen from your muscles and other tissues. This will give you enough energy for up to 20 minutes of activity.

• After using up glycogen, your body will use up fats for energy.

• Aerobic exercises like running and swimming are beneficial for weight control.

REVIEW

Comparing Photosynthesis and Cellular Respiration

• If storing energy is compared to money in a savings account, photosynthesis deposits the energy and cellular respiration withdraws the money.

• Cellular Respiration is the reverse reaction of photosynthesis.

• What is the formula for photosynthesis?– 6CO2 + 6H2O + light 6O2 + C6H12O6

• What is the formula for cellular respiration (think about the opposite)?– 6O2 + C6H12O6 6CO2 + 6H2O + ATP

– Photosynthesis uses CO2 in the atmosphere, but cellular respiration puts it back

– Photosynthesis releases O2 into the atmosphere but cellular respiration using O2 to release energy from the food

– Cellular respiration occurs in all eukaryotes and some prokaryotes

– Photosynthesis occurs only in plants, algae, and some bacteria. Other organisms (heterotrophs) get their food by consuming other organisms.

Which path produces the most ATP?

• Where does glycolysis take place?

• What phrase means without oxygen?

• What phrase means with oxygen?

• Where does the Krebs Cycle take place?

Which path produces the most ATP?

• Where does the Electron Transport Chain take place?

• What is the NET ATP for anaerobic respiration?

• What is the NET ATP for aerobic respiration?

• Which path produces the most ATP?

Notes: Cellular Respiration Chapter 4 section 4.4; 4.5 and 4.6.

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