Cellular Respiration Review

Cellular Respiration1. Define cellular respiration.

A process that releases energy from food, such as the simple sugar glucose, when there is oxygen present.

2. Name several organisms that undergo cellular respiration

Nearly all living things undergo cellular respiration*.

Exceptions include a few microscopic marine animals (Loricifera) and some bacteria.

Cellular Respiration3. Using chemical formulas, write the balanced equation for cellular respiration.

4. Now write out the equation using words.

Oxygen + Glucose yields Carbon dioxide + Water + Energy

6O2 + C6H12O6 6CO2 + 6H2O + Energy

Cellular Respiration5. What organelle in eukaryotes is involved in cellular respiration?

The mitochondrion

6. What is a common analogy for mitochondria? Mitochondria are sometimes

called “cellular power plants” or the “powerhouses” of the cell.

Cellular Respiration7. Where in eukaryotes are mitochondria found?

In all cells. Depending on the organism and the type of cell, the number of mitochondria can range from one to thousands.

Root tip of a corn plant.

Mitochondria

Cellular Respiration8. What kind of human cells contain the most and least number of mitochondria?

Cells that require the most energy contain the highest number of mitochondria. The cells of the brain, skeletal muscle, heart muscle, and the eye contain the greatest number (as many as 10,000 per cell) while the skin cells, which do not require much energy, contain only a few hundred.

Skeletal Muscle

Cellular Respiration9. Identify the mitochondria in this micrograph of a human pancreatic cell.

Pancreas cell

Nucleus

Nucleolus

Endoplasmic reticulum

Pancreas

The pancreas secretes insulin in response to glucose levels in the blood.

Mitochondria

Cellular RespirationIdentify the following structures of the mitochondrion.

10 11

12

13

Cellular RespirationIdentify the following structures of the mitochondrion.

Outer membrane

11

12

13

Cellular RespirationIdentify the following structures of the mitochondrion.

Outer membrane

Inner membrane

12

13

Cellular RespirationIdentify the following structures of the mitochondrion.

Outer membrane

Inner membrane

Inner membrane space

13

Cellular RespirationIdentify the following structures of the mitochondrion.

Outer membrane

Inner membrane space

Matrix

Inner membrane

Cellular Respiration14. What are the three main stages of cellular respiration?

Glycolysis (Converting glucose to pyruvic acid)

The Krebs cycle (Breaking down pyruvic acid into CO2)

Electron Transport (Making lots of ATP)

Pyruvic acidThree Carbon dioxide

ATP

ATP

ATPATPATP ATP

ATPATP

ATP

ATPATPATP

Glucose Two pyruvic acid

Cellular Respiration15. Where in the mitochondrion does each stage of cellular respiration occur?

Glycolysis takes place in the cell’s cytoplasm outside the mitochondrion

The Krebs cycle occurs in the matrix

The Electron Transport Chain operates in the inner membrane.

Cellular Respiration16. What happens during glycolysis?

Four enzymes are used to break glucose into two molecules of G3P*

Five enzymes then convert G3P into pyruvic acid**

Four ATP are produced.

Two ATP are invested to get this done.

*G3P is Glyceraldehyde-3-phosphate ** Pyruvic acid is known as pyruvate

A net of two ATP are made.

Glucose

Two G3P

Two pyruvic

acid

ATP

ATP

ATPATP

ATPATPATP

ATP

Two electron carriers pick up electrons during the process

Electron carriers

Electron carriers

Cellular Respiration17. What happens in the Krebs cycle?

Pyruvic acid enters the mitochondrial matrix where it will enter the Krebs cycle.

Acetyl CoA Oxaloacetate

Electron carriers

MatrixMitochondrion

EnzymesPyruvic acid

Cellular Respiration17. What happens in the Krebs cycle?

Here pyruvic acid will interact with enzymes and other molecules.

Acetyl CoA Oxaloacetate

Electron carriers

MatrixMitochondrion

Enzymes

Cellular Respiration17. What happens in the Krebs cycle?

Electron carriers

After a series of chemical reactions, three carbon dioxide molecules are produced.

MatrixMitochondrion

Enzymes

Cellular Respiration17. What happens in the Krebs cycle?

Electron carriers

In addition, a molecule of ATP is generated…

MatrixMitochondrion

EnzymesATP

Cellular Respiration17. What happens in the Krebs cycle?

Electron carriers* also pick up excess electrons.

MatrixMitochondrion

Enzymes

ATP

Electron carriers

* Electron carriers NAD+ and FAD

Cellular Respiration

MatrixMitochondrion

Enzymes

ATP

Electron carriersElectron carriersElectron carriersElectron carriersElectron carriers

* Electron carriers NAD+ and FAD

17. What happens in the Krebs cycle?

Electron carriers* also pick up excess electrons. They then travel to the inner membrane.

Cellular Respiration

MatrixMitochondrion

Enzymes

* Electron carriers NAD+ and FAD

18. What do the carriers do with their electrons?The electron carriers drop off their electrons at the inner membrane.

Electron carriers

Electron carriers Electron

carriers

Electron carriers

Electron carriers

Cellular Respiration

MatrixMitochondrion

* Electron carriers NAD+ and FAD

The carriers then return to the matrix to pick up more electrons while other molecules are recycled.

Electron carriers

Electron carriers Electron

carriers

Electron carriers

Electron carriers

Acetyl CoAOxaloacetateEnzymes

18. What do the carriers do with their electrons?

Cellular Respiration

Matrix

Inner membrane

At the inner membrane, the electron carriers attach themselves to membrane proteins.

Outer membrane

Inner membrane

space

Cytoplasm

Electron carriers

19. What happens to the electrons at the inner membrane?

H + ions

ATP

Synthase

Cellular Respiration

Matrix

Inner membrane

The electrons are then passed to the protein.

Outer membrane

Inner membrane

space

Cytoplasm

Electron carriers

19. What happens to the electrons at the inner membrane?

H + ions

ATP

Synthase

Cellular Respiration

Matrix

Inner membrane

Some of the energy from the transfer of electrons is used to pump hydrogen ions (H+) into the inner membrane space.

19. What happens to the electrons at the inner membrane?

Outer membrane

Inner membrane

space

Cytoplasm

H + ions

ATP

Synthase

Cellular Respiration

Matrix

Inner membrane

Meanwhile, the shuttle protein ubiquinone moves in to pick up the electrons.

19. What happens to the electrons at the inner membrane?

Outer membrane

Inner membrane

space

Cytoplasm

H + ions

Ubiquinone

ATP

Synthase

Cellular Respiration

Matrix

Inner membrane

The shuttle will move the electrons to the next protein.

19. What happens to the electrons at the inner membrane?

Outer membrane

Inner membrane

space

Cytoplasm

H + ions

Ubiquinone

ATP

Synthase

Cellular Respiration

Matrix

Inner membrane

Some of the energy from the transfer of electrons will be used to pump more H+ ions across the membrane.

19. What happens to the electrons at the inner membrane?

Outer membrane

Inner membrane

space

Cytoplasm

H + ions

Cytochrome C

ATP

Synthase

Cellular Respiration

Matrix

Inner membrane

The electrons will then be shuttled by cytochrome c to their last protein.

19. What happens to the electrons at the inner membrane?

Outer membrane

Inner membrane

space

Cytoplasm

H + ions

Cytochrome C

ATP

Synthase

Cellular Respiration

Matrix

Inner membrane

Again, H+ ions will be pumped across the membrane.

19. What happens to the electrons at the inner membrane?

Outer membrane

Inner membrane

space

Cytoplasm

H + ions

ATP

Synthase

Cellular Respiration

Matrix

Inner membrane

Finally, an oxygen atom will pick up the two electrons along with two H+ ions to form a molecule of water.

19. What happens to the electrons at the inner membrane?

Outer membrane

Inner membrane

space

Cytoplasm

H + ions

O2

H2O

ATP

Synthase

Cellular Respiration

Matrix

Inner membrane

Water will exit the mitochondrion

20. Where does the water molecule go?

Outer membrane

Inner membrane

space

Cytoplasm

H + ions

H2O

ATP

Synthase

Cellular Respiration

Matrix

Inner membrane

As more H+ is pumped into the inner membrane space, the space becomes more acidic. This causes the pH to drop.

21. How will the pH in the inner membrane space change?

Outer membrane

Inner membrane

space

Cytoplasm

H + ions

pH 7.2

pH 7.8ATP

Synthase

Cellular Respiration

Matrix

Inner membrane

There are more H+ ions in the inner membrane space, which sets up a concentration gradient.

22. How does the concentration of H+ ions in the matrix compare to that in the inner membrane space?

Outer membrane

Inner membrane

space

Cytoplasm

H + ions

High H+ Concentration

Low H+ ConcentrationATP

Synthase

Cellular Respiration

Matrix

Inner membrane

The H+ ions will flow down their concentration gradient from the inner membrane space toward the matrix.

23. In which direction is the concentration gradient?

Outer membrane

Inner membrane

space

Cytoplasm

H + ions

Gra

dien

t

High H+ Concentration

Low H+ ConcentrationATP

Synthase

Cellular Respiration

Matrix

Inner membrane

The H+ ions will flow through an enzyme called ATP synthase. This flow provides the energy needed to generate ATP from ADP.

24. Through what membrane protein will the H+ ions flow?

Outer membrane

Cytoplasm

H + ions

ADP

ATP

Synthase

PATP

Cellular Respiration

Matrix

Inner membrane

One glucose molecule yields about 36 to 38 ATP (2 ATP from glycolysis, 2 ATP from the Krebs cycle, and 32 to 34 ATP from the electron transport chain).

25. About how many ATP can be generated by cellular respiration from one glucose molecule?

Outer membrane

Cytoplasm

H + ionsATP

ATP

Synthase

ATP

ATP

ATPATP

ATP

ATP

ATP

ATP ATPATPATP

ATP

ATP

ATP

ATP ATP

ATP

ATP

Inner membrane

space