Topics 2, 7 & 8 Biochemistry

2.8 & 8.1 Cell Respiration

1 – Cell Respiration and the Mitochondria

Read & Consider Understandings 2.8.1-2.8.2, 8.2.2, & 8.2.11

• Brainstorm: What is ATP, how is it formed, how is it used?

Cell Respiration Cellular respiration is the controlled release of

energy, in the form of ATP, from organic compounds in cells.

ATP – Universal Energy Currency ATP can be used in different contexts and is

continuously recycled. Moves easily in cells by facilitated diffusion Takes part in many reactions of metabolism Delivers energy in small amounts, sufficient to

drive individual reactions.

ADP + Pi = ATP

The free energy available in ATP is 30-34 kJ/mol; some of this energy is lost as heat, but

much of it is made available for the current reaction.

Mitochondria

Draw, label, and annotate the mitochondria structure.

Indicate how the structure contributes to the function of mitochondrion in the cell

2 – Aerobic Respiration

Read & Consider Understandings 2.8.4, 8.2.1-8.2.10

• What does aerobic mean? What are the benefits of aerobic respiration?

Aerobic Respiration

GOAL convert glucose to usable energy Aerobic – oxygen is present

Cell Respiration: C6H12O6 + 6O2 6CO2 + 6H2O + ENERGY

Cell Respiration Overview

1. Glycolysis (cytoplasm)

2. Link reaction (mitochondrial matrix)

3. Krebs Cycle (mitochondrial matrix)

4. Electron transport (mitochondrial membrane)

Oxidation & Reduction

Oxidation involves the loss of electrons from an element, whereas reduction involves a gain of electrons; and that oxidation frequently involves gaining oxygen or losing hydrogen, whereas reduction frequently involves losing oxygen or gaining hydrogen.

Glycolysis = Glucose Pyruvate1. Glucose is split into two 3-carbon molecules2. These products are converted to different 3-

carbon molecules called pyruvic acid3. In the cytoplasm pyruvic acid is ionized and

is now a pyruvate ion (2 molecules)4. Additionally, a small amount of ATP is formed

using the energy locked up in glucose

glycolysis glucose + lysis

Glycolysis Review

1. Phosphorylation2. Lysis3. Oxidation

2 ATP Pyruvate

Fructose Biphosphate

GENERAL STEPS – 1. Glucose enters the cytoplasm2. Glucose (6-C) is split into 2x 3-C carbon molecules3. These are then converted to pyruvic acid (also 2x 3-

C)4. It is then ionized and referred to as pyruvate (x2)5. A small amount of ATP is formed by this process6. Pyruvate moves into the mitochondria by facilitated

diffusion (via enzymes).7. Hydrogen is removed from pyruvate by H acceptors8. Oxygen is added to carbon to form CO2 waste

9. H acceptors react with additional oxygen donating their hydrogen to form water.

10. A large amount of ATP is generated.

Link Reaction:

1. Pyruvate is decarboxylated (carbon dioxide is removed) and oxidized (hydrogen is removed)

2. Hydrogen is added to acceptors NAD+ to form NADH2

x2 (there are two pyruvate molecules for each glucose molecule)

3. The remaining 2-C fragments (acetyl groups) are attached to coenzyme A to form acetyl CoA

Krebs cycle or Citric Acid Cycle 1. Acetyl CoA enters the cycle and reacts with a 4-C

molecule called oxaloacetate or2. This reaction forms 6-C citrate and coenzyme A

(CoA) is released3. This cyclic reaction converts citrate back into OAA;

products: 2 x CO2

1 ATP 3 reduced NAD+ formed (3 x NADH2) 1 reduced FAD+ (1 x FADH2) another type of hydrogen

acceptor found in the cycle

4. Because two molecules of pyruvate enter the cycle, the Krebs cycle must occur two times per glucose molecule.

So far…

STEP CO2 ATP NADH2 FADH2

glycolysis 0 2 2 0link reaction

2 0 2 0

Krebs 4 2 6 2TOTAL 6 4 10 2

 Electron Transport Chain: H atoms or more correctly electrons from NADH2 and FADH2 are passed along a series of electron carrier proteins embedded in the smooth double membrane of the mitochondria as well as in the double membrane of the cristae.

1. Electrons from reduced NAD+ and FAD+ (NADH2 & FADH2) are passed along the electron transport chain.

2. As they are passed energy is released in a controlled way. In this way ATP may be formed in great quantities.

Oxidative Phosphorylation & Chemiosmosis

1. Hydrogen is removed from NADH2 and FADH2 by dehydrogenase.

2. The Hydrogen ion is then moved to the inner membrane space while the electrons are passed along the electron transport chain.

3. Energy from the electron transport chain drives any additional hydrogen into the inner membrane space lowering pH and creating a chemical gradient.

4. At the end of the electron transport chain hydrogen that will be allowed to flow back in in the next step is combined with oxygen to form the waste product of water.

5. A total of 34 ATP molecules will be formed by oxidative phosphorylation.

6. Hydrogen is allowed to flow back into the matrix activating ATPase which is the enzyme that catalyzes the formation of ATP.

Outcomes

Review Draw a diagram to show the process of glycolysis.

Include: cytoplasm, lysis, oxidation, ATP formation. Draw a diagram to show the link reaction

Include: Pyruvate, CoA, Acetyl CoA, oxidation, decarboxylation, mitochondria, matrix.

Draw a diagram of the Krebs cycle. Include: Acetyl CoA, 4-C compound, 6-C compound, 5-C

compound, rearrangement, oxidation, decarboxylation, ATP formation, NAD/FAD reduction.

Draw a diagram showing the stages of the electron transport chain. Include: H+, e-, integral proteins, e- carriers, NADH, FADH2,

oxidation, return to Krebs cycle, pumping H+, H+ concentration, electron transfer, chemiosmosis, O2, and H2O.

3 – Anaerobic Respiration

Read & Consider Understanding 2.8.3

• What organisms regularly use anaerobic respiration? Do humans?

3.7.3 Explain that, during anaerobic cell respiration, pyruvate can be converted in the cytoplasm into lactate, or ethanol and carbon dioxide, with no further yield of ATP.

Yeast Vertebrates

Uptake of oxygen can be an indicator of an organisms energy demands.

Works Cited "AP Biology Lab 5: Cell Respiration."

LabBench. N.p., n.d. Web. 02 July 2015. Crash Course. "ATP & Respiration: Crash

Course Biology #7." YouTube. YouTube, n.d. Web. 02 July 2015.

La Sala, Michelle. "Boston 2013." Free Play Magazine. N.p., n.d. Web. 1 July 2015.

Paine, Chris. "2.8 Cell Respiration." Bioknowledgy. N.p., n.d. Web. 02 July 2015.

Shearman, Hayden. “Sprinting Cadence and Power.” A Runner’s Guide. N.p., 13 August 2013, Web. 1 July 2015.