CHAPTER 8 Cellular Energy

8-3 Cellular Respiration

JOURNALExplain how Cellular Respiration is related to Photosynthesis.

anaerobic process

aerobic respiration

aerobic process

glycolysis

Krebs cycle

fermentation

Cellular Energy

Vocabulary

Cellular Respiration

Cellular Respiration: “What”The process that releases energy

from food in the presence of oxygen.

Sugar + oxygen carbon dioxide + water + energy

Opposite of photosynthesis!

Cellular Respiration: “Why”

Function: Harvest electrons from carbon compounds (glucose), and use that energy to make ATP, which provides energy for cells to do work.

Cellular Respiration: “Where”

Cellular Energy

Occurs in two main parts. Glycolysis Aerobic respiration

Cellular Respiration: “How”

Aerobic vs. AnaerobicAerobic – pathways

that require oxygenAnaerobic – does not directly require oxygen

Cellular Respiration Overview Video

Glycolysis Glucose is broken down in the cytoplasm

through the anaerobic process of glycolysis.

You must put energy in to get energy out!

GlycolysisGlycolysis has a net result of two ATP, two NADH and two pyruvate.

Most of the energy from the glucose is still contained in the pyruvate.

Glycolysis ReviewWhere does glycolysis take place? CytoplasmWhat are the energy carrying molecules

in involved in glycolysis? ATP, NADHWhat is the main molecule being broken

down? What is it broken down into? Glucose pyruvate (pyruvic acid)Does glycolysis require oxygen? No. It is anaerobic.

In the presence of oxygen, pyruvate is transported into the mitochondrial matrix, where it is eventually converted to carbon dioxide

KREB’S CYCLE

Krebs CycleThe series of reactions in which pyruvate is broken down into carbon dioxide is called the Krebs cycle.

1. Pyruvate reacts with CoA to from acetyl-CoA. CO2 is released and NADH is formed.

2. Acetyl CoA forms Citric Acid

3. Citric Acid is broken down. Two CO2 molecules are released. One ATP, three NADH and one FADH2 are formed.

Remember, two pyruvates are formed during glycolysis. Both go through the Kreb’s cycle. So… for every ONE glucose molecule, there are two “turns” of the Kreb’s Cycle!

Net Yield = -six CO2, -two ATP, -eight NADH, -two FADH2

Krebs Cycle(Citric Acid Cycle)

Electron TransportFinal step in the breakdown of glucose

Point at which (the most) ATP is produced

Produces 32 ATP

In eukaryotes, one molecule of glucose yields 36 ATP under ideal conditions

Cellular Respiration Totals

So what happens when oxygen is not available?

The cell can still undergo Glycolysis to produce ATP, but without oxygen the electron transport chain does not work, so waste builds up.

Cellular Energy

Anaerobic Respiration(Fermentation) The anaerobic pathway that follows

glycolysis Occurs in the cytoplasm

Two main types Lactic acid fermentation Alcohol fermentation

Lactic Acid Alcohol

Occurs in yeast and some bacteria

Produced by skeletal muscles when the body can’t supply enough oxygen; causes fatigue and soreness

Still Unsure? Watch this three-part series.

Part 1: Introduction and Glycolysis

Part 2: The Kreb’s Cycle

Part 3: Electron Transport Chain

JOURNAL

List the three parts of cellular respiration. At which stage is oxygen crucial? What type of pathway is this (aerobic or anaerobic)?

Comparing Photosynthesis and Cellular Respiration

Photosynthesis removes carbon dioxide from the atmosphere and cellular respiration puts it back. Photosynthesis releases oxygen into the atmosphere, and cellular respiration uses that oxygen to release energy from food.

Comparing photosynthesis and cellular respiration

Quick lab, page 264

How does exercise affect disposal of wastes from cellular respiration?

After completing the lab, read pages 264-265 in your textbook for further information.

JOURNALCreate a table or diagram that

demonstrates the processes of photosynthesis and cellular respiration. Try to name what type of organism each process occurs in, which organelle each process takes place in, what is needed for each process and what is a result of each process (what goes in, what comes out?)