Chapter 8 Section 3 – Cellular Respiration

Overview of Cellular Respiration

Living organisms obtain energy by breaking down organic molecules during cellular respiration.

It is a catabolic pathway in which organic molecules are broken down to release energy for use by the cell.

The equation for cellular respiration is the opposite of the equation for photosynthesis.

The Reactants of Cellular Respiration are:

Glucose (C6H12O6) – eat Oxygen (O2) – breathe in

The Products of Cellular Respiration are:

Heat – released throughout your body Carbon Dioxide (CO2) – breathe out Water (H2O) – breathe out

Cellular Energy

Cellular Energy

Cellular respiration occurs in two main stages:

Glycolysis – occurs in the cytoplasm

Aerobic respiration – occurs in the mitochondria

Glycolysis

• The splitting of glucose

• Occurs in the cytoplasm

• Does not require oxygen

https://www.youtube.com/watch?v=3GTjQTqUuOw

Glycolysis• Final products of glycolysis for each molecule of

glucose are:

– 2 ATP’s– 2 molecules of NADH– 2 molecules of pyruvate for each glucose molecule

that is broken down

• 4 molecules of ATP are actually produced when glucose is split, but the energy from 2 of those are needed for the reactions to take place.

Cellular Energy

Aerobic Respiration In aerobic respiration, oxygen is used to break

down glucose molecules. As a result 36 ATP can be made from 1

glucose molecule.

Aerobic respiration follows glycolysis and occurs inside the mitochondria.

The 2 pyruvate molecules are transported to the mitochondria.

Cellular Energy

Two pyruvate molecules from glycolysis is transformed into acetyl CoA and enters the Krebs cycle.

https://www.youtube.com/watch?v=-cDFYXc9Wko

https://www.youtube.com/watch?v=-_8aYKcQZ_Q

Cellular Energy Krebs Cycle (sometimes referred to as the

citric acid cycle)

• Series of reactions in which pyruvate is broken down into carbon dioxide.

• There are two “turns” of the Krebs cycle for each glucose molecule.

Why?

Cellular Energy

Krebs cycle results in the net production of:

• 8 NADH• 2 FADH2• 2 ATP• 6 CO2

Cellular Energy

Electron Transport Chain

• NADH & FADH2 enter electron transport chain in mitochondria cristae.

• High energy electrons and hydrogen ions from NADH and FADH2 produced in the Krebs cycle are used to convert ADP to ATP.

Cellular Energy

Electron Transport Chain

• Oxygen is the final acceptor of electrons.

• Protons and electrons are transferred to oxygen to form water.

• Produce 32 more ATP.

Summary of Cellular respiration

https://www.youtube.com/watch?v=-Gb2EzF_XqA

Cellular EnergyAnaerobic Respiration

The first step in anaerobic respiration is also called glycolysis.

Anaerobic = without oxygen

Plant and animal cells cannot survive off of anaerobic respiration.

Not very efficient

Cellular EnergyAnaerobic Respiration

There are 2 types of anaerobic respiration:

1. Lactic acid fermentation • A process that occurs in animal cells• Causes your muscles to burn when

you perform short bursts of activity

2. Alcohol fermentation• A process that occurs in plants• This is how alcohol, such as wine

and beer, is made

Lactic Acid Fermentation

Alcohol Fermentation

Review the two equations for photosynthesis and cell respiration.

They are reversed!

Cellular Energy

Products for photosynthesis are oxygen and glucose, the reactants for cellular respiration.

Cellular respiration uses O2 to break the sugars down and releases the CO2 back into the atmosphere to be used again by plants.

Cellular Respiration & Photosynthesis are Interrelated

Cellular Energy

Cellular Respiration & Photosynthesis are Interrelated

Notice! Molecules such as O2 and CO2 are recycled through the environment, however the energy is not!

Energy enters our environment as light and leaves back into outer space as heat.

Cellular Respiration & PhotosynthesisCellular Energy