Cellular Respiration 8.3

Main Idea: Living organisms break down organic molecules (food) in the presence of oxygen during cellular respiration to get energy.

C6H12O6 + 6O2 -> 6CO2 +6H2O + Energy

Know this equation! What are the reactants and what are the products?

2 Main Parts: Anaerobic (without oxygen)

GlycolysisLactic Acid FermentationAlcohol Fermentation

Aerobic (with oxygen)Krebs CycleElectron Transport

Let’s start with GlycolysisWhat is glycolysis?

Breakdown of glucose in the cell’s cytoplasm

Page 229 in your book- Figure 8.12Glucose is broken down into 2 three-carbon molecules. (2 ATP are used)

NAD+ becomes NADH (electron carrier)

2 three-carbon molecules become 2 pyruvate and 4 ATP are produced.

What are the net products of glycolysis?2 Pyruvate 2 ATP

Why not 4 ATP?

Because 2 ATP are used to start the reaction so only a net of 2 ATP are produced.

Krebs CyclePyruvate converted to CO2 in the

mitochondrial matrix. ATP, NADH, and FADH2 are produced.

Page 230 Figure 8.13Acetyl CoA formedAcetyl CoA moves to mitochondrial matrix

and combines with a 4-carbon compound: Citric Acid made

Citric Acid Broken downAcetyl CoA and citric acid are generated

and the cycle begins again.

RememberFor every glucose molecule there is

2 turns of the Krebs cycle.What is the net yield of products of

the Krebs cycle?6 CO22 ATP 8 NADH2 FADH2

Electron TransportFinal Step in breakdown of glucoseHappens in the mitochondrial membrane

Page 230 figure 8.14NADH and FADH2 release electrons & H+

becoming NAD+ and FADH+ is pumped into the intermembrane space

across the inner membraneH+ diffuses back across membrane into

matrix (chemiosmosis)O2 is the final electron receptorProtons and e- are transferred to oxygen to

form H2O

In Eukaryotes1 molecule of glucose gives us 36 ATPFrom what cycles are these ATP produced

and how many are produced in each cycle?

Glycolysis 2 ATPKrebs 2 ATPElectron Transport 32 ATP

ATP is used to provide energy for the cell

In Prokaryotes cellular respirationNo Mitochondria so there are differencesElectron transport happens in the cellular

membrane

Because we don’t have to move pyruvate to the mitochondria in prokaryotes 2 ATP are “saved”.

Net total ATP = 38

Why are 2 more ATP produced in prokaryotic cellular respiration than in eukaryotic cellular respiration?

Anaerobic Respiration Without oxygenGlycolysisLactic Acid Fermentation Alcohol Fermentation

FermentationOccurs in the cell’s cytoplasmIt regenerates ATP and produces small

amount of ATPLactic Acid Fermentation

Pyruvate converted to lactic acid with help of enzymes

Skeletal muscles produce lactic acid when O2 supply is low

Some microorganisms produce lactic acid -> used in cheese, yogurt, sour cream

Alcohol Fermentation: pyruvate converted to ethyl alcohol and CO2

Moonshining