CHAPTER 6Aerobic and anaerobic cell

respiration

6.2 What does respiration mean?

can mean breathing or ventilation of lungs or gills

Can refer to gas exchange in the blood at the cellular level (oxygen in/carbon dioxide out)

Can refer to the complex set of reactions that allow cells to burn sugar to make ATP

6.2/6.3

6.3 What systems of the body are

responsible for carrying these reactions out?Respiratory (oxygen/carbon dioxide

exchange)Cardiovascular (transport)Digestive (digestion and absorption of

glucose)

We can “burn” molecules other than glucose

There are MANY steps in this process. Balanced equation is simplified

6.6 OVERVIEW Three general reactions- aerobic cell

respirationGlycolysis – happens in cell cytoplasmKreb’s Cycle – happens in matrix of

mitochondriaOxidative Phosphorylation/ETC- occurs

in proteins in inner mitochondrial membrane called the Electron Transport Chain

GLYCOLYSIS Splitting of sugar Glucose split into two three carbon

molecules called pyruvate and energy is released.

Energy is used to make 2 ATP by substrate Level Phosphorylation- ATP made without ETC

Energy is also used to make 2 NADH-an energy storage molecule to be “cashed out” later

No oxygen needed in this step!

KREB’S CYCLE/CITRIC ACID CYCLE Each pyruvate is broken down into 3

CO2 molecules Energy stored in

4 NADH1 FADH2 (also a “check” to be cashed

out)1 ATP ( made by SLP- no ETC)

Is a cycle – begins and ends with same molecule

How many times must the cycle run/glucose?

KREB’S CYCLE Cycle turns twice for each glucose

8 NADH2 FADH22ATP6CO2

PHASE ATP NADH FADH2

GLYCOLYSIS 2 by SLP 2 0

KREB’S CYCLE2X per glucose

2 by SLP 8 2

ETC ????? 0 0

ELECTRON TRANSPORT Energy rich electrons stored in NADH

and FADH2 are cashed in at a cascade of proteins in the inner mitochondria membrane

As electrons fall they lose energy- exergonic

Energy released is COUPLED with the active transport of H+ ions across the membrane

Called chemiosmosis

OXIDATIVE PHOSPHORYLATION Oxygen accepts the electron at the end

of the chain- H+ combine with oxygen and the electron to make water (waste)

H+ accumulate in intermembrane space Rush back to matrix through ATP

synthase- (light bulb shaped protein) release lots of energy

Energy is used to add a phosphate to ADP to make ATP !!!

This is called oxidative phosphorylation

ATP VOCAB Phosphorylation- to make ATP Oxidative – using oxygen as last

electron acceptor (ETC) Substrate level- without ETC, using

enzymes in the mitochondria and cytoplasm

HOW MANY ATPS ?Phase ATP NADH FADH2

Glycolysis 2 2 (worth 2 ATP each)

0

KREB’S 2 8 (worth 3 ATP each)

2 (worth 2 ATP each)

ETC cash out value

N/A 4 ATP + 24 ATP= 28 ATP

4 ATP

TOTAL ATP = 36 / glucose

NADHS 2 from glycolysis are only worth 2 ATPs. They have to travel through two

mitochondrial membranes

8 NADHs from Kreb’s are already in mitochondria – are worth 3 ATPs each

Prokaryotes make 38 ATPs – no internal membranes to pass through