CELLULAR RESPIRATION

Glycolysis

Releases a small amount of energy This is a process that takes one molecule of

glucose and breaks it in half which produces two molecules of pyruvic acid

2 molecules of ATP are used up in order for this process to take place and 4 are produced at the end of this process, therefore glycolysis has a net gain of 2 molecules of ATP

If oxygen is present it leads to two other pathways that release a great deal of energy, if oxygen is not present glycolysis is followed by a different pathway

No Oxygen Present

When there isn’t any oxygen (known as anaerobic), glycolysis is followed by a process called fermentation

There are two main types of fermentation: alcoholic and lactic acid

Fermentation

Yeasts and some microorganisms use this type

Ethyl alcohol and carbon dioxide are waste (sometimes NAD+ is also in this category)

Ex: when bread starts to rise, CO2 forms bubbles in the bread to make it rise

This process regenerates NAD+

This is produced in your muscles during rapid exercise when the body cannot supply enough oxygen

Alcoholic Lactic Acid

Oxygen is Present

About 90% of the chemical energy that was available in glucose is still unused and the only way to release it is through oxygen

When oxygen is present (aerobic) glycolysis is followed by the Krebs cycle and the electron transport chain

These three processes make up a process called cellular respiration

Cellular Respiration

The process which occurs within mitochondria in which cells use oxygen to burn sugar for fuel   (re- = back‚ again; spira = to breathe)

The equation is: 6O2 + C6H12O6 6CO2 + 6H20 + Energy

The Krebs Cycle

The 2nd stage of cellular respiration Pyruvic acid is broken down into carbon dioxide

in a series of energy-extracting reactions It begins when pyruvic acid produced by

glycolysis enters the mitochondria It gets broken down and carbon dioxide gets

released (its what we breathe out) and the ATP that is produced can then be used of cellular activities (for every turn of the cycle, one ATP molecule is produced)

NADH and FADH2 are released into the 3rd stage

Electron Transport Chain

This takes place in the inner mitochondrial membrane

NADH and FADH2 are passed along through this chain

At the end of this chain is an enzyme that combines these electrons with hydrogen and oxygen to form water

The Totals

Remember glycolysis produces 2 molecules of ATP (in the absence of oxygen that is all that gets produced)

The Krebs cycle and electron transport chain enable the cell to produce 34 more molecules of ATP (this means that 18 times more ATP is produced during aerobic respiration)

The 36 molecules of ATP produced represent 38% of the total energy of glucose (the rest is heat)

Cellular Respiration Song

When your cells burn sugar fuelfrom your meal (such a deal!),there are three parts to the joband you get some ATP.

First you do glycolysis.Split that sugar right in half,and you make two ATPs:store some energy.

Second comes the Kreb’s cycle,break it down to CO2

in your mitochondria,and you make more ATP.

Third, your mitochondriatransport those electrons.Grab their energy to makelots and lots of ATP.

Then you dump those electronsand some extra hydrogen.Bond them onto oxygenand you get some water.

Forty total ATPs:glycolysis uses two,and eukaryotes use two moreso the total’s thirty-six.