CELLULAR RESPIRATION

Cellular respiration includes most of the reactions that provide energy!

What is the most useable source of energy??

Carbohydrates!

The body will use up carbohydrate storages first before going to another source of energy.

Glycogen Glycogen is composed of many glucose

molecules. It is a storage carbohydrate. Glycogen will be broken down into single glucose molecules and released into the blood when energy is required.

 

After carbohydrates are used up, the body will use fat for energy, then finally protein. If the body is using protein for energy that means that it is actually breaking down its own structure!

If we use glycogen what do plants use as an energy source??

Starch!

Starch can be broken down into maltose, which is soluble.

During respiration chemical bonds are broken. There is energy stored in these bonds.

  Cellular respiration is the aerobic

harvesting of energy from food by cells. This is different than the typical ‘respiration’ we think of. Breathing respiration and cellular respiration are very closely related though….

When we breathe in air, it will enter our lungs and pass to our bloodstream. The blood will carry the oxygen to the muscle cells. These cells will use the oxygen in cellular respiration to make energy, ATP.

General Equation of Cellular Respiration: Glucose + 6O2 6CO2 + 6H2O + ATP

The cell uses the ATP made to contract muscles.  Glucose molecules contain LOTS of energy! One

tablespoon contains about 40 kilocalories of energy available for use.

To understand how much this is…... an adult might use this much energy if they were to work out vigorously for about 15 minutes.

   

Cells use smaller particles of energy, ATP. Through cellular respiration, glucose will be broken down and release chemical bond energy, which the cell stores as ATP.

But just how do cells get the energy from molecules such as glucose??

The available energy is contained in the arrangement of electrons in the chemical bonds that hold organic molecules, such as glucose, together.

Cellular respiration will shuttle the electrons through a series of reactions that will release the energy.

Cells transfer energy from glucose to ATP by energy coupling

During cellular respiration, glucose will be oxidized (loss of electrons), while oxygen is reduced (gain of electrons). These types of reactions are known as redox reactions

The hydrogen Carriers of Cellular Respiration: NADH and FADH2 are the two hydrogen and

electrons carriers used in cellular respiration. Both NADH and FADH2 are coenzymes. They shuttle electrons through redox reactions.

There are Three Main Stages in Cellular Respiration:

Glycolysis Occurs in the cytoplasm. Glucose is broken down into pyruvic acid

Krebs cycle Occurs in the mitochrondria Decomposes pyruvic acid and its derivatives to

carbon dioxide Electron transport chain

Obtains electrons from electron carriers The electrons go through a series of reactions,

in which energy is released.

GLYCOLYSIS

Occurs in the cell’s cytoplasm

Begins with one molecule of glucose. Glycolysis requires two molecules of ATP  Glucose is split into 2 three carbon

molecules. Through a series of reactions involving enzymes, the three carbon molecules are rearranged.

 

Electrons from the three carbon molecules are transferred to molecules of NAD+, forming NADH.

As NAD+ is reduced to NADH, four ATP molecules are produced.

  Through a series of reactions, the three carbon

molecules are converted to pyruvate.   Glycolysis requires 2 ATP and produces 4 ATP,

therefore there is a net production of 2 ATP. Two Pyruvic acids are produced.

  NADH and pyruvate will be used in the second stage

of cellular respiration; the krebs cycle. 

http://www.science.smith.edu/departments/Biology/Bio231/ 

KREBS CYCLE

Also known as the citric acid cycle. Occurs in the mitochondria.

Pyruvate is broken down and split into a two carbon molecule and carbon dioxide (which is given off as a waste product).

 

Electrons are transferred from the two carbon molecule to NAD+ forming NADH.

CoenzymeA (CoA) binds to the two carbon molecule. This intermediate product enters the Krebs cycle.

The two-carbon intermediate is added to a four carbon molecule to form citric acid (a 6 carbon molecule). CoA is released and goes back to the previous stage.

  Citric acid is broken down to a five carbon

molecule with the help from an enzyme. NADH is also made. NADH is removed from the cycle.

The five carbon molecule is broken down into a four carbon molecule with the help from an enzyme.

A molecule of NADH is made, as well as one molecule of ATP. NADH will be removed from the cycle. Carbon dioxide is also given off as a waste product.

The four carbon molecule is rearranged with the help of enzymes. NADH and FADH2 molecules are made. Both types of molecules will leave the cycle.

The final products of the Krebs cycle:Three molecules of carbon dioxideOne molecule of ATPFour molecules of NADHOne molecule of FADH2

http://www.science.smith.edu/departments/Biology/Bio231/

BUT REMEMBER...

** NOTE: Glycolysis produces TWO molecules of pyruvate, therefore the products of the Krebs cycle should actually be doubled, since we have only calculated the total products for one pyruvate. **

ELECTRON TRANSPORT CHAIN

Occurs in the inner membrane of the mitochrondria.

Requires oxygen. Made up of proteins. Energy is supplied by NADH and FADH2 in

order to pump hydrogen ions against a concentration gradient.

  Requires oxygen as an electron acceptor.

Two molecules of NADH and one molecule of FADH2 are used to supply electrons to the proteins.

The high energy electrons travel through the proteins of the ETC. The proteins use the energy from the electrons to pump hydrogen ions across the inner membrane. The hydrogen ions build up on the inside of the inner membrane.

The movement of the hydrogen ions is done through a protein channel, which is a part of the ATP synthase.

The ATP synthase adds phosphates to ADP to make ATP.

  For every pair of electrons, three ATP

molecules are made.  Oxygen will pick up electrons and hydrogen ions

to form water. Water is given off as a waste.

 Final products of the Electron Transport Chain:34 ATPWater

http://www.science.smith.edu/departments/Biology/Bio231/etc.html

Overall Products of Cellular Respiration: 38 ATP Water 3 CO2 molecules

http://www.phschool.com/science/biology_place/biocoach/cellresp/intro.html

  http://www.classzone.com/cz/books/bio_07/ge

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