Cellular Respiration Download

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Cellular Respiration
The Big Picture
 The process of cellular respiration is carried out by all eukaryotic cells that can obtain oxygen to break down
sugar in order to create the energy molecule ATP.
 The chemical reaction is:
C6H12O6 + 6 O2 → 6 H2O + 6 CO2 + 36 ATP
reactants →
products
 The majority of this process occurs in the mitochondria.
The Process of Cellular Respiration:
o Step 1- Glycolysis occurs in the cytoplasm.
o Sugar (a 6-carbon molecule) is broken in half using 2 ATP.
o This creates pyruvic acid (two 3-carbon molecules), 4 ATP (but only netting 2), and NADH (previously
NAD+ which carries the charged electron).
o Step 2- the Kreb’s Cycle occurs in the mitochondria (matrix).
o Pyruvic acid is broken down and released as CO2 while moving from the first reaction into the
mitochondria. The electron carriers NADH and FADH2 (carrying electrons from the breaking of the
pyruvic acid for later use), along with 2 ATP are also produced.
o Step 3- the Electron Transport Chain is attached to the inner membrane of the mitochondria.
o The electrons in NADH and FADH2 are placed into a series of proteins where the energy is released a
little at a time and used to create 32 ATP. The electrons are then used to attach oxygen and
hydrogen together to make water.
 During cell respiration the cell will bring in glucose (sugar) and oxygen and produces carbon dioxide, water, and
36 ATP molecules.
Fermentation
The Big Picture
 Fermentation is a process used to break down sugar without oxygen.
 There are situations (such as sprinting) in which the cell does not have enough oxygen to break down sugar
through cell respiration.
 Some smaller organisms never carry out cell respiration because they do not require that much energy and the
alternative is faster.
 While fermentation is faster it only creates 2 ATP from a sugar molecule. Therefore it is not as efficient as cell
respiration which created 36 ATP for each sugar molecule.
 There are two kinds of fermentation but each organism only carries out one or the other.
Lactic Acid Fermentation
Occurs in the cytoplasm.
 Step 1: Glycolysis
o The bond in the middle of glucose is broken forming two 3 carbon molecules called pyruvic acid. This
requires 2 ATP, but it makes 4 ATP and NADH
 Step 2:
o The electron stored in NADH is used to rearrange pyruvic acid into lactic acid.
Human muscle cells will carry out this type of fermentation for quick energy or when there is not enough oxygen to
meet the energy demands such as during a sprint.
Alcoholic Fermentation
Occurs in the cytoplasm.
 Step 1: Glycolysis
o The bond in the middle of glucose is broken forming two 3 carbon molecules called pyruvic acid. This
requires 2 ATP, but it makes 4 ATP and NADH
 Step 2:
o The electron stored in NADH is used to break off a carbon as CO2 and rearrange the remaining two
carbons into ethyl alcohol.
Yeast and bacteria are the two most common organisms to carry out alcoholic fermentation. We use fermenting yeast to
make CO2 bubbles causing bread to rise.
Cellular Respiration
The Big Picture
 The process of cellular respiration is carried out by all eukaryotic cells that can obtain oxygen to break down
sugar in order to create the energy molecule ATP.
 The chemical reaction is:
C6H12O6 + 6 O2 → 6 H2O + 6 CO2 + 36 ATP
reactants →
products
 The majority of this process occurs in the mitochondria.
The Process of Cellular Respiration:
o Step 1- Glycolysis occurs in the cytoplasm.
o Sugar (a 6-carbon molecule) is broken in half using 2 ATP.
o This creates pyruvic acid (two 3-carbon molecules), 4 ATP (but only netting 2), and NADH (previously
NAD+ which carries the charged electron).
o Step 2- the Kreb’s Cycle occurs in the mitochondria (matrix).
o Pyruvic acid is broken down and released as CO2 while moving from the first reaction into the
mitochondria. The electron carriers NADH and FADH2 (carrying electrons from the breaking of the
pyruvic acid for later use), along with 2 ATP are also produced.
o Step 3- the Electron Transport Chain is attached to the inner membrane of the mitochondria.
o The electrons in NADH and FADH2 are placed into a series of proteins where the energy is released a
little at a time and used to create 32 ATP. The electrons are then used to attach oxygen and
hydrogen together to make water.
 During cell respiration the cell will bring in glucose (sugar) and oxygen and produces carbon dioxide, water, and
36 ATP molecules.
Fermentation
The Big Picture
 Fermentation is a process used to break down sugar without oxygen.
 There are situations (such as sprinting) in which the cell does not have enough oxygen to break down sugar
through cell respiration.
 Some smaller organisms never carry out cell respiration because they do not require that much energy and the
alternative is faster.
 While fermentation is faster it only creates 2 ATP from a sugar molecule. Therefore it is not as efficient as cell
respiration which created 36 ATP for each sugar molecule.
 There are two kinds of fermentation but each organism only carries out one or the other.
Lactic Acid Fermentation
Occurs in the cytoplasm.
 Step 1: Glycolysis
o The bond in the middle of glucose is broken forming two 3 carbon molecules called pyruvic acid. This
requires 2 ATP, but it makes 4 ATP and NADH
 Step 2:
o The electron stored in NADH is used to rearrange pyruvic acid into lactic acid.
Human muscle cells will carry out this type of fermentation for quick energy or when there is not enough oxygen to
meet the energy demands such as during a sprint.
Alcoholic Fermentation
Occurs in the cytoplasm.
 Step 1: Glycolysis
o The bond in the middle of glucose is broken forming two 3 carbon molecules called pyruvic acid. This
requires 2 ATP, but it makes 4 ATP and NADH
 Step 2:
o The electron stored in NADH is used to break off a carbon as CO2 and rearrange the remaining two
carbons into ethyl alcohol.
Yeast and bacteria are the two most common organisms to carry out alcoholic fermentation. We use fermenting yeast to
make CO2 bubbles causing bread to rise.
Cellular Respiration
1st Stage- Glycolysis
Occurs in the cytoplasm.
o The bond in the middle of glucose is broken forming two 3 carbon molecules called pyruvic acid.
o Like most chemical reactions, glycolysis requires some activation energy in the form of 2 ATP to start the
reaction.
o Once the bond is broken the electron that was being shared is placed in an electron carrier called NAD+ to make
NADH. This way the electron’s energy can be used later.
o The energy that is released by the breaking bond is used to create 4 ATP molecules meaning this step makes 2
net ATP.
nd
2 Stage- Kreb’s Cycle
o The pyruvic acid made in the first reaction is moved onto the mitochondria.
o As the pyruvic acid is moved one of the carbons is broken off and released as CO2. The breaking of this bond
releases another electron which is placed on NAD+ making NADH to be used later.
o The energy that was released by the bond breaking is used to form a new bond between the remaining two
carbons and a coenzyme A to form Acetyl-CoA.
o Once Acetyl-CoA is made the molecule has the correct shape to react with the enzymes in the next part.
o Through a series of chemical reactions the Acetyl-CoA is broken down. The remaining two carbons are released
as CO2.
o The electrons from each broken bond are placed into the electron carriers NADH and FADH2 so that their energy
can be used later.
o The energy released from the breaking of the bonds is used to create 1 ATP.
o Remember that there were 2 pyruvic acids so this process occurs twice for a total of 2 ATP.
3rd Stage- Electron Transport Chain (ETC)
o The electron carriers NADH and FADH2 made in the first steps are moved to the inner membrane of the
mitochondria.
o The electrons are removed and passed down a series of proteins releasing a little bit of energy at a time.
o The energy released is used to create 32 ATP.
o At the end of the ETC the electrons are used to create bonds between oxygen and hydrogen to make water.