Cellular Respiration

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Cellular Respiration

• LOs
• Able to understand the processes of glycolisis,
  the citric acid cycle, krebs cycle and electron
  transport system.
• Able to compare between photosynthesis and
  cellular respiration

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Cellular Respiration

• Process that unlocks stored energy
• Nutrient molecules store energy in bonds
• Chemical reactions produce ATP
• ATP provides cellular energy

Skunk cabbage using metabolic heat to melt snow
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ATP

• ATP powers cellular work
• A cell does three main kinds of work
• Mechanical work, beating of cilia, contraction of
  muscle cells, and movement of chromosomes
• Transport work, pumping substances across
  membranes against the direction of spontaneous
  movement
• Chemical work, driving endergonic reactions such
  as the synthesis of polymers from monomers

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• The bonds between phosphate groups can be broken
  by hydrolysis.

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So what?

• Energy is stored in these bonds.
• So?
• The breaking of the chemical bond releases the
  energy
• ATP H2O? ADP P ENERGY

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Photosynthesis and cellular respiration provide
energy for life
Photosynthesis is the process where green plants
use sunlight, carbon dioxide, and water to make
food and oxygen (chloroplasts- chlorophyll) 6CO2
6H2O energy --gt  6O2 C6H12O6

• Cellular Respiration is the process where cells
  use this food to release stored energy
  (mitochondria)
• takes glucose, breaks it down into atoms, and
  by mixing it with the atoms from more oxygen,
  produces carbon dioxide, water and energy ... A
  new energy is form and it can be used by all
  cells
• 6O2 C6H12O6 --gt  6H2O 6CO2 energy (ATP)

The theoretical maximum yield of cellular
respiration is 36 ATP per molecule of glucose
metabolized. 
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Chemical Reactions for Photosynthesis

• Light dependent reactions
• Light independent reactions

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• Cellular respiration
• The process by which mitochondria break down
  glucose to make ATP

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Cellular respiration metabolic reactions
/processes to convert biochemical energy from
nutrients into adenosina triphospahte (ATP), and
then release waste products.
ATP covalent bonds between atoms
6O2 C6H12O6 --gt  6H2O 6CO2 energy (ATP)
Glucose looses electrons and hydrogen and oxygen
gains electrons and hydrogen During this process
heat energy is released. This is a redox
reaction a chemical reaction that transfers
electrons from one substance to another aka
oxidation- reduction reactions. Oxidation is the
loss of electrons during a redox reaction and
reduction is the acceptance of electrons during a
redox reaction.
The reactions involved in respiration are
catabolic reactions that involve the redox
reaction (oxidation of one molecule and the
reduction of another). Respiration is one of the
key ways a cell gains useful energy to fuel
cellular reformations.
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Cellular Respiration - Aerobic respiration
requires oxygen in order to generate energy (ATP)

• Chemical reactions to yield energy
• Break down carbohydrates
• Series of reactions

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Aerobic Cellular Respiration

• Oxygen dependent

• Byproducts
• Raw materials for photosynthesis
• Carbon dioxide
• Water

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• Cellular respiration
• Three metabolic processes
• Glycolysis - cytosol
• Krebs cycle - takes place in the matrix of the
  mitochondria
• Oxidative phosphorylation - via the electon
  transport chain is carried out on the inner
  mitochondrial membrane

In the absence of oxygen, respiration consists of
two metabolic pathways glycolysis and
fermentation. Both of these occur in the cytosol.
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Glycolosis
Glyco glucose Lysis break down Occurs in the
cytoplasm This stage occurs in BOTH aerobic and
anaerobic respiration Glucose breaks down into 2
pyruvate (2 ATP are also made) Glucose is a
6-carbon sugar Pyruvate is a 3-carbon molecule
(there are two of them)
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Glycolosis - glucose is split into pyruvic acid.
Glucose, a six carbon sugar, is split into two
molecules of a three carbon sugar. In the
process, two molecules of ATP, two molecules of
pyruvic acid and two "high energy" electron
carrying molecules of NADH are produced.
In the presence of oxygen, glycolysis is the
first stage of cellular respiration.
Without oxygen, glycolysis allows cells to make
small amounts of ATP. This process is called
fermentation.
There are 4 important stages in Glycolysis
Activation of glucose by ATP Splitting of
glucose into two roughly equivalent
phosphorylated halves Reduction of NAD to
NADH Phosphorylation of ADP
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Glycolysis Reactants and Products

• Reactants
• 1 glucose
• Enzymes are needed
• 2 ATP are needed to start

• Products
• 2 Pyruvates (go to next step)
• 4 ATP (2 are gained)
• 2 NADH (go to ETC)

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Intermediate step

• Pyruvate is converted to acetyl CoA
• Occurs in the cytoplasm
• See diagram on simple explanation handout

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Intermediate step Reactants and products

• Reactants
• 2 pyruvate (from glycolysis)

• Products
• 2 Acetyl CoA (go to next step)
• 2 CO2 (given off as waste)
• 2 NADH (go to ETC)

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Krebs Cycle (Citric Acid Cycle)

• Occurs in the matrix of mitochondria
• A series of reactions occur (this is not just one
  step)
• Main purpose is to generate electrons for use in
  ETC
• 2 ATP is given off
• See diagram on simple explanation handout

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Krebs Cycle Reactants and Products

• Reactants
• 2 Acetyl CoA

• Products
• 2 ATP
• 6 NADH (go to ETC)
• 2 FADH2 (go to ETC)
• 4 CO2 (given off as waste)

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Electron Transport Chain

• Occurs in inner membrane of mitochondria
• Series (chain) of coupled redox reactions
  (electrons are transported through the chain)
• Electrons carried to this step by NADH and FADH2
  (produced in previous steps)
• Oxygen is used in this step
• Water is given off

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Electron Transport Chain Reactants and Products

• Reactants
• 10 NADH
• 2 FADH2
• Oxygen

• Products
• 34 ATP
• H2O

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Where do we get 38 ATP?

• 2 ATP made in glycolysis
• 2 ATP made in Krebs Cycle
• 34 ATP made in ETC
• 1 NADH 3 ATP
• 10 X 3 30
• 1 FADH2 2 ATP
• 2 X 2 4

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Anaerobic Respiration (Fermentation)
Fermentation is the anaerobic harvest of food
energy. Anaerobic respiration occurs when your
cells need more ATP than your bloodstreams
delivery of oxygen can supply.
Common in yeast, molds, some bacteria
Carbon hydrogen not fully oxidized Less energy
than aerobic respiration. It can produce 2ATP per
glucose molecule.
By oxidizing the NADH produced in glycolysis,
fermentation regenerates NAD, which can take
part in glycolysis once again to produce more ATP.
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Anaerobic Respiration (Fermentation)

• Glycolysis
• Yields 2 pyruvate and 2 ATP
• With no oxygen present, cellular respiration does
  not occur
• ONLY 2 ATP ARE PRODUCED (compare to aerobic
  respiration)

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Two Types of Fermentation

• Alcoholic Fermentation
• Pyruvate converted to ethyl alcohol and CO2
• Carried out by yeast and some bacteria
• Used in producing alcohol (both consumable and
  for ethanol), and for baking

• Lactic Acid Fermentation
• Pyruvate converted to lactic acid
• Carried out by muscles when working hard (muscles
  need ATP but cant get O2 )
• Causes muscle soreness and cramps

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Photosynthesis

• Carried out by most (not all) autotrophs
• 6CO2 6H2O light energy? C6H12O6 6O2
• Basically this reaction is the OPPOSITE of
  cellular respiration
• See simple explanation handout and text

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Steps of Photosynthesis

• Light reaction (depends on light)
• Traps sunlight
• Produces electrons and ATP required to power the
  dark reaction
• Oxygen given off here
• Dark reaction, aka Calvin Cycle (does not
  directly depend on light)
• Uses ATP and electrons from light reaction and
  CO2 to make glucose
• See diagram on simple explanation handout

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Cellular respiration - in presence of O2

• Yields
• ATP from ADP
• Carbon dioxide water from glucose oxygen

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• Three Phases Of Aerobic Cellular Respiration
• Aerobic Cellular Respiration happens in
  Mitochondria. Three main reactions are involved
• Glycolisis occurs in cytoplasm of mitochondria
  (requires 2 ATP to start/ makes 2 ATP)
• Krebs Cycle occurs in matrix of mitochondria
  (makes 2 ATP)
• Electron Transport Chain occurs in mitochondria
  makes majority of ATP (32 ATP)
• Out of 38 ATP Produced - energy of 2 ATP required
  to start the process.

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