Cellular Respiration

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Cellular Respiration

• Do our cells breathe?

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Cellular Respiration

• Using glucose to make energy (ATP)

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Questions for this Lesson

• If plants need ATP (energy) to form glucose, how
  can glucose be a source of energy for plants and
  animals?
• How does our body use glucose to make energy?
• Why do your muscles get really sore when you
  exercise intensely, but not when you pace
  yourself?
• How do you get wine from grapes?

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Where Do Plants Get Energy?

• Plants get energy from the sun and store it in
  the bonds of ___________.

glucose
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Glucose Turns into Energy

• How do we get energy?
• by eating food.
• What types of food provide the most energy?
• Carbs (sugars or glucose) have the most energy
• e.g. candy bars, wheat, potatoes, rice, pasta

• What does your body do to the food you eat?
• - Our body digests our food (breaks apart bonds),
  releasing energy

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Breaking Bonds

• Breaking bonds releases energy!
• Energy is stored in the glucose bonds breaking
  them releases the energy
• What form of energy do our cell (and our body)
  use?
• the molecule ATP
• So.. our body breaks down
• glucose and uses it to make ATP (ENERGY!)
• Which organelle is
• responsible for producing
• energy for our cells?
• The MITOCHONDRIA

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What is ATP?

• ATP (adenosine triphosphate) is a nucleic acid
  that can transfer energy within the cell.
• Ex a small amount of energy from a glucose
  molecule can be used directly
• The extra energy is transferred to ATP.
• The energy in ATP is stored in the bonds between
  the phosphates (ATP has 3 phosphates).

http//www.brooklyn.cuny.edu/bc/ahp/LAD/C7/graphic
s/C7_atp_2.GIF
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Steps of Cellular Respiration

• Remembercellular respiration is using glucose to
  make energy
• Step 1 glycolysis
• glyco refers to glucose
• lysis break apart
• Glycolysis break down 1 glucose into 2 pyruvic
  acid molecules, which have three carbons each
  (splits glucose in half)
• Also makes 2 ATP! ?
• Takes place in the cytoplasm

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Steps of Cellular Respiration (cont)Why
Glycolysis?

• Why would we need to break down glucose in the
  cytoplasm first before we use it in the
  mitochondria? (think transport)
• Glucose molecules are too large to move into the
  mitochondria, so glycolysis makes them smaller to
  get through the mitochondrias membranes

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Steps of Cellular Respiration (cont)

• After glycolysis, there are two possible paths
• Aerobic respiration requires oxygen
• Anaerobic respiration does not require oxygen
  happens if oxygen is lacking

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Aerobic Cellular Respiration

• An aerobic process (requires oxygen).
• Reaction releases energy from the chemical bonds
  of carbohydrates.
• Takes place in the mitochondria.
• Equation
• 6O2 C6H12O6 6H20 6CO2
  36ATP
• Oxygen Glucose Water Carbon
  Dioxide Energy

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HOLD IT!Notice Anything Similar?

• Equation for photosynthesis
• Energy 6H2O 6CO2 C6H12O6
  6O2
• Equation for aerobic cellular respiration
• 6O2 C6H12O6 6H20 6CO2
  36ATP

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Organisms that Do Aerobic Cellular Respiration
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ts/images/GlebeCottagePlants.jpg
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Organisms that Do Aerobic Cellular Respiration

• Plants
• Animals
• Fungi
• Protists
• Some bacteria
• almost everything alive!

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Aerobic Cellular Respiration

• Recap Step 1 glycolysis 2 ATP molecules are
  produced in cytoplasm and enter mitochondria.
• For aerobic respiration, in mitochondria
• Step 2 Krebs Cycle (Citric Acid Cycle) in
  matrix
• Step 3 Electron Transport Chain in inner
  membrane
• ATP is generated in each step, but most of the
  ATP is made in the
• Electron Transport Chain

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Krebs Cycle (matrix)

• Right before the Krebs Cycle, the Pyruvate from
  glycolysis is converted to Acetyl-CoA.
• During Krebs, the Acetyl-CoA is broken down into
  CO2 electrons (H).
• 2 ATP are created.
• The electrons then
• move on to the
• Electron Transport
• Chain.

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Glycolysis Krebs Overview

• We start with one molecule of glucose and end up
  with 6 CO2 molecules, a handful of electrons (H)
  and 4 ATP molecules.
• The CO2 is waste that will move out of the cell
  (and which you exhale).
• The 4 ATP molecules can be used by the cell as
  energy.
• What about the other 32 ATPs from our equation?

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Electron Transport Chain

• Embedded in the mitochondria inner membrane are
  proteins called electron carriers.
• The electrons (H) from Glycolysis and the Krebs
  Cycle are passed from electron carrier to
  electron carrier (like a bucket brigade).
• With every pass,
• energy is released
• from the electrons,
• and ATP is made.
• As a result, 32 ATP
• are made in the
• Electron Transport
• Chain.

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Summary of Aerobic Respiration
C6H12O6 6O2 ? 6CO2
6H2O 36 ATP Glucose Oxygen ?
Carbon dioxide Water ATP
(Krebs Cycle)
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Other Catabolic Pathways

• What happens with respiration of lipids,
  proteins, and nucleic acids?
• Starch broken down into glucose, which enters
  glycolysis
• Fats broken down into fatty acids and glycerol
  fatty acids are cut into 2-carbon compounds,
  converted to Acetyl-CoA, and enter the Krebs
  Cycle
• Proteins broken down into amino acids, which can
  be converted into Acetyl-CoA or other compounds
  that enter the Krebs cycle at various points
• The amino group is removed excreted as urea.

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Nucleic Acids
Proteins
Carbohydrates
Lipids
Fatty Acids/ Glycerol
Sugars
Nucleotides
Amino Acids
Pyruvate
Acetyl-CoA
Krebs Cycle
H2O
Urea
CO2
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Importance of Oxygen

• During aerobic respiration, where do the
  electrons (H) end up as they are passed from
  protein to protein?
• They end up in the loving arms of oxygen.
• When oxygen accepts electrons, water is made.
• If oxygen wasnt there to accept the electrons,
  the Electron Transport Chain would get backed up,
  and no energy would be produced.
• What type of respiration happens when there is no
  oxygen? and where does it happen?

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Anaerobic Cellular Respiration

• AKA fermentation
• An anaerobic process (does not require oxygen)
• Two types of fermentation
• Alcohol fermentation
• Lactic acid fermentation
• Both take place in the cytoplasm.

http//www.schmohz.com/images/beer-fermenter.jpeg
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Alcohol Fermentation

• Pyruvic acid NADH
• NAD
• alcohol
• CO2
• 2 ATP

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Organisms that do alcohol fermentation

• Yeast perform alcohol fermentation in the absence
  of oxygen.
• The alcohol produced is the type that we drink.
• The CO2 produced is used to make bread rise.

http//www.utoronto.ca/greenblattlab/images/a/yeas
t201.jpg
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Lactic Acid Fermentation

• Pyruvic acid NADH
• NAD
• lactic acid
• 2 ATP
• Lactic acid is what makes your muscles sore when
  you exercise.

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Organisms that do lactic acid fermentation

• Humans (and other animals) - when they are
  exercising and their muscles arent getting
  enough O2 to keep up with the energy demand.
• The build up of lactic acid is what makes your
  muscles start to burn.

http//www.donlemmonsknowhow.com/img/exercise-sess
ion.jpg
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Whats the big deal about aerobic vs. anaerobic
respiration?

• You get way more ATP from aerobic cellular
  respiration than you do from anaerobic cellular
  respiration (fermentation).
• Fermentation is mostly used to provide organisms
  with short-term bursts of energy when oxygen is
  not available.

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