Chapter 8 Cellular Energy *Photosynthesis *Cellular Respiration

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(No Transcript)
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Chapter 8Cellular EnergyPhotosynthesisCellula
r Respiration
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• ENERGY - is
• the ability to do work
• ALL ORGANISMS
• need and use energy!!!!

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Where do organisms get the energy that they need?

• it comes from food, however, the ultimate source
  of most of our energy is the SUN

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Law of Thermodynamics

• Energy cannot be created or destroyed, but it can
  be converted into other forms

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Metabolism

• The sum of a cells chemical reactions
• Metabolism Catabolism Anabolism
• Catabolism to break down
• Ex cellular respiration
• Anabolism to build up
• Ex photosynthesis
• This results in a continuous flow of energy
  within an organism.

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• organisms meet their energy needs
• in different ways
• AUTOTROPHS plants, some bacteria protists
• produce their own food
• chemoautotrophs go through chemosynthesis
• photoautotrophs go through photosynthesis
• HETEROTROPHS fungi, animals, some bacteria
  protists cannot produce their own food
• must obtain energy from the foods they consume

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• ENERGY
• energy comes in many forms light, heat,
  electricity, nuclear, kinetic,
• Some organisms consume foods in order to get the
  stored energy out of them

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ATP

• cellular activities require the use of energy
• one of the main chemical compounds that cells use
  to store energy is ATP (adenosine triphosphate)
• ATP consists of
• 1. a N-containing part called adenine
• 2. a 5-Carbon sugar - called ribose
• 3. three phosphate groups (P and O)

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Metabolic Pathway of ATP and ADP

• form a cycle of releasing and absorbing energy

releases Energy
ATP
requires (absorbs) energy
ADP
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ATP and Glucose

• most cells have only a small amount of ATP
  (enough to last for a few seconds of activity)
• more is made as needed by using the stored energy
  (glycogen)

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• 2 processes of great importance
• that enable living things to
• meet their energy needs
• 1. PHOTOSYNTHESIS
• the production of organic compounds
• 2. CELLULAR RESPIRATION
• the break down of organic compounds
  

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• Light Energy
• Chemical Energy
• (organic compounds)
• ATPs
• ADPs P groups energy (that can be used to
  do cellular activities)

• PHOTOSYNTHESIS
• CELLULAR
• RESPIRATION
• ATP- ADP CYCLE

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Photosynthesis

• process by which a cell captures light energy
  (photons) and uses it to make food
• (usually carbohydrates, like glucose)
• photosynthesis occurs in photoautotrophs
• plants
• algae
• some bacteria (prokaryotes)

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• PHOTOSYNTHESIS - process in which water, carbon
  dioxide, and light energy are converted into
  oxygen and organic compounds
• the ORGANIC COMPOUNDS made during
  photosynthesis are usually carbohydrates
  (sugars and starches)

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• PHOTOSYNTHESIS general equation
• 6 CO2 6 H2O light (energy)
  C6H12O6 6 O2
• What are the reactants?
• What are the products?
• Where does the light energy come from?
• Where does the H2O come from?
• Where does the CO2 come from?

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Photosynthesis - Overview
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• most photosynthetic organisms are eukaryotes,
  therefore, photosynthesis
• occurs inside the CHLOROPLAST
• prokaryotes lack chloroplasts,
• in these organisms, photosynthesis
• occurs in the cytoplasm

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• PIGMENTS
• ALL photosynthetic organisms contain PIGMENTS
  (light absorbing substances)
• the principal photosynthetic pigment is (green)
  CHLOROPHYLL
• in addition to chlorophyll there are other
  pigments called ACCESSORY PIGMENTS (ex.
  Carotenoids)

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Chloroplast Structure

• chloroplasts contain disc like structures called
• THYLAKOID DISKS
• these are arranged in stacks called GRANA
• PIGMENTS are found inside the thylakoid disks
• a fluid called STROMA surrounds the thylakoid
  disks

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• PHOTOSYNTHESIS
• consists of 2 major sets of reactions
• 1. LIGHT DEPENDENT REACTIONS
• 2. LIGHT INDEPENDENT REACTIONS
• (or CALVIN CYCLE)
• What do the names indicate
• about these reactions?

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Light Dependent Reactions(occur in thylakoid
disk containing chlorophyll)Light Independent
Reactions (occur in stroma)
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Light dependent reaction What are the
reactants? products?Light independent reaction
(Calvin Cycle)? What are the reactants? products?
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Alternative Pathways

• Used when water and/or carbon dioxide are not
  present or in insufficient amounts
• 2 types
• The C4 pathway
• Sugar cane, corn
• The CAM pathway
• Pineapple, cacti, orchids

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Factors Affecting Photosynthesis

• availability of water
• availability of carbon dioxide
• temperature
• light intensity

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Biochemical (Metabolic) Pathway
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• Light Energy
• Chemical Energy
• (organic compounds)
• ATPs
• ADPs P groups energy (that can be used to
  do cellular activities)

• PHOTOSYNTHESIS
• CELLULAR
• RESPIRATION
• ATP- ADP CYCLE

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Cellular Respiration

• process that releases energy
• (in the form of ATPs)
• from food (organic compounds)
• All living things undergo some form of cellular
  respiration, but remember living things differ so
  this process may differ

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• There are 2 possible ways in which a cell can
  accomplish cellular respiration and harvest
  energy from food.
• (aerobic) Cellular Respiration oxidative
  respiration
• or
• Fermentation (anaerobic respiration)
• both start with the same first step
• GLYCOLYSIS

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(aerobic) Cellular Respiration or Oxidative
Respirationreleases energy (in the form of
ATPs) from food (organic compounds) in the
presence of oxygen
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3 steps of (aerobic) Cellular Respiration

• 1. Glycolysis
• 2. Krebs Cycle
• 3. Electron Transport Chain

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1. Glycolysis

• occurs in the cytoplasm
• anaerobic
• splitting of glucose into pyruvic acid
  (pyruvate)
• net gain of 2 ATP and 2 pyruvate

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2. Krebs Cycle

• occurs in mitochondrion (of eukaryotes)
• aerobic
• breaks down pyruvic acid
• produces CO2 and a net gain of 2 ATP

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3. Electron Transport Chain

• occurs in mitochondria(of eukaryotes)
• aerobic
• uses electrons to release energy and produce ATP
• produces H2O and up to 34 ATP

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How many ATPs from (aerobic) Cellular
Respiration?

• Glycolysis (2)
• Krebs Cycle (2)
• Electron Transport Chain (maximum 34)
• possible 38
  ATPs
• the actual number of ATPs varies from cell to
  cell
• most eukaryotic cells produce 36 ATPs

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General Equation for (aerobic) Cellular
Respiration

• C6H12O6 6O2 ? 6CO2 6H2O ATP
  (energy)
• What are the reactants?
• What are the products?

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• if no oxygen is present..
• glycolysis is followed by fermentation
• Fermentation (anaerobic respiration) releases
  energy (in the form of ATP)
• from food (organic compounds)
• in the absence of oxygen

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2 steps of Fermentation (anaerobic respiration)

• 1. Glycolysis
• 2. Fermentation

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1. Glycolysis

• occurs in the cytoplasm
• anaerobic
• splitting of glucose into pyruvic acid
  (pyruvate)
• net gain of 2 ATP and 2 pyruvate

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2. Fermentation

• occurs in the cytoplasm
• anaerobic
• the break down of pyruvic acid in the absence of
  oxygen
• net gain of 0 ATP

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How many ATPs from FERMENTATION?

• Glycolysis (2)
• Fermentation (0)
• possible 2 ATP
• fermentation is not nearly as efficient in
  releasing energy from food as is (aerobic)
  Cellular Respiration

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2 common types of Fermentation

• LACTIC ACID FERMENTATION
• converts pyruvic acid into lactic acid
• process used to make yogurt, cheese, sour cream
• occurs in some fungi and some bacteria
• occurs in skeletal muscle cells of animals
  lactic acid or sore muscles

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2 common types of Fermentation

• ALCOHOLIC FERMENTATION
• converts pyruvic acid into ethanol (ethyl
  alcohol)
• process used in the making of bread and alcoholic
  beverages - wine, beer,
• occurs in yeasts, some bacteria, some plants
• ethanol is added to gasoline to make gasohol

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Visualizing Cellular Respiration
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Lets see the process again
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• Photosynthesis
• and
• Cellular Respiration
• are a metabolic (biochemical) pathways
• BECAUSE..

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• The products of photosynthesis are used as the
  reactants in cellular respiration
• The products of cellular respiration are used as
  the reactants in photosynthesis

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• Cellular Respiration Virtual Lab