PHOTOSYNTHESIS

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CHAPTER 8 PHOTOSYNTHESIS
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ENERGY AND LIFE

• Living things depend on energy
• Sun is source of most energy
• 2 types of organisms,
• AUTOTROPHS make their own food (Ex plants,
  bacteria, protists)
• HETEROTROPHS get energy from the foods they
  consume (animals, fungi)

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Research On Photosynthesis

• VAN HELMONT- determined in the 1600s that plants
  grew because of water.
• PRIESTLEY- found that plants release oxygen.
• JAN INGENHOUSZ- found aquatic plants produce
  oxygen bubbles in the light, therefore plants
  need sunlight to produce oxygen

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AN OVERVIEW OF PHOTOSYNTHESIS

• Plants use the energy of sunlight to
• convert water carbon dioxide into high energy
  carbohydrates (sugar)
• oxygen is a waste product.
• light
• 6H2O 6CO2 ? C6H12O6 6O2
• Reactants Products

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What Else Does The Photosynthesizer Need?

• Chlorophyll- a chemical pigment that traps the
  energy of the sun and converts it to chemical
  energy

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Capturing Light Energy

• White light ROY G BIV
• Chlorophyll captures (absorbs) energy at the ends
  of the spectrum (red/orange blue/violet)
• What you see is the wavelengths that are
  reflected. (green)

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2 Types of Chlorophyll

• Chlorophyll a
• Chlorophyll b

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How Chlorophyll Works

• Sunlight excites e-s in the chlorophyll molecule.
  
• These excited e-s perform the work of
  photosynthesis.

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Where Photosynthesis Occurs

• In the chloroplast

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CHLOROPLASTS

• contain saclike photosynthetic membranes called
  THYLAKOIDS
• Thylakoids arranged in stacks called GRANA.
• Surrounding grana is a gel-like substance-STROMA.
• Photosynthesis begins in thylakoid membranes.

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The Recipe of Photosynthesis
Photosynthesis Cycle and Teasers
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Flow of energy in Photosynthesis

• Sunlight energizes the e-s in chlorophyll
• Carriers are needed to move these e-s ( their
  energy) to fuel photosynthesis
• Carrier molecules are used!

• ANALOGY
• Fire heats up coals
• Carrier is needed to move these coals to another
  place
• A bucket is used!

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e- Carriers the e- Transport Chain

• NADP
• (Nicotinamide adenine dinucleotide phosphate)
• Accepts holds a pair of e-s an H atom to
  become NADPH

• ATP
• (adenosine triphosphate)
• Holds energy in the bond holding the 3rd
  phosphate

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Photosynthesis is Many Reactions

• Light-dependent rxns
• "charging the batteries"
• Location thylakoid membranes
• ReactantsH2O, NADP ADP
• Products O2, NADPH ATP

• Calvin cycle (light- independent rxns)
• Discharging your batteries
• Location stroma
• Reactants CO2, NADPH, ATP
• Products Sugar, NADP, ADP

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• 1. Summarize the light-dependent reactions
• 2. What reactions make up the Calvin Cycle?
• 3. How is light energy converted into chemical
  energy during photosynthesis?

• 4. What is the function of NADPH?5. Why are the
  light dependent reactions important to the Calvin
  Cycle?

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Photosynthesis is Many Reactions

• Light-dependent rxns
• Requires sunlight energy

• Calvin cycle (light- independent rxns)
• Doesnt require sunlight energy!

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ATP synthase

• Is an enzyme (-ase ending is a hint)

• Is a membrane protein.
• It is a protein pump that allows H ions to pass
  thru the cell membrane
• This is necessary for the formation of ATP

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CHEMICAL ENERGY AND ATP

• All living things use chemical energy
• A chemical compound that cells use to store and
  release energy is ATP (ADENOSINE TRIPHOSPHATE).
• ATP is like a fully charged battery ready to
  power the machinery of a cell.
• ATP powers many cellular activities Ex
• active transport across cell membranes,
• protein synthesis
• muscle contraction.

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FACTORS THAT AFFECT PHOTOSYNTHESIS

• Amount of Water
• Amount of CO2
• Temperature
• Intensity of Light
• Wavelength of light

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SUMMARY OF PHOTOSYNTHESIS

• The process of photosynthesis includes the
  LIGHT-DEPENDENT REACTIONS as well as the CALVIN
  CYCLE.
• LIGHT DEPENDENT REACTIONS
• produce oxygen gas and convert ADP and NADP into
  the energy carriers ATP and NADPH.
• CALVIN CYCLE
• uses ATP and NADPH from the light-dependent
  reactions to produce high energy sugars.

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CHAPTER 9 CELLULAR RESPIRATION

• (In the last chapter, we learned how
  photosynthe-sizing organisms (such as plants)
  take energy from sunlight trap it in sugar
  (glucose) molecules.)
• Now we will learn how living things release this
  energy to fuel their daily activities.

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CHEMICAL ENERGY AND FOOD

• The CALORIE is used to measure the amount of
  energy present in food.
• .

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calorie v. Calorie-whats the difference?

• calorie- the amount of energy needed to raise the
  temperature of 1 gram of water by 1 degree
  Celsius.
• Calorie- 1000 calories
• More accurately named a kilocalorie
• The unit used on food packages.

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Quick Review of Organic Molecules in Living Things

• Carbohydrates (sugars, starches, etc.)
• Proteins
• Lipids (mainly fats)
• Nucleic acids (ATP, NADP, RNA, DNA)

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Wheres the Energy?

• Energy is trapped in the chemical bonds in
  organic compounds in food.
• Ex plants convert sunlight energy into chemical
  energy in glucose (sugar)
• When we break down glucose ( other organic
  compounds), the energy is released again!

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Cellular Respiration

• the process living things use to releases energy
  by breaking down glucose and other food molecules
  in the presence of oxygen

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Cellular Respiration

• Cells do not burn glucose, instead they slowly
  release energy from glucose and other food
  compounds
• They do this in many small steps-WHY?

If all the energy was released once, it would be
too much for the cell and it would be destroyed!
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Summary of Cell Respiration

• Sugar oxygen ? water carbon dioxide energy
• C6H12O6 6O2 ? 6H2O 6CO2 energy

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Cellular Respiration

• ATP is the main molecule that is used to provide
  direct energy for cell activities. (electron
  carrier)
• Remember, ATP is like a rechargeable battery.
• Basically, the energy in 1 glucose molecule is
  transferred into many ATP molecules to be used
  little by little. (Kind of like breaking a 100
  bill into 1s or 5s to be used little by little
  for purchases.)

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Releasing Energy From Glucose Step 1 Glycolysis

• GLYCOLYSIS is the process in which one molecule
  of glucose is broken in half, producing two
  molecules of pyruvic acid.
• C6H12O6 ? (2) 3-Carbon molecules (pyruvic acid)
• (see Fig 9-3, p 223 of text)

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Glycolysis, cont.

• GLYCOLYSIS comes from the Greek word glukus
  meaning sweet and the Latin word lysis which
  means decomposing.
• Thus GLYCOLYSIS means breaking glucose.

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Glycolysis, cont.

• Takes place in the cytoplasm
• Releases a small amount of energy
• (2 ATP 2 NADH) H2O
• Is ALWAYS the first step of releasing energy from
  glucose.

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SUMMARY OF GLYCOLYSIS

• Reactants Glucose, ADP, NAD
• Products 2 ATP, NADH, H2O

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WHAT FOLLOWS GLYCOLYSIS?

• AFTER glycolysis, living things can release more
  energy from sugar.
• How they do it depends on WHETHER OR NOT O2 IS
  PRESENT.

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Releasing Energy From Glucose Flow Chart

RED Fermentation

Red Blue Cell Respiration
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Releasing Energy From Glucose Step 2A
Fermentation

• When O2 is not present, GLYCOLYSIS is followed by
  a process called FERMENTATION.
• No airAnaerobic Pathway
• FERMENTATION releases a small amount of energy
  from food by producing ATP w/o O2

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2 Types of Fermentation

• ALCOHOLIC FERMENTATION produces carbon dioxide
  and alcohol. This type of fermentation causes
  bread dough to rise.
• Reactants pyruvic acid, NADH
• Products CO2 , alcohol (ethanol), NAD
• .

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2 Types of Fermentation, cont.

• 2. LACTIC ACID FERMENTATION is produced in your
  muscles during rapid exercise when the body
  cannot supply enough oxygen to the tissues.
• With rapid exercise your muscles run out of
  oxygen. Your muscle cells rapidly begin to
  produce ATP by LACTIC ACID FERMENTATION

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Fermentation

• Also occurs in the CYTOPLASM

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Step 2BKREBS CYCLE

• Occurs
• when O2 is present (aerobic)
• In the mitochondria (the powerhouse of the cell)

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THE KREBS CYCLE

• Pyruvic acid is converted into citric acid (Krebs
  is also known as Citric Acid Cycle)
• Citric acid is then broken down, releasing carbon
  dioxide and many ATPs in a series of small
  reactions
• REACTANTS O2, pyruvic acid, NAD, FAD, ADP
• PRODUCTS CO2, NADH, FADH, ATP,

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Energy Efficiency of Cell Respiration

• about 38 of the total energy of glucose is
  trapped in ATP can be used by the cell.
• The remaining 62 is released as heat, which is
  why your body feels warmer after vigorous
  exercise.

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QUICK VS. LONG TERM ENERGY

• QUICK ENERGY-
• 1. ATP stored in muscles-only enough ATP for a
  few seconds of intense activity
• 2. Lactic Acid Fermentation- when the ATP is
  almost gone, the muscles begin producing most of
  their ATP by this method.
• This can last about 90 seconds.

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QUICK VS. LONG TERM ENERGY (cont.)

• LONG TERM ENERGY- cellular respiration is the
  only way to generate a continuing supply of ATP.
• C.R. produces a lot of energy BUT it does so more
  slowly than fermentation
• 3. You have enough glycogen, (a carb) in your
  muscles other tissues) for about 15 or 20
  minutes of activity.

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QUICK VS. LONG TERM ENERGY (cont.)

• LONG TERM ENERGY (CONT.)
• 4. After that, your body begins to break down
  other stored molecules including fats for energy.
  This is why aerobic forms of exercise like
  running, swimming etc. are beneficial for weight
  control.