Photosynthesis and Cellular Respiration

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Photosynthesis and Cellular Respiration
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Outline

• I. Photosynthesis
• A. Introduction
• B. Reactions
• II. Cellular Respiration
• A. Introduction
• B. Reactions

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Review What is ATP?
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Review What is ATP?

• Adenosine Triphospate
• Adenine Ribose 3 Phosphate groups
• One of the principle chemical compounds that
  cells use to STORE and RELEASE energy.

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Storing Energy

• ADP (Adenine diphospate)
• Only 2 phosphates (hence the di)
• Key to how living things STORE energy!
• (When energy is available, the cell stores it by
  adding phosphate to make ATPstored battery ready
  to power cell).

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Releasing Energy

• Shooting off 1 phosphate ? ENERGY!!
• ATP provides energy for a variety of cellular
  activities!
• Ex active transport across cell membranes,
  protein synthesis, and muscle contraction

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ADP? ATP

• Cells regenerate ATP from ADP as needed by using
  energy in FOOD, aka

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ADP? ATP

• Cells regenerate ATP from ADP as needed by using
  energy in FOOD, aka GLUCOSE!

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Photosynthesis

• Photo light
• Synthesis putting together

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Photosynthesis

• Converting sun energy into chemical energy usable
  by cells (glucose)
• Autotrophs self feeders, organisms capable of
  making their own food
• Photoautotrophs use sun energy e.g. plants
  photosynthesis-makes glucose from light
• Chemoautotrophs use chemical energy, NOT
  sunlight
• e.g. bacteria that use sulfide or methane

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Photosynthesis

• Photosynthesis takes place in specialized
  structures inside plant cells called chloroplasts
• Light absorbing pigment molecules e.g.
  chlorophyll

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Why are leaves green?

• Chlorophyll absorbs all of the light waves except
  green. Because the green is not absorbed, it is
  reflected, so that is the only color wavelength
  our eye can pick up.
• Accessory pigments help to fill in this gap
• Carotenoids orange (like carrots)
• Xanothphyl yellow

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Inside the chloroplast

• Thylakoids Sac-like photosynthetic membranes
  arranged in stacks.
• Organize chlorophyll/other pigments into
  photosystems (clusters that collect light).

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What does a plant need to survive?
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Overall Reaction

• 6CO2 6H2O light energy ? C6H12O6 6O2
• Carbon dioxide water light ? glucose oxygen
• KNOW BOTH OF THESE EQUATIONS.
• YOU WILL SEE THEM AGAIN!

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2 types of reactions in photosynthesis

• Light dependent
• Light independent (CALVIN CYCLE)

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Electron Carriers

• Overview
• Sun excites electrons gain energy
• Need special carrier! (Think red-hot coal!)
• Electron acceptor molecules (ex NADP)
• NADP uses hydrogen ions (H) to trap some of the
  sunlight in chemical form converts to NADPH.
• Carries e- to other chemical reactions in the cell

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Light Dependent Reactions

• Occur in the thylakoid!
• Produce oxygen gas
• Converts ADP and NADP into energy carriers ATP
  NADPH

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Light Dependent Reactions

• Overview
• Pigments in Photosystems absorb light electrons
  gain energy
• Electrons are passed on to the Electron Transport
  Chain
• Does the chorophyll run out of electrons?

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Light Dependent Reactions

• In Thylakoid
• System that provides new e- to chlorophyll to
  replace ones lost
• Electrons come from water! H2O
• Enzymes on inner surface membrane of thylakoid
  break up each H2O into
• 2 e- (replace e- lost to the ETC)
• 2Hions (released inside thylakoid membrane)
• 1 oxygen atom (released into the air!)

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Light-dependent Reactions

• 5. H ions cant cross membrane directly
• ATP synthase!
• Allows H ions to pass through it!
• As it turns, binds ADP and phosphate group .
• Producing ATP!

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Energy Shuttling

• Recall ATP cellular energy-nucleotide based
  molecule with 3 phosphate groups bonded to it,
  when removing the third phosphate group, lots of
  energy liberated superb molecule for shuttling
  energy around within cells.
• Other energy shuttles-coenzymes (nucleotide based
  molecules) move electrons and protons around
  within the cell
• NADP, NADPH NAD, NADP FAD, FADH2

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This light dependent reaction is the source of
nearly ALL of the oxygen in Earths atmosphere!
Thanks photosynthesis!
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Light-dependent Reactions

• Photosystem light capturing unit, contains
  chlorophyll, the light capturing pigment
• Electron transport system sequence of electron
  carrier molecules that shuttle electrons, energy
  released to make ATP
• Electrons in chlorophyll must be replaced so that
  cycle may continue-these electrons come from
  water molecules, Oxygen is liberated from the
  light reactions
• Light reactions yield ATP and NADPH used to fuel
  the reactions of the Calvin cycle (light
  independent or dark reactions)

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Uses H2O, ADP, and NADPMakes Oxygen, ATP, and
NADPH
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Calvin Cycle (light independent or dark
reactions)

• ATP and NADPH generated in light reactions used
  to fuel the reactions which take CO2 and H to
  make glucose.
• Simplified version of how carbon and energy enter
  the food chain

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Harvesting Chemical Energy

• Plants and animals both use products of
  photosynthesis (glucose) for metabolic fuel
• Heterotrophs must take in energy from outside
  sources, cannot make their own e.g. animals
• When we take in glucose (or other carbs),
  proteins, and fats-these foods dont come to us
  the way our cells can use them

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Photosynthesis vs. Cellular Respiration
Photosynthesis Cellular Respiration
ENERGY
CO2 and O2
Water
Glucose
Location Where does it take place?
Light
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Photosynthesis vs. Cellular Respiration
Photosynthesis Cellular Respiration
ENERGY Energy is stored
CO2 and O2
Water
Glucose
Location Where does it take place?
Light
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Photosynthesis vs. Cellular Respiration
Photosynthesis Cellular Respiration
ENERGY Energy is stored
CO2 and O2 Uses CO2 Produces O2
Water
Glucose
Location Where does it take place?
Light
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Photosynthesis vs. Cellular Respiration
Photosynthesis Cellular Respiration
ENERGY Energy is stored
CO2 and O2 Uses CO2 Produces O2
Water Uses water
Glucose
Location Where does it take place?
Light
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Photosynthesis vs. Cellular Respiration
Photosynthesis Cellular Respiration
ENERGY Energy is stored
CO2 and O2 Uses CO2 Produces O2
Water Uses water
Glucose Produces glucose from energy
Location Where does it take place?
Light
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Photosynthesis vs. Cellular Respiration
Photosynthesis Cellular Respiration
ENERGY Energy is stored
CO2 and O2 Uses CO2 Produces O2
Water Uses water
Glucose Produces glucose from energy
Location Where does it take place? Chloroplasts of green plants, algae, and some microorganisms
Light
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Photosynthesis vs. Cellular Respiration
Photosynthesis Cellular Respiration
ENERGY Energy is stored
CO2 and O2 Uses CO2 Produces O2
Water Uses water
Glucose Produces glucose from energy
Location Where does it take place? Chloroplasts of green plants, algae, and some microorganisms
Light Requires light(light-dependent reaction Calvin Cycle can occur in light or dark.)
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Cellular Respiration Overview

• Transformation of chemical energy in food into
  chemical energy cells can use ATP
• These reactions proceed the same way in plants
  and animals. Process is called cellular
  respiration
• Overall Reaction
• C6H12O6 6O2 ? 6CO2 6H2O

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Cellular Respiration Overview

• Breakdown of glucose begins in the cytoplasm
  the liquid matrix inside the cell
• At this point life diverges into two forms and
  two pathways
• Anaerobic cellular respiration (aka fermentation)
• Aerobic cellular respiration

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C.R. Reactions

• Glycolysis
• Series of reactions which break the 6-carbon
  glucose molecule down into two 3-carbon molecules
  called pyruvate
• Process is an ancient one-all organisms from
  simple bacteria to humans perform it the same way
• Yields 2 ATP molecules for every one glucose
  molecule broken down
• Yields 2 NADH per glucose molecule

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Anaerobic Cellular Respiration

• Some organisms thrive in environments with little
  or no oxygen
• Marshes, bogs, gut of animals, sewage treatment
  ponds
• No oxygen used anaerobic
• Results in no more ATP, final steps in these
  pathways serve ONLY to regenerate NAD so it can
  return to pick up more electrons and hydrogens in
  glycolysis.
• End products such as ethanol and CO2 (single cell
  fungi (yeast) in beer/bread) or lactic acid
  (muscle cells)

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Aerobic Cellular Respiration

• Oxygen requiredaerobic
• 2 more sets of reactions which occur in a
  specialized structure within the cell called the
  mitochondria
• 1. Krebs Cycle
• 2. Electron Transport Chain

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Krebs Cycle

• Completes the breakdown of glucose
• Takes the pyruvate (3-carbons) and breaks it
  down, the carbon and oxygen atoms end up in CO2
  and H2O
• Hydrogens and electrons are stripped and loaded
  onto NAD and FAD to produce NADH and FADH2
• Production of only 2 more ATP but loads up the
  coenzymes with H and electrons which move to the
  3rd stage

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Electron Transport Chain

• Electron carriers loaded with electrons and
  protons from the Krebs cycle move to this
  chain-like a series of steps (staircase).
• As electrons drop down stairs, energy released to
  form a total of 32-34 ATP
• Oxygen waits at bottom of staircase, picks up
  electrons and protons and in doing so becomes
  water

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Energy Tally

• 34-36 ATP for aerobic vs. 2 ATP for anaerobic
• Glycolysis 2 ATP
• Krebs 2 ATP
• Electron Transport 32-34 ATP
• 36-38 ATP
• Anaerobic organisms cant be too energetic but
  are important for global recycling of carbon

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Photosynthesis vs. Cellular Respiration

• Comparing/Contrasting worksheet!

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Photosynthesis vs. Cellular Respiration
Photosynthesis Cellular Respiration
ENERGY Energy is stored Energy is released
CO2 O2 Uses CO2 Produces O2
Water Uses water
Glucose Produces glucose from energy
Location Where does it take place? Chloroplasts of green plants, algae, and some microorganisms
Light Requires light(light-dependent reaction Calvin Cycle can occur in light or dark.)
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Photosynthesis vs. Cellular Respiration
Photosynthesis Cellular Respiration
ENERGY Energy is stored Energy is released
CO2 O2 Uses CO2 Produces O2 Uses O2 Produces CO2
Water Uses water
Glucose Produces glucose from energy
Location Where does it take place? Chloroplasts of green plants, algae, and some microorganisms
Light Requires light(light-dependent reaction Calvin Cycle can occur in light or dark.)
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Photosynthesis vs. Cellular Respiration
Photosynthesis Cellular Respiration
ENERGY Energy is stored Energy is released
CO2 O2 Uses CO2 Produces O2 Uses O2 Produces CO2
Water Uses water Produces Water
Glucose Produces glucose from energy
Location Where does it take place? Chloroplasts of green plants, algae, and some microorganisms
Light Requires light(light-dependent reaction Calvin Cycle can occur in light or dark.)
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Photosynthesis vs. Cellular Respiration
Photosynthesis Cellular Respiration
ENERGY Energy is stored Energy is released
CO2 O2 Uses CO2 Produces O2 Uses O2 Produces CO2
Water Uses water Produces Water
Glucose Produces glucose from energy Burns glucose from energy
Location Where does it take place? Chloroplasts of green plants, algae, and some microorganisms
Light Requires light(light-dependent reaction Calvin Cycle can occur in light or dark.)
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Photosynthesis vs. Cellular Respiration
Photosynthesis Cellular Respiration
ENERGY Energy is stored Energy is released
CO2 O2 Uses CO2 Produces O2 Uses O2 Produces CO2
Water Uses water Produces Water
Glucose Produces glucose from energy Burns glucose from energy
Location Where does it take place? Chloroplasts of green plants, algae, and some microorganisms Glycolysis Cytoplasm of eukaryotic, prokaryotic cellsAerobic respiration mitochondria of ALL eukaryotes
Light Requires light(light-dependent reaction Calvin Cycle can occur in light or dark.)
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Photosynthesis vs. Cellular Respiration
Photosynthesis Cellular Respiration
ENERGY Energy is stored Energy is released
CO2 O2 Uses CO2 Produces O2 Uses O2 Produces CO2
Water Uses water Produces Water
Glucose Produces glucose from energy Burns glucose from energy
Location Where does it take place? Chloroplasts of green plants, algae, and some microorganisms Glycolysis Cytoplasm of eukaryotic, prokaryotic cellsAerobic respiration mitochondria of ALL eukaryotes
Light Requires light(light-dependent reaction Calvin Cycle can occur in light or dark.) Occurs in dark and light