Lecture 4 BIOL L100 Indiana University Southeast David Partin, Instructor

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Lecture 4BIOL L100 Indiana University
SoutheastDavid Partin, Instructor
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Todays Plan

• Lecture 4 Metabolism, Photosynthesis and
  Cellular Respiration (Ch6-8)
• Video Clip
• One-Minute Paper
• Lab

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Chapters 6, 7 8

• Metabolism
• Photosynthesis
• Cellular Respiration

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Metabolism

• What is metabolism?
• The sum of all chemical reactions occurring in
  the body.
• Why do we need all those chemical reactions?
• There are lots of jobs that must be done to keep
  us alive! Breathing, digestion, movement,
  thinking, immunity, growth, etc.
• All those reactions require energy. Where do we
  get the energy from?

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Living things depend on the Sun!
(wasted energy)
(wasted)
(stored in glucose)
(wasted)
(Used for Movement)
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2 Laws of Thermodynamics

• 1st Law Energy cannot be created or destroyed,
  but it can change from one form to another.
• Solar, chemical, mechanical, heat energy, etc.
• 2nd Law When energy changes forms, some of the
  energy is wasted or lost as
• HEAT!

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Living things depend on the Sun!
(wasted energy)
(wasted)
(stored in glucose)
(wasted)
(Used for Movement)
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Photosynthesis

• Solar energy 6CO2 6H2O C6H12O6 6O2
• (carbon (water) (glucose)
  (oxygen)
• dioxide)
• Reactants solar energy, carbon dioxide and
  water
• CO2 and H2O diffuse into the plant cell.
• Products glucose and oxygen
• Photosynthesis transforms solar energy into the
  chemical energy of a carbohydrate.
• The photosynthetic process takes place with
  organelles called chloroplasts.

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Photosynthesis2 sets of reactions

• Light reactions
• Solar energy Chemical energy
• (ATP, NADPH)
• Calvin Cycle reactions (aka Dark reactions)
• Chemical energy Chemical energy
• (ATP, NADPH) (carbohydrate)

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Solar energy can be converted to chemical
energy.This chemical energy can be stored in
the covalent bonds that hold together the atoms
in a molecule of glucose.Chemical energy can be
converted to mechanical energy. See Spot run! ?
Spot the Dog
Chemical energy is stored in each of these
covalent bonds.
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• Before an organism can use the chemical energy in
  glucose, the energy must be stored in ATP.
• ATP is the currency of cellular energy.
• ATP directly supplies the energy necessary for
  nearly all chemical reactions in the body.

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ATP

• Adenosine Triphosphate

Very high energy bonds between phosphate groups
(like charges repel)
nucleotide
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ATP

• Chemical energy is stored in the high energy
  bonds that hold the phosphate groups together in
  the ATP molecule.
• When ATP is broken down, a phosphate group is
  released along with free energy that can be used
  for metabolism.

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Functions of ATP

• Chemical work ATP supplies the energy needed to
  build organic molecules in the cell.
• Transport work ATP supplies the energy to pump
  substances across the cell membrane.
• Mechanical work ATP provides energy for
  movement. (muscle contraction, flagella,
  chromosome movement during mitosis, etc.)

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Exergonic releases energy
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So how where is ATP formed?
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Outside the mitochondria

• Glycolysis (glyco sugar lysis breakdown)
• Glucose (6 carbons) is converted to pyruvate (3
  carbons)

P.S. Dont memorize this diagram!
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Inside the mitochondria

• Krebs cycle (aka Citric Acid cycle or TCA cycle)

• Big Picture
• Organic molecules from glycolysis enter the
  mitochondria. These molecules are processed in
  the Krebs cycle. The products of the Krebs cycle
  are
• Carbon Dioxide (waste product)
• ATP (used for energy)
• etc.

Dont memorize this diagram!
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Cellular Respiration
Cellular respiration is the process of breaking
down glucose to produce carbon dioxide , water
and ATP. Aerobic respiration requires oxygen and
produces 32 ATP molecules per glucose.
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Fermentation (AKA anaerobic respiration)
Anaerobic respiration (aka fermentation) does
not require oxygen. It is a less efficient
process than aerobic respiration, producing only
2 net ATP. The products of fermentation include
either lactate or alcohol. When our muscles need
more oxygen than they are supplied, cellular
respiration becomes anaerobic. Lactic acid is
released as a waste product.
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What happens to the products of the Krebs cycle?

• ATP is used as an energy source.
• Carbon dioxide exits the cell by diffusion.
• Eventually, it will diffuse into the bloodstream.
  
• After that, CO2 will diffuse from the bloodstream
  into the alveoli of the lungs.
• Then, it is released into the atmosphere by
  exhalation.
• Plants will absorb the carbon dioxide to use in
  the photosynthetic process all over again.

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Big Picture

• Organisms require energy for metabolism.
• That energy ultimately comes from the suns
  energy stored in the chemical bonds of glucose,
  produced by photosynthesis.
• Mitochondria within cells have the machinery
  necessary to turn that glucose into ATP that the
  cell can use for energy.

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Living things depend on the Sun!
(wasted energy)
(wasted)
(stored in glucose)
(wasted)
(Used for Movement)
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Any questions?

• Whats next?
• Break!
• One Minute Paper
• Lab

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Photosynthesis Lab Overview

• Plants in test tubes, covered with soda solution
• Rubber stopper bent pipette plug
• Beaker of water between test tubes light
• Watch soda solution change levels with and
  without light

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Preparation for next lecture

• Read Chapter 9