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A presentation created for an Introductory Biology high school class learning about Energetics. Basic overview of Cellular Respiration.
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Recap:
What is energy?
What do living things use energy for?
Brainstorm Question:
If energy cannot be created… then how do
organisms acquire energy?
How much energy is in a
Snickers bar?
Energy is measured in calories.
1 Calorie = the amount of heat required to raise the temperature
of 1g of water by 1ºC
Q: How do they figure this out for each food?
Q: Energy is not listed in the ingredients…
PEANUTS:
-high in plant oils
(lipis)
-high in starch
(carbs.)
PEANUT BUTTER
NOUGAT:
-high in oils (lipids)
-protein rich (egg
whites)
-high in sucrose (carbs)
CHOCOLATE:
-high in saturated
animal fats (lipids)
-high in fructose
(carbs)
-protein rich (milk)
CARAMEL:
-high in sucrose
(carbs)
…so where is it?
Energy is stored in the chemical bonds
of organic molecules.
The highest energy yield comes from
fats, carbs and proteins:
Carbohydrates 57%
Fats 30%
Protein13%
"Fuel Blend" Required by Humans
How does the body extract the
energy from the chocolate bar?
COMBUSTION
Combustion reaction
takes place in the
body to extract
energy from the fuel.
Same reaction that
happens in a car
engine or a burning
candle.
Q: Fuel does not spontaneously combust, what else is
needed?
Potential energy is stored in the bonds
between the atoms.
Breaking these bonds is exergonic, it
gives off energy.
The combustion reaction in the body=
CELLULAR RESPIRATION
Cellular respiration takes place in every
cell in the body.
A closer look…
Fuel alone does not combust (think of a lump of sugar on a plate).
Q: What does an engine need to start?
Q: What does a match need to burn?
Q: What does cellular respiration require other than fuel?
A few different enzymes involved to help extract the most energy from the bonds.
a spark + oxygen
friction/ heat + oxygen
enzymes + oxygen
The Reaction:
Reactants?
Products?
If energy is not tangible, how
can it be stored?
We don’t use all energy right away
Stored in the body as chemical energy
Cell batteries= molecules
ADP= uncharged ATP=
CHARGED
ATP
ATP molecules are synthesized during cellular respiration.
ATP then used to provide energy for other reactions through out the body.
When charge is drained, ADP is recycled in cells, gets charged again.
Produced in exergonic reactions, used in endergonic reactions.
Q: Example of an endergonic reaction where it may be used?
Back to our Snickers bar…
Let’s harvest the energy from a glucose molecule in it…
(remember the body will also get energy from the fats and proteins in it, but we will use glucose as an example since it’s body’s main fuel)
Q: Glucose does not show up in the ingredients either, where is it?
TEM micrograph of mitochondria in human lung tissue cell
Where the respiration process takes
place
STEP 1:
GLYCOLI
SIS
STEP 3:
ELECTRON
TRANSPORT
CHAIN
STEP 2:
KREBS
CYCLE
Cytosol
Introducing the main players…
Glucose
Oxygen
NAD+/ NAHD
FADH/FADH2
ADP/ATP
ATPase
1. Who will play what molecule
2. Read the handout with the player info
3. Familiarize yourself with your role
4. Get up and find your position around or
inside the mitochondria
Basic steps
1. GLYCOLYSIS (in cytoplasm)
Glucose broken up into 2 3-C molecules
(pyruvate)
Some ATP made
H+s and E-s given off from broken bonds
loaded onto coenzymes (NAD+ and FADH)
Loaded coenzymes “shuttle” E-s and H+s to
mitochondria.
2. KREBS CYCLE (in mitochondrial
matrix)
Atoms in the pyruvate molecules go through
several rearrangements
Pyruvate molecules get broken down further
More H+s and E-s get loaded onto
coenzymes and shuttled away
By product of Cycle is CO2, waste gas
3. ELECTRON TRANSPORT CHAIN (across mitochondrial intermembrane space)
NADH and FADH2 unload electrons into inner mitochondrial membrane
Carrier proteins pass electrons along membrane, creating gradient
H+s get unloaded into inter membrane space
ATPase uses gradient to pump hydrogen atoms across the inner membrane into matrix
ATP Synthase (ATPase)
Acts like a windmill
The movement of
protons creates the
energy for ATPase to
make ATP from ADP+P
More detailed ATP Synthase animation
ATPase dance (too funny!)
Oxygen then combines with H+s and E-s to
create water (byproduct of respiration)
Overview of Respiration video
Lab: Calorimeter
To determine how much energy is in
food.
Next up…
Can you respire without breathing?
What is more important for life- oxygen
or the sun?
This special edition Snickers bar is extra “charged”- it
contains caffeine, taurine and B-vitamins. How do these
ingredients contribute to the energy content of this
chocolate bar?
FOOD FOR
THOUGHT
Image Credits
Snickers bar (slide 5)- Flickr (Got Jenna)
Calories graphic (slide 6)- www.deo.ucsf.edu
Respiration graphic (slide 12)-http://bioweb.wku.edu/courses/BIOL115/Wyatt/Metabolism/Respiration.gif
Mitochondria (slide 17)- Public domain (tinojasontran)
TEM human lung tissue (slide 16)- Public domain (Louisa Howard)
Cell (slide 16)- European Bioinformatics Institute
Calorimeter (slide 26)- www.sciencebuddies.com
ATP synthase animation (slide 24)- Dr. Kaiser http://student.ccbcmd.edu/~gkaiser/biotutorials/energy/atpsynthase_an.html permission pending
Snickers Charged (slide 28)- Flickr (the futuristics)
Snickers bar info (slides 4 +15)- www.snickers.com
Clipart (slides 3+26)- Discovery School Clipart gallery