Download Cellular Respiration

Sunlight Powers Life
Obtaining “Food”
• Biologists classify organisms according to how
they obtain food
• Autotrophs “self-feeder”
– Organisms that make their own “food”
• Examples: plants
– Also called producers
Obtaining Food
• Heterotrophs “other eaters”
– Organisms that cannot make their own food
• Examples, humans and other animals
– Also called consumers
Obtaining Food
• Types of Heterotrophs
– Herbivore – plant eater
– Carnivore – animal eater
– Omnivore – plant and animal eater
– Decomposer – breaks down organic matter
fungi
bacteria
Harvesting Energy
• Organisms harvest energy in several ways:
• Cellular Respiration
– Converts chemical energy from organic molecules
(food) into usable energy
• By heterotrophs
• Photosynthesis
– Plants use light to convert water and carbon dioxide
into energy (a sugar)
• By autotrophs
» NOTE: there are some organisms that will use neither
light nor organic matter and make energy through
chemicals
Energy Flow
• Energy flows through an ecosystem from the
sun to autotrophs and then to heterotrophs.
Intro. To Energy
• Energy is the ability to do work.
• Energy cannot be created or destroyed. It can
be converted from one form to another.
– First Law of Thermodynamics
Intro. To Energy
How do organic compounds in food provide energy?
• Remember, organic molecules are things like,
carbohydrates, fats, and proteins
– During chemical reactions, bonds break releasing
ENERGY (and the resulting atoms can also be rearranged)
– This ENERGY is now available
to do work.
Intro. To Energy
Your body uses ALL types of organic molecules to help
produce its energy.
So consume some proteins, fats and sugars
Putting Chemical Energy to Work
• In cells complex molecules (like carbohydrates
and proteins) are broken into smaller
molecules.
– Like an engine uses chemical reactions to power a
car. Cells break down food into energy.
How ATP Packs Energy
• The energy of food originally comes from the
sun.
• The chemical energy stored in organic food,
must first be converted to energy stored in
another molecule…..
ATP
Adenosine triphosphate
The principal chemical compound
that cells use to store energy.
The triphosphate
adenine
The
adenosine
3 phosphate groups make up the “tail” –
it is the source of energy used for most
cellular work
Ribose (5-C sugar)
As Bonds are broken between the phosphates, energy is released
ATP and Cellular Work
• The process of breaking bonds and
transferring energy is sped up by….
Enzymes !!!
Cellular Respiration
• All the cell’s chemical processes make up the
cell’s metabolism.
Cellular Respiration
• Is the process that releases energy by breaking
down organic (food) molecules in the presence
of oxygen
• The equation for cellular respiration
• C6H12O6 + 6 O2
6 CO2 + 6 H2O + Energy (ATP)
Cellular Respiration
• What does the equation tell us?
– C6H12O6
is a carbohydrate and enters into the reaction (the cell)
– O2 is oxygen and enters into the cell
– CO2 is carbon dioxide is produced and leaves the cell
– H2O is water and is produced
– ATP is energy and is produced to do work
• We will follow these through cellular respiration and see where they
enter and leave during the process.
Cellular Respiration Road map
eelectron
carriers
eElectron
carriers
Pyruvic
acid
Glucose
Glycolsis
Krebs
Cycle
Electron
Transport
Chain
Cytoplasm
Mitochondrion
ATP
ATP
ATP
Cellular respiration takes place in several steps so energy is released a little at a time,
otherwise it would be lost as heat and light
Cellular Respiration Road map
REMINDER:
• The energy made during Cellular Respiration is
carried in a molecule called ATP
• Adenosine Triphosphate
You will see the energy of
ATP shown as this star
burst.
ATP
Glycolysis
-Glycolysis is the first step in breaking down a glucose
molecule. (C6H12O6 )
-Takes place in the cytoplasm of the cell.
-Does NOT require oxygen
-Produces a small amount of ATP
-electron carriers are produced (which store energy for later)
-Glucose is broken downe-to Pyruvate
2 ATP are required to
start the process
4 total are produced.
Only 2 are gained
(4-2 = 2)
2 ATP gained
cytoplasm
The Krebs Cycle
• The Krebs Cycle finishes the breakdown of
Pyruvate
• Pyruvate, produced during Glycolysis enters
the Krebs Cycle
• This happens only in the presence of oxygen.
The Krebs Cycle
-Takes place in the Mitochondria (within the matrix)
-Pyruvate is broken down
-CO2 (carbon dioxide) is produced as a waste
-2 ATP are gained
-electron carriers are produced
The
Krebs
Cycle
2 ATP
2 ATP
The Krebs Cycle
• A Review
CO2 produced as
waste
Pyruvate
enters
Electron carriers
produced
e- (electrons) carry
energy (like ATP) We
will see how the
energy in the electrons
is utilized in the next
step
Krebs
Cycle
ATP
CO2
produced as
waste
Electron Transport Chain
• This is the final stage of cellular respiration
• Takes place in the inner membranes of the
mitochondria
Electron Transport Chain
• The chain uses electrons from glycolysis and
Krebs to make Lots of Energy !
-Oxygen is required for this
-Water is produced as waste
-Generates 34 ATP
ee-eeGlycolysis
2 ATP
Krebs
2 ATP
Electron
Transport
34 ATP
Electron Transport Chain
The “fall” of electrons creates Lots of energy
•
H+
Intermembrane
space
Inner
membrane
matrix
H+
H+
H+
H+
H+
ee-
H+
H+
H+
O2
H2O
Oxygen is
required to
“pull” the
electrons down
the chain
ATP
H+
Adding up the ATP Molecules
• From Glycolysis ----------- 2ATP
• From Krebs ----------------- 2 ATP
• From Electron Transport 34 ATP
Total
38 ATP
Harvesting energy without oxygen
• What happens when your body is forced to work without
oxygen?
– For example, what happens when you sprint to catch a bus?
– Your leg muscles are forced to work without enough oxygen because you
are spending ATP more quickly than your lungs and bloodstream can
deliver oxygen to your muscles for cellular respiration.
• Fortunately, some of your cells can produce ATP and
continue working for short periods without oxygen.
Fermentation
• Fermentation – makes ATP without using
oxygen.
• Fermentation makes ATP directly from
glycolysis.
• By burning enough glucose (2ATP),
fermentation can regenerate enough ATP
molecules for short bursts of activity.
– Like sprinting to catch a bus
Fermentation – Two types depending on the organism
Lactic Acid and Alcohol
Anaerobic respirationno oxygen
Alcohol or
Lactic Acid
Aerobic respiration – with oxygen
Pyruvate
Krebs
Cycle
Lactic Acid Fermentation in Humans
• Fermentation in muscle cells converts the
glucose to pyruvic acid, but then produces a
product called lactic acid.
• The lactic acid then diffuses into the blood.
– The lactic acid is the “burn” you feel in your
muscles.
Lactic Acid Fermentation in
Microorganisms
• Fungi and Bacteria in an anaerobic
environment (an environment without
oxygen)are forced to ferment sugar and other
foods.
– Gives sour taste to foods like yogurt and cheeses,
also creates sauerkraut and pickles
Alcohol Fermentation
• When Yeast (some bacteria) are kept in an anaerobic
environment they will produce ALCOHOL and release
carbon dioxide gas.
– Carbon dioxide makes bread rise.
Some products produced by fermentation