Transcript 3/14 Cellular Respiration

Cellular Respiration
Homework
Objectives
Know the chemical formula for three-stage
cellular respiration
Know the differences between cellular
respiration and photosynthesis:
What kinds of organisms perform them
Where in the cell they happen
Inputs
Outputs
Energy movement
ATP and glucose’s roles
Photosynthesis Review
Summarize the main points of chemical
batteries and photosynthesis in a
paragraph.
Aerobic Respiration
Recall that aerobic respiration uses
oxygen.
After glycolysis, some cells (humans
included) can put the pyruvate through
two aerobic respiration stages.
Aerobic respiration charges more ATP
than anaerobic respiration.
Cellular Respiration
Break down glucose, get energy… what’s
the rest?
C6H12O6 + _____ -> ____ + ____ + energy
Cellular Respiration
C6H12O6 + 6O2 -> 6CO2 + 6H2O + energy
What was the equation for photosynthesis
again…?
Cellular Respiration
Glucose is broken down in three stages, each
of which captures some of the stored energy
and uses it to make some ATP molecules.
Not all organisms do all 3 stages all the time.
These are the “normal” stages for heterotrophs
like us, we’ll talk last about other ways to do it.
http://www.qcc.cuny.edu/BiologicalSciences/F
aculty/DMeyer/respiration.html
Three stages:
Glycolysis
Krebs Cycle
Electron Transport Chain
Glycolysis
Where glycolysis happens:
What goes into glycolysis:
What comes out of glycolysis:
Krebs Cycle
Also called Citric Acid Cycle.
The Krebs Cycle happens in the
mitochondria.
If it only happens in mitochondria, which
organisms cannot do the Krebs Cycle?
QuickTime™ and a
decompressor
are needed to see this picture.
QuickTime™ and a
decompressor
are needed to see this picture.
Krebs Cycle
The Krebs Cycle happens in the
mitochondria.
Only eukaryotes can do it.
Krebs Cycle breaks pyruvic acids down into
CO2.
Remember, energy is released when bonds are
broken. This energy charges more ATP and
NADH batteries.
Krebs Cycle
Breaks down 2
pyruvates (3 carbons
each) into 6 CO2
Charges 6 total ATP.
(These ATP charges
are not all just from
ATP, but are the
equivalents of an ATP.
Each NADH, for
instance, holds two
times as much energy
as an ATP, so we’ll
count it as just “2 ATP”
to make things easier.)
Krebs Cycle
http://www.youtube.com/watch?v=lvoZ2
1P4JK8
http://www.johnkyrk.com/krebs.html
The charged ATP is used to power
cellular activities. It also charges other
chemical batteries, which carry that
energy to the next stage…
Electron Transport Chain
Electron Transport Chain (E.T.C.)
happens along membranes inside the
mitochondria.
QuickTime™ and a
decompressor
are needed to see this picture.
QuickTime™ and a
decompressor
are needed to see this picture.
Electron Transport Chain
http://www.johnkyrk.com/mitochondrion.ht
ml
http://highered.mcgrawhill.com/sites/0072437316/student_view0/c
hapter9/animations.html#
ETC takes the energy from chemical
batteries charged in the Krebs Cycle
and glycolysis, and charges 24 ATP with
it.
Electron Transport Chain
The electron transport chain
works by taking energetic
electrons from charged batteries
like NADH and FADH2, which
depowers them back to NAD+
and FAD.
These electrons are given to
proteins embedded in the
membranes inside the
mitrochondria. The proteins use
the energy they’ve received to
move protons across the
membrane, out of the matrix.
Electron Transport Chain
The protons are now highly
concentrated in the
intermembrane space and not
concentrated in the matrix, and
they want to reach equilibrium
again. Another protein in the
membrane called ATP
synthase lets them do that,
using their movement like a
water wheel uses water.
Electron Transport Chain
The protons moving down along the ATP
synthase to get back where they started
“turns the wheel,” which churns out ATPs.
At the end, oxygen gets rid of the low-energy
electrons that are left over, combining with
hydrogen ions to make water. Water =
electron transport chain waste product.
Cellular Respiration
http://www.qcc.cuny.edu/BiologicalSciences/
Faculty/DMeyer/respiration.html
Cellular respiration charges 36 ATP total
using the energy in one glucose.
_______ + ____ -> _____ + _____ + 36 ATP
Cellular Respiration Review
Summary sentence of aerobic cellular
respiration:
Stage 1:
Stage 2:
Stage 3:
Cellular Respiration Review
Cellular respiration is breaking down glucose to
get energy.
Glycolysis (in the cytoplasm)
Glucose (C6H12O6) broken down into two three-carbon
molecules, pyruvic acid. Charges some batteries: 6 ATP
and some medium-sized “bad” batteries that go to
Electron Transport Chain.
Krebs Cycle (in mitochondria)
The 2 pyruvic acids are broken down into 6 CO2.
Charges some batteries: 6 ATP and some medium-sized
“bad” batteries that go to Electron Transport Chain.
Electron Transport Chain (in mitochondria)
Medium-sized “bad” batteries are decharged, that energy
charges 26 ATP.
Other pathways
A final word:
Glucose is not the only way to get and
store energy. Other things we eat that
we might get energy from?
Other pathways
 Pyruvic acid can be converted back into glucose or
glycogen, but once you’re in the Krebs cycle, you
can’t go back.
 Lipids, glycogen, protein are other long-term energy
molecules besides glucose.
 Glycogen is a chemical battery, stores energy long-term in
the liver. Can be an alternative outcome instead of going
through glycolysis to get pyruvic acid.
 Lipids are good for storing energy, proteins not so much.
 Glucose energy can be stored as a lipid, instead of going
through the Krebs cycle and electron transport.
 Proteins aren’t good for storage, but they can be broken down
for energy if needed.