Cellular Respiration
• What is it?
extracting the energy from
glucose and using it to charge
ADP to make ATP
• Who performs cell respiration?
One way or another, EVERY
LIVING THING
What’s the BIG PICTURE
• Well…that depends on the conditions.
– If there is no oxygen (or no mitochondria), only
steps in the cytoplasm happen
– With O2 more
energy can be
“extracted”
from glucose
to put into
ATP molecules
Cellular Respiration
–What are the steps?
–Anaerobic cell respiration
• Glycolysis + Fermentation
–Aerobic cell respiration
• Glycolysis + Krebs Cycle + ETC
• Purpose is the same, just different
methods.
Cell Respiration - Two types
- Anaerobic respiration: O2 not
needed;
- done by yeast, certain bacteria,
exhausted muscle cells of animals
- produces 2 ATP per glucose
- Two steps:
- glycolysis
- fermentation: alcohol or lactic acid
Step 1
• Glycolysis – “glucose splitting”
–Glucose split into 2 pyruvate
–2 ATP used
–4 ATP and 2 NADH made
–Happens in cytoplasm
–First step of BOTH ANAEROBIC
AND AEROBIC RESPIRATION
Steps
• Fermentation –
- conversion of pyruvate to
Alcohol and CO2 (yeast) or Lactic
acid (exhausted muscle cells)
- no more ATP generated
- Purpose: “empties” electron
carriers so glycolysis can happen
again
Cell Respiration - SECOND type
- Aerobic respiration: O2 needed
- Requires mitochondria
- Produces 36 ATP per glucose
- Three steps:
- Glycolysis (followed by shuttle step)
- Krebs
- Electron transport Chain
Equation for Aerobic C. R.
C6H12O6
+ 6O2 --- 6CO2+ 6H2O
ADP + P
ATP
- getting the energy back out of
storage
The equation that we use for cellular respiration is really
AEROBIC cell respiration
Mitochondria
• Krebs cycle takes place
in the matrix
– Purpose: to break
apart C-C and C-H
bonds
– Energy transferred to
electron carriers and a
few ATP
Step 1 – Preparation for Krebs
Cycle
Step 1
• Glycolysis: EXACTLY the same
as the beginning of anaerobic
respiration
–BUT next step is different…
Step 1.5
• Shuttle step– converts pyruvate
to Acetyl-coA and moves it into the
mitochondria
–Releases some CO2, fills up some
electron carriers
Step 2
Krebs cycle – fills up electron
carriers
– Acetyl CoA broken down to CO2
–2 ATP, 2 FADH, 6 NADH made
PER GLUCOSE
–Happens in mitochondria
Step 3
• Electron Transport chain –
–All the filled electron carriers
(NADH, FADH2) dump their
electrons here
–Energy in electrons is transferred to
to make 32 ATP
–“dead” Electrons “caught” by O2 to
make H2O
Steps
• Final Tally: See summary sheet!
Respiration
• What do we notice about
respiration in comparison to
Photosynthesis?
THE BIG PICTURE
• Is energy recycled?
• What about the reactants and
products??