Transcript Cellular Respiration - Liberty Union High School District

Part 2: Cellular Respiration:
Section 4.4 & 4.5
What’s the
point?
The point
is to make
ATP!
ATP
2006-2007
The energy needs of life
What do we need energy for?
 synthesis
 building biomolecules
 reproduction
 movement
 active transport
 temperature regulation
What do we need to make energy?
 The “Furnace”
Make ATP!
Make ATP!
All I do all day…
And no one
even notices!
 mitochondria
 Fuel
 food
 carbohydrates,
fats, proteins
food
 The Helpers
 oxygen
 enzymes
O2
ATP
Mitochondria
MITOCHONDRION
Intermembrane
space
Outer
membrane
Inner
membrane
Cristae
Matrix
Overview of cellular respiration
High-energy
electrons carried by
NADH
GLYCOLYSIS
Glucose
Cytoplasmic
fluid
Pyruvic
acid
Krebs
Cycle
ELECTRON
TRANSPORT
CHAIN
Mitochondrion
Cellular Respiration Equation:
Glucose
Oxygen
gas
Carbon
dioxide
 Does this look familiar?
Water
Energy
 Cellular Respiration:
 Series of reactions in which cells
break down stored energy in food
to make chemical energy (ATP) for
performing all life functions.
 Happens in the
mitochondria
of both plant
and animal cells.
It starts with Glycolysis
 Breaking down glucose
 “glyco – lysis” (means splitting sugar)
glucose      pyruvate
2x 3C
6C
 ancient pathway which harvests energy
 inefficient
 generates only 2 ATP for every 1 glucose
 occurs in cytoplasm of the cell
In the
cytoplasm?
Why does
that make
evolutionary
sense?
After Glycolysis?
The fate of Pyruvate
NO O2
O2 present
Anaerobic
Fermentation
happens (occurs in
cytoplasm)
Aerobic Respiration
happens (occurs in a
mitochondria)
Yeast
Alcohol
Bacteria, Animal muscles
Lactic Acid
Krebs
Cycle
ETC
If O2 is present, Aerobic
Respiration occurs
 If
is present in the cells, aerobic
respiration will happen
 Aerobic Respiration: series of reactions
that happen in the presence of oxygen, in a
mitochondria, and produce LOTS of ATP
 Happens in 2 parts:
 Krebs cycle (aka: Citric Acid Cycle)
 Electron Transport Chain (ETC)
Krebs cycle
 aka: Citric Acid Cycle
 Occurs in mitochondrial matrix
 8 step pathway
 each step catalyzed by specific enzyme
 Evolved later than glycolysis
Hans Krebs
1900-1981
 does that make evolutionary sense?
 bacteria 3.5 billion years ago (glycolysis)
 free O2 2.7 billion years ago (photosynthesis)
 eukaryotes 1.5 billion years ago (aerobic
respiration = organelles  mitochondria)
Electron Carriers = Hydrogen Carriers
 Krebs cycle
produces large
quantities of
electron carriers
•
NADH
• FADH2
 These go to
Electron
Transport Chain
What’s so
important about
electron carriers?
H+
H+
H+
H+
+
H+ H H+
H+
ADP
+ Pi
ATP
H+
Overview of Respiration
Anaerobic Respiration
Chapter 4.6
What if oxygen is missing?
 Can’t complete aerobic respiration
O2
 Anaerobic respiration / Fermentation:
 Happens in the cytoplasm of the cell
 The pyruvate from glycolysis is broken down to
either lactic acid (animals or bacteria) or
alcohol and CO2 (yeast)
 This is done when organisms are low in oxygen
 Ex. Hibernating animals, people doing strenuous
exercise, bacteria or yeast living in low oxygen
environments.
2 Types of Fermentation
 alcohol fermentation
 Done by yeast
 glucose  ATP + CO2+ alcohol
 make beer, wine, bread
 lactic acid fermentation
 Done by bacteria, animals
 glucose  ATP + lactic acid
 make yogurt
 Waste product in muscles during
anaerobic exercise
But both only make a little bit of ATP!
O2
Alcohol Fermentation
pyruvate  ethanol + CO2
3C
NADH
2C
NAD+
 Dead end process
 at ~12% ethanol,
kills yeast
 can’t reverse the
reaction
Count the
carbons!
1C
bacteria yeast
Lactic Acid Fermentation
animals
pyruvate  lactic acid

3C
NADH
3C
NAD+
 Reversible process
 once O2 is available,
lactic acid is
converted back to
pyruvate by the liver
Count the
carbons!
O2
Pyruvate is a branching point
Pyruvate
O2
O2
fermentation
anaerobic
respiration
mitochondria
Krebs cycle
aerobic respiration
Products of
Fermentation
 Lactic Acid fermentation:
 cheese, yogurt (bacteria),
 Lactic Acid builds up in human
muscles during strenuous extercise
 Alcoholic fermentation:
 beer, wine, & bread.
Check this out!
 Cellular Respiration Video
 http://www.youtube.com/watch?v=j7gPtA
Sv0SQ