Download (pg 104-110) - Cellular Respiration

Respiration vs. Cellular
Respiration
Ch 5 – Cellular Respiration
pages 104-110
Breathing supplies oxygen to our cells and
removes carbon dioxide
Breathing provides for the exchange of O2 and CO2
Between an organism and its environment
Biology
Mrs. Stolipher
• Respiration refers to the process of breathing, while
Cellular Energy
cellular respiration refers to the production of ATP
•The O2 needed to burn food is outside the bodies of
organisms
- ATP is needed in cells in order to perform work
- mitochondria use O2 in the process of cellular
respiration
- the muscular, respiratory, & circulatory systems
combine forces to bring reactants (food & O2 to cells &
remove wastes (CO2 & H2O) from cells
STAGES OF CELLULAR RESPIRATION
Cellular respiration occurs in three main
stages
1.
2.
3.
Glycolysis
Krebs cycle
Electron Transport Chain
Cellular respiration is the process cells use to
harvest the energy in organic compounds,
particularly glucose. The breakdown of
glucose during cellular respiration can be
summarized by the following equation:
C6H12O6 + 6O2 → 6CO2 + 6H2O + energy
glucose oxygen
gas
carbon
dioxide
water
ATP
Glycolysis
Occurs in the cytoplasm
Breaks down glucose into pyruvate, producing a
small amount of ATP
2 ATPs used, 4 ATPs made, 2 ATPs NET
2
2
NAD+
NADH
+ 2
H+
Glucose
2 Pyruvate
2 ADP
+2
P
2
ATP
1
Breakdown of Pyruvate
Net Energy Production for Glycolysis:
2 ATP (immediately usable for cellular work)
Pyruvate
is chemically groomed for the Krebs
cycle
2 NADH
Prior to the Krebs cycle
2 pyruvic acids (for each glucose entering the
process)
Enzymes process pyruvate, releasing CO2 and
producing NADH
and acetyl
CoA
+
+ H+
NADH
NAD
2
CoA
Pyruvate
1
3
CO2
Acetyl CoA
(acetyl coenzyme A)
Coenzyme A
Krebs Cycle
• occurs in mitochondrial matrix (fluid contained w/in
inner membrane)
• pyruvic acid is oxidized, reducing NAD+ to NADH
• Net Energy Production
completes the breakdown of glucose,
generating many NADH and FADH2 molecules
2 NADH (for each glucose)
is a series of 8 steps (reactions) in which
enzymes strip away electrons and H+ from
each acetyl CoA to make CO2
Produces e- carriers (NADH & FADH2) that
temporarily store chemical energy
2 acetyl CoA
Acetyl CoA
CoA
CoA
• Coenzyme A is released at the first step; it goes back
to get more pyruvic acid
2
CO2
KREBS CYCLE
3
FADH2
3
FAD
NAD
NADH
+
3 H+
ATP
ADP +
P
+
• Occurs in the mitochondrial matrix (fluid portion of
mitochondria
• Reactants: acetyl CoA, ADP, phosphate, NAD+,
FAD (also an electron carrier)
• NET ENERGY PRODUCTION for each glucose
entering the process (Krebs Cycle must happen 2x
– 1 for each pyruvic acid)
2 ATP, 6 NADH, 2 FADH2
2
Most ATP production occurs during ETC
•
•
•
•
ETC is on the cristae (inner mitochondrial
membrane)
NADH (from conversion of pyruvic acid & Krebs) &
FADH2 (from Krebs) “drop off” their e- , which travel
down the ETC to oxygen
Energy released by the e- is used to pump H+ from
the matrix into the space between the
mitochondrial membranes
In chemiosmosis, the H+ ions diffuse back through
the inner membrane to the matrix through ATP
synthase complexes, which capture the energy to
make ATP
Electron Transport Chain of
Aerobic Respiration
• NET ENERGY PRODUCTION for ETC
NADH
High-energy electrons
carried by NADH
32-34 ATPs for each glucose entering the
whole cellular respiration process
THESE ATPs ARE ONLY PRODUCED IF O2 IS
AVAILABLE AS A FINAL ELECTRON
ACCEPTOR
NADH
FADH2
and
OXIDATIVE
PHOSPHORYLATION
(Electron Transport
and Chemiosmosis)
GLYCOLYSIS
Glucose
CITRIC ACID
CYCLE
Pyruvate
Mitochondrion
Cytoplasm
CO2
CO2
ATP
ATP
Substrate-level
phosphorylation
Substrate-level
phosphorylation
ATP
Oxidative
phosphorylation
Respiration in the Absence of
Oxygen
When oxygen is not present, NAD+ is
recycled in another way. Under anaerobic
conditions, electrons carried by NADH are
transferred to pyruvate produced during
glycolysis.
Lactic Acid Fermentation
This process recycles NAD+ needed to
continue making ATP through glycolysis.
Fermentation enables glycolysis to continue
producing ATP in muscles as long as the
glucose supply lasts.
In some organisms, a three-carbon pyruvate
is converted to a three-carbon lactate through
lactic acid fermentation.
The recycling of NAD+ using an organic
hydrogen acceptor is called fermentation.
3
Lactic Acid and Alcoholic Fermentation
When oxygen is not present, cells recycle
NAD+ through fermentation.
Alcoholic Fermentation
In some organisms, the three-carbon
pyruvate is broken down to ethanol (ethyl
alcohol), a two-carbon compound, through
alcoholic fermentation.
As in lactic acid fermentation, NAD+ is
recycled, and glycolysis can continue to
produce ATP.
Production of ATP
When oxygen is present, aerobic respiration
occurs to produce ATP. When oxygen is not
present, fermentation occurs instead.
The
fuel for respiration ultimately comes from
photosynthesis
All organisms
Can harvest energy from organic molecules
Plants, but not animals
Can also make these molecules from inorganic
sources by the process of photosynthesis
Cellular Respiration vs. Photosynthesis
Photosynthesis Cellular
Respiration
Function
Produces &
stores food
(energy)
Releases energy
Location
Chloroplast
Mitochondria
Reactants
Light,H2O, CO2
C6H12O6, O2
Products
C6H12O6, O2
ATP, CO2, H2O
4