Transcript owen cell Respiration

Cellular Respiration
7.1 Glycolysis and Fermentation
7.2 Aerobic Respiration
Cell Respiration
Living cells constantly use energy for
activities such as movement, protein
synthesis, active transport and cell
division.
Most of the energy to power these
processes comes from ATP.
A cell must constantly replace ATP
The cell does this by breaking down
organic food molecules. Releasing
energy that is used to join ADP and
phosphate to form ATP
The breakdown of food to release
energy occurs by 2 kinds of
processes:
1. respiration 2. fermentation
Cell Respiration
A fuel molecule such as glucose is
oxidized to form carbon dioxide and
water.
Energy is captured through the
formation of up to 36 to 38 ATPs per
glucose molecule
It is the process by which cells extract
fee energy from the energy stored in
chemical bonds of food molecules
(glucose)
This is done in a series of catabolic
pathways featuring redox reactions
and using oxygen as the final electron
acceptor
The energy released is used to
regenerate the cell’s supply of ATP
ATP donates the energy to various
energy requiring processes such as
metabolic reactions, active transport,
muscle contractions, etc…
3 Metabolic stages of Cell
Respiration
1.Glycolysis
2. Kreb Cycle
3. Oxidative phosphorylation
Mitochondria
Site of cell respiration
Most ATP production occurs here
Parts of the Mitochondria:
1. Cristae: folds of mitochondria is where
electron transport occurs
2. Matrix: open area of mitochondria,
where kreb cycle occurs
3 Cytosol: outside mitochondria , where
glycolysis occurs.
a. Matrix
b. Cristae
c. Inner membrane
d. Outer
membrane
ATP
Glycolysis
Occurs in cytosol outside
mitochondria
Converts the 6-carbon glucose into 2
3-carbon pyruvic acid molecules
4 ATP are make, but due to a
deficiency of 2 ATP, the step
generates a positive 2 ATP
If oxygen is present then the reaction
proceeds to kreb cycle
If oxygen is absent, it will proceed to
fermentation
Fermentation occurs in the cytosol,
has a net gain of 2 ATP per glucose
and is only 2.1% efficient
Between glycolysis and kreb cycle is
a transition reaction in which pyruvate
( pyruvic acid) is converted to acetyl
CoA and 2 CO2 are removed
Glycolysis
Lactic Acid
Fermentation
Alcoholic
Fermentation
Krebs Cycle
Electron Transport
Chain
Kreb Cycle
Is located within the mitochondria matrix
Also called Citric acid cycle, or TCA
Completes glucose oxidation by breaking
down a pyruvic acid derivative (acetyl CoA)
into carbon dioxide
Is a circular sect of reactions because the
reaction is ongoing, never reaching an
endpoint.
Requires 2 turns of the kreb cycle per
glucose ( each turn releasing 2
carbon dioxides, 3 NADH, 1 ATP, 1
FADH2
NADH and FADH2 are coenzymes
(NAH accepts 2 electrons and 1
hydrogen while FAD accepts 2
electrons and 2 hydrogen)
Oxidative phosphorylation
Accounts for most ATP produced during
respiration (32 to 34)
Includes electron transport chain made of
electron carriers molecules built into the
inner mitochondrial membrane
Oxygen pulls energized electrons
harvested during glycolysis and kreb cycle
down the electron transport chain to a
lower energy state.
This exergonic slide of electrons is
coupled to ATP synthesis
Electron transport accepts electrons
from glucose during glycolysis and
transition reaction and kreb cycle…
usually NAD+ carries these electrons
The electrons then drop off the supply
of energy needed to pump the
hydrogen ions from the matrix to the
intermembrane space of the
mitochondria ( this is chemiosmosis)
The NAD+ and Fad then return to
pick up more hydrogen ( both
reusable)
When NADH delivers electrons, it
has enough energy to make 3 ATP.
When FADH2 delivers electrons, it
has enough energy to make 2 ATP
Cytochrome: the molecule that helps
with electron transport
Chemiosmosis: ability of some
members to use hydrogen ion s
gradient to drive ATP formation
Oxidative phosphorylation: refers to
the production of ATP as a result of
energy released by electron transport
system
Electron Transport Chain of Aerobic Respiration
protons
protons
protons
NAD+
FADH2
O2
ADP
+
Phosphate
Electron Transport Chain of Aerobic Respiration
protons
protons
protons
NAD+
FADH2
O2
ADP
+
Phosphate
Energy Yield of Aerobic Respiration –
* One glucose can generate up to 38 ATP molecules.
* 38 x 12 kcal divided by 686 kcal = 66 % efficiency.
* About 20 times more efficient than glycolysis alone.
* Note: a car engine is only about 25 % efficient.
http://www.sirinet.net/~jgjohnso/cellularresp.html
Photosynthesis and Cellular Respiration
(opposite reactions)
* The final products of plant photosynthesis (sugar and
oxygen) are used by animals for the process called
cellular respiration. The products of respiration are
carbon dioxide and water, which plants need for
photosynthesis.
* Since photosynthesis and respiration are opposite
processes, they form a cycle that keeps the levels of
oxygen and carbon dioxide fairly constant in the
atmosphere.
Glycolysis
Lactic Acid
Fermentation
Alcoholic
Fermentation
Krebs Cycle
Electron Transport
Chain