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Cellular Respiration Review
Transcript of Cellular Respiration Review
Happens in the cytoplasm
Uses glucose from outside the cell
2 molecules of 3-carbon
For this to happen, 2 ATP
An input of 2 ATP are required,
but the process will give the cell 4 ATP!
- 2 ATP + 4 ATP = net gain of 2 ATP
Cellular Respiration Review
Means "Breaking glucose"
Pyruvic Acid then heads
to the mitochondria
We also need an input of 2 NAD+
During glycolysis both molecules of NAD+ will be
filled with electrons and become NADH
These NADH molecules will head to the Electron
Transport Chain in the mitochondria
Matrix: inside the inner
Intermembrane space: between
the inner and outer membrane
Krebs cycle: in the matrix
Electron Transport Chain: on the inner
Requires 2 pyruvic acids from glycolysis
3-carbon pyruvic acid loses one carbon
to become a 2-carbon molecule
This 2-carbon molecule bonds to
a 4-carbon compound already in the cycle, becoming a 6-carbon compound.
One carbon at a time is removed until we're back to a 4-carbon compound, ready to begin the cycle again!
Each carbon that comes off is given off as carbon dioxide. The Krebs cycle is why we breathe out CO2!!
We also get a little ATP from Krebs, and a LOT of electron carriers:
NADH, just like in glycolysis
FADH2 as well - it works just like NADH!
Note: the diagram shows what happens to ONE pyruvic acid, but remember that each glucose makes TWO pyruvic acids - so this cycle happens twice for each molecule of glucose.
NADH and FADH2 arrive to drop off their electrons.
Once their electrons are dropped off, they become NAD+ and FAD again, ready to be reused in glycolysis and Krebs.
If the ETC shuts down, there won't be any NAD+ and FAD being recycled, so glycolysis and Krebs will shut down as well!
High energy electrons move through the ETC, giving off their energy to power the active transport of hydrogens across the inner membrane
When the electrons get to the end of the ETC, they are picked up by oxygen. Hydrogens bond to this molecule to create water, which is a by-product of respiration.
Hydrogens are pumped across the inner membrane by active transport. This raises the concentration of hydrogen in the intermembrane space.
Because of the high concentration of hydrogen outside the inner membrane, we have a concentration gradient.
Hydrogens diffuse (hi -> lo) across the inner membrane through the only available opening, the protein ATP synthase. (Facilitated diffusion!)
ATP synthase is powered by the diffusion of hydrogen. The protein spins and adds a P to ADP, creating ATP! This is where most of the ATP gets made during respiration.
Note: if there is no oxygen to pick up electrons, the whole process gets backed up and respiration shuts down. When your cells aren't getting enough oxygen, they switch to lactic acid fermentation to get ATP, which is less efficient and causes a burning ("The Burn") in your muscles.
Big idea: Respiration breaks down sugar (glucose) to make energy (ATP) for the cell to use.
Formula: Glucose + Oxygen ATP + CO2 + H2O
Most ATP gets made in the Electron Transport Chain
We need a constant flow of new electrons dropped off at the ETC to make all the ATP.
The Krebs cycle and glycolysis grab electrons, put them on electron carriers, and send them to the ETC.
Let's see how it works!
3 main steps:
Overview Image: Glycolysis
Note: The cell uses 2 ATP and gains 4 ATP. This image just shows the net, or overall, change in ATP.
is broken into:
High concentration of hydrogens in the intermembrane space
Low concentration of hydrogens in the matrix
More on the hydrogen concentration gradient in the ETC:
Note: not shown in the formula are the molecules that get recycled:
ATP ADP + P
NADH NAD+ + H
FADH2 FAD + 2H