Cellular respiration Flashcards
What is the first law of thermodynamics?
Energy cannot be created or destroyed, only converted into other forms.
What are the four major energy requirements of the cell?
- For mechanical work e.g. motor proteins (movement within a cell)
- To make new material e.g. for growth and replacement
- For transport e.g. transport of molecules across membranes (against conc gradient - active transport)
- To maintain order
What is the structure of the mitochondria?
Has a double membrane (inner and outer). The inner membrane folds to form cristae. It is 1-10 micrometres long and contains mitochondrial DNA and ribosomes.
What are two features of the mitochondria that are important to maximise the rate of respiration?
Cristae - Increases surface area in the mitochondria for reactions
Inter-membrane space - allows the mitochondria to build concentration gradients from electron transfer.
What is stage 1 of respiration? What happens?
Glycolysis.
In the cytosol, glucose is converted into 2 smaller pyruvate molecules. Generates 2ATP and 2 high energy electron carrying molecules to release later on, NAD+ to make NADH.
What is stage 2 of respiration? What happens?
Pyruvate oxidation and citric acid cycle.
In the mitochondrial matrix, 2 pyruvate molecules are converted to Acetyl CoA and sent into the citric acid cycle, goes round the citric acid cycle and produces ATP. NADH and FADH2 electron carriers made from the reaction of pyruvate to Acetyl CoA.
What is part 1, stage 3 of respiration? What happens?
Electron transport train.
Electron carriers shuttle high energy electrons to the inner membrane (moves through protein complexes, when proteins leave they are accepted by oxygen. If oxygen isn’t there, it cannot work. Electrons need something to leave in. The last place the electrons go to when they are finished).
Driving the movements of protons across the matrix to the inter-membrane space. When carriers come out they have less energy. Now have build up of H+ on the inter-membrane space.
Compartmentalisation is important so that the concentration gradient can be made up.
What is part 2, stage 3 of respiration? What happens?
ATP synthase in the inner membrane.
This complex spans the membrane space to the mitochondrial matrix.
The proton gradient across the inner membrane powers ATP synthase.
It converts ADP + Pi ——-> ATP.
Most of the ATP comes from this stage.
Why does the cell want ATP?
It enables the controlled release of energy.
