Cellular Respiration Flashcards
What do all living cells need to work
Energy from an outside source
Where does energy from organic molecules come from
The sun
How is energy from photosynthesis recycled
Photosynthesis = oxygen and organic materials -> used for cellular respiration -> breaks down fuel = generates ATP, carbon dioxide and water = used for photosynthesis
Why are catabolic pathways useful in cellular respiration
Transfer of electrons from fuel plays a major role.
Linked to work by drive of ATP.
Regenerates ATP from ADP + Pi
What is aerobic respiration
Form of cellular respiration.
Oxygen is consumed as reactant.
Carried out by most eukaryotes and prokaryotes.
Organic compounds + oxygen —> carbon dioxide + water + energy
Main sources of fuel
Carbohydrates, fats and protein
How can a substance be reduced but not actually lose an electron
Some reactions change the degree of electron sharing in covalent bonds eg methane combustion
Why is hydrogen a good fuel for oxidation
Bonds are an excellent source of hilltop electrons.
Energy released when electrons fall down the electron gradient during oxygen transfer.
Why is the activation energy barrier important in carbohydrates and fats
Without, glucose would combine almost instantly with oxygen
How is glucose stored as energy as NADH
Glucose + NAD+ —dehydrogenase—> C=O + NADH + H+
Electrons are oxidised from glucose and passed through the electron carrier.
Then dehydrogenased.
Coenzymes deliver electrons and protons to NAD+.
Releasing NADH + H+
Why is NADH a neutral molecule
2 negative electrons are added and 1 proton is added
State the stages of aerobic cellular respiration
Glycolysis
Pyruvate oxidation
Citric acid cycle
Oxidative phosphorylation
Where does glycolysis occur
In the cytosol
Where does the Krebs cycle and oxidative phosphorylation occur
In the mitochondrial membrane
Where are the proteins built into in eukaryotes and prokaryotes
Eukaryotes: the inner membrane of the mitochondria
Prokaryotes: the plasma membrane
Roughly, how does the electron transport chain work
Electrons removed from glucose move to the top high-energy tier via NADH.
At the bottom low-energy tier, oxygen captures electrons.
Electrons move from one carrier to the other in redox reactions.
Why isn’t oxygen and hydrogen explosive in cellular respiration
Hydrogen is derived from organic materials instead of H2.
Steps in ETC break the fall of electrons to oxygen, releasing energy in the steps.
What is the energy investment and payoff phase
Investment - spends ATP
Payoff - pays off ATP from substrate level phosphorylation and NAD+ is reduced to NADH by electrons from oxidation of glucose
Steps of glycolysis
Phosphorylation of glucose to glucose phosphate.
Splitting the glucose = triose-phosphate.
Oxidation of triode-phosphate.
Production of ATP.
Why do you phosphorylise glucose
To make glucose more reactive.
Provide energy to activate glucose.
Lower the activation energy.
How is triose-phosphate made
Phosphorylised glucose is split into 2 3-carbon molecules.
How is triose-phosphate oxidised
Hydrogen is removed from each TP molecule and transferred to a hydrogen-carrier molecule
NAD+ —> NADH
How is pyruvate made
From triose-phosphate
How does pyruvate enter the mitochondria from the cytosol and why
Via active transport when oxygen is present because pyruvate is a charged molecule, so needs a transport protein.
