5- Energy Transfers Flashcards
What are the 4 stages of aerobic respiration and where do they occur
Glycolysis (cytoplasm)
Link reaction (mitochondrial matrix)
Krebs cycle (mitochondrial matrix)
Oxidative phosphorylation (inner membrane of mitochondria called cristae)
What’s glycolysis
First stage of aerobic and anaerobic respiration
Itself is an anaerobic process
What are the 3 steps of glycolysis
Phosphorylation glucose to glucose phosphate using 2 ATP molecules
Glucose phosphate is converted into 2 triose phosphate molecules
Both triose phosphate molecules are oxidised forming 2 pyruvate molecules, a co enzyme reduced NAD is formed, 4 ATP molecules are made so a net gain of 2 ATP molecules
How does reduced NAD and pyruvate move from cytoplasm (glycolysis) to mitochondrial matrix (link reaction)
Active transport
What happens in the link reaction
Pyruvate is oxidised forming acetate, co enzyme reduced NAD is formed, 1 molecule of carbon dioxide is released
Acetate combines with co enzyme A producing acetylcoenzyme A (acetyl co A)
This occurs twice due to formation of 2 pyruvate molecules from glycolysis
Formation of 2 acetylco A, 2 CO2 molecules, 2 reduced NAD
What happens in the Krebs cycle
Acetylco A reacts with a 4C molecule producing a 6C molecule releasing coenzyme A (reused in link reaction)
Through redox reactions 2 carbon dioxide molecules are lost, 3 reduced NAD 1 reduced FAD and an ATP molecule are produced (substrate level phosphorylation), 4C molecule produced
6 reduced NAD, 2 reduced FAD, 2 ATP and 4 CO2 molecules are produced as the cycle occurs twice from 2 acetylco A molecules from link reaction
What’s oxidative phosphorylation
In mitochondrial matrix, reduced NAD and reduced FAD release hydrogen splitting into protons and electrons
Electrons transported along electron transfer chain, released energy, used to actively transport protons from mitochondrial matrix to inter membrane space
Chemiosomotic theory
Electrochemical gradient is created, protons move by facilitated diffusion down its conc gradient through ATP synthase, it also phosphorylates ADP and a phosphate to ATP
Oxygen is the final electron acceptor picking up protons forming water
2H+ + 2ē +0.5O2 —> H2O
Most ATP produced in this stage
What happens in anaerobic respiration
Occurs in cytoplasm when there is an absence of oxygen
Pyruvate produced in glycolysis is reduced as it takes a hydrogen from reduced NAD producing ethanol and CO2 in plants and microbes, produces lactate in animals
NAD can be reused in glycolysis, ensures more ATP production
How can lipids be used as respiratory substrates
Lipids hydrolysed into to glycerol and fatty acids
glycerol phosphorylated into triose phosphate then entering glycolysis and krebs
Fatty acids broken into 2C fragments converted into acetyl co A, enters krebs
Lots of H atoms, produces double amount of ATP releasing double the energy in oxidative phosphorylation compared to carbs
How can proteins be used as respiratory substrates
Hydrolysed into amino acids, deaminated (amino group removed)
3C compounds converted to pyruvate
4/5C compounds converted into intermediates in krebs
How to set up a respirometer
1-The organism that is going to be investigated is placed in one tube and a nonliving material of the same mass is placed in another tube. Soda lime and cotton wall is placed in each tube to prevent soda lime coming into contact with the organism. Soda lime absorbs all the carbon dioxide produced.
2-Coloured fluid is pulled into the reservoir of each manometer, and is allowed to flow into the capillary tube,there must be no Air bubbles.
3-Two rubber bungs are now fitted with the tubes
4-The spring clips are opened (this allows the pressure throughout the apparatus to equilibriate with atmospheric pressure) allow to respiration to equal.
Conclusions from a respirometer experiment
1-As organisms respire they take oxygen from the air around them and give out carbon dioxide. The removal of oxygen from the tube reduces the volume and pressure, causing the manometer fluid to move towards the organism. Carbon dioxide given out is absorbed by the soda lime. The distance moved by the fluid is therefore affected by only the oxygen taken up I’m not by the carbon dioxide given out.
2-You won’t expect the manometer fluid in the tube with no organism to move but it may do so because of temperature changes, this allows you to control for this variable by subtracting the distance moved by the fluid in the controlled manometer to give you an adjusted distance moved.
3-This gives you a value for the volume of oxygen absorbed by the organism per minute.
What does soda lime/NaOH do
Absorb CO2
What’s the structure of a chloroplast
Outer membrane, inter membrane space, inner membrane -control what enters and leaves the organelle
Stroma- fluid filled centre, contains enzymes needed in the light independent reaction
Thylakoids/ granum (stacks of thylakoids)- folded membranes containing photosynthetic proteins (chlorophyll), electron carrier proteins embedded within membranes which are involved in light dependent reaction
Lamella- join thylakoids together
How many stages does photosynthesis have
2
Light dependent reaction
Light independent reaction
