W4L1 - Energy: Respiration and Photosynthesis Flashcards
(18 cards)
What do living things burn to get energy?
- Either glucose (preferred), fat, or protein
- 1 molecule of glucose has 2870kJ
- Cold burn (Not released as heat or expansion)
Biochemically, how is energy ‘burned’?
Oxidised State:
- NAD
- No electron
Reduced State:
- NADH
- Picks up 2 electrons in an aqueous environment; Once it gives it away goes back to NAD
Energy is the process of converting NAD to NADH back to NAD.
How do ALL cells set up proton gradients and get energy? (3)
- Use either light or chemical energy to set up proton gradients
- Compartment 1 and 2 have different numbers of protons
- In an unstable environment, gateway allows proton to diffuse back, converting differential to stored energy into ATP
- Similar to hydroelectric power generation
What is ATP and why do cells need it?
- Cells cannot store electricity well
- Put the energy from gradient back into a covalent bond that is easier to shunt
around and break again to release the energy to do work- Covalent bond = ATP > Holds energy
ADP & ATP: What to do we need to know
ADP (Low Energy) > Exergonic Reaction (Release Energy) > ATP (Higher Energy) > Endergonic Reaction (Take Energy) > ADP (Low Energy)
How many ATP do we make a day?
65kg of ATP a day (88 million molecules)
How is ATP made from food? (4)
Respiration
- Glucose is ‘burned’ to release energy from bonds between carbon
- Electrons are transferred to NAD
- Electrons are then used to pump protons to set up a potential difference
- Potential difference is then harvested to attach phosphate to ADP to make ATP
Respiration: Step One (3).
Glycolysis
- 1 Glucose generates 2 ATPs
- Breaks bond
- 2 molecules of NAD to NADH
- Carbon snipped into 2 pyruvates
- This process generates 2 ATPs and pyruvates become waste
- Does not use oxygen
- Occurs in all cells
2 Problems of Glycolysis
- Pyruvates become toxic if too much
- Run out of NAD (Used up NAD to NADH)
Given the problems of glycolosis, what do cells do to solve them? (4)
Fermentation
- Need to recycle NADH to NAD+ so it can be used for further glycolysis
- Dump electrons back to where they came from
- Pyruvate is reduced to either lactic acid (strategy 1) or ethanol (strategy 2), both of which are toxic waste products and must be removed
- Anaerobic (no O2) respiration
- Not very efficient
- Toxic waste
Aerobic Respiration
Cellular Respiration
- Occurs in mitochondria
- Requires O2
- Pyruvate > Pyruvate Oxidation > Citric Acid Cycle/Kreb’s Cycle > Electron Transport Chain
- Kreb’s Cycle:
- Converts Pyrovate to CO2
- Makes a lot of NADH
- Kreb’s Cycle:
What is the mitochondria? (3)
- Afterburner
- Cells with high metabolic needs have large numbers of mitochondria
- Major generators of ATP for the cell
- 2 Compartments
- Matrix
- Intermembrane Space
- ATP generated from proton gradient from the 2 compartments
- 2 Compartments
What is Kreb’s Cycle (2)
Kreb’s Cycle:
- Converts Pyrovate to CO2
- Makes a lot of NADH
In aerobic respiration, what is the electron transport chain? (3)
- Electron transport chain oxidizes the NADH back to NAD and gives the electrons to O2
- Electron jumps from complex 1, 2, 3, 4 (proteins in mitochondria membrane), which drops electron onto O2 .
- Jumps quickly because electrons have lots of energy with covalent spins
- Now O2 is negative, it picks up H+ from aqueous environment (H2O - Non-Toxic)
In addition to passing alone the electron, what does the electron transport chain do? (2)
Chemiosmosis
- Electron transport chain uses energy from the electrons it holds to pump H+ against their gradient (into the intermembrane space).
- Complex 5 (ATP synthase) harnesses the energy as H+ flow back in, converting ADP to ATP
What is the design of ATPase (3)
- One of the two Rotational shaft design in biology (First is flagellum)
- Many in mitochondria inner membrane
- Turbine is driven by protons
TLDR Aerobic Respiration (4)
- Aerobic respiration is the alternative to fermentation.
- Requires O2
- Pyruvate from glycolysis is sent into the mitochondrion and completely oxidised to CO2 and H2O therein
- Get 32 ATPs from 1 glucose [16 fold increase over anaerobic respiration (glycolysis) but must have O2]
Can aerobic respiration occur in prokaryotes?
- In some prokrayotes (especially gram-negative 2 walls)
- Electron transport chain and ATPase are in the plasma membrane
- Protons are pumped into the space between the two membranes (two compartments like a battery)
