Cellular Energetics Flashcards
L5-L7, And photosynthesis
1st Law of Thermodynamics
The total energy in the universe cannot be increased or reduced, energy can only be converted from one form to another
2nd law of thermodynamics
Every energy transfer increases the entropy/chaos in the universe by losing energy to the environment eg heat is lost from an engine
Cellular respiration
metabolic process with which an organism obtains energy by oxidising nutrients and releasing waste products
Metabolism
totality of an organisms chemical reactions
Anabolism
Use energy to build complex molecules
Catabolism
release energy through metabolic breakdown
Gibbs free energy
The portion of the systems energy that can perform work
Exergonic
A reaction which releases energy
Endergonic
A reaction which requires energy
Mitchells Chemiosmosis Theory
Chemical energy generated from electron transport across a transmembrane electrochemical gradient
^G = ^H-T^S
^: Delta
^G: Change in free energy
^H: Change in total energy
T: Temperature
^S: Entropy
For a reaction to happen spontaneously…
^G must be negative
Photosynthesis
A process in phototrophs in which inorganic atmospheric compounds (CO2 + H2O) are converted into high energy organic compounds (carbohydrates)
Describe chlorophyll pigments
- Have 4 pyrolle groups which alternate between single and double bonds
- Have a tetrapyrole ring
Purpose of single/double bonds in chlorophyll pigments
- Pi electrons can be shared across via the electron cloud.
- Single bonds: only absorb UV light
- Sharing e- allows visible and infrared light to be absorbed
Antenna pigments
Extend the range of light a plant is able to capture, especially green light which chlorophyll struggles to absorb
Photosynthetic reaction centres
Repeatedly pass on the light energy to other reaction centres until it is ready to use the light/it hold it long enough for biochemistry to take place
Z Scheme
Path of electron flow and reduction potentials of the components in photosynthesis
- Thylakoid membrane
P680 and P700 are
Poor reducing agents but are good reducing agents when excited
Parts of ATP synthase
In membrane:
Anchor
Stator
In mitochondrial matrix:
Rotor
Head (6 (3&3) subunits of alpha and beta subunits)
Describe ATP synthase
- Brings ADP and phosphate together
- Movement of protons through ATP synthase generates movement
- Rotation of rotor causes small conformational changes between the 3 pairs of alpha and beta subunits. Causing synthesis of ATP
- Pero rotation 3 ATP are synthesised
Cyclic electron transport
Light energy harvested at photosystem I is used for ATP synthesis but not NADPH synthesis. Yields ATP but not NADPH
How are dark reactions identified
Cuvette
Inject CO2
Pulse chase experimental approach
2D chromatography
Describe the structure of RuBisCO
- ribulose bisphosphate carboxylase
- makes up 50% of soluble plant proteins
- most abundant enzyme in nature
- 8 large subunits (encoded by nuclear genome)
- 8 small subunits (encoded by chloroplast genome)
- 3.6 bill years old
