L12. Breaking down & building cellular components Flashcards
what is needed to maintain order in cells
- they need to break things down into building blocks
- those are then used in anabolic pathways to build things for the cell
- the energy is then dissipated as heat
where does energy come from
- photosynthesis (plants, algae, and some bacteria)
- cellular respiration (most living organisms)
explain photosynthesis
- input of energy from sunlight
- CO2 + H2O -> O2 + sugars
explain cellular respiration
- sugars + O2 (both from photosynthetic organisms) -> H2O + CO2
- it harvests energy by oxidation of molecules (controlled burning)
explain redox reactions
- reduction: gain of electrons
- oxidation: loss of electrons
redox reactions - what happens to to chemical bonds
- reduction: increase in C-H bonds
- oxidation: decrease in C-H bonds
what is catabolism
- breakdown of foodstuffs into smaller molecules
- generates a useful form of energy and building blocks
- reaction is favorable
what is anabolism
- uses energy harnessed by catabolism to drive the synthesis of the many molecules that form the cell
- reaction is unfavorable
what is free energy (G)
- it measures the energy of a molecule which could in principle be used to do useful work at constant temperature
- chemical reactions only proceed only in the direction that leads to a loss of free energy
explain ΔG
- it is equal to: (G in product) - (G in reactant)
- when favorable: ΔG = negative
- when unfavorable: ΔG = positive
explain how reactions are coupled
using a favorable reaction that has a more negative ΔG than the unfavorable ΔG
explain the standard free energy change (ΔG°)
- it is a measurable and standardized unit
- can be used for comparing different reactions
- can use to see if a reaction can be coupled
- all reactants are set to 1 mole/liter
- ΔG can be calculated from ΔG° of concentration of products and reactants are known
ΔG° - why is it better than ΔG
- ΔG depends on the concentration of the reactants at a given temperature (not useful for comparison)
- ΔG° is better bc it is independent of concentrations and instead depends on intrinsic factors
how to measure enzymatic activity
- use a device where an enzyme and substrate are injected into a mixing chamber
- after meeting at the mixing tube, they enter another tube that zooms past a detector
- this detector can then observe reactions when they are only a few milliseconds old
measuring enzyme activity - speed of motion
- 1st need to have a series of increasing substate concentration prepared with a fixed amount of enzyme added
- then determine the initial reaction rates (velocity)
measuring enzyme activity: speed of motion - why are initial velocities used
there is a saturation point where they enzyme cannot bind anymore
measuring enzyme activity: speed of motion - explain the graph
- square root graph
- Km = Michaelis constant
- Km = [substrate] at 1/2 V max
measuring enzyme activity: speed of motion graph - how to make it linear
- graphing reciprocals
- x-intercept = -1/Km
- y-intercept = 1/V max
explain activated carriers
- that are used to couple reactions
- catabolic reactions make energy carriers and they will be broken down to be used for an anabolic reaction
energy carriers - ATP
- used to couple unfavorable reactions bc breaking it down (hydrolysis) is favorable
- an unfavorable reaction uses ATP and it will be hydrolyzed
- this then creates a high energy intermediate that will facilitate the rest of the unfavorable reaction
explain condensation
- unfavorable
- expels water
explain hydolysis
- favorable
- consumes water
how are condensation and hydrolysis coupled
energy carriers are hydrolyzed to make energy for to use condensation for macromolecule synthesis
activated carriers of electrons
- FADH2
- NADPH: oxidizes, passes along electrons, and donates electrons to create bonds
- NADH: strips electrons
- NADPH+: electron carrier and is the oxidized form of NADPH
