L12. Breaking down & building cellular components Flashcards
1
Q
what is needed to maintain order in cells
A
- 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
2
Q
where does energy come from
A
- photosynthesis (plants, algae, and some bacteria)
- cellular respiration (most living organisms)
3
Q
explain photosynthesis
A
- input of energy from sunlight
- CO2 + H2O -> O2 + sugars
4
Q
explain cellular respiration
A
- sugars + O2 (both from photosynthetic organisms) -> H2O + CO2
- it harvests energy by oxidation of molecules (controlled burning)
5
Q
explain redox reactions
A
- reduction: gain of electrons
- oxidation: loss of electrons
6
Q
redox reactions - what happens to to chemical bonds
A
- reduction: increase in C-H bonds
- oxidation: decrease in C-H bonds
7
Q
what is catabolism
A
- breakdown of foodstuffs into smaller molecules
- generates a useful form of energy and building blocks
- reaction is favorable
8
Q
what is anabolism
A
- uses energy harnessed by catabolism to drive the synthesis of the many molecules that form the cell
- reaction is unfavorable
9
Q
what is free energy (G)
A
- 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
10
Q
explain ΔG
A
- it is equal to: (G in product) - (G in reactant)
- when favorable: ΔG = negative
- when unfavorable: ΔG = positive
10
Q
explain how reactions are coupled
A
using a favorable reaction that has a more negative ΔG than the unfavorable ΔG
10
Q
explain the standard free energy change (ΔG°)
A
- 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
11
Q
ΔG° - why is it better than ΔG
A
- 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
12
Q
how to measure enzymatic activity
A
- 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
13
Q
measuring enzyme activity - speed of motion
A
- 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)
