Intro to Cell Energetics

AP Bio

First Law of Thermodynamics

law of conservation of E

• E cannot be created nor destroyed

• ttal amount of available E in the universe is constant

what are the three types of cellular work

• chemical work

• transport work

• echanical work

chemical work

type of cellular work involving the synthesis of polymers

transport work

type of cellylar work involving the mvt of molecules across the membranes via a protien pump

mechanical work

type of cellular work involving the contraction of muscle cells movement of chromosomes during cell divisions and the movement of cilia and flagella

what type of E do cells utilize

chemical E

where is E stored in the cell

chemical bonds

• when bonds are broken, E is released

• when bonds are created, E is stored

metabolic pathways

1. occur in a series of reactions

2. each reaction in the series is aided by enzymes

3. complex molecules are either gradually being broken down or created

metabolism

sum total of all metabolic pathways in an organism

second law of thermodynamics

entropy = measure of disorder

• process will be spontaneous when it results in an increase of total entropy in the universe

what is the importance of the laws of therm. in organisms

death occurs due to a lostt of E/ a loss of order

exergonic reactions

type of metabolic reaction

• increased entropy (increased disorder)

• bonds are broken

• results in a net release of chemical E

• products are at a lower E level than reactants

endergonic reactions

type of metabolic reaction

• decreased entropy (decreased disorder)

• bonds are created

• results in a net absorption of chemical E

  • E absorbed from the environment is stored in the bonds of molecules

catabolic pathway

type of metabolic pathway

• series of reactions that result in a net increase of entropy and a net release of chemical E

• complex molecules are graduallly broken down

anabolic pathway

type of metabolic pathway

• series of reactions that result in a net decrease of entropy and a net absorption of chemical E

• complex molecules sre gradually created

• example of cellular work

energy coupling

• E released by exergonic reactions are used to drove endergonic reactions

• E released by catabolic pathwats are used to drive anabolic pathways

• catabolic pathwats don’t directly drive cellular work

• cells utilize ATP as an intermediate in energy coupling

ATP

adenosine triphosphate

• modified RNA adenine nucleotide (has three phosphates instead of one)

• made by cellular respiration or fermentation

• E molecules of life because it contains high E bonds

  • phosphate phosphate bonds

  • contains high amt of stored E

• created via cellular respiration or fermentation

  • broken down by hydrolysis

• harder to make a phosphate bond than it is to break it

  • to make: metabolic pathway

  • break: hydrolysis

ATP hydrolysis

• atp is hydrolyzed —> ADP, a phosphate group, and E are released

• w the help of enzymes, the cell is able to couple the E of ATP hydrolysis to an endergonic rxn = energy coupling

E coupling via ATP

• E released by the breakdown of carbon-carbon bonds (monomers)(catabolic pathways) drive the synthesis of ATP (anabolic pathway)

• E released by the by thet hydrolysis of ATP (catabolic pathway) drives cellular (anabolic pathways)

phosphorylation

• ATP works by coupling the E of the ATP hydrolysis to the phosphorylation of another molecule

  • E released by the hydrolysis of ATP is used to transfer the new phosphate group to another molecule

  • recipient of the phosphate group is phosphorlyated

  • most biomolecules are activated by phosphorylation

  • phosphorlyated molecules are more reactive/active because the addition of the phosphate causes a change in shape

  • aided by enzymes

phosphorylation of protein pumps

• ATP is hydrolyzed and becomes ADP + P

• protein pump is phosphorlyated when P is added, causing it to change in shape which “pumps” material across the membrane

phosphorylation

• phosphorylation of all molecules ecvept ADP is coupled with the hydrolysis of ATP

• E required to phosphylate ADP is derived from cellular respiration