life at cellular level 3 Flashcards
state the 1st law of energy.
energy can be converted from one form to another as long as the total amount of energy in the universe stays the same.
state the 2nd law of energy
a change from one type of energy to another leads to an increase in disorder.
as useful energy is used up, useless energy increases( HEAT)
how do cells use energy?
cells use energy to maintain order( nutrients, from sun). they generate heat in the process.
define GIBBS free energy= useful energy
G=H -TS. H= enthalpy (heat released to surrounding) S= entropy T=absolute temperature defines the spontaneity of a reaction.
what does Gibbs free energy depend on?
whether energy is given up
whether there is an increase in disorder
when do reactions occur spontaneously?
when delta G<0
how do unfavourable biological reactions take place?
energy coupling: there is a flow of energy between a favourable biological reaction (e.g. catabolic reactions) and an unfavourable biological reaction (e.g. anabolic reactions) which allows delta G to be negative.
what is metabolism
a series of biological reactions which allow food to be used in the production of tissue and/or for energy production
catabolic reactions and what is meant by exergonic
the processes by which complex molecules are broken down into smaller molecules and energy is released (exergonic).
anabolic reaction and what is meant by endergonic
the processes by which smaller molecules and energy are used to form more complex ones.
features of a metabolic pathway
each step is catalysed by an enzyme
spontaneous: it moves towards equilibrium but doesn’t reach it
occurs in small steps to allow the production of more useful substances.
Flow of energy between anabolic and catabolic reactions through hydrolysis of ATP into ADP and phosphate and condensation of ADP and Pi
facilitated by intermediate METABOLITES
some reactions could not occur without enzymes because their activation energy would be too high.
how does flow of energy occur?
1-transfer of phosphoric groups
2-hydrogen atoms
3-electron transfer in REDOX reactions. (electron motive force)
example of glucose to pyruvate
1-glucose forms PEP due as it has a higher potential energy
2-PEP releases some energy to form pyruvate and some to reform a molecule of ATP.
Laevo and dextrose chiral centres
How they rotate the plane of polarised light.
