mod 6 chap 6 Flashcards
Metabolism
carbon is backbone of organic molecules that make up cells adn cells often use carbon based copmoudsn to store energy
how organsims obtain enegry and carbon is fundemental that it prvoides metabolic classification of life
organisms have two ways of harvesting eenrgy from their envinrment and two sources of carbon - 4 princple wasy organsism acquire enegry and materials
phototrophs
organisms that capture enegry from sunlight
plants are common example
sugars like glucose conain eengry in chem bonds that can be used to syntheize ATP which in turn can pwoer work of cell
chemotrophs
other organisms derive their energy directly from chem compounds
animals are example
they ingest other organisms obtaining glucose that they break down - chem bonds contain energy that is converetd to enegry carried in bonds of atp
autotrophs
organsim can be classfied based on carbon source
some organisms can convert co2 into glucose an organic form of carbon
self feeders
plants
heterotrophs
other organisms obtain carbon from organic molecules syntehsized by other ogranisms
tehse organisms eat other organisms or molecules derived from other organisms
other feeders
animals
metabolism
encopases teh set of chemical rxns that convert molecules into other molecules and transfer energy in living organisms
catabolism is teh set of chem rxns that break down moelcules into smaller units and in the process produce atp
analbolism is ste of chem rxn sthat build molecules from smaller units and require an input of energy in form of ATP
ex. breaking down carbs and amcronmoeces is catabolic while building them in anabolic
Energy
energy is important in biological systems becasue its needed to do work
kinetic enegry is energy of motion - its ascoiated with any kind of moveemnt
potential enegry is stored energy - dpeends on strcuture of object or its position to a field andd its reelased by. a change in the objects structure or position ex. electrochemical gradient is potentail energy
enegry can be coneverted form one form to anotehr
chemical energy
form of potential eengry held in chem bonds between pairs of atoms in a moelcule
covalent bonds form whne sharing of e- between two atoms reuslts in a more stable config - the more stable the more lower potential energy - energy is reuried to break a covalent bond because its going from a lower enegry state to a higher one which requires input of energy
energy is relased when covlanet bonds form
strong bonds are hard to break beacsue teh arrangemnt of orbitals in tehse moelcules is much more stable than if the two atoms didnt share e- - this stable arrangemnt means not a lot of enegry is required to keep it toegther so they dont contain much chem eenrgy
some covalent bonds are weak - easly broken because its not that stable - lots of enegry needed to keep these bonds so they contain lot of chem energy
organic molecules are a source of chem emerngy and called fuel moelcules becasu etehy contain weak covalent bonds
ATP
chem energy in macrmolecules is harnessed by cells to do work
cells dont use this enegry all at once
though series of chem rxns collectly called celuular resipration, they package tjis enegry into a chem form thats accesible to cell - ATP is a form
chem enegry in ATP is used to drive many cellular processes
ATP serves as gobetween acting as intermediary between fuel moelcules that store a large amount of potential eenrgy in their bonds and the activties of teh cell that require an input of energy
atp made of adenosine - base adenine and ribose sugar - ribose atatched to triphosphate
the use of atp as enegry source in nearly all cells reflects it use early in evolution of life on earth
accesible chem enegry of ATP held in bodsn conencting phosphate groups
at cell pH these phospahtes are neg charged and repel eachotehr so the bonds conencting them contain a lot of energy - this enegry is released when new more stable bonds are formed that contain less chem energy
the enegry released in turn is used to power work of cell
first law of thermodynamics
the law of conservation of energy which states that the universe conatins a cosntant amount of enegry
enegry is neitehr created or destroyed
energy justc ahnesg from one form to anotehr
second law of thermodynamics
when we change energy forms tje total amount of energy remains constant
but change energy forms, the enegry available to do work decreases
energy transformations arent 100% efficient beacsue amount of enegry available to do work decreases every time enegry changes forms
energy not availble to do work takes on form of increase in disorder
second law states that trasnformtaion of energy is assocaited with an increase in disorder of universe
like when kinetic energy changd to potential amount of disorder increasses - degree of disorder is called entropy
entropy can also be considered the number of possible psouton and motions (microstates) a molecule can have - as entropy inc the number of poositons and motions availble also inc
in chem rxns entropy inc usually happens through tehrmal energy release which we experience as heat
thermal enegry is form of kinetic eenrgy correpsonding to motion of molecules and results in a given temp - higher temp, more rapid moevment and more disorder
catabolic rxns result in increase of entropy as single ordered moelcule is broken down into several smaller ones with more freedom to move around
anabolic rxns decrease entropy becasue they use invidual building blocks to syntehsize an ordered molecule
this doesnt viilate 2nd law becasue it applies to universe as whole - a local dec in enttropy results in higher inc in entropy of surroundings
all cells and organisms requrie constant input of enegry to maintain their high degree of organization and function - this input comes form sun or enegry stored in chem compounds
this energy allows moelcules to be built and otehr work to be carried out and leads to entropy
chem rxns
chem rxns are central to life rpocesses
a chem rxn is process by which molecules called reactants are transofmed into otehr moelcules called prodcts - atoms change shared bonds
many chem rxns are readily reversible: prodcts can react to form reactants
reversability indicated by double arrow
chemcial equillibrium
the rate of forward reaction equals rate of revrse reaction and teh conc of reactants and products dont change
diretcion of rxn can be ifnelucned by cocn of reactants and products
ex. inc teh cocn of reactants then this favours forward rxn to produce more products
this explain how many rxn in metabolic pathways proceed: products of many reactions are quickly consmyed by next rxn to drive the first rxn forward
laws of thermodynamics detrmine whetehr chm rxn requries or releses enegry
amount of enegry aviable to do work is gibbs free energy
we can compare fre enegry of reactants and products to detrmine whetehr the rxn releasds enegry thats available to do work
if products have more free energy then gibbs is pos and net input of enegry is needed to drive rxn forwrad - endergonic - not spontanous
if products have less free energy than reactants then gibbs is neg and enegry is released and available to do work - exergonic - spontanoues
total amount of enegry is equal to energy available to do work and enegry not availble to do work
- this equation is total amount of energy which is enthalpy H is equal to gibbs free enegry + enegry lost to entropy (s) mutkplied with absolute temp because temp infleuces the moveemnt of molecules and tehrefore degree of disorder
G= H -TS
equation is useful to see if chem rxn takes place spontanously and whetehr net enegry is required or released
hydrolysis of atp is exergonic
atp reacts ith water to form ADP and inogrnaic phosphate
this si hydrolysis rxn - the water moelcule is split - rxn breaks down polymers into subunit
rxn of ATP with water is exergonic beacsue less free energy in products than in reactants
phosphate groups of ATP are neg charged and repel each other - ADP is more stable beacuse one less phosphate meaning less chem energy in the bond so value of enthalpy is neg - entropy increases so pos value - therefore gibss is neg and reaction is spontanous and releases energy to do work
free energy of ATP hydrolysis is ifneluced by many factors including cocn of reactants and rpoducts, pH of solution, temp and pressure
release of free enegry during atp hydrolysis comes form breaking weaker bonds (more chem enegry) in reactants and forming mroe stable bonds (with less chem enegry ) in the products - the release fo free enegry then drives chem rxns and other processes that require net input of energy
