lec 5 Flashcards
what is an isozyme? how does this compare to an interspecific enzyme homolog?
isozymes are enzymes w similar functions but different structures, implying that they evolved independently
interspecific enzyme homologs are differ forms of enzymes coded by homologous gene loci –> adapted independently
what is the diff bw linear and branching metabolic pathways?
linear follow one given path, whereas branching pathways follow different routes depending on different stimuli
what is an allosteric modulator? when do they work more/less? what is an example of each?
modulators that incr enzyme action. they follow the principle of mass action (higher conc = more binding)
an example of each is the PFK enzyme, where citrate decreases enzyme activity and AMP increases enzyme activity
what is PFK aka phosphofructokinase (good question!)
when citrate combines according to mass action, it decr catalytic (breakdown) activity of PFK
alternatively, AMP incr catalytic activity of PFK when it combines to regulator site. why?
food for thought: the body always has citrate and AMP lying around. do they counteract each other?
PFK is a key regulator enzyme in glycolysis
citrate is a byproduct of gylcolysis - when citrate builds up, it indicates that lots of sugar is being catalyzed, so less is needed. to inhibit PFK, citrate binds to an allosteric site, pushing it to inactive configuration.
similarly, AMP accumulates when ATP is low, which signals a need for more energy. AMP binds to an allosteric site on PFK towards active configuration, causing more glycolysis.
in a sense, the presence of citrate and AMP counteract each other. however, they follow the principle of mass action, which dictates how PFK will act
what do protein kinases do ?
function in multi-enzyme sequences to bring about amplifying effects
a kinase moves phosphates
how does a cell bring about amplification of an effect? (key word to use: what does a kinase do?)
through protein kinases, whereby the phosphorylation of of one kinase begets the phosphorylation of multiple other kinases for the intended effect.
what is the difference between alpha and beta glucose rings?
alpha glucose ring chains have hydroxyl monomers aligned in the same orientation, whereas beta glucose ring chains have hydroxyl monomers in a flipped upside down formation. (if this isn’t adding up, there is a picture in lec notes)
if no animals have cellulase, how do cows break down cellulose?
they don’t, they have bacteria in da lumen that do it for them
what explains the distribution of LDH genes in killifish?
LDH-B allele freq vary across the north-south cline of the US atlantic coast, due to enzymes having diff affinities at diff temps
IMPORTANT TAKE HOME MESSAGE IS killifish allele distribution exhibits isozyme
