BIOC13H3 Lecture Notes - Lecture 8: Blood Sugar, Glycogen, Fatty Acid Metabolism
29 Apr 2018
School
Department
Course
Professor
BIOC13:(Lecture(9( ( Midterm(2(
Feb(8,(2018(
25#
Glycogen!
Glucose(Homeostasis(
• Vertebrates#store#glucose#in#the#blood,#giving#readily#accessible#source#of#
energy#for#places#like#the#brain#
• Size#of#organism#differ#in#the#amounts#of#
glucose#they#store#
• Generally,#bigger#animals#store#less#glucose#
• Weight(specific(metabolic(weight#finds#that#
bigger#animals#generally#have#lower#metabolic#
rate#à #don’t#need#as#much#readily#available#
glucose#
• Birds#have#high#levels#of#glucose#when#
compared#to#most#mammals#of#their#size#
o Don’t#want#to#be#heavy#since#they#fly#
o Glycogen#is#heavier#that#glucose#as#it#
attracts#more#water#molecules,#making#
it#70%#water#weight#
o Storing#as#free#glucose#in#the#blood#means#they#don’t#have#to#be#so#
heavy#and#they#don’t#have#to#drink#lots#of#water#
Why(Store(Carbohydrates?(
• When#you#eat,#blood#glucose#levels#(BGL)#rise#
• This#triggers#insulin#secretion#to#take#up#glucose#and#store#it#as#glycogen#
o Take#up#glucose#from#blood#via#GluT#and#then#phosphorylate#it#to#trap#it#
in#the#tissue#
• G6P#has#many#fates#in#the#cell#
o In#pentose(phosphate(pathway#
it#can#be#used#to#become#other#
carbohydrates#like#the#riboses#in#
DNA#
o Can#be#converted#to#G1P#and#
then#used#to#make#glycogen#in#
the#liver#and#muscles#
o Go#through#regular#glycolysis#for#
ATP#generation#or#fat#synthesis#
(for#storage)#
• Glucose#can#be#converted#into#Acetyl-
CoA#and#used#to#make#fatty#acids#(an#irreversible#step)#
• Lots#of#tissues#rely#on#glucose#so#we#don’t#want#all#glucose#to#be#turned#into#fat#
• Gluconeogenesis#allows#for#the#creation#of#glucose#from#non-carbohydrate#
sources#(ie.#proteins)#
• Need#power#for#intense#activities#like#running#a#sprint#and#fats#don’t#meet#
demands#for#that#
BIOC13:(Lecture(9( ( Midterm(2(
Feb(8,(2018(
26#
o Glucose#is#water#soluble#and#can#therefore#be#delivers#to#areas#quicker#
o When#glucose#is#depleted,#have#that#phenomenom#of#“hitting#the#wall”#
where#you#can’t#do#intense#work#anymore#since#only#running#on#fat#
Storage(As(Free(Glucose(Isn’t(Good(
Osmotic(Influence(Glycogen(vs(Glucose(
• Keeping#concentration#of#glucose#low#in#the#blood#means#that#it#won’t#really#
effect#osmosis#
• Osmotic#pressure#is#colligative#caring#only#about#the#moles#of#a#substance#it#
has#NOT#the#weight#of#the#substance#
o Storing#1000#mols#of#glucose#would#have#greater#osmotic#influence#than#
1#mol#of#glycogen#(even#if#1#mol#of#glycogen#weighs#the#same#as#1000#
mols#of#glucose)#
• Allows#you#to#store#greater#amounts#of#glucose#without#having#to#worry#about#
how#it’s#going#to#effect#tonicity#of#the#cell#environment#
Reactivity(of(Glucose(
• Glucose#is#also#very#reactive#with#lots#of#proteins,#creating#AGE#which#can#
damage#the#body#à #don’t#want#this#
o Want#to#avoid#this#by#keeping#
free#glucose#low#but#still#have#
energy#storage#for#doing#
work#(GLYCOGEN!)#
• Glucose#would#also#turn#on#a#
pathway#to#recruit#white#blood#cells,#
causing#damage#Ă #this#is#what#
happens#in#diabetes#
• Glycolyted#hemoglobin#has#
increased#affinity#for#oxygen,#meaning#that#it#wouldn’t#unload#oxygen#and#give#
it#to#cells#à #cells#are#hypoxic#and#can’t#go#through#oxidative#phosphorylation#
to#get#energy#
o Make#cell#more#susceptible#to#death#
o Also#occurs#in#diabetes#
• Birds#avoid#the#issue#of#glycolyted#hemoglobin#by#having#hemoglobin#less#
susceptible#to#this#
o Their#red#blood#cells#are#less#permeable#so#glucose#can’t#easily#bind#to#
hemoglobin#
o Red#blood#cells#also#have#shorter#life#span#to#quickly#get#rid#of#this#
glycolylated#hemoglobin#
Glycogen(Structure(
• 2#different#types#of#glycogen#
granules#
o Small,#β#particles#and#
large#α#particles#(which#
