Final Exam Flashcards
What are the 5 co enzymes included in the pyruvate dehydrogenase complex?
TPP, FAD, Lipoate, NAD, COA (co enzyme A)
what are the vitamins needed to make each co enzyme in the Pyruvate dehydrogenase complex?
TPP (thiamine)
FAD (Riboflavin)
NAD (Niacin)
COA (Pantothenate)
what is the function of Coenzyme A in acetyl co A production?
accepts and carries acetyl groups
PHD is a multi enzyme complex consisting of what 3 enzymes? Each enzyme also has specific co factors, what are they?
- pyruvate dehydrogenase (TPP)
- dihydrolipoyl transacetylase (Lipoate, COA)
- Dihydrolipoyl (FAD NAD)
what is the net result of CAC?
2CO2, FADH2, GTP
the activity of citrate synthase largely depends on?
oxaloacetate
Acetyl CoA oxdation involving citrate synthase is thermodynamically _________ _________
favourable/irreverisble
Citrate synthase is inhibitted by?
NADH, Citrate, Succinyl COA
what is the difference between the open and closed conformation of citrate synthase?
open - free enzyme does not have binding site for acetyl COA
closed- binding of oxaloacetate creates a site for acetyl COA
what is lost and gained during the step of CAC involving isocitrate dehydrogenase?
CO2 lost
NADH gained
acetyl COA oxidation involving isocitrate dehydrogenae is thermodynamically ____________ __________
favourable/irreversible
Isocitrate dehydrogenase is a major regulatory componant of what?
the citric acid cycle
acetyl co A oxidation involving aketoglutarate dehydrogenase is thermodynamically ______ _________
favourable/ irreversible
why is FAD reduced instead of NAD in the reaction of CAC with succinate dehydrogenase?
because the free energy change is not enough to reduce NAD
Is the step in CAC with malate dehydrogenase favourable or unfavourable?
highly thermodynamically unfavourable and reversible
Oxidative decarboxylations in CAC give ?``
2 NADH
SLP in CAC gives?
GTP
Dehydrogenation gives reduced _______ in CAC
FADH2
the Last step in CAC gives _______
NADH
There are _____ acetyl COA/pyruvate
2
citric acid cycle intermediates are important for many other pathways (4), name each pathway and what is used?
- Glucose biosynthesis uses oxaloacetate, it is transported as malate
- Lipid biosytheis uses acetyl COA from ATP citrate lyase
- Amino acid biosynthesis uses aketoglutarate and oxaloacetate
- Protein biosynthesis uses succinyl-CoA
in eukaryotes oxidative phosphorylation occurs in the ?
mitochondria inner membrane
glycolysis occurs in the __________
cytoplasm
citric acid cycle occurs in the _________ ________
mitochondrial matrix
What step from CAC is not located in the mitochdrial matrix?
succinate dehydrogenase, this step occurs in the inner membrane
the glyoxylate cycle is found where?
plants and some microorganisms
what is the net production of the glyoxylate cycle?
2 acetyl COA to oxylacetate
the glyoxylate cycle allows a net conversion of acetyla COA to ________________ that does not occur in animals
glucose
the glyoxylate cycle is compartmentalized in the glyoxysome and bypasses the ____________ with what enzymes(2)?
decarboxylation with isocitrate lyase and malate synthase
what is a major difference between the gyoxylate cycle and the citric acid cycle?
there is no CO2 lost
what are two advantages of fats over polysaccharides?
- fatty acids carry more energy per carbon because they are more reduced
- fatty acids carry less water because they are non polar
glucose and glycogen are for ______ term energy storage while fats are for ________ term
short term, long term
in vertebrates, dietary fatty acids are absorbed in the _______ __________
small intestine
NEFA stands for?
non esterfied fatty acids or free fatty acids
what is hydrolysis of triglycerides catalyzed by?
lipases
some lipases are reuglated by hormones such as _______ and _______
glucagon and epinephrin
_______ keeps fats in a stored state
perilipin
during mobilization of fats what does a prescence of epinephrin mean? and glucagon?
epinephrin means need energy now
glucagon means out of glucose
what are lipid transporters in the blood?
chylomicrons
____________act as signals for receptors for uptake of lipids
apolipoproteins
in an adipocyte, fats plus glycerol =?
triacylglycerols for storage
in myocytes B-oxidation of ______ ______ for ______
fatty acids for energy
where are fats degraded into fatty acids and glycerol?
cytoplasm of adipocytes
Glycerol kinase activates _______ at the expense of _______
glycerol , atp
attatchment of fatty acids to phospholipids requires ?
conversion to fatty acetyl COA
descirbe the 3 stages of fatty acid oxydation?
- oxidative conversion of two carbon units into acetyl COA via B oxidation with concomitant generation of NADH and FADH
- oxidation of acetyl COA via citric acid cycle with cincomitant generation of NADH and FADH2
- Generates ATP from NADH and FADH2 via respiratory chain
name all 4 enzymes in the beta oxidation pathway?
- acyl coa dehydrogenase
- enoyl coa hydratase
- B hydroxyacyl coa dehydrogenase
- acyl coa acetyltransferase (thiolase)
to create palmitic acid the B oxidation pathway must be undergone ______ times
7
what is formed in each cycle of B oxidation pathway?
FADH and NADH so 7 total
how do electrons from FADH and NADH enter the ETC?
electron transfering flavoprotein (ETF)
after B oxidation what happens to acetyl coa?
enters the citric acid cycle and further oxidizes into CO2, this creates more GTP, NADH, FADH2
For the oxidation of unstaturated fatty acids what is additionally requires? what does monunsaturated fatty acids need vs poly?
two additional enzymes,
- isomerase which converts the cis double bond at carbon 3 to trans
- reductase, that reduces cis double bonds not at carbon 3
- monounsaturated fatty acids need isomerase while poly need both
what is the difference between mitochondrial acyl COA dehydrogenase and peroxisomal acyl COA dehydrogenase?
mitochondrial - passes electron to ETC, energy captured as ATP
peroxisomal - passes electrons straight to molecular oxygen
where does B oxidation mainly occur in plants?
peroxisomes
B oxidation can occur in the peroxisomes in some animals, how?
can only occur in specialized tissues such as the liver, and is for very long fatty acids or branched fatty acids
do liver peroxisomes contain CAC enzymes?
no
how are ketone bodies formed?
when oxaloacetate is depleted acetyl COA is converted into ketone bodies
what gluconeogenic conditions result in ketones?
diabetes, starvation, this slows the CAC and results in reduced oxaloactetate
_______ is the source of ketone bodies?
liver
what happens if ketosis is left untreated?
diabetes mellitus, blood concentration of 90mg/100ml, urinary excretions of 5000 mg/24hrs
what are the 3 metabolic circumstances that lead to amino acid oxidation?
- leftover amino acids from normal protien turnover
- dietary amino acids that exceed bodys protein synthesis needs
- proteins in the body can be broken down to supply amino acids for energy when carbs are scarce
what is the first step in amino acid oxidation?
removal of the amino group (transamination)
what is the fate of Nitrogen for aquatic vertebrates?
release amonia to environment
what is the fate of nitrogen for terrestrial vertebrates?
nitrogen in form of urea
what is the fate of nitrogen for birds and reptiles?
nitrogen as uric acid
why is urea better than ammonia?
far less toxic than ammonia, high solubility
transamination is catalyzed by?
aminotransferases
what cofactor is used in transamination?
pyridoxal phosphate cofactor
what accepts the amino groups in transamination?
a keto glutarate
ammonia added to glutamate makes _______. Where does this product go?
glutamine, safely transported into the bloodstream
why is glutamine important in transamination?
- glutamine acts as temporary storage of nitrogen
- can donate amino group when needed for amino acid biosynthesis
- excess is processed in kidneys, liver and intestines
Glutamate can also donate ammonia to pyruvate to make _______
alanine
what is the importance of alanine with regards to amino acid oxidation?
glycolysis makes pyruvate, if pyruvate isnt gotten rid of lactic acid will build up. Oyruvate can be converted to alanine for transport into the liver.
what is the second step after transamination?
oxidative deamination
oxidative deamination occurs in the ______________ -_____________________
mitochondrial matrix
what happens in oxidative deamination?
ammonia is processed as urea for excretion
urea cycle enzymes increase when?
high protein diet or starvation
ammonia is highly toxic and must be ______ or ______
utilized or excreted
what is the first step of the urea cycle?
carbamoyl phosphate synthase 1 captures free amonia in the mitochondrial matrix
free ammonia released from glutamate is converted to ______ for excretion
urea
can all amino acids be synthesized in humans?
no some must be obtained through diet
what is the chemiosmotic theory?
phosphorylation of ATP is not a result of direct reaction between ATP and a high energy phosphate. The energy needed to phosphorylate ADP is provided by the flow of protons (3) down the electrochemical gradient. The energy released by the electron transport is used to transport protons against the graident.
carbohydrates, lipids and amino acids are the main source of _____ _____ for the cell to make atp?
reduced feuls
in eukaryotes what is the ultimate electron acceptor?
O
What does it mean when a membrane must couple proteins?
couple a downhill flow of electrons with an uphill flow of protons across the membrane , membranes must contain a protein that couples the downhill flow of protons to the phosphorylation of ADP
What are the 4 compartments of the mitochondrion?
- outer membrane
- IMS
- Inner membrane
- Matrix
The elctron transport chain takes place where?
inner membrane of mitochondrion
where does the CAC take place ?
the mitochndrion matrix
what are the initial electron acceptors for complex 1 and 2?`
FMN (flavin mononucleotide) FAD (Flavin adenine dinucleotide)
each complex containes multiple redox centres consiting of what?
- FAD, FMN
- cytochromes a,b,c
- ion sulfur cluster
- coenzymes Q
- copper proteins
describe the electron carrier cytochrome?
- one electron carrier
- iron coordinating phosphoryn ring derivatives, a,b,c differ by ring additions
how many electrons do iron sflur clusters carry?
one
iron sulfur clusters coordinate by?
cysteins in the protein
iron and sulfur clusters contain an equal amount of iron and slufur ( T or F)
T
Ubiquinone consists of ____ protons and ____ electrons that give an alcohol called ____________
2, 2 , ubiquonol
ubiquinone ______ diffuses in the membrane
freely
what does ubiquinone start as and what does it progress too?
starts as a liquid soluble compund that rapidly accepts electrons, then becomes mobile electron carrier transporting electrons from complexes 1 2 and 3
what are proton wires and where are they located?
complex one, series of amino acids under go protonation and deprotonation to get net transfer of proton from one side of membrane to other
describe what happens in complex one?
FMN accepts 2 e from NADH, iron sulfur centers pass one e at a time toward ubiquinone binding site, this electron transfer causes protons to move from the matrix to IMS. appoximtely 4 protons are translocated by proton wires.
describe what happens in complex 2?
FAD accepts 2 electrons from succinate, elelctrons passed one at a time via iron sulfer centres to ubiquinone which becomes reduced QH2.
*reaction of succinate to fumarate with succinae dehydrogenase
does complex 2 transport protons?
no
What happens in complex 3?
two electrons from QH2 reduce cytochrome c, the Q cycle results in 4 additioal protons transported
During the Q cycle ____ protons are transported per ___ electrons for Cytc
4, 2
during the Q cycle __ protons come from QH2 and __ protons are picked up from the matrix
2, 4
during the Q cycle two molecules of QH2 become oxidised resulting in what?
releasing protons into IMS
during the Q cycle ___ QH2 becomes reduced resulting in a net transfer of ____ protons per reduced coenzyme Q
1, 4
what is cytochrome C and what does it do in the ETC?
the second mobile electron carrier, it is a heme containing protein in the IMS, it carries a single electron from the cytochrome bc1 complex to cytochrome oxidase
what is heme iron?
can be ferrous or feric (reduced) oxide
mammalian cytochrome oxidase is a membrae protein with _____ subunits
13
cytochrome oxidase has ___ heme groups which are____ and _____
2, a3 and a3
describe the function of the copper ions in cytochrome oxidase?
CUA - two ions that accept electrons from Cyt c
CUB - bonded to heme a3 and transfers 4 electrons to oxygen
what happens in complex 4?
cytochrome oxidase passes electrons to o2, 4 electrons reduce one oxygen molecule into 2 water molecules, 4 protons picked up from matrix
complex 3 and 4 associate together to form a __________
respirasome
the protons in the ETC created the electrochemical proton gradient by 3 means, what are they?
- active transport of protons across the membrane
- chemically remove protons from the matrix
- release protons into the inter membrane space
_________ -________ sets up proton motive force
electron transports
what is the purpose of DNP?
transports protons down the gradient during uncoupling oxidative phosphorylation
what is the uncoupling protein?
thermogenin
how does UCP-1 generate heat?
short circuiting the mitochindrial protein battery
the mitochondrial ATP synthase complex has two subunits what are they?
f1- soluble part in matrix, individually catalyzes hydrolysis of ATP
f0- integral membrane complex, transports protons from IMS to matrix, dissipating proton gradient
the f1 subunit has 3 ab dimers what are they?
open - empty
loose -binding ADP and Pi
tight - catalyzes ATP formation and binds product
_____ H needed to synthesize 1 ATP
4
oxidation of 1 glucose molecule to CO2 yeilds ___ or ___ ATP
30, 32
glycolysis under anearobic conditions ( fermentation) yeilds how many ATP?
2
what are 3 ways oxidative phosphorylation is regulated?
- substrate availibility
- inhibitor IF1, onyl active at low pH, prevents hydrolysis of ATP
- inhibition of Oxphos leads to accumulation of NADH
