Final Exam Flashcards
(124 cards)
1
Q
What are the 5 co enzymes included in the pyruvate dehydrogenase complex?
A
TPP, FAD, Lipoate, NAD, COA (co enzyme A)
2
Q
what are the vitamins needed to make each co enzyme in the Pyruvate dehydrogenase complex?
A
TPP (thiamine)
FAD (Riboflavin)
NAD (Niacin)
COA (Pantothenate)
3
Q
what is the function of Coenzyme A in acetyl co A production?
A
accepts and carries acetyl groups
4
Q
PHD is a multi enzyme complex consisting of what 3 enzymes? Each enzyme also has specific co factors, what are they?
A
- pyruvate dehydrogenase (TPP)
- dihydrolipoyl transacetylase (Lipoate, COA)
- Dihydrolipoyl (FAD NAD)
5
Q
what is the net result of CAC?
A
2CO2, FADH2, GTP
6
Q
the activity of citrate synthase largely depends on?
A
oxaloacetate
7
Q
Acetyl CoA oxdation involving citrate synthase is thermodynamically _________ _________
A
favourable/irreverisble
8
Q
Citrate synthase is inhibitted by?
A
NADH, Citrate, Succinyl COA
9
Q
what is the difference between the open and closed conformation of citrate synthase?
A
open - free enzyme does not have binding site for acetyl COA
closed- binding of oxaloacetate creates a site for acetyl COA
10
Q
what is lost and gained during the step of CAC involving isocitrate dehydrogenase?
A
CO2 lost
NADH gained
11
Q
acetyl COA oxidation involving isocitrate dehydrogenae is thermodynamically ____________ __________
A
favourable/irreversible
12
Q
Isocitrate dehydrogenase is a major regulatory componant of what?
A
the citric acid cycle
13
Q
acetyl co A oxidation involving aketoglutarate dehydrogenase is thermodynamically ______ _________
A
favourable/ irreversible
14
Q
why is FAD reduced instead of NAD in the reaction of CAC with succinate dehydrogenase?
A
because the free energy change is not enough to reduce NAD
15
Q
Is the step in CAC with malate dehydrogenase favourable or unfavourable?
A
highly thermodynamically unfavourable and reversible
16
Q
Oxidative decarboxylations in CAC give ?``
A
2 NADH
17
Q
SLP in CAC gives?
A
GTP
18
Q
Dehydrogenation gives reduced _______ in CAC
A
FADH2
19
Q
the Last step in CAC gives _______
A
NADH
20
Q
There are _____ acetyl COA/pyruvate
A
2
21
Q
citric acid cycle intermediates are important for many other pathways (4), name each pathway and what is used?
A
- 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
22
Q
in eukaryotes oxidative phosphorylation occurs in the ?
A
mitochondria inner membrane
23
Q
glycolysis occurs in the __________
A
cytoplasm
24
Q
citric acid cycle occurs in the _________ ________
A
mitochondrial matrix
25
What step from CAC is not located in the mitochdrial matrix?
succinate dehydrogenase, this step occurs in the inner membrane
26
the glyoxylate cycle is found where?
plants and some microorganisms
27
what is the net production of the glyoxylate cycle?
2 acetyl COA to oxylacetate
28
the glyoxylate cycle allows a net conversion of acetyla COA to ________________ that does not occur in animals
glucose
29
the glyoxylate cycle is compartmentalized in the glyoxysome and bypasses the ____________ with what enzymes(2)?
decarboxylation with isocitrate lyase and malate synthase
30
what is a major difference between the gyoxylate cycle and the citric acid cycle?
there is no CO2 lost
31
what are two advantages of fats over polysaccharides?
1. fatty acids carry more energy per carbon because they are more reduced
2. fatty acids carry less water because they are non polar
32
glucose and glycogen are for ______ term energy storage while fats are for ________ term
short term, long term
33
in vertebrates, dietary fatty acids are absorbed in the _______ __________
small intestine
34
NEFA stands for?
non esterfied fatty acids or free fatty acids
35
what is hydrolysis of triglycerides catalyzed by?
lipases
36
some lipases are reuglated by hormones such as _______ and _______
glucagon and epinephrin
37
_______ keeps fats in a stored state
perilipin
38
during mobilization of fats what does a prescence of epinephrin mean? and glucagon?
epinephrin means need energy now
| glucagon means out of glucose
39
what are lipid transporters in the blood?
chylomicrons
40
____________act as signals for receptors for uptake of lipids
apolipoproteins
41
in an adipocyte, fats plus glycerol =?
triacylglycerols for storage
42
in myocytes B-oxidation of ______ ______ for ______
fatty acids for energy
43
where are fats degraded into fatty acids and glycerol?
cytoplasm of adipocytes
44
Glycerol kinase activates _______ at the expense of _______
glycerol , atp
45
attatchment of fatty acids to phospholipids requires ?
conversion to fatty acetyl COA
46
descirbe the 3 stages of fatty acid oxydation?
1. oxidative conversion of two carbon units into acetyl COA via B oxidation with concomitant generation of NADH and FADH
2. oxidation of acetyl COA via citric acid cycle with cincomitant generation of NADH and FADH2
3. Generates ATP from NADH and FADH2 via respiratory chain
47
name all 4 enzymes in the beta oxidation pathway?
1. acyl coa dehydrogenase
2. enoyl coa hydratase
3. B hydroxyacyl coa dehydrogenase
4. acyl coa acetyltransferase (thiolase)
48
to create palmitic acid the B oxidation pathway must be undergone ______ times
7
49
what is formed in each cycle of B oxidation pathway?
FADH and NADH so 7 total
50
how do electrons from FADH and NADH enter the ETC?
electron transfering flavoprotein (ETF)
51
after B oxidation what happens to acetyl coa?
enters the citric acid cycle and further oxidizes into CO2, this creates more GTP, NADH, FADH2
52
For the oxidation of unstaturated fatty acids what is additionally requires? what does monunsaturated fatty acids need vs poly?
two additional enzymes,
1. isomerase which converts the cis double bond at carbon 3 to trans
2. reductase, that reduces cis double bonds not at carbon 3
* monounsaturated fatty acids need isomerase while poly need both
53
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
54
where does B oxidation mainly occur in plants?
peroxisomes
55
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
56
do liver peroxisomes contain CAC enzymes?
no
57
how are ketone bodies formed?
when oxaloacetate is depleted acetyl COA is converted into ketone bodies
58
what gluconeogenic conditions result in ketones?
diabetes, starvation, this slows the CAC and results in reduced oxaloactetate
59
_______ is the source of ketone bodies?
liver
60
what happens if ketosis is left untreated?
diabetes mellitus, blood concentration of 90mg/100ml, urinary excretions of 5000 mg/24hrs
61
what are the 3 metabolic circumstances that lead to amino acid oxidation?
1. leftover amino acids from normal protien turnover
2. dietary amino acids that exceed bodys protein synthesis needs
3. proteins in the body can be broken down to supply amino acids for energy when carbs are scarce
62
what is the first step in amino acid oxidation?
removal of the amino group (transamination)
63
what is the fate of Nitrogen for aquatic vertebrates?
release amonia to environment
64
what is the fate of nitrogen for terrestrial vertebrates?
nitrogen in form of urea
65
what is the fate of nitrogen for birds and reptiles?
nitrogen as uric acid
66
why is urea better than ammonia?
far less toxic than ammonia, high solubility
67
transamination is catalyzed by?
aminotransferases
68
what cofactor is used in transamination?
pyridoxal phosphate cofactor
69
what accepts the amino groups in transamination?
a keto glutarate
70
ammonia added to glutamate makes _______. Where does this product go?
glutamine, safely transported into the bloodstream
71
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
72
Glutamate can also donate ammonia to pyruvate to make _______
alanine
73
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.
74
what is the second step after transamination?
oxidative deamination
75
oxidative deamination occurs in the ______________ -_____________________
mitochondrial matrix
76
what happens in oxidative deamination?
ammonia is processed as urea for excretion
77
urea cycle enzymes increase when?
high protein diet or starvation
78
ammonia is highly toxic and must be ______ or ______
utilized or excreted
79
what is the first step of the urea cycle?
carbamoyl phosphate synthase 1 captures free amonia in the mitochondrial matrix
80
free ammonia released from glutamate is converted to ______ for excretion
urea
81
can all amino acids be synthesized in humans?
no some must be obtained through diet
82
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.
83
carbohydrates, lipids and amino acids are the main source of _____ _____ for the cell to make atp?
reduced feuls
84
in eukaryotes what is the ultimate electron acceptor?
O
85
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
86
What are the 4 compartments of the mitochondrion?
1. outer membrane
2. IMS
3. Inner membrane
4. Matrix
87
The elctron transport chain takes place where?
inner membrane of mitochondrion
88
where does the CAC take place ?
the mitochndrion matrix
89
what are the initial electron acceptors for complex 1 and 2?`
FMN (flavin mononucleotide) FAD (Flavin adenine dinucleotide)
90
each complex containes multiple redox centres consiting of what?
1. FAD, FMN
2. cytochromes a,b,c
3. ion sulfur cluster
4. coenzymes Q
5. copper proteins
91
describe the electron carrier cytochrome?
- one electron carrier
| - iron coordinating phosphoryn ring derivatives, a,b,c differ by ring additions
92
how many electrons do iron sflur clusters carry?
one
93
iron sulfur clusters coordinate by?
cysteins in the protein
94
iron and sulfur clusters contain an equal amount of iron and slufur ( T or F)
T
95
Ubiquinone consists of ____ protons and ____ electrons that give an alcohol called ____________
2, 2 , ubiquonol
96
ubiquinone ______ diffuses in the membrane
freely
97
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
98
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
99
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.
100
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
101
does complex 2 transport protons?
no
102
What happens in complex 3?
two electrons from QH2 reduce cytochrome c, the Q cycle results in 4 additioal protons transported
103
During the Q cycle ____ protons are transported per ___ electrons for Cytc
4, 2
104
during the Q cycle __ protons come from QH2 and __ protons are picked up from the matrix
2, 4
105
during the Q cycle two molecules of QH2 become oxidised resulting in what?
releasing protons into IMS
106
during the Q cycle ___ QH2 becomes reduced resulting in a net transfer of ____ protons per reduced coenzyme Q
1, 4
107
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
108
what is heme iron?
can be ferrous or feric (reduced) oxide
109
mammalian cytochrome oxidase is a membrae protein with _____ subunits
13
110
cytochrome oxidase has ___ heme groups which are____ and _____
2, a3 and a3
111
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
112
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
113
complex 3 and 4 associate together to form a __________
respirasome
114
the protons in the ETC created the electrochemical proton gradient by 3 means, what are they?
1. active transport of protons across the membrane
2. chemically remove protons from the matrix
3. release protons into the inter membrane space
115
_________ -________ sets up proton motive force
electron transports
116
what is the purpose of DNP?
transports protons down the gradient during uncoupling oxidative phosphorylation
117
what is the uncoupling protein?
thermogenin
118
how does UCP-1 generate heat?
short circuiting the mitochindrial protein battery
119
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
120
the f1 subunit has 3 ab dimers what are they?
open - empty
loose -binding ADP and Pi
tight - catalyzes ATP formation and binds product
121
_____ H needed to synthesize 1 ATP
4
122
oxidation of 1 glucose molecule to CO2 yeilds ___ or ___ ATP
30, 32
123
glycolysis under anearobic conditions ( fermentation) yeilds how many ATP?
2
124
what are 3 ways oxidative phosphorylation is regulated?
1. substrate availibility
2. inhibitor IF1, onyl active at low pH, prevents hydrolysis of ATP
3. inhibition of Oxphos leads to accumulation of NADH
