29-34 Flashcards
1
Q
what is the main fat?
A
TAG
2
Q
what is excess energy consumed as glucose stored as?
A
fat
3
Q
what percentage of the human body is fat?
A
5-25%
4
Q
what are stored carbohydrates called?
A
glycogen
5
Q
what fraction of glycogen is water?
A
2/3
6
Q
what happens when TAG reacts with lipase?
A
it splits into FFA and glycerol which is passively diffused in the blood
7
Q
what is FFA?
A
free fatty acids
8
Q
what is FFA in the blood?
A
hydrophobic so it is surrounded by albumin to form albumin-FFA which passively used within the tissues
9
Q
what is FABP?
A
fatty acid binding protein
10
Q
what does FABP do?
A
binds to the FFA and transports it across the cell membrane from the blood
11
Q
does fatty acid activation after or before B-oxidation?
A
before
12
Q
where does fatty acid oxidation occur?
A
before it enters the mitochondria
13
Q
how are fatty acids activated?
A
by the attachment to CoA to make fatty acyl-CoA
energy is required to add the CoA from a hydrolysis of ATP to AMP
14
Q
what is the structure of acetyl-CoA?
A
a 2-carbon chain
15
Q
where does oxidation of fatty acids occur?
A
the mitochondrial matrix
16
Q
how many membranes are between the cytosol and matrix?
A
2
17
Q
what is the outer mitochondrial matrix called?
A
the fatty acyl-CoA carrier
18
Q
what does the inner mitochondrial matrix require of the acetyl-CoA?
A
it need to to into acyl-carnitine
19
Q
what does carnitine do?
A
binds to fatty acid acyl and removes the CoA in the intermembrane space of the mitochondria
20
Q
what enzyme changes acyl-CoA to acyl-carnitine?
A
carnitine acyltransferase
21
Q
what is the carnitine acyltransferase reaction?
A
exchanges the CoA and carnitine on a fatty acid using an enzyme called carnitine acyltransferase
22
Q
what does B-oxidation use?
A
fatty acids with an even number of carbons that are saturated (no double bonds)
23
Q
what is not directly made in B-oxidation?
A
ATP
24
Q
what is the energy from B-oxidation go?
A
transferred to the co-enzymes NAD and FAD
25
what is the product of B-oxidation?
acetyl-CoA
26
what is the first reaction of B-oxidation?
an oxidation reaction that releases 2 molecules and forms a double bond while storing energy in FAD which goes to FADH2
27
what happens in the second reaction of B-oxidation?
a hydration reaction that breaks the double bond and binds H2O to the molecule
28
what happens in the third reaction of B-oxidation?
an oxidation reaction that removes 2 hydrogen bonds that the energy is captured in NAD+ which turns into NADH+ + H+
29
what happens in the fourth reaction of B-oxidation?
a cleavage between the A and B carbons
then acetyl-CoA is released and coASH is added to the remaining carbon chain
30
what does each reaction of oxidation of palmitic acid gain?
one NADH, FADH2 and one acetyl-CoA
31
what is CAC?
citric acid cycle
32
what are other names for the CAC?
tricarboxylic cycle (TCA)
krebs cycle
33
where does CAC occur?
in the mitochondria
34
what does the CAC start and finish with?
the same molecule
35
what does acetyl-CoA add to the CAC?
2 carbos
36
what does the 2 carbons that are added into the CAC come out as?
2 carbon dioxide
37
what do we capture when the carbon is oxidised?
a bit of energy (ATP) to use later in the cycle
38
what are the 2 parts that the CAC happen in?
carbon coming in and then being released.
take the molecule and rearranging the molecules to end up with 2 carbon binding
39
which of the 2 parts of the CAC is energy captured in?
both parts
40
what is oxaloacetate?
a 4 carbon molecule and it reacts with the acetyl-CoA in a condensation reaction and then the citrate is synthesised
41
what is needed when a molecule gets bigger?
energy
42
what is isomerisation of the citrate?
the rearrangement of citrate to isocitrate maeks the molecule susceptible to decarboxylation
43
what catalizes the isomerisation of citrate?
aconitase
44
how do people make poisons to attack the CAC?
using fluroacetate which is like acetate except has a fluro ion instead of a hydrogen so its very similar
fluroacetyl-CoA goes through the citrate synthase to produce flurocitrate which is converted into a substrate that binds tightly to aconitase and inactivates the enzyme
45
what does the inactivation of aconitase by flurocitrate do?
stops the CAC
we make excess acetyl-CoA and it doesnt get used
the delta G of the reaction will become unfavourable and the glycolysis and B-oxidation wont work and we make less ATP
46
what is the removal of the first carbon of citrate?
this is an oxidative decarboxylation which is the moving a carboxy group through an oxidation reaction
this happens in 2 steps
47
what is the first step of oxidative decarboxylation reaction of citrate?
turning isocitrate into oxalosuccinate which is the oxidation part of the reaction and we reduce this molecule and store the energy released in NAD+
48
what is the second step of oxidative decarboxylation reaction of citrate?
turning oxalossucinate into A-ketoglutarate as it chops off the carbon and it becomes a carbondioxide
49
what enzyme catalizes the oxidative decarboxylation of citrate?
isocitrate dehydrogenase
50
what is the removal of the second carbon of citrate?
oxidative decarboxylation which is very similar to the pyruvate dehydrogenase reaction
CO2 is released and the energy is captured turning NAD+ into NADH+
51
how is succinyl-CoA to succinate?
the removal of the CoA releases enough energy to drive the synthesis of GTP
52
what is GTP the energy equivilant of?
ATP
53
what does GTP + ADP go to?
GDP + ATP
this doesnt require any energy to happen
54
what is the energy that is released from the chopping off of CoA used for?
phosphorylation reaction of turning GDP into GTP which holds the energy as our succinyl-CoA to succinate
55
what is substrate-level phosphorylation?
the direct use of energy from a substrate molecule to drive the synthesis of ATP
56
how does succinate go to oxaloacetate?
reactions similarily used in B-oxidation
succinate - fumarate
fumarate - malate
malate to oxaloacetate
57
how does succinate go to fumarate?
single bond to double bond in an oxidation reaction with the help of an enzyme called succinate dehydrogenase as energy is captured in FAD turning it to FADH2
58
how does fumarate go to malate?
a hydration reaction as hydroxal group is added on and double bond is broken with the help of an enzyme called fumarase
59
how does malate go to oxaloacetate?
oxidation reaction as another double bond is formed and the hydroxy group is released releasing a bit of energy that is captured in NAD which is now NADH + H+ with the help of an enzyme called malate dehydrogenase
60
what is the SDH?
located in the mitochondrial matrix
it uses FAD as a co-enzyme
SDH is part of CAC where FAD is reduced
61
what is needed to reduce FAD?
an electron transport chain?
62
what is ETC?
electron transport chain
63
what does the ETC do in the mitochondrial matrix?
turns the FADH2 into FAD to continue the reaction
64
what is the overall delta G of the CAC
-44.3kJ/mol
this is negative so the reaction is energetically favourable
65
what is the energy stored in amino acid bonds used for?
making stuff such as anything made with N such as haem
66
what is deaminoation of amino acids?
the removing of the amino group from the amino acid
it generates a carbon skeleton which can be used for the capturing of energy and a free amino group which we cant extract energy from even if there is energy still in these bonds
67
how does redox reactions deaminate amino acids?
it removes the amino group from the amino acid with the help of enzymes and releases it into the solution
this only works for some amino acids
68
what is transaminating?
the deamination of amino acids by transferring their amino group to a keto group
69
what enzyme catalysises transaminating?
aminotransferase enzymes (transaminase)
70
what does transaminase do?
takes the amino group and bonds it to another molecule such as a ketone by taking the nitrogen from one carbon skeleton to another
71
what is pyridoxal phosphate?
a co-enzyme that is required for transamination reactions
72
what is PLP?
pyridoxal phosphate
73
what is pyridoxal phosphate derrived from?
vitamin B6
74
how is PLP used?
its a co-enzyme that carries an amino group for us attaches it to the keto acid
75
what are the 2 forms that PLP can exist in?
pyridoxal phosphate which has no amino group
pyridoxamine phosphate which has the amino group
76
what is the first step of transamination?
the amino group is transferred from the amino acid to the pyridoxal phosphate and it becomes pyridoxamine phosphate
77
what is the second step of transamination?
the amino group is transferred pyridoxamine which now becomes pyridoxal phosphate and the amino group goes to the keto acid
78
what are some common amino acid/keto acid pairs in metabolism?
glutamate - A-ketoglutamate
asparate - oxaloacetate
alanine - pyruvate
79
where can amino acids be fed into the CAC?
at points where carbon skeletons enter the cycle
80
what is the second function of transamination reactions?
to remove excess nitrogen via the liver
if we have amino acids as our main source of energy then it can led to the build up of nitrogen which can be toxic
we can turn nitrogen back into amino acds via the transamination reaction
81
tranamination turns nitrogen into what to be excreted safely?
urea
82
what is oxidative phosphorylation the coupled process of?
how are they coupled together?
ETC and the phosphorylation of ADP to ATP by ATP-synthase
they are coupled by a proton gradient
83
what does the ECT in the mitochondria require?
oxygen
84
what are the barriers to proton?
membranes
85
how do we isolate the mitochondria from cells?
by treating it with strong or mild detergent
86
what does treating cells with strong detergent do?
solubilizes all membranes so the ETC does not work as the ETC is not in a membrane so no proton gradient can form
87
what does treating with mild detergent to a cell?
removes the outer membrane so ETC still works as ETC is in the inner mitochondrial membrane
the inner membrane provides a barrier to form a proton gradient
88
electrons from what are fed into the ETC?
NADH and FADH2
89
what happens to NADH and FADH2 once fed into the ETC?
the will ultimatly reduce molecular oxygen to water
90
what is pumped as electrons are transported through the ETC?
protons to form a gradient
91
what is the electron transport chain?
an organised series of complexes between which mobile carries transport electrons
its organized into 4 complexes, each complex contains multiple carriers
92
what are the carriers in the ETC?
2 mobile carriers, ubiquinone and cytochrome c
93
what is UQ?
ubiquinone
94
what is cyt c?
cytochrome c
95
what is UQ the same as?
co-enzyme Q
96
what is required to move electrons through the ETC?
a series of redox reactions
97
what does each carrier of the ETC do?
accepts electrons (is reduced) in one redox reaction and then donates electrons (is oxidised) in another redox reaction
98
what happens as electron move through the carriers of the ETC?
energy is released which is used to translocate protons across the mitochondrial inner membrane
99
what is the sequence of NADH in the ETC?
NADH - complex I - UQ - complex III - cyt c - complex IV - O2
100
what is the sequence of FADH2 in the ETC?
FADH2 - complex II - UQ - complex III - cyt c - complex IV - O2
101
what do inhibitors do in the ETC?
stop the flow of electrons through the ETC
no proton gradient is formed so ATP is not made and there is a build up of reduced co-enzymes (NADH and FADH2)
102
what does retenone do?
inhibits electron transfer from complex I to UQ
103
what does cyanide do?
binds to a carrier in complex IV
104
what does carbon monoxide do?
binds where O2 binds
105
what is Complex I?
where NADH is oxidised and 2 electrons are released into the ETC.
4 protons are pumped for each NADH oxidised
106
what is Complex II?
where FADH2 is oxidised as well as the SDH reaction with is shared with the citric acid cycle
2 electrons are released into the ETC and no protons are pumped
107
what does both complex I and complex II do?
pass 2 electrons to UQ which can then move within the inner mitochondrial membrane
108
how many forms can UQ exist as?
2
109
what does UQ do?
carries hydrogen atoms
undergoes 2-electron redox reactions but can accept or release one electron at a time
110
how many electrons does CoQ release into complex III at a time?
1
111
what is complex III?
releases one electron at a time to cytochrome c
it pumps 4 protons across the inner membrane
112
what does cytochrome c do?
moves on the outer surface of the inner mitochondrial membrane
carries one electron at a time form complex III to complex IV
113
what is cytochrome c?
a haem containing proteion and carries 1 electron via reversible Fe2+/Fe3+ redox reactions
114
what is complex IV?
accepts 1 electron at a time from cytochrome c
it reduces oxygen to water (terminal electron acceptor)
for 1 NADH/FADH2 (2 electrons) = 2 H+ pumped
115
what is the reaction equation that happens in complex IV?
1 NADH/FADH2 (2 electrons) = 1/2 O2 + 2H+ goes to H2O
116
what is pmf?
proton-motive force
117
what is the proton-motive force?
the proton gradient across the inner mitochondrial membrane that results in 2 energetic gradients
118
what are the 2 energetic gradients?
electrical gradient
chemical gradient
119
what is the chemical gradient?
due to different H+ concentrations on either side of the membrane
120
what is the electrical gradient?
due to the charge difference across the membrane
121
what is the electrochemical gradient known as?
know as the proton-motive force
122
what produces the pmf?
the ETC
123
what is in an artificial liposome?
bacteriorhodopsin
124
what is bacteriorhodopsin?
a light induced proton pump so in light it pumps protons to make the proton gradient so ATP synthesis can occur in light even if the ETC doesnt work
125
what is DNP?
2,4-dinitrophenol
its a poison
126
what does DNP do?
its an uncoupler
it shuffles H+ from the intermembrane space to the matrix thus dissapating the proton gradient
127
what occurs in the presense of DNP?
the ETC works but ATP is not made
128
what is the F1F0-ATP synthesis?
how ATP is produced in the mitochondria
129
what is the F1 section of F1F0?
the matrix
130
what is the F0 section of the F1F0?
in the intermitochondrial membrane
131
do the rotor subunits turn?
yes
132
do the stator subunits turn?
nope
133
what drives the rotor subunits?
a proton flow
134
what does the rotor subunit movement do?
causes conformational changes in the stator that drives ATP synthesis
causes conformational change in the catalytic Alpha and Beta subunits of F1
135
what is O in the rotor subunits?
open where ATP is released and ADP and Pi bind
136
what is L in the rotor subunits?
loose where it holds the ADP and Pi in preperation for catalysis
137
what is T in the rotor subunit?
tight where catalysis happens and ATP is formed
138
how many protons are needed for the production of 1 ATP?
4
139
what is the exchange if a NADH into ATP?
10 protons pumped in ETC so 2.5 ATP can be produced
140
what is the exchange of a FADH2 into ATP?
6 protons pumped in ETC so 1.5 ATP can be produced
141
what is hydrolysis?
the breaking down of the constituent molecules
142
what type of intermediate are acetyl-CoA?
high energy
143
can ATP be stored?
nope
144
what does alcohol do to the nervous system?
binds to the GABA(A) receptor
145
what is GABA?
gamma-aminobutyrate
its a neuro transmitter derived from glutamate
146
what is the GABA(a) receptor do?
a membrane bound ligand-gated chloride channel as its a membrane protein
when activated it selectivly conducts Cl- ions causing an inhibitory effect on neurotransmission by reducing the chance of successful action potentials
147
what effect does alcohol have on GABA(A) receptors?
it down regulates the signal from these receptors by increasing the flow of chloride that passes into the cell membrane
148
hiow much energy is in alcohol?
29kJ/g
149
what si alcohol dehydrogenase?
it is the enzyme that is responsible for the decrease in alcohol in the body over time
it moves alcohol into an aldehyde
150
what are factors of aldehyde?
very reactive but they are more toxic than alcohol
151
what does aldehyde dehydrogenase do?
conserves energy and converts the aldehyde into acetate which is a lot less harsh than an aldehyde
152
what ate the 2 forms of aldehyde dehydrogenase?
cystolic
mitochondrial
153
what does antabase do?
inhibits aldehyde dehydrogenase causing the individual to feel unwell due to build up of acetaldehyde
154
what happens if we have too much fatty acids in VLDLs?
it can take away to be stored in adipose tissue which can result in fatty liver or steatosis
155
what happens if we have sufficient ATP?
B-oxidation of fatty acids and the fatty acids will just remained stored in adipose tissue
156
what are the consequences of alcohol on the CAC?
slows the CAC and electron transport, slows pyruvate dehydrogenase and glycolysis, fatty acid oxidation
157
what does the pool of fatty acids build up in the liver result in?
the fatty acids accumulating in the blood
this causes pyruvate to go to lactate which decreases the blood pH and inhibits gluconeogenesis which can decrease the glucose in the body which is induced by alcohol and can result in a coma
158
what is the microsomal ethanol oxidisng system?
the detoxification in the blood
159
what does oxidase do?
made in response to alcohol and somtimes this fires and makes O2 which can cause oxidative damage
it also metabilses other drugs
160
what can chronic alcohol metabolism lead to?
toxic acetaldehyde reactive oxygen species which leads to fatty liver, inflamation leads to alcohol hepatitis which leads to necrosis which leads to cirrhosis which leads to a coma or even death
161
what does liver dysfunction cause?
a build up of NH3
