Module 5.7 Flashcards
1
Q
What is respiration
A
Respiration is the process that occurs in living cells and releases the energy stored in organic molecules such as glucose .
2
Q
What is the energy in respiration immediately used as ?
A
The energy is immediately used to synthesise molecules of ATP , from ADP , and inorganic phosphate (pI) .
3
Q
What can ATP be hydrolysed to release ?
A
energy needed to drive biological processes . Microorganisms (both eukaryotic microbes such as yeast and prokaryotes such as bacteria ) , plants , animals and fungi and Protoctists all respire to obtain energy .
4
Q
Why do living organisms need energy ?
A
Energy is the capacity to do work . The energy that is stored in complex organic molecules e.g. fats and carbohydrates , and proteins - is potential energy .
-It also is chemical energy , converted from light energy during the process of photosynthesis .
5
Q
Why do living organisms need energy ? (2)
A
It is also chemical energy , converted from light energy during the process of photosynthesis ( topic 5.6.1) . When this energy is released , from organic molecules , via respiration , it can be used to make ATP to drive biological processes such as
6
Q
what biological processes does ATP support
A
-active transport
-endocytosis
-exocytosis including secretion of large molecules from cells .
-synthesis of large molecules such as proteins
7
Q
what biological processes does ATP support (2)
A
DNA replication
cell division
movement - movement of flagella or cilia or undulipodia and motor proteins .
-activation of chemicals .
8
Q
what are anabolic reactions
A
they are metabolic reactions where large molecules are synthesises from smaller molecules .
9
Q
what are catabolic reactions
A
metabolic reactions involving the hydrolysis of large molecules into smaller ones .
10
Q
what do metabolic reactions and kinetic energy allow
A
allows them to move
e.g - diffuse down a concentration gradient from one place to another , they use their kinetic energy to do so .
11
Q
check figure 1 for the energy transfer between and within living organisms .136
A
…
12
Q
learning tip about respiration and energy releases within it
A
respiration releases energy from respiratory substrates such as glucose but it does not create or make energy . however , some of the released energy can be used to make ATP .
13
Q
What is ATP
A
ATP , is the standard intermediary between energy - releasing and energy consuming metabolic reactions in both eukaryotic and prokaryotic cells .
14
Q
what does figure 2 show
A
figure 2 , shows the structure of an ATP molecule , it is a phosphorylated nucleotide . Each molecule of ATP , consist of adenosine which is the nitrogenous base adenine plus the carbon sugar ribose , and three phosphate groups .
15
Q
What is the stability of ATP
A
ATP is relatively stable (it does not break down ADP and Pi) , when in solution in cells , but it is readily hydrolysed by enzyme catalysis . However , whilst in solution it can be easily be moved from place to place within a cell .
16
Q
the role o f ATP synthase in the formation and breakdown in ATP
A
-The energy-releasing hydrolysis of ATP , is coupled with an energy-consuming metabolic reaction . ATP , is the immediate energy source for this metabolic reaction .
17
Q
what happens when atp is hydrolysed
A
-When ATP is hydrolysed ADP and P , a small quantity of energy is released for use in the cells . Cells can therefore obtain energy , they need for a process in small manageable amounts that will not cause damage or be wasteful .
-ATP is referred to as the universal energy currency , as it occurs in all living cells , and is a source of energy that can be used in cells by a small amount .
18
Q
what happens when some of the energy is released from the hydrolysis of ATP
A
The release of heat , both in respiration and during ATP hydrolysis , may appear to be inefficient and wasteful . Heat , however , helps keep living organisms ‘warm’ and enables their enzyme catalysed reactions to proceed at or near the optimum rate book1 2.4.4 .
19
Q
What does figure 4 show on page 137
A
shows the chemical energy released from the hydrolysis of ATP .
20
Q
What are cristae
A
they are highly folded mitochondrial membrane
21
Q
what is the mitochondrial matrix
A
fluid filled inner part of mitochondira
22
Q
RECAP on the shape of mitochondria
A
-Mitochondria may be rod-shaped thread - like or spherical , with diameters of 0.5-1.0 micrometres , and lengths of 2-5micrometers Occasionally up to 10 .
23
Q
What is the membrane structure like for mitochondria .
A
24
Q
What is key about the mitochondrial membrane
A
it is smooth , and the inner membrane is folded into cristae (singular crista ) , giving it a large surface area .
25
what is embedded in the inner membrane of mitochondria
embedded in the inner membrane are proteins that transport electrons , and protein channels associated with ATP , synthase enzyme that allow protons to diffuse through them .
26
what is between the inner and outer mitochondrial membranes of the envelope
it is the intermembrane space .
27
what is in the mitochondrial matrix
it is enclosed by inner membrane , is semi-rigid and gel-like . It contains mitochondrial ribosomes lopped mitochondrial DNA and enzymes for the link reaction and the krebs cycle .
28
What is the contents of the matrix (1)
-enzymes that catalyse the stages of these reactions .
-Molecules of the coenzyme NAD , and FAD .
29
Contents of matrix (2)
oxalacetate - the four carbon compound that accepts the acetyl group form the link reaction .
-Mitochondrial DNA - some of which codes for mitochondrial enzymes and other proteins .
30
contents of the matrix (3)
mitochondrial ribosomes structurally similar to prokaryotic ribosomes , where these proteins are assembled .
31
What is the outer membrane of the mitochondria consist of
the phospholipid composition of the outer membrane is similar to that of membranes around other organelles in eukaryotic cells .
-It contains proteins some of which form channels or carriers that allow the passage of molecules such as pyruvate into the mitochondrio .
32
inner membrane mitochondria
the lipid composition of the inner membrane differs from that of the outer membrane . This lipid bilayer is less permeable to small ions such as hydrogen ions than is the outer membrane .
33
what do the folds in the cristae of the mitochondria enable
the folds cristae in the inner membrane gives a large surface area for the electron carriers and ATP synthase enzymes embedded in them .
34
what are the electron carriers used for
the electron carriers are protein complexes arranged in electron transport chains . Electron transport chains are involved in the final stage of aerobic respiration , oxidative phosphorylation.
35
check figure 3 of the electron transport chain
it summarises events that takes place along the electron transport chain .
36
what is the use for ATP synthase enzymes
ATP synthase enzymes are large and protrude from the inner membrane into the matrix . Protons can also pass through them .
37
LEARNING TIP OF THE MITOCHONDRIA
The outer layer of the mitochondrion should always be described as an envelope because it consists of two membranes .
38
each electron transport chain (1)
each electron carrier protein contains a cofactor a non protein haem group that contains an iron ion .
39
each electron transport chain (2)
what can the iron ion do
the iron ion can accept and donate electrons becasue it can become reduced (Fe2+) by gaining an electron and then become oxidised (Fe3+) , when donating the electron to the next electron carrier . Electron carrier . ELectron carrier proteins are OXIDO REDUCTASE ENZYMES .
40
each electron transport chain (3)
The electron carriers also have a coenzyme that , using energy released from the electrons pump protons from the matrix to the intermembrane space.
41
each electron transport chain (4) what happens when protons accumulate in the intermembrane
protons accumulate in the intermembrane space and a proton gradient forms across the membrane .
42
each electron transport chain (5)
What does the proton gradient can produce a flow of protons through the channels in the ATP synthase enzymes to make ATP . You will learn more about this 5.7.5 (already learnt abt synthesis of ATP by phosphorylation 5.6.3)
43
meaning of glycolysis
glycolysis is the first stage of respiration a 10 stage metabolic pathway that converts glucose to pyruvate .
44
where does glycolysis occur
it occurs in the cytoplasm of all living organisms that respire including prokaryotes .
45
how long is the sequence for glycolysis
it involves a sequence of 10 reactions , each catalysed by a different enzyme some with the help of the coenzyme NAD .
46
What is the pathway outline for glycolysis (1)
1. Phosphorylation of glucose to hexose bisphosphate .
47
What is the pathway outline for glycolysis (2)
splitting each hexose bisphosphate molecule into two triose phosphate molecules .
48
What is the pathway outline for glycolysis (3)
oxidation of triose phosphate to pyruvate .
49
revise figure 1 on 5.7.2
...
50
What is NAD
what does it oxidise .
it is a non-protein molecule that helps dehydrogenase enzymes to carry out oxidation reactions .
-Nad oxidise substrate molecules during glycolysis in the link reaction and the krebs cycle .
51
where is Nad synthesised
NAD , is synthesised in living cells from nicotinamide , (vitamin B3) the five carbon sugar ribose , the nucleotide base adenine and two phosphoryl groups (F2) REPRESENTS ITS MOLECULAR STRUCTURE .
52
how many hydrogen toms can the nicotinamide accept .
two hydrogen atoms becoming reduced NAD /
53
What is the function of reduced NAD
reduced NAD , carries the protons and electrons to the cristae of the mitochondria , and delivers them to be used in oxidative phosphorylation for the generation of ADP from Pi .
54
What happens when reduced NAD gives up the protons and electrons that it accepted during one of the first three stages of respiration .
It becomes oxidised and can be reused to oxidise more substrate in the process becoming reduced again .
55
1st stage of glycolysis - phosphorylation - explain process . (1)
Glucose is a hexose sugar , which means it contains six carbon atoms . Its molecules are stable and needed to be activated before they can be split into three carbon compounds . One molecule of ATP is hydrolysed and the released phosphoryl group is added to glucose to make hexose monophosphate .
56
1st stage of glycolysis - phosphorylation - explain process . (2)
Another molecule of ATP is hydrolysed and the phosphoryl group added tot he hexose phosphate , to form a molecule of hexose bisphosphate . This sugar has one phosphate group at carbon atom number one and another at caron atom six .
57
What happens to the energy from the hydrolysed ATP .
The energy from the hydrolysed ATP molecules activates the hexose sugar , and prevents it from being transported out of the cell .
58
How does hexose bisphosphate split
each molecule of hexose bisphosphate is split into two three carbon molecules , triose phosphate , each with a phosphate group attached .
59
stage one of oxidation of triose phosphate to pyruvate (1)
(This process is anaerobic but it involves oxidation as it involves the removal of hydrogen atoms from substrate molecules .
dehydorgenase enzymes aided by the coenzyme NAD , remove hydrogen from triose phosphate .
60
stage one of oxidation of triose phosphate to pyruvate (2)
the two molecules of NAD , accept , the hydrogen atoms (proton and electrons ) and become reduced .
61
stage one of oxidation of triose phosphate to pyruvate (3)
at this stage , of glycolysis of two molecules NAD are reduced for every molecule of glucose undergoing this process . Also at this stage , four molecules of ATP are made for every triose phosphate molecules undergoing oxidation .
62
What are the products of glycolysis (1)
for each molecule of glucose , at the end of glycolysis there are ;
-two molecules of ATP , four have been made but two were used to kick start the process so the net gain is two molecules of ATP .
63
What are the products of glycolysis (2)
-Two molecules of reduced NAD
-Two molecules of pyruvate
64
What are the first two stages of respiration
1.glycolysis
2.the link reaction
65
what are the final stages of respiration
3.krebs cycle
4.oxidative phosphorylation
66
how do the last three stages of aerobic respirationt ake place
under aerobic conditions .
-Under aerobic conditions the pyruvate molecules from glycolysis are activate transported into the mitochondria for the link reaction .
67
what does pyruvate do under anaerobic conditions
in the absence of oxygen (anaerobic conditions ) pyruvate is converted in the cytoplasm to lactate or ethanol . In the process , the reduced NAD molecules are reoxidised so that glycolysis can continue to run , generating two molecules of ATP for every glucose molecule metabolised .
68
check figure 3 for overall process of respiration
...
69
meaning of decarboxylation
removal of a carboxyl group from a substrate molecule .
70
meaning of dehydrogenation
removal of hydrogen atoms from a substrate molecule .
71
substrate level phosphorylation
production of ATP from ADP and pi during glycolysis and the krebs cycle .
72
where does pyruvate produced in glycolysis go
it is transported across the outer and inner mitochondrial membranes via specific pyruvates H+ symport , a transport protein hat transports two ions or molecules int he same direction and into the matrix .
73
what happens after pyruvate is transported to the matrix
-pyruvate is converted to a carbon acetyl group during the link reaction .
-the acetyl group is oxidised during the krebs cycle .
74
where does the link reaction occur
link reaction occurs in the mitochondrial matrix .
75
give an overview of the link reaction
pyruvate is decarboxylated and dehydrogenated catalysed by a large multi-enzyme complex , pyruvate dehydrogenase which catalyses the sequence of reactions that occur during the link reaction ,
76
is atp produced in this reaction
no
77
link reaction step 1
the carbonyl group is removed and is the origin of some of the carbon dioxide produced during respiration .
78
link reaction step 2
this decarboxylation of pyruvate together with dehydrogenation produces an acetyl group .
79
link reaction step 3
the acetyl group combines with coenzyme A CoA to become acetyl CoA .
80
link reaction step 4
the coenzyme NAD becomes reduces .
-The equation summarises the link reaction for two molecules of pyruvate derived from one molecule of glucose learn equation .
81
what is the important equation in the link reaction 5
2pyurvate+2NAD+2CoA-->2C03+2 reduced NAD + 2 acetyl CoA
82
link reaction step six
Coenzyme A accepts the acetyl group and in the form of acetyl CoA , carries the acetyl group on to the krebs cycle .
83
check figure 1 for the structure of the acetyl coA
...
84
Where does the krebs cycle take place
like the link reaction , the krebs cycle takes place in the mitochondrial matrix .
85
what is the krebs cycle
-it is a series of enzyme catalysed reactions that oxidise that acetate from the link reaction to two molecules of carbon dioxide , while conserving , energy by reducing coenzymes NAD and FAD .
86
what do the coenzymes in krebs cycle do
these reduced coenzymes then carry the hydrogen atoms to the electron transport the hydrogen atoms to the electron transport chain on the cristae where they will be involved in the production of more ATP molecules .
87
check figure 2 for the structure
FAD
88
Check figure 3 for the overall krebs cycle
...
89
stage one of the krebs cycle
the acetyl group released from the acetyl CoA combines with a four carbon compound oxaloacetate to form a six carbon compound citrate .
90
stage two of the krebs cycle
citrate is decarboxylated and dehydrogenated producing five carbon compound one molecule of carbon dioxide and one molecule of reduced NAD .
91
stage three of the krebs cycle
the five carbon compound is further decarboxylated and dehydrogenated , producing a four carbon compound one molecule of carbon dioxide and one molecule of reduced NAD .
92
stage four of the krebs cycle
this four carbon compound combines temporarily with and is then released from coenzyme A . At this stage substrate - level phosphorylation takes place , producing one molecule of ATP .
93
stage five of the krebs cycle
the four carbon compound is dehydrogenated producing a different four carbon compound and a molecule of reduced FAD .
94
stage six of the krebs cycle
rearrangement of the atoms in the four carbon molecule , catalysed by an isomerase enzyme , further followed by dehydrogenation regenerate a molecule of oxaloacetate so the cycle can continue .
95
how many turns of the krebs cycle are there for one molecule of glucose .
two
96
how many reduced nad per molecule of glucose is there in the link reaction ?
2
97
how many reduced fad per molecule of glucose is there in the link reaction ?
0
98
how many carbon dioxide d per molecule of glucose is there in the link reaction ?
2
99
how many ATP per molecule of glucose is there in the link reaction ?
0
100
how many reduced NAD per molecule of glucose is there in the krebs cycle ?
6
101
how many reduced FAD per molecule of glucose is there in the krebs cycle ?
2
102
how many carbon dioxide per molecule of glucose is there in the krebs cycle ?
4
103
how many ATP per molecule of glucose is there in the krebs cycle ?
2
104
will the link reaction and the krebs cycle occur in the absence of oxygen
no , although , oxygen is not directly used in the link reaction and Krebs cycle , these stages will not occur in the absence of oxygen so they are aerobic .
105
what happens at the end of the krebs cycle
by the end of the krebs cycle the production of carbon dioxide from glucose is completed
106
what other substrates other than glucose can respire aerobically (1)
-fatty acids , are broken down to many molecules of acetate that enter the krebs cycle via acetyl CoA
107
what other substrates other than glucose can respire aerobically (2)
glycerol may be converted to pyruvate and enter the krebs cycle via the link reaction .
108
what other substrates other than glucose can respire aerobically (3)
amino acids may be deaminated (the amino group NH2 is removed ) and the rest of the molecule can enter the krebs cycle directly or be changes to pyruvate or acetyl CoA .
109
Learning Tip
the link reaction is the only stage of respiration that does not produce any ATP .
110
What is chemiosmosis
the flow of protons down their concentration gradient , across a membrane through a channel associated with ATP synthase .
111
oxidative phosphorylation
FINAL STAGE YAYAYAY
the formation of ATP using energy released in the electron transport chain and int he presence of oxygen , it is the last sign in aerobic respiration .
112
Where does oxidative phosphorylation take place
in the mitochondria
113
what does chemiosmosis involve
it involves electron carrier protein arranged in chains called the electron transport chains embedded in the mitochondrial membranes and a process is called chemiosmosis .
114
What strucutre in the mitochondria aids with chemisomosis
the folded cristae gives a large surface area for the electron carrier proteins and the ATP synthase enzymes topic 5.7.3
115
reduced NAD and reduced FAD are reoxidised when they deliver their hydrogen atoms to the electron transport chain .
116
the hydorgen atoms release from the reduced coenzymes split into protons and electrons
117
the protons go into solution in the mitochondrial matrix
118
where do electrons pass down in chemiosmosis
the electrons from the hydrogen atoms pass along the chain of electron carriers , each electron carriers proteins has an iron ion in the next electron carrier in the chain becoming reoxidised to Fe 3+ .
119
electron carrier transport chain
as electron pass along the chain , some of their energy is used to pump protons across the inner mitochondrial membrane , into the intermembrane space.
120
The proton gradient and chemiosmosis
a protons accumulate in the intermembrane space , a proton gradient generates a chemiosmotic potential that is also known as a proton motive ion . As they are a source of potential energy .
121
the proton gradient and chemiosmosis (2)
ATP , is made using the energy of the proton motive force . Protons , cannot easily , diffuse through the lipid bilayer of the mitochondrial membrane as the outer membrane has a low degree of permeability to protons and the inner membrane is impermeable to protons .
122
How do proteins react to the gradient in chemiosmosis ?
Protons can , however , diffuse through the protein channels associated with ATP synthase enzymes , that are in the inner membrane .
123
What happens due to the fact that protons are diffusing down their concentration gradient through these channels ?
The flow of protons cause a conformational shape change in the ATP synthase enzyme that allows ADP and Pi to combine forming atp . This flow of protons is known as chemiosmosis it is coupled to the formation of ATP .
124
What is the formation of ATP in this way ?
it is known as oxidative phosphorylation .
125
what is the final electron acceptor in chemiosmosis
oxygen is the final electron acceptor because it combines with electrons coming off the electron transport chain and with protons diffusing down the ATP synthase channel , forming water . The equation below summarises the reaction ;
-4H++4E-+O2--->2H20
126
How mnay reduced NAD is in glycolysis
2
127
How many reduced NAD is in the link reaction
2
128
How many reduced NAD is in the krebs cycle
6
129
how many reduced FAD is in the krebs cycle
0
130
how many reduced FAD is in the link reaction
0
131
how many reduced FAD is in the krebs cycle
2
132
how many ATP can be produced theoretically for 10 molecules of reduced NAD
25 Molecules of ATP theoretically .
133
how many ATP can be produced theoretically for two molecules of reduced FAD
Three molecules of ATP .
134
so how many glucose molecules can oxidative phosphorylation produce theoretically
28 molecules of ATP per molecule of glucose
135
what is the net gain of APT per molecule of glucose for Glycolysis
2
136
what is the net gain of APT per molecule of glucose for the link reaction
0
137
what is the net gain of APT per molecule of glucose for the krebs cycle
2
138
what is the net gain of APT per molecule of glucose for oxidative phosphorylation
28 therefore the total is 32
139
why is the theoretical yield of ATP rarely achieved part one
some ATP is used actively to transport pyruvate into the mitochondria
140
why is the theoretical yield of ATP rarely achieved part two
some ATP is used in a shuttle system that transports reduced NAD made during glycolysis into mitochondria .
141
why is the theoretical yield of ATP rarely achieved part three
some protons may leak out through the mitochondrial membrane .
142
What happens if oxygen is absent in respiration (1)
oxygen cannot act as the final electron acceptor at the end of oxidative phosphorylation . Protons diffusing through channels associated with ATP synthase are not able to combine with electrons and oxygen to form water .
143
What happens if oxygen is absent in respiration (2)
the concentration of protons increases in the matrix and reduces the proton gradient across the inner mitochondrial membrane .
144
What happens if oxygen is absent in respiration (3)
oxidative phosphorylation ceases
145
What happens if oxygen is absent in respiration (4)
Reduced NAD and reduced FAD are not able to unload their hydrogen atoms and cannot be reoxidised .
146
what happens if oxygen is absent in respiration (5)
the krebs cycle stops as does the link reaction .
147
how does an organism survive in the absence of oxygen
for the organisms to survive these adverse conditions , glycolysis can take place , but the reduced NAD generated during the oxidation place , but the reduced NAD generated during the oxidation of triose phosphate to pyruvate has to be reoxidised so that glycolysis can continue .
148
how does an organism survive in the absence of oxygen (2)
These reduced coenzyme molecules cannot be reoxidised at the electron transport chain , so another metabolic pathway must operate to reoxidise them .
149
150
Reduced NAD has to be reoxidised - eukaryotic cells have two metabolic pathways to reoxidise the reduced NAD ;
-Fungi such as yeast , and plants use the ethanol fermentation pathway .
-Mammals use the lactate fermentation pathway .
-BOTH TAKES PLACE IN THE CYTOPLASM OF CELLS .
151
STAGE one of the ethanol fermentation pathway
-each molecules of pyruvate produced during glycolysis is decarboxylated and converted to ethanal . This stage in the pathway is catalysed by pyruvate decarboxylase , which has a coenzyme thiamine diphosphate bound to it .
152
STAGE two of the ethanol fermentation pathway
the ethanal accepts hydrogen atoms from reduced NAD , becoming reduced to ethanol . The enzyme ethanol dehydrogenase catalyses the reaction .
153
STAGE three of the ethanol fermentation pathway
in the process , the reduced NAD , is re-oxidised and made available to accept more hydrogen atoms from triose phosphate , thus allowing glycolysis to continue .
154
How does lactate fermentation pathway occur
lactate fermentation occurs in mammalian muscle tissue during vigorous activity , such as when running fast to escape a predator , when the demand for ATP for muscle contraction is high and there is an oxygen deficit .
155
lactate fermentation pathway (1)
Pyruvate , produced , during glycolysis , accept hydrogen atoms , from the reduced NAD , also made during glycolysis . The enzyme lactate dehydrogenase catalyses the reaction there are two outcomes .
-Pyruvate is reduced to lactate .
-The reduced NAD become reoxidised .
156
lactate fermentation pathway (2)
The reoxidise NAD can accept more hydrogen atoms from triose phosphate during glycolysis , and glycolysis can continue to produce enough ATP , to sustain muscle contraction for a short period
157
what happens after lactate is produced in the muscle tissue , carried away from the muscles in the blood , to the liver . When more oxygen is available to things can happen to lactate ;
converted to pyruvate , which may enter the Krebs cycle via the link reaction .
-recycled to glucose and glycogen .
158
what would happen if lactate was not removed from the muscle tissues
the pH would be lowered and this would inhibit the action of many of the enzymes involved in glycolysis and muscle contraction .
159
The ATP yield from anaerobic respiration
neither ethanol fermentation nor lactate fermentation produces any ATP . However , because this allows glycolysis to continue , the net gain of the two molecules of ATP per moleucle of glucose is still obtained .
160
what does glucose only being partly being broken down allow for
it allows many more molecules to undergo glycolysis per minute and therefore the overall yield of ATP is quite large . However , for each molecule of glucose , the yield of ATP via anaerobic respiration is about 1/15 of that produced during aerobic respiration .
161
LEARNING TIP ABOUT enzyme pyruvate decarboxylase
found in yeast , has a coenzyme , thiamine diphosphate bound to it . Thiamine is vitamin B1 , do not confuse it with thymine (nucleotide base ) .
162
