Topic 12 - Respiration Flashcards
(122 cards)
1
Q
What is energy needed for? (2 things)
A
- Movement
2. Anabolic Reactions
2
Q
What are examples of movement that energy is needed for? (3 things)
A
- Moving substances across membranes against the concentration gradient - active transport
- Transporting a protein from ribosome to Golgi Apparatus
- Contracting a muscle
3
Q
What are anabolic reactions?
A
A chemical reaction which carries out the process of synthesising large molecules from smaller ones
4
Q
Give 2 examples of anabolic reactions
A
- DNA Replication
2. Protein Synthesis
5
Q
What is ATP known as?
A
The universal energy currency of cells
6
Q
In all known organisms, what is ATP used for?
A
To supply energy
7
Q
Where does energy from ATP mostly originate from?
A
Sunlight - Plants and photosynthetic organisms capture energy from sunlight and transfer it to chemical potential energy in organic molecules
8
Q
What does ATP stand for?
A
Adenosine TriPhosphate
9
Q
What type of nucleotide is ATP?
A
A phosphorylated nucleotide
10
Q
Why is ATP the perfect energy currency? (3 things)
A
- Hydrolysis of an ATP molecule can be done quickly and easily in any part of the cell where energy is required
- Hydrolysis of 1 molecule of ATP releases a useful quantity of energy
- ATP is a relatively stable molecule in a range of pH that normally occurs in cells, doesn’t break down unless there’s a catalyst - ATPase
11
Q
How is ATP made?
A
When a phosphate group combines with ADP
12
Q
There are 2 ways to combine ADP with phosphate. What are they?
A
- Using energy provided directly by another chemical reaction - Substrate linked reaction
- Chemiosmosis - Takes place in the inner membranes of the mitochondria where it uses energy released by the movement of Hydrogen ions down their concentration gradient
13
Q
How is ATP made in humans?
A
Made by respiration, by substrate linked reactions and chemiosmosis
14
Q
How is ATP made in plants?
A
ATP is made in respiration and photosynthesis
15
Q
Why do humans need to continuously breathe for respiration to happen?
A
To get oxygen which can oxidise the glucose and release energy so that ATP molecules can be synthesised
16
Q
What is the main organic molecule used in respiration?
A
Carbohydrates, especially glucose
17
Q
What is special about the brain cells and the respiratory substrate they can use?
A
Brain cells, along with other cells, can only use glucose as their respiratory substrate
18
Q
What other respiratory substrates are there apart from glucose?
A
Proteins, fats, amino acids, glycerol, fatty acids
19
Q
What are the 4 stages in breaking down glucose?
A
- Glycolysis
- Link Reaction
- Krebs Cycle
- Oxidative Phosphorylation
20
Q
What occurs in glycolysis?
A
The splitting or lysis of glucose
21
Q
Where does glycolysis occur?
A
The cyctoplasm
22
Q
What are the reactants in glycolysis?
A
2 ATP molecules and 1 glucose (6C)
23
Q
What are the products of glycolysis?
A
Net gain of 2 ATP molecules and 2 pyruvate molecules and reduced NAD
24
Q
The first stage of glycolysis is phosphorylation. Wha happens here?
A
Phosphate groups are transferred from ATP to the glucose molecule. This raises the energy of the glucose molecule, making it easier for them to react because it makes the glucose molecule unstable.
25
How does the phosphorylation of the glucose molecules happen to end up producing 2 molecules of triose phosphate?
1. 2 ATP molecules are used for each molecule of glucose
2. The donation of the first phosphate group forms glucose phosphate
3. The atoms of the glucose phosphate are rearranged to form fructose phosphate
4. The 2nd ATP molecule donates another phosphate
5. This forms fructose bisphosphate (6C)
6. Fructose bisphosphate breaks down
7. This produces 2 molecules of triose phosphate ( 2 X 3C)
26
How does glycolysis work from 2 triose phosphate molecules turning into 2 pyruvate and a net gain of 2 ATP?
1. The hydrogen is removed from the triose phosphate
2. The hydrogen is transferred to a carrier molecule NAD
3. The triose phosphate is oxidised
4. The NAD is now reduced NAD
5. 2 molecules of reduced NAD produced for each molecule of glucose entering glycolysis
6. Triose phosphate is converted into pyruvate (3C)
7. During this, 2 ATP is produced by transferring a phosphate group from a substrate to an ADP molecule - substrate linked phosphorylation
27
What does a pyruvate molecule have a lot of?
Chemical potential energy
28
What happens to the pyruvate produced in glycolysis if oxygen is available in the cells?
The pyruvate moves through the 2 membranes making up the mitochondrial envelope by active transport (small amount of ATP used for this). Pyruvate enters the mitochondrial matrix
29
Where does the link reaction take place?
The mitochondrial matrix
30
What are the reactants in the link reaction?
Pyruvate (3C)
31
What are the products of the link reaction?
Acetyl CoEnzyme A
32
What happens in the link reaction to produce Acetyl Coenzyme A?
1. Pyruvate produced from glycolysis enters the mitochondrial matrix
2. Enzymes remove CO2 and H from pyruvate
3. This is decarboxylation and dehydrogenation
4. The remainder molecule combines with coenzyme A
5. This produces acetyl coenzyme A
33
What is coenzyme A?
A complex molecule made of a nucleoside combined with a vitamin
Nucleoside = adenine + ribose
Vitamin = Pantothenic acid, Vitamin B5
34
What is coenzyme A needed for?
For an enzyme to catalyse a reaction. Coenzymes don't take part in reactions themselves
35
What does the coenzyme do?
Carries and supplies acetyl groups needed for the conversion of oxaloacetate to citrate
36
How is reduced NAD produced int he link reaction?
The hydrogen that is removed from pyruvate is transferred to NAD, producing more reduced NAD
37
What is the word equation for the link reaction?
Pyruvate + CoA + NAD ------------> Acetyl coA + CO2 + reduced NAD
38
Where does the Krebs Cycle take place?
Mitochondrial matrix
39
What are the reactants in the Krebs cycle?
2 Acetyl CoA
40
What are the products of the Krebs Cycle?
2 CO2, 1 Reduced FAD, 3 reduced NAD, 1 ATP
41
How is the 1 ATP in the Krebs cycle produced?
By the direct transfer of a phosphate group from one of the substrates int eh reactions to an ADP molecule
Substrate linked reaction
42
What is the Krebs Cycle known as?
A circular pathway of enzyme controlled reactions
43
What happens in the Krebs Cycle?
1. Acetyl CoA (2C) combines with oxaloacetate (4C) to form citrate (6C)
2. Citrate is decarboxylated and dehydrogenated in a series of steps
3. This causes CO2 to be released as waste gas, and the release of Hydrogen which is accepted by the carriers FAD and NAD
4. Reduced NAD and Reduced FAD produced
5. Oxaloacetate is regenerated to combine with another acetyl CoA
44
Where does oxidative phosphorylation and the ETC take place?
Inner mitochondrial membrane
45
What is the ETC?
A series of membrane proteins called electron carriers held in the inner membrane (cristae)
46
How does the ETC work?
1. Electron carriers are close to one another
2. Electrons can easily be passed from one carrier to the next, along a chain
3. Each carrier is first reduced (electron added to it)
4. Then it's oxidised (electron remover and passed on)
47
What are the reactions that take place in the ETC called?
Redox reactions
48
What happens in oxidative phosphorylation for an electron to be transferred to the first electron carrier in the ETC?
1. Reduced NAD made in the cytoplasm in glycolysis passes through the mitochondrial envelope to the matrix
2. Reduced NAD and reduced FAD made in the Krebs cycle and reduced NAD made int he link reaction passes into the inner membrane from the matrix
3. The hydrogen being carried by reduced NAD and reduced FAD is removed
4. Each hydrogen in made of a proton and electron
5. The proton (aka H+ ion) and electron split apart
6. The electron is transferred to the first electron carrier in a series of electron carriers
49
What happens in oxidative phosphorylation after an electron is transferred to the first electron carrier in the ETC to produce a concentration gradient?
1. An electron has energy that started off as chemical potential energy in the glucose molecule at the start of glycolysis
2. As the electron moves from one carrier to the next, energy is released
3. Some of this energy is used to actively move protons from the matrix into the intermembrane space
4. This produces a higher concentration of protons in the intermembrane space than the matrix
5. So there's a concentration gradient of protons across the inner mitochondrial membrane
50
What happens in oxidative phosphorylation after a concentration gradient of protons is established across the inner mitochondrial membrane?
Give a symbol equation
1. Protons pass back into the matrix by facilitated diffusion
2. Protons move through protein channels in the membrane that are formed by a large protein molecule and contain the enzyme ATP synthase
3. As protons pass through the channel, energy is used to synthesise ATP in chemiosmosis
4. Oxygen is needed to accept electrons as they arrive at the end of the ETV
5. 4 electrons combine with 4 protons and an oxygen molecule to make H20
02 + 4H+ -------------> 2H20
51
What happens if there is no oxygen?
The processes in the mitochondria stop. The Link, Krebs, and ETC can't take place
52
Why does glycolysis release only a small quantity of chemical potential energy from glucose compared to the ETC?
Because glucose is only partially oxidised in glycolysis. Reactions int he mitochondria release much more energy as there is complete oxidation
53
Draw the table for aerobic respiration with title headings stage, ATP used, ATP made, net gain in ATP
Check 12RE Notes 12.2
54
Draw the diagram for glycolysis explaining what's happening
Check 12RE Notes 12.2
55
Draw the diagram for the link reaction, explaining what's happening
Check 12RE Notes 12.2
56
Draw the diagram for the Krebs cycle, explaining what's happening
Check 12RE Notes 12.2
57
How would you describe the mitochondria?
Rod shaped, filamentous organelles
58
What is the size of the mitochondria?
0.5 to 1.0 micrometer in diameter
59
Are mitochondria rigid organelles?
No, they can change shape
60
What do highly active cells have more of?
Highly active cells have more mitochondria
61
Describe the structure of a mitochondria (3 things)
1. Surrounded by an envelope of 2 phospholipid membranes
2. The outer membrane is very smooth
3. The inner membrane is very folded
62
Why is the inner membrane of the mitochondria folded?
Because it contains cristae to give the membrane a larger total surface area
63
What is significant about mitochondria from more active cells?
Hint: It's about the cristae
They have longer, more densely packed cristae
64
Which is more permeable, the outer or inner membrane of the mitochondria?
The outer membrane is relatively permeable to small molecules and the inner membrane is less permeable
65
What does the outer membrane of the mitochondria allow for with regards to aerobic respiration?
Allows for the movement of substances needed and produced by the link reaction, Krebs, ETC.
66
What substances can pass through the outer membrane of the mitochondria?
O2, CO2, ATP, ADP, Inorganic phosphate, FAD, NAD
67
What does the inner membrane of the mitochondria have scattered all over it?
Tiny spheres (9nm in diameter)
68
What are the tiny spheres attached to the inner membrane by?
By stalks
69
What are the tiny spheres on the inner membrane of the mitochondria?
ATP synthase
70
What is the intermembrane space like compared to the matrix?
Intermembrane space has lower pH than the matrix as protons are transported across the inner membrane from the matrix so it sets up the concentration gradient needed for ATP formation
71
Does a high concentration of protons mean a higher or lower pH?
Lower pH
72
What does the matrix of the mitochondria contain? (3 things)
1. Small 70S ribosomes
2. Several identical copies of mitochondrial DNA to synthesise proteins
3. Circular DNA
73
What happens if there's no or very little oxygen in mitochondria? (5 things)
1. There's nothing to accept the electrons at the end of the chain
2. The ETC stops working
3. No further ATP is formed by oxidative phosphorylation
4. No free carriers in chain to accept hydrogen from NAD and FAD so the NAD and FAD remain reduced
5. The Krebs cycle stops running, as there is no oxidised NAD or FAD to enable dehydrogenation to take place
74
In anaerobic conditions, how can glycolysis still continue to take place and produce a small amount of ATP?
By ethanol fermentation or lactate fermentation
75
Where does lactate and ethanol fermentation take place?
In the cytoplasm
76
In what type of organisms does ethanol fermentation take place?
Yeast and other microorganisms and some plant tissues
77
What happens in ethanol fermentation?
1. Hydrogen from reduced NAD is passed to ethanal
2. Pyruvate is decarboxylated to ethanal
3. Ethanal is reduced to ethanol by the enzyme alcohol dehydrogenase
78
In what type of organisms does lactate fermentation take place?
Other microorganisms and mammalian muscles
79
What happens in lactate fermentation?
1. Pyruvate acts as a hydrogen acceptor
| 2. Pyruvate is converted to lactate by enzyme lactate dehydrogenase
80
What are the differences between lactate fermentation and ethanol fermentation? (3 things)
1. Lactate can be oxidised and converted back to pyruvate, to be fed into the Krebs cycle and generate ATP. Ethanol is a waste product and can't be further metabolised
2. Lactate can be converted to glycogen and stored. Ethanol is a waste product
3. Oxidation fo lactate needs extra oxygen resulting in oxygen debt or Excess post-exercise O2 consumption so we continue to breathe more deeply or heavily after exercise
81
How do lactate and ethanol fermentation allow glycolysis to keep running even with no oxygen available?
Ethanol and lactate fermentation return reduced NAD to its oxidised state so they are ready to accept more hydrogen
82
What type of crop is rice?
A staple crop
83
What type of condition can most varieties of rice survive in?
Dry conditions
84
Where is rice usually grown in large quantities?
Grown in paddies, where the ground is intentionally flooded
85
Rice can tolerate growing in water whilst most weeds that compete with it can't. Why does this benefit rice crops?
It decreases the competition for light and mineral salts, so rice yield increases.
86
Why is it that the roots of plants in water don't get enough oxygen for aerobic respiration? (3 things)
1. In water the leaves are submerged so photosynthesis can't take place as there isn't enough carbon dioxide.
2. Gases diffuse more slowly in water than in air
3. The concentration of dissolved oxygen and carbon dioxide in water is less than in air
87
How do some varieties of rice respond to flooding to help them?
They grow taller so the top parts of the leaves and flower spikes are always held above water. This allows oxygen and carbon dioxide to be exchanged through the stomata on the leaves.
88
What forms the aerenchyma tissue?
Stems and roots of rice plants have loosely packed cells forming aerenchyma tissue
89
What is useful about aerenchyma tissue in plants?
The gases can diffuse through aerenchyma to other parts of the plant, including underwater.
This ensures that the cells in roots at least have some oxygen present in order to aerobically respire
90
When the oxygen isn't enough to supply all cells in the plant, what does the plant, or more specifically the cells in the submerged roots, do?
Uses ethanol fermentation from time to time
91
When ethanol builds up in tissues it can be toxic, how do cells in the plant deal with this?
1. Cells in rice roots can tolerate much higher levels of ethanol than most plants
2. Cells produce ethanol dehydrogenase to break down ethanol
This means the plant can grow actively even with little O2 using ATP produced in ethanol fermentation
92
What is commonly the initial source of energy?
Glucose
93
What are the other respiratory substrates apart from glucose?
Lipids, amino acids, carbohydrates
94
What happens when lipids are respired?
pairs of carbon atoms are removed and fed directly into the Krebs Cycle
95
What happens when amino acids are respired?
They are first converted into pyruvate or acetyl coenzyme A, then move directly into the Krebs Cycle
96
In most cells, what's the order of respiratory substrates that are respired?
1. Glucose
2. Lipids
3. Amino acids as they usually have other important, specialised functions other than being sources of energy
97
What's the energy density of carbohydrate?
15.8 kJg^-1
98
What's the energy density of lipids?
39.4 kJg^-1
99
What's the energy density of protein?
17.0 kJg^-1
100
What is the energy density?
The energy released when respired
101
What respiratory substrate has the greatest energy density?
Lipids
102
What do respiratory substrates with a high energy density contain a high proportion of?
High proportion of Hydrogen atoms in their molecules
103
Why is it that the more hydrogen a molecule has per gram, the more energy it can provide?
Most energy released in aerobic respiration comes from the oxidation of hydrogen to water when reduced NAD and reduced FAD release their Hydrogens to the ETC
104
What is the symbol equation for aerobic respiration?
C6H12O6 + 6O2 ----------------> 6CO2 + 6H2O
105
What is the respiratory quotient?
A ratio of oxygen taken in to carbon dioxide produced. It can help you work out which substrate is being used in respiration and used to see if anaerobic respiration is occurring.
106
What is the formula for finding the RQ value?
vol. CO2 given out / vol. O2 taken in per unit time
Can also be moles, or molecules
107
What is the RQ value for carbohydrate?
1.0
108
What is the RQ value for lipid?
0.7
109
What is the RQ value for protein?
0.9
110
How can oxygen uptake during respiration be measured?
Using a respirometer
111
Draw a small diagram with labelled parts to show how a respirometer works
Check 12RE 12.5 Notes
112
What 2 factors need to be kept constant because they alter the volume of air in the apparatus?
Temperature and pressure
113
Why is soda lime needed in the respirometer?
To absorb the CO2 produced
114
What does the control tube in the respirometer need to have?
An equal amount of inert material which compensates for change in atmospheric pressure
115
How do you find the RQ of an organism with the respirometer?
1. Oxygen consumption is found in cm^3min-1
| 2. Then the apparatus is set up with soda lime
116
What type of fluid is in a respirometer?
Manometer fluid
117
What happens to the level of the fluid in the respirometer if the CO2 produced is greater than the O2 absorbed?
The scale shows the increase in volume of air of the respirometer
118
What happens to the level of the fluid in the respirometer if the CO2 produced is smaller than the O2 absorbed?
The volume of air in the respirometer decreases
119
What redox indicator dyes can you use when investigating respiration in yeast?
DCPIP and Methylene Blue Solution
120
What happens to the dyes when they become reduced?
Go from blue to colourless
121
How do the dyes become colourless?
Dye picks up hydrogen and becomes reduced
122
How would you measure the rate of respiration using dyes?
By measuring the rate of change from blue to colourless
