1
Q
What is glucose
A
Is is a 6-carbon ring molecule produced during photosynthesis
2
Q
What occurs during respiration
A
The carbon framework of glucose is broken down and the carbon hydrogen bonds broken.
The energy released is then used in the synthesis of ATP by chemiosmosis.
3
Q
What is a feature of ATP
A
It is constantly being synthesised and used in energy-requiring reactions and processes.
4
Q
What occurs in prokaryotes
A
A similar process for respiration however they don’t have mitochondria so many of the cellular reactions take place on plasma membranes
5
Q
What is the flowchart of the steps that occur in respiration
A
DRAW IT
6
Q
Where does glycolysis occur
A
In the cytoplasm of the cell
7
Q
What are features of what is required for glycolysis
A
It does not require oxygen and is an anaerobic process
8
Q
What occurs in glycolysis
A
Glucose is split into 2 smaller 3-carbon pyruvate molecules
ATP and reduced nicotinamide adenine dinucleotide (NAD) are also produced
9
Q
What are the steps for glycolysis (1)
A
- Phosphorylation- the first step of glycolysis requires 2 molecules of ATP. Two phosphates, released from two ATP molecules, are attached to a glucose molecule forming hexose biphosphate.
- Lysis - this destabilises the molecule causing it to split into two triode phosphate forming two triode phosphate molecules
10
Q
What are the steps for glycolysis (2)3
A
- Phosphorylation - another phosphate group is added to each triose phosphate forming two triose biphosphate molecules
The two phosphates come from inorganic phosphorus ions present in the cytoplasm
11
Q
What are the steps for glycolysis (3)
A
- Dehydrogenation and formation of ATP - the two triose biphopshate molecules are then oxidised by the removal of hydrogen atoms to form two pyruvate molecules. NAD coenzymes accept the removed hydrogens forming two reduced NAD molecules.
12
Q
What are the steps for glycolysis (4)
A
AT the same time 4 ATP molecules are producing using phosphates from the triose biphosphate molecules.
13
Q
What is glycolysis and example of
A
Substrate level phosphorylation
14
Q
What is substrate level phosphorylation
A
The formation of ATP without the involvement of the electron transport chain, and ATP is instead formed from the transport of phosphate groups from a phosphorylated intermediate to ADP.
15
Q
What are the ATP molecules used and what does this mean
A
To start the process at the beginning of glycolysis so the net yield of ATP for glycolysis is 2 molecules of ATP
16
Q
Draw the mitochondria and the different parts present inside of it
A
DRAW IT
17
Q
What are do the different parts of the mitochondria do (1)
A
Outer mitochondrial membrane - separates the contents of the mitochondrion form the rest of the cell, creating a cellular compartment with ideal conditions for respiration
Matrix - contains enzymes for the Krebs cycle and the link reaction also contains mitochondrial DNA
18
Q
What are do the different parts of the mitochondria do (2)
A
Inner mitochondrial membrane - contains electron transport chain and ATP synthase
Cristae - are projections of the inner membrane increasing the SA for oxidative phosphorylation
Intermembrane space - protons are pumped into this space by the electron transport chain - the space is small so the concentration builds up quickly
19
Q
What is oxidative decarboxylation and what is another name for it
A
The first step in aerobic respiration
The link reaction also
20
Q
Why is oxidative decarboxylation called the link reaction
A
It is the step that links anaerobic glycolysis occurring in the cytoplasm, to the aerobic steps of respiration, occurring in the mitochondria.
21
Q
What is the general flowchart for oxidative decarboxylation
A
DRAW IT
22
Q
How does the pyruvate enter the mitochondria in eukaryotes
A
It enters the mitochondrial matrix, by active transport via specific carrier proteins.
23
Q
What occurs after the pyruvate enters the mitochondrial matrix (1)
A
It then undergoes decarboxylation - CO2 is removed along with hydrogen
The hydrogen atoms removed are accepted by NAD. NAD is reduced to form NADH.
The resulting two carbon acetyl group is then bound to coenzyme A forming acetylcoenzyme A.
24
Q
What occurs after the pyruvate enters the mitochondrial matrix (2)
A
Acetyl COA delivers the acetyl group to the next stage of aerobic respiration known as the Krebs cycle.
The reduced NAD is used in oxidative phosphorylation to synthesise ATP.
25
What happens to the CO2 that is produced in the link reaction
The CO2 will diffuse away or be removed from the organism as a metabolic waste, or in autotrophs be used in photosynthesis.
26
Where does the Krebs cycle occur and what does each complete cycle result in
In the mitochondrial matrix with each complete cycle resulting in the breakdown of an acetyl group.
27
What are the products from the oxidative decarboxylation reaction that feed into the Krebs cycle
Acetyl groups are all that remain of the glucose and enter the Krebs cycle
28
What are the different processes that occur in the Krebs cycle
Decarboxylation, dehydrogenation and substrate-level phosphorylation.
29
What are the hydrogen atoms released in the Krebs cycled used for and what is produced as a byproduct of the Krebs cycle
They are picked up by the coenzymes NAD and FAD
CO2 is also produced as a by-product of the reaction and the ATP produced is available from use by energy-requiring processes within the cell
30
What are the reduced NAD and FAD used in
The final oxygen-requiring stage of aerobic respiration to produce large quantities of ATP by chemiosmosis.
31
What are the steps of the Krebs cycle (1)
1. Acetyl COA delivers an acetyl group to the Krebs cycle. The acetyl group combines with 4 carbon oxaloacetate to form six-carbon citrate
2. The citrate molecule undergoes decarboxylation and dehydrogenation producing one reduced NAD and CO2. A 5 carbon compound is formed
32
What are the steps of the Krebs cycle (2)
3. The 5 carbon compound undergoes further decarboxylation and dehydrogenation reactions, eventually regenerating oxaloacetate, and the cycle continues. More CO2, two more reduced NAD, and one reduced FAD is produced.
ATP is also produced by substrate level phosphorylation
33
What are coenzymes required for in respiration (1)
To transfer protons, electrons and functional groups between many of the enzyme-catalysed reactions.
34
What are coenzymes required for in respiration (2)
As without coenzymes transferring electrons and protons between these reactions many respiratory enzymes would be unable to function as redox reactions would not occur.
35
What are NAD and FAD examples of
Coenzymes that accept protons and electrons released during the breakdown of glucose during respiration.
36
What are the differences between NAD and FAD (1)
. NAD takes part in all stages of cellular respiration but FAD only accepts hydrogens in the Krebs cycle
. NAD takes one hydrogen and FAD accepts two hydrogens
37
What are the differences between NAD and FAD (2)
Reduced NAD is oxidised at the start of the electron transport chain releasing protons and electrons whereas reduced FAD is oxidised further along the chain
Reduced NAD results in the synthesis of 3 ATP molecules, but reduced FAD only results in the synthesis of two ATP molecules
38
How should NAD be represented
As NAD is actually charged it should be represented as NAD+, and when it accepts two protons and an electron pair it forms NADH + H. The reduced NAD then transfers the proton and electron pair to a subsequent reaction.
39
What are coenzymes derived from
Vitamins
40
What happens to the hydrogen atoms that are collected by NAD and FAD and where does this occur
They are delivered to the electron transport chain present in the membranes of the Cristae of the mitochondrion
41
What occurs in the electron transport chain (1)
The hydrogen atoms dissacociate into hydrogen ions and electrons.
The high energy electrons are used in the synthesis of ATP by chemiosmosis.
42
What occurs in the electron transport chain (2)
energy is released during redox reactions as the electrons reduce and oxidise electron carriers as they flow along the electron transport chain.
This energy is used to create a proton gradient leading to the diffusion of protons through ATP synthase resulting in the synthesis of ATP.
43
What occurs in the electron transport chain (3)
At the end of the electron transport chain the electrons combine with hydrogen ions and oxygen to form water. Oxygen is the final electron acceptor and the electron chain can’t operate unless oxygen is present.
44
What is respiration that involves the complete breakdown of glucose therefore
An aerobic process as oxygen is required to be the final acceptor
45
What is the phosphorylation of ADP to ATP dependant on
Electrons moving along electron transport chains. This requires the presence of oxygen and is known as oxidative phosphorylation.
46
Why does the hydrogen released by NAD and FAD not combine directly with oxygen
It could combine directly with oxygen, releasing energy from the formation of bonds during the production of water. However this energy would not be used to synthesise ATP, and would instead only increase the temperature of the cell.
47
What is oxidative phosphorylation
The coupling of the flow of protons down the electrochemical gradient through ATP synthase to the phosphorylation of ADP to produce ATP.
48
What is the comparison between aerobic and anaerobic respiration
Aerobic respiration is a much more efficient process than anaerobic respiration so it was rapidly selected for
49
What are obligate anaerobes
Organisms that can’t survive in the presence of oxygen with almost all being prokaryotes and a few fungi.
50
What are facultative anaerobes
Synthesise ATP by aerobic respiration if oxygen is present but can switch to anaerobic respiration in the absence of oxygen e.g yeast
51
What are obligate aerobes
They can only synthesise ATP in the presence of oxygen for example, mammals.
52
What can the individual cells in some organisms be
The individual cells of some organisms, such as muscle cells in mammals, can be described as facultative anaerobes because they can supplement ATP supplies by employing anaerobic respiration in addition to aerobic respiration when oxygen concentration is low.
53
What is a limitation of those individual cells carrying out anaerobic respiration
This can only be for short periods and oxygen is eventually required. The shortfall of oxygen during the period of anaerobic respiration produces compounds that have been broken down when oxygen becomes available again, so the organsims as a whole is an obligate anaerobe.
54
What is fermentation
It is a form of anaerobic respiration and is the process by which complex molecules are broken down into simpler inorganic compounds without the use of oxygen or the involvement of the electron transport chain.
55
What occurs during fermentation to do with how much ATP is produced
The inorganic compounds like glucose aren’t fully broken down so fermentation produces much less ATP than aerobic respiration.
With the small quantity of ATP being produced by substrate level phosphorylation alone.
56
What are the two main types of anaerobic respiration and their products
Alcoholic fermentation - occurs in yeast and some plant cells, where the product is ethanol and CO2
Lactate fermentation results in the production of lactate and is carried out in animal cells
57
Why does a lack of oxygen stop aerobic respiration (1)
When there is no oxygen to act as the final electron acceptor at the end of the electron transport chain in oxidative phosphorylation the flow of electrons stops, meaning the synthesis of ATP by chemiosmosis also stops.
58
Why does a lack of oxygen stop aerobic respiration (2)
The reduced NAD and FAD are no longer able to be oxidised as there is nowhere for the electrons to go.
So as a result NAD and FAD can’t be regenerated and so decarboxylation and oxidation of pyruvate and the Krebs cycle comes to a halt as there are no coenzymes to accept the hydrogens being removed.
59
Why does glycolysis halt during a lack of oxygen too
Due to the lack of NAD
60
What occurs during anaerobic respiration in mammals (1)
Pyruvate can act as a hydrogen acceptor taking the hydrogen from reduced NAD, catalysed by the enzyme lactate dehydrogenase.
The pyruvate is converted into lactate and NAD is regenerated.
61
What occurs during anaerobic respiration in mammals (2)
This can be used to keep glycolysis going so a small quantity of ATP is still synthesised.
62
In mammals what will be occurring at the same time as anaerobic respiration
It will be supported by ATP form aerobic respiration, which is still being produced as fast as oxygen can get delivered to other parts of the body.
63
What happens to the lactic acid and what is required for it to be broken down
It is removed from muscles and taken to the liver by the bloodstream.
It is then converted back to glucose in the liver, but oxygen is required to complete this process. This is the reason for oxygen debt and heavy breathing after exercise.
64
Why can’t lactate fermentation occur indefinitely
—> reduced quantities of ATP produced would not be enough to maintain vital processes for a long period of time
—> accumulation of lactic acid causes a fall in pH leading to proteins denaturing. Respiratory enzymes are made form proteins and will cease to function at low PHs too.
65
What can an increase in physical fitness do
Increase the blood supply and flow through muscles. Increasing the rate of lactic acid removal allowing the intensity and duration of exercise to be increased.
66
What occurs during alcoholic fermentation (1)
Pyruvate is first converted to ethanol, catalysed by the enzyme pyruvate decarboylase.
Ethanol can then accept a hydrogen atom from reduced NAD becoming ethanal.
The regenerated NAD can then continue to act as a coenzyme and glycolysis can continue.
67
What are features of alcoholic fermentation
Is it not a reversible process like lactate fermentation
This is not a short-term process and can continue indefinitely in the absence of oxygen.
68
What are features of ethanol
It is a toxic waste product to yeast cells, and they are unable to survive if the ethanol accumulate above approximately 15%.
69
What are other respiratory substrates
Molecules such as triglycerides, and amino acids are broken down to release energy for the synthesis of ATP too.
70
How are triglycerides used as a respiratory substrate
Triglycerides are hydrolysed to fatty acids and glycerol, this will then enter the Krebs cycle by CoA and glycerol.
Glycerol is first converted to pyruvate before undergoing oxidative decarboxylation.
The fatty acids in a triglyceride molecule can lead to the formation of 50 CoA molecules., resulting in the synthesis of up to 500 ATP molecules.
71
What is the order of how much energy each respiratory substrate releases
Lipids release twice as much energy as carbohydrates, alcohols contain more energy than carbohydrates but less than lipids. Proteins are roughly equivalent to carbohydrates.
72
How are proteins used as respiratory substrates and what is a feature of it
They have to be hydrolysed to amino acids and then the amino acids have to be deaminted before they enter the respiratory pathway, usually via pyruvate.
—> these steps require ATP, reducing the net production of ATP
73
What is the RQ of a substrate
It is calculated by dividing the volume of CO2 released by the volume of oxygen taken in during respiration of that particular substrate.
RQ = CO2 produced/ O2 consumed
74
How is RQ measured
using a respirometer
75
Why do lipids release so much energy
As they contain a greater proportion of C-H bonds than carbohydrates which is why they produce so much more ATP in respiration.
76
Why is the RQ for lipids relatively low
Due, to the greater number of carbon-hydrogen bonds, lipids require relatively more oxygen to break them down, and release relatively less CO2.
77
What is the RQ for lipids, carbohydrates and amino acids
Carbohydrates - 1.0
Protein - 0.9
Lipids - 0.7
78
How can u determine the respiratory substrate
By measuring the O2 taken in and CO2 released and calculating RQ the type of substrate being used for respiration can roughly be determined
79
What is the RQ during the normal activity of mammals and what does this tell you
The RQ is in the range of 0.8-0.9, during anaerobic respiration it increases above 1.0
Indicating a mix of carbohydrates, amino acids and lipids are being used.
80
How many atp molecules are produced by substrate level phosphorylation in the Krebs cycle
1 ATP molecule is produced per turn of the cycle in the Krebs cycle
A Level Biology OCR
flashcards
Decks in class (77)
# Cards
-
Magnification34
-
Biological Molecules (water)26
-
Staining12
-
Cells And Organelles59
-
Mono And Disaccharides28
-
Polysaccharides26
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Prokaryotic Cells13
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Stem Cells34
-
Testing For Sugars17
-
Enzymes64
-
Lipids32
-
Proteins67
-
Inorganic Ions10
-
Chromatography12
-
ATP21
-
Nucleic Acids And Nucleotides35
-
DNA Replication28
-
Protein Synthesis33
-
Cell Division (Mitosis And The Cell Cycle)36
-
Biological Membranes41
-
Transport Across Membranes69
-
Cell Divison By Meiosis34
-
Specialised Cells And Tissues55
-
Surface Area To Volume Ratio12
-
Gas Exchange In Mammals/Humans56
-
Circulatory Systems23
-
Blood Vessels41
-
Gaseous Exchange In Bony Fish And Insects49
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Plant Transport56
-
The Heart33
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Transpiration And Movement Of Water Throuhg The Roots59
-
Blood And Tissue Fluid23
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Transport Of Carbon Dioxide And Oxygen50
-
Potometers13
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Adaptations Of Xerophytes And Hydrophytes23
-
Biodiversity And Sampling57
-
ECGs18
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Translocation21
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Factors Affecting Biodiversity, Reasons To Conserve It And Conservation Methods58
-
Plant Diseases48
-
Statical Tests8
-
The Human Immune System73
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Classification And Evolution31
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Phylogeny15
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The Human Immune System Part 255
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Evolution51
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Ecosystems61
-
Succession27
-
Populations39
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Ecosystem Management - Masai Mara Case Study15
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Mutations36
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Gene Regulation64
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Patterns Of Inheritance69
-
Biotechnology70
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Cloning And Enzymes Used In Biotechnology68
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Manipulating Genomes43
-
Sequencing16
-
Computational Biology And Bioinformatics27
-
Genetic Engineering64
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Thermoregulation40
-
The Endocrine System (1)49
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Non Specific Animal Defenses And Animal Diseases27
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Cloning And Biotech33
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Neuronal Communication (1)63
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The Endocrine System (2)42
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Neuronal Communication (2)66
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Respiration80
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Energy For Biological Processes30
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Photosynthesis56
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Neuronal Communication (3)71
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The Endocrine System (3)33
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The Kidney82
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Urine Diganosis And Dialysis46
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Excretion, Homeostasis And The Liver38
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The Endocrine System (3)31
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Plant Responses (1)58
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Plant Responses (2)58
