week 13.0 Flashcards
(228 cards)
1
Q
Why is glucose considered a central fuel for our bodies?
A
Glucose is considered a central fuel for our bodies because when fully broken down, it provides a significant amount of energy. It can also be stored efficiently in a polymer form and can be used to create other important molecules such as amino acids, membrane lipids, and DNA and RNA components.
2
Q
How does the oxygen requirement for breaking down glucose compare to breaking down fat?
A
When fully breaking down glucose, less oxygen is required compared to breaking down fat. While fat provides more energy in the form of calories, it requires more oxygen to convert into energy.
3
Q
Why is glycolysis the primary metabolic pathway when there is an abundance of nutrients or a lack of oxygen?
A
When there is an abundance of nutrients or a lack of oxygen, the primary metabolic pathway is glycolysis because it breaks down glucose, requiring less oxygen to produce energy.
4
Q
Why is brisk walking more effective for burning fat compared to intense running?
A
Brisk walking can be more effective for burning fat compared to intense running because fat metabolism requires more oxygen. When food is not available, the body relies on fat as an energy source, but it requires a higher oxygen supply.
5
Q
How is glucose stored in plants and in our bodies?
A
In plants, glucose is stored as starch, which provides nutrients during digestion. In our bodies, glucose is stored as glycogen for later use.
6
Q
Which tissues in our bodies rely mainly on glucose for their energy needs?
A
Tissues such as the liver, red blood cells, and some other cells rely mainly on glucose for their energy needs.
7
Q
How does glucose utilization differ in Escherichia coli bacteria?
A
Escherichia coli bacteria have the ability to convert glucose into any molecule they need for growth. They can use glucose in various ways for different metabolic processes.
8
Q
What are the two main pathways of glucose utilization mentioned in the text?
A
The two main pathways of glucose utilization mentioned in the text are glycolysis and the pentose phosphate pathway.
9
Q
What is the primary outcome of glycolysis?
A
pyruvate and ATP
10
Q
What is the function of the pentose phosphate pathway?
A
The pentose phosphate pathway uses glucose as an alternative source of energy and specifically produces riboses, which are important components of RNA, DNA, and other essential molecules in our body.
11
Q
How is glucose stored for later use?
A
Glucose is stored in a polymer form known as glycogen
12
Q
Besides energy production and storage, what other role does glucose play in the body?
A
Glucose is involved in the synthesis of polymers such as the extracellular matrix and cell wall polysaccharides.
13
Q
Can you summarize the main uses of glucose in the body?
A
Glucose is primarily used for glycolysis to produce energy, but it can also be used through the pentose phosphate pathway for the production of important molecules. It can be stored as glycogen for later use and is involved in the formation of various polymers in the body.
14
Q
What is the main goal of glycolysis?
A
The main goal of glycolysis is to produce energy in the form of ATP and NADH+H+.
15
Q
What is the composition of ATP?
A
ATP is composed of three phosphate groups, ribose (a sugar molecule), and adenine (a component of DNA and RNA).
16
Q
How is the energy stored in ATP released?
A
The energy stored in ATP is released by breaking the high-energy bonds between the phosphate groups.
17
Q
What are some of the cellular processes that utilize the energy released from ATP?
A
The energy released from ATP is used for various cellular processes such as muscle contraction.
18
Q
Besides ATP, what other molecules are synthesized from glucose during glycolysis?
A
Ribose and adenine are also synthesized from glucose during glycolysis.
19
Q
What happens to pyruvate, the end product of glycolysis?
A
- In the presence of oxygen, pyruvate can enter the mitochondria where it undergoes further reactions to produce energy in a process called cellular respiration.
- Alternatively, pyruvate can be used as a building block to create important molecules needed by the body, such as amino acids, proteins, fats, nucleic acids and glucose.
20
Q
How is energy stored during glycolysis?
A
Some of the energy released during glycolysis is stored in the form of ATP and NADH+H+.
21
Q
Can you summarize the importance of glycolysis?
A
Glycolysis is important because it converts glucose into pyruvate, producing energy in the form of ATP and NADH+H+. ATP provides energy for cellular processes, while pyruvate can be used for further energy production and can be used as a building block to create important molecules in the body, such as proteins, fats, and nucleic acids.
22
Q
Where does glycolysis take place in the cell?
A
Glycolysis takes place in the cytosol, which is the fluid part of the cell.
23
Q
In which cells does glycolysis occur at a particularly high rate?
A
Glycolysis occurs at a particularly high rate in the brain and muscles.
24
Q
Why does the brain require a lot of energy?
A
The brain requires a lot of energy for neuronal signaling.
25
Why do muscles need energy?
Muscles need energy to maintain contractions and perform their functions.
26
What is gluconeogenesis?
Gluconeogenesis is the synthesis of glucose from pyruvate.
27
Where does gluconeogenesis take place?
Gluconeogenesis takes place in the cytosol, similar to glycolysis.
28
How does glycolysis regulate the conversion of substrates?
Glycolysis has three regulatory reactions that determine the direction of the conversion process, ensuring whether glucose is used or synthesized within the cells.
Glykolys är en process där glukos bryts ner för att producera energi i cellerna. För att kontrollera denna process och avgöra om glukos ska användas eller bildas, finns det tre reglerande reaktioner. Dessa reaktioner fungerar som vägskäl och bestämmer vilken riktning omvandlingen tar. Om cellen behöver energi kommer processen att gå framåt och glukos kommer att brytas ner för att generera ATP. Å andra sidan, om cellen har tillräckligt med energi och behöver lagra glukos, kommer processen att gå bakåt och glukos kommer att bildas för att lagras för framtida användning. Dessa reglerande reaktioner säkerställer att glukosmetabolismen är anpassad efter cellens energibehov.
29
Can you summarize the key points about glycolysis and gluconeogenesis?
Glycolysis occurs in all cells, with higher rates in the brain and muscles. It takes place in the cytosol and is responsible for producing energy. Gluconeogenesis, also occurring in the cytosol, is the synthesis of glucose from pyruvate. Glycolysis has three regulatory reactions that control the conversion of substrates and determine the use or synthesis of glucose in the cells.
30
How can glycolysis be divided?
Glycolysis can be divided into two phases: the preparatory phase and the payoff phase.
31
What happens in the preparatory phase of glycolysis?
In the preparatory phase, some energy is invested to prepare the glucose molecule for further breakdown and energy production.
32
How many reactions are involved in the preparatory phase of glycolysis?
The preparatory phase consists of the first five reactions in the glycolysis pathway.
33
What is the purpose of the investment of ATP in the preparatory phase?
The investment of ATP in the preparatory phase helps prepare the glucose molecule for further breakdown and energy production.
34
How many ATP molecules are used up in the initial reactions of the preparatory phase?
Two ATP molecules are used up in the first and third reactions of the preparatory phase.
35
What is the purpose of the payoff phase in glycolysis?
The purpose of the payoff phase is to generate energy.
36
What molecules are produced in the payoff phase of glycolysis?
The payoff phase produces ATP and NADH+H+.
37
In which reactions of glycolysis is ATP generated?
ATP is generated in the 7th and 10th reactions of glycolysis.
38
What is the role of NADH+H+ in glycolysis?
NADH+H+ is a cofactor that is generated in the 6th reaction of glycolysis and plays a crucial role in various cellular functions and processes.
39
Why are ATP and NADH+H+ important?
ATP and NADH+H+ are energy-rich molecules that provide the energy necessary for cellular functions and processes.
40
Why do phosphorylated intermediates play an important role in glycolysis?
Phosphorylated intermediates in glycolysis are important because they are not easily transported out of the cell, saving energy for the cell and allowing them to be used for various cellular functions.
41
What is the advantage of phosphorylation in glycolysis?
Phosphorylation forms high-energy bonds with molecules, and when these bonds are broken, they release a significant amount of potential energy that can be utilized for processes like muscle contraction.
42
How does phosphorylation affect enzyme reactions in glycolysis?
When molecules are phosphorylated, it makes enzymes better at their job. It lowers the energy needed to start reactions and helps enzymes pick the right molecules to work on. This makes the reactions happen more efficiently.
43
What are the benefits of phosphorylated intermediates in glycolysis?
The benefits include energy conservation, release of potential energy, and enhanced enzyme efficiency through lowered activation energy and increased specificity.
44
Which step of glycolysis involves the phosphorylation of glucose?
Step 1 of glycolysis involves the phosphorylation of glucose.
45
Why is glucose phosphorylated in the first step of glycolysis?
In the first step of glycolysis, glucose gets a phosphate group added to it. This helps to keep glucose inside the cell and starts the process of breaking it down.
46
What is the purpose of phosphorylating glucose in glycolysis?
During glycolysis, a phosphate group is added to glucose, which prepares it for other reactions and allows the release of energy.
47
What molecule is used to phosphorylate glucose in the first step of glycolysis?
ATP (adenosine triphosphate) is used to phosphorylate glucose in the first step of glycolysis.
48
How does the phosphorylation of glucose contribute to the overall energy production in glycolysis?
The phosphorylation of glucose in step 1 of glycolysis helps to initiate the breakdown of glucose and ultimately leads to the production of ATP, which is a crucial energy molecule.
49
Why is the induced fit conformational change in hexokinase important when glucose is being phosphorylated?
Varför är den inducerade förändringen i hexokinas viktig när glukos blir fosforylerad?
The induced change brings glucose and ATP magnesium closer together and helps phosphorylate glucose, while preventing ATP from being broken down incorrectly.
Den inducerade förändringen gör att glukos och ATP-magnesium kommer närmare varandra och hjälper till att fosforylera glukos, samtidigt som det förhindrar att ATP bryts ner på fel sätt.
50
How does the phosphorylation of glucose contribute to the regulation of glycolysis?
The product of the phosphorylation reaction, glucose-6-phosphate, negatively regulates hexokinase through a feedback mechanism, ensuring that glycolysis is tightly controlled.
51
Why is the phosphorylation of glucose in step 1 of glycolysis considered an irreversible reaction?
The phosphorylation of glucose in step 1 is an irreversible process that helps keep glucose inside the cell and prevents its escape.
52
What is the role of hexokinases in the phosphorylation of glucose?
Hexokinases are special enzymes that help attach a phosphate group from ATP to glucose. This creates a new molecule called glucose-6-phosphate.
53
Which step of glycolysis involves the phosphorylation of glucose?
Step 1 of glycolysis involves the phosphorylation of glucose.
54
Which step of glycolysis is responsible for the phosphorylation of glucose?
Step 1 of glycolysis is responsible for the phosphorylation of glucose.
55
What is the purpose of phosphorylating glucose in step 1 of glycolysis?
When glucose is phosphorylated in step 1 of glycolysis, it means that a phosphate group is added to the glucose molecule. This makes glucose more reactive and can be broken down more easily to produce energy. The phosphorylation also helps keep glucose inside the cell by reducing its concentration outside the cell. by phosphorylating glucose in step 1 of glycolysis, it ensures that there is enough glucose available for the cell to produce energy. This helps maintain a steady supply of fuel for energy production within the cell.
56
What molecule provides the energy required for the phosphorylation of glucose in step 1?
ATP provides the energy needed for the phosphorylation of glucose in step 1 of glycolysis.
57
How does the presence of Mg2+ assist in the phosphorylation of glucose in step 1?
The presence of Mg2+ bound to ATP helps shield the negative charges on ATP, facilitating the attack of the oxygen atom at the 6th carbon of glucose during phosphorylation.
58
Which step of glycolysis involves the conversion of glucose 6-phosphate into fructose 6-phosphate?
Step 2 of glycolysis, known as phosphohexose isomerization, involves the conversion of glucose 6-phosphate into fructose 6-phosphate.
59
What is the purpose of the phosphohexose isomerization step in glycolysis?
In glycolysis, there is a step called phosphohexose isomerization. Its purpose is to make the next steps in the process easier and require less energy. It does this by changing a molecule called glucose 6-phosphate into another molecule called fructose 6-phosphate. This helps the rest of the glycolysis process go more smoothly and saves energy.
60
Which enzyme catalyzes the conversion of glucose 6-phosphate to fructose 6-phosphate in Step 2 of glycolysis?
The conversion of glucose 6-phosphate to fructose 6-phosphate in Step 2 of glycolysis is catalyzed by the enzyme phosphohexose isomerase.
61
How does the rearrangement of glucose 6-phosphate to fructose 6-phosphate in Step 2 conserve energy?
The rearrangement of glucose 6-phosphate to fructose 6-phosphate in Step 2 of glycolysis conserves energy by making the subsequent reactions more favorable, thus requiring less energy.
62
What type of catalysis is involved in the phosphohexose isomerization reaction in Step 2 of glycolysis?
The phosphohexose isomerization reaction in Step 2 of glycolysis involves acid-base catalysis, where certain molecules act as catalysts to facilitate the conversion of glucose 6-phosphate to fructose 6-phosphate.
63
Which step of glycolysis is referred to as the "Second Priming Phosphorylation"?
Step 3 of glycolysis is known as the "Second Priming Phosphorylation."
64
What is the purpose of the Second Priming Phosphorylation step?
The purpose of the Second Priming Phosphorylation step is to further activate glucose and prepare it for the subsequent reactions in glycolysis.
65
What is the role of fructose 6-phosphate in the Second Priming Phosphorylation step?
In the Second Priming Phosphorylation step, fructose 6-phosphate acts as a feed-forward activator for the enzyme phosphofructokinase-1.
66
What is the product of the Second Priming Phosphorylation step?
The product of the Second Priming Phosphorylation step is fructose 1,6-bisphosphate.
67
Why are the phosphate groups in fructose 1,6-bisphosphate important for glycolysis?
The phosphate groups in fructose 1,6-bisphosphate allow for the formation of two three-carbon sugars with one phosphate group each, enabling energy production in later steps of glycolysis.
68
How is the Second Priming Phosphorylation step regulated?
The Second Priming Phosphorylation step is regulated through activation and inhibition via allosteric regulation. Activators such as adenosine monophosphate (AMP), adenosine diphosphate (ADP), and ribulose 5-phosphate enhance the activity of phosphofructokinase-1, while inhibitors like high concentrations of ATP, phosphoenolpyruvate, and citrate suppress its activity.
69
What is the significance of the Second Priming Phosphorylation step being considered the committed step and the rate-limiting step of glycolysis?
Being the committed step and the rate-limiting step, the Second Priming Phosphorylation step exerts significant control over the flux of glucose through glycolysis, ensuring efficient management of glucose concentration and energy utilization within the cell.
70
How does the regulation of the Second Priming Phosphorylation step ensure efficient energy utilization?
The regulation of the Second Priming Phosphorylation step allows for adjustments in response to signals of energy availability and demand in the cell. Activators and inhibitors help maintain appropriate glycolytic activity based on the cell's immediate energy needs.
71
What are the possible fates of glucose regardless of the cell's immediate energy needs?
Regardless of the cell's immediate energy needs, glucose can be stored as glycogen or converted into fatty acids through the breakdown of pyruvate into acetyl coenzyme A.
72
How does the Second Priming Phosphorylation step set the stage for greater energy gain later on in glycolysis?
By utilizing ATP at this early stage, the Second Priming Phosphorylation step sets the stage for greater energy gain in later steps of glycolysis by activating glucose and preparing it for further breakdown.
73
Which step of glycolysis involves the cleavage of fructose 1,6-bisphosphate?
Step 4 of glycolysis, known as the Aldol Cleavage of F-1,6-bP, involves the cleavage of fructose 1,6-bisphosphate.
74
What enzyme is responsible for the cleavage of fructose 1,6-bisphosphate?
The enzyme aldolase is responsible for the cleavage of fructose 1,6-bisphosphate.
75
What are the products of the Aldol Cleavage of F-1,6-bP?
The products of the Aldol Cleavage of F-1,6-bP are dihydroxyacetone phosphate and glyceraldehyde 3-phosphate.
76
How is dihydroxyacetone phosphate different from glyceraldehyde 3-phosphate?
Dihydroxyacetone phosphate is a ketose due to the presence of a keto group, while glyceraldehyde 3-phosphate is an aldose due to the presence of an aldehyde group.
77
Is the cleavage of fructose 1,6-bisphosphate thermodynamically favorable?
No, the cleavage of fructose 1,6-bisphosphate is not thermodynamically favorable. It requires an input of energy.
78
How are the concentrations of dihydroxyacetone phosphate and glyceraldehyde 3-phosphate regulated in the cell?
The concentrations of dihydroxyacetone phosphate and glyceraldehyde 3-phosphate are kept low in the cell. They are rapidly utilized, which drives the reaction forward and promotes the production of these products.
79
What is the significance of the cleavage of fructose 1,6-bisphosphate into dihydroxyacetone phosphate and glyceraldehyde 3-phosphate?
The cleavage of fructose 1,6-bisphosphate into dihydroxyacetone phosphate and glyceraldehyde 3-phosphate is an essential part of glucose breakdown in our cells. These molecules serve as intermediates in further metabolic processes.
80
How is dihydroxyacetone phosphate utilized in cellular metabolism?
Dihydroxyacetone phosphate can be further used for the synthesis of glycerol, which serves as the backbone for storing fat in the form of triacylglycerides.
81
How does the breakdown of glucose into triacylglycerides relate to the consumption of sugary foods?
The breakdown of glucose into triacylglycerides involves synthesizing the glycerol backbone and the fatty acids derived from pyruvate conversion to acetyl-CoA. The consumption of sugary foods can contribute to the production of these fat components and has been linked to the rise in obesity rates.
82
What does the interconnectedness of glucose metabolism and various physiological outcomes emphasize?
The interconnectedness of glucose metabolism and various physiological outcomes highlights the importance of understanding the relationships between glucose metabolism and its impact on overall health and physiological processes.
83
Which step of glycolysis involves the interconversion of dihydroxyacetone phosphate and glyceraldehyde 3-phosphate?
Step 5 of glycolysis, known as the Triose Phosphate Interconversion, involves the interconversion of dihydroxyacetone phosphate and glyceraldehyde 3-phosphate.
84
Why do we need to create two identical molecules of dihydroxyacetone phosphate and glyceraldehyde 3-phosphate?
Creating two identical molecules of dihydroxyacetone phosphate and glyceraldehyde 3-phosphate ensures the efficiency of the glycolysis process.
85
What does it mean for dihydroxyacetone phosphate and glyceraldehyde 3-phosphate to be isomers?
Being isomers means that dihydroxyacetone phosphate and glyceraldehyde 3-phosphate have the same composition but different structures.
86
Why is it important to keep the concentration of glyceraldehyde 3-phosphate low?
The concentration of glyceraldehyde 3-phosphate is kept low to ensure the thermodynamically unfavorable reaction of creating two identical molecules occurs efficiently.
87
What does the completion of the preparative phase of glycolysis signify?
The completion of the preparative phase of glycolysis is signified by the creation of two identical molecules of glyceraldehyde 3-phosphate.
88
How does the metabolic pathway ensure the efficiency of glycolysis in terms of dihydroxyacetone phosphate and glyceraldehyde 3-phosphate?
The metabolic pathway ensures efficiency by interconverting dihydroxyacetone phosphate and glyceraldehyde 3-phosphate to create two identical molecules of glyceraldehyde 3-phosphate.
89
What would happen if dihydroxyacetone phosphate and glyceraldehyde 3-phosphate were not converted into two identical molecules?
If dihydroxyacetone phosphate and glyceraldehyde 3-phosphate were not converted into two identical molecules, it would lead to different reactions and pathways, disrupting the efficiency of glycolysis.
90
How does the interconversion of dihydroxyacetone phosphate and glyceraldehyde 3-phosphate contribute to the overall efficiency of glycolysis?
The interconversion ensures that both dihydroxyacetone phosphate and glyceraldehyde 3-phosphate can proceed through the subsequent steps of glycolysis in a synchronized manner, optimizing the overall efficiency of the process.
91
What is the significance of the thermodynamic favorability of the reaction involving glyceraldehyde 3-phosphate?
The thermodynamic favorability of the reaction involving glyceraldehyde 3-phosphate ensures that the conversion of dihydroxyacetone phosphate and glyceraldehyde 3-phosphate into two identical molecules occurs efficiently, despite it being thermodynamically unfavorable otherwise.
92
How does the interconversion of dihydroxyacetone phosphate and glyceraldehyde 3-phosphate contribute to the overall metabolic efficiency of the glycolysis pathway?
The interconversion of dihydroxyacetone phosphate and glyceraldehyde 3-phosphate allows for the synchronization of reactions and pathways, promoting metabolic efficiency within the glycolysis pathway.
93
What is the purpose of the payoff phase of glycolysis?
The purpose of the payoff phase of glycolysis is to obtain energy in the form of ATP and NADH+H+.
94
How does the payoff phase differ from the preparatory phase of glycolysis?
The preparatory phase of glycolysis involves creating two identical molecules of glyceraldehyde 3-phosphate, while the payoff phase focuses on the production of ATP and cofactors.
95
How many times do the remaining reactions occur during the payoff phase compared to the preparatory phase?
The remaining reactions in the payoff phase occur twice, resulting in twice as much ATP and cofactors being produced.
96
What is the significance of the reactions occurring twice during the payoff phase?
The reactions occurring twice in the payoff phase contribute to the production of a greater amount of ATP and cofactors compared to the preparatory phase.
97
What should be considered when calculating the total ATP production during glycolysis?
It is important to consider that the remaining reactions in the payoff phase occur twice, leading to twice as much ATP and cofactors being produced, when calculating the total ATP production during glycolysis.
98
How does the payoff phase contribute to the overall energy yield of glycolysis?
The payoff phase, by generating ATP and cofactors, contributes to the overall energy yield of glycolysis, enabling the production of energy-rich molecules for cellular processes.
99
What are the specific energy-carrying molecules generated during the payoff phase of glycolysis?
The payoff phase of glycolysis generates ATP and NADH+H+ as energy-carrying molecules.
100
Why is it important to obtain ATP and NADH+H+ during glycolysis?
Obtaining ATP and NADH+H+ during glycolysis is crucial as they serve as energy sources and reduce carriers, respectively, contributing to various cellular functions and processes.
101
How does the payoff phase contribute to the overall efficiency of glycolysis?
The payoff phase, by producing ATP and NADH+H+, enhances the overall efficiency of glycolysis by providing energy-rich molecules that can be utilized by the cell.
102
How does the understanding of the payoff phase help in evaluating the energy output of glycolysis?
Understanding the payoff phase is important for accurately calculating the total ATP production during glycolysis, which allows for a comprehensive evaluation of the energy output of the pathway.
103
What is the main reaction that occurs in Step 6 of glycolysis?
The main reaction in Step 6 of glycolysis is the oxidation of glyceraldehyde 3-phosphate.
104
Which enzyme catalyzes the oxidation of glyceraldehyde 3-phosphate in Step 6?
The oxidation of glyceraldehyde 3-phosphate in Step 6 is catalyzed by the enzyme dehydrogenase.
105
What type of enzymes do dehydrogenases belong to?
Dehydrogenases belong to a class of enzymes called oxidoreductases.
106
What are the cofactors required by dehydrogenases to carry out the oxidation reaction?
Dehydrogenases require NAD or FAD as cofactors to carry out the oxidation reaction.
107
What is the product of the oxidation of glyceraldehyde 3-phosphate in Step 6?
The product of the oxidation of glyceraldehyde 3-phosphate in Step 6 is NADH+H+.
108
How is inorganic phosphate involved in Step 6?
In Step 6, inorganic phosphate is added instead of ATP during the oxidation of glyceraldehyde 3-phosphate.
109
What role does NADH+H+ play in activating the electron transport chain?
NADH+H+ produced in Step 6 serves as the reduced form of the cofactor and plays a role in activating the electron transport chain.
110
Why is Step 6 sensitive to heavy metal inhibitors?
Step 6 is sensitive to heavy metal inhibitors because the active site of the glyceraldehyde 3-phosphate dehydrogenase enzyme contains a cysteine residue that can bind to heavy metals, inhibiting the enzyme's activity.
111
How is the NADH+H+ cofactor reoxidized after Step 6?
The reoxidation of NADH+H+ occurs in the electron transport chain.
112
What is the significance of the product formed in Step 6, 1,3-biphosphoglycerate?
1,3-biphosphoglycerate, the product of Step 6, contains highly energetic phosphorus groups that serve as a potent source of energy after hydrolysis.
113
What are the two forms in which nicotinamide adenine dinucleotide (NAD) exists?
Nicotinamide adenine dinucleotide (NAD) exists in two forms: the oxidized form and the reduced form.
114
How does the reduced form of NAD, known as NADH, pick up hydrogen?
The reduced form of NAD, NADH, picks up one hydrogen directly, while the other hydrogen "tags along."
115
What is the role of NADH in our body's energy production?
NADH plays a crucial role in our body's energy production.
116
How is NADH different from FADH2?
NADH and FADH2 both carry hydrogen, but in NADH, one hydrogen is directly attached, while the other hydrogen "tags along." In contrast, both hydrogens in FADH2 are attached to its structure.
117
What happens to NADH after activating the electron transport chain?
After activating the electron transport chain, NADH creates a lot of potential energy in our body.
118
What is the role of glyceraldehyde-3-phosphate dehydrogenase in glycolysis?
Glyceraldehyde-3-phosphate dehydrogenase helps oxidize glyceraldehyde-3-phosphate (GA3P) in glycolysis.
119
What is the significance of step 6 in glycolysis?
Step 6 is crucial for generating a high-energy phosphate compound and is the first step where energy is produced.
120
What happens during the oxidation of GA3P in step 6?
The aldehyde group in GA3P reacts with NAD+ and forms NADH+H+ during the oxidation process.
121
Why is the cysteine residue in the active site of glyceraldehyde-3-phosphate dehydrogenase important?
The cysteine residue in the active site of the enzyme binds the substrate covalently and creates a high-energy thioester intermediate.
122
What is the effect of heavy metals like mercury on the enzyme glyceraldehyde-3-phosphate dehydrogenase?
Heavy metals like mercury can irreversibly inhibit the enzyme by reacting with the thiol group (SH) in the cysteine residue.
123
Why is the coupling of step 6 with the next reaction important?
The coupling of step 6 with the next reaction in the pathway helps overcome the thermodynamic unfavorable nature of the reaction and pulls the process forward.
124
What is the role of phosphoglycerate kinase in glycolysis?
Phosphoglycerate kinase catalyzes the production of ATP in step 7 of glycolysis.
125
What is the requirement for the reaction catalyzed by phosphoglycerate kinase?
The reaction requires the presence of magnesium.
126
What class of enzymes does phosphoglycerate kinase belong to?
Phosphoglycerate kinase belongs to the enzyme class called kinases.
127
What is the process called when ATP is produced directly from a molecule in the metabolic pathway?
The process is called substrate-level phosphorylation.
128
How many ATP molecules are produced through substrate-level phosphorylation in glycolysis?
Only 2 ATP molecules are produced through substrate-level phosphorylation in glycolysis.
129
How does the overall ATP production compare between full glucose oxidation and glycolysis?
Full glucose oxidation can generate 32 ATP molecules, with only 4 of them coming from substrate-level phosphorylation.
130
Why is full aerobic glycolysis considered a more efficient way to gain energy compared to anaerobic glycolysis?
Full aerobic glycolysis involves both substrate-level and oxidative phosphorylation, which generates a larger amount of ATP, while anaerobic glycolysis relies solely on substrate-level phosphorylation.
131
What is the specific role of phosphoglycerate kinase in glycolysis?
Phosphoglycerate kinase facilitates the first production of ATP in step 7 of glycolysis.
132
What is the name of the process by which ATP is produced in step 7?
The process is called substrate-level phosphorylation.
133
What is the high-energy compound that donates its phosphate group to ADP in the production of ATP?
The high-energy compound is 1,3-biphosphoglycerate.
134
What group of enzymes does phosphoglycerate kinase belong to?
Phosphoglycerate kinase belongs to the group of enzymes called kinases.
135
What is the name of the enzyme responsible for transferring phosphate groups between ATP and other molecules?
Kinases are responsible for transferring phosphate groups between ATP and other molecules.
136
Is the reaction catalyzed by phosphoglycerate kinase reversible?
Yes, the reaction is highly favorable and can be reversed if needed.
137
How is the reaction catalyzed by phosphoglycerate kinase coupled to another reaction in glycolysis?
The reaction is coupled with the glyceraldehyde-3-phosphate dehydrogenase (GA3PDH) catalyzed reaction.
138
What is the specific role of phosphoglycerate mutase in glycolysis?
Phosphoglycerate mutase facilitates the migration of a phosphate group within the phosphoglycerate molecule in step 8 of glycolysis.
139
What is the intermediate formed during the migration of the phosphate group?
The intermediate formed is called 3-bisphosphoglycerate.
140
Where does the phosphate group move to during the migration process?
The phosphate group moves to the second carbon atom of the molecule, creating 2-phosphoglycerate.
141
What type of reaction is the migration of the phosphate group considered?
The migration of the phosphate group is a type of isomerization reaction, specifically a mutase reaction.
142
Does the migration of the phosphate group change the overall structure of the molecule?
No, the migration of the phosphate group does not change the overall structure of the molecule.
143
What is the purpose of the migration of the phosphate group in step 8 of glycolysis?
The purpose is to facilitate the formation of a high-energy phosphate compound in later steps of glycolysis.
144
How is the concentration of the reactant, 3-phosphoglycerate, maintained in the reaction?
The concentration of 3-phosphoglycerate is kept high by the previous step (phosphoglycerate kinase) to drive the reaction forward.
145
What is the purpose of step 9 in glycolysis?
The purpose of step 9 is to generate a high-energy phosphate compound.
146
What is the enzyme involved in step 9?
The enzyme involved in step 9 is a lyase.
147
What happens during the dehydration reaction in step 9?
During the dehydration reaction, water is removed from 2-phosphoglycerate, resulting in the formation of phosphoenolpyruvate (PEP).
148
How does phosphoenolpyruvate impact the third step of glycolysis?
Phosphoenolpyruvate acts as an inhibitor for the third step of glycolysis, exerting a negative feedback effect on that particular step.
149
Why is the dehydration reaction necessary?
The dehydration reaction is necessary to create a more suitable metabolite that can contribute to the production of ATP in the next step.
150
Is the dehydration reaction in step 9 thermodynamically favorable?
The dehydration reaction is slightly thermodynamically unfavorable/reversible.
151
How is the concentration of the product, phosphoenolpyruvate, controlled in the reaction?
The concentration of the product is kept low in order to drive the reaction forward.
152
What is the enzyme involved in step 10 of glycolysis?
The enzyme involved in step 10 is pyruvate kinase.
153
How many ATP molecules are produced in step 10?
In step 10, one ATP molecule is produced. If we consider the overall glycolysis process, two ATP molecules are produced due to the cleavage of glucose into two pyruvate molecules.
154
What is the role of phosphoenolpyruvate in step 10?
Phosphoenolpyruvate donates its phosphate group to ADP, creating pyruvate and ATP.
155
What is the role of phosphoenolpyruvate in step 10?
Phosphoenolpyruvate donates its phosphate group to ADP, creating pyruvate and ATP.
156
How does phosphoenolpyruvate play a regulatory role in glycolysis?
Phosphoenolpyruvate can bind to pyruvate kinase to activate pyruvate formation. However, pyruvate itself can inhibit pyruvate kinase through negative feedback regulation.
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How much ATP is produced from one glycolysis of glucose to pyruvate?
From one glycolysis of glucose to pyruvate, a total of 7 ATP molecules are obtained.
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How does full glucose oxidation compare to glycolysis in terms of ATP production?
Through full glucose oxidation, which converts pyruvate into CO2 and water, 32 ATP molecules can be produced.
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What can inhibit the reaction in step 10?
The reaction in step 10 can be inhibited by high concentrations of ATP, acetyl-CoA, and alanine.
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How can a high-protein diet or tissue breakdown affect glycolysis?
A high-protein diet or tissue breakdown can provide amino acids as an alternative energy source, potentially inhibiting the reaction in step 10 of glycolysis.
161
What is the enzyme involved in step 10 of glycolysis?
The enzyme involved in step 10 is pyruvate kinase.
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What is the process called that is used to produce ATP in step 10?
The process used to produce ATP in step 10 is substrate-level phosphorylation.
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How many ATP molecules can be produced from one glucose molecule in step 10?
From one glucose molecule, a net total of 2 ATP molecules can be produced in step 10.
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What is the role of pyruvate kinase in step 10?
Pyruvate kinase catalyzes the transfer of a phosphate group from phosphoenolpyruvate (PEP) to ADP, leading to the formation of pyruvate and ATP.
165
What are the tautomers of pyruvate?
The tautomers of pyruvate are the enol form and the keto form.
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What is tautomerization?
Tautomerization is the spontaneous and non-enzymatic conversion of one isomeric form to another.
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Which form of pyruvate, enol or keto, is more stable?
The keto form of pyruvate is more stable and common than the enol form.
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How does the stability of the keto form of pyruvate promote the reaction in step 10?
The stability of the keto form ensures that pyruvate quickly converts from its enol form to the more stable keto form, promoting the synthesis of more pyruvate at a faster rate.
169
What are the three main pathways that pyruvate can follow?
The three main pathways that pyruvate can follow are aerobic conditions, anaerobic fermentation (lactate production), and ethanol fermentation.
170
What happens to pyruvate in aerobic conditions?
In aerobic conditions, pyruvate is converted into acetyl-CoA, which activates the citric acid cycle for complete glucose oxidation and energy production.
171
What is the pathway of pyruvate under anaerobic conditions?
Under anaerobic conditions, pyruvate is converted into lactate through fermentation.
172
Where does lactate production occur in the human body?
Lactate production occurs in contracting muscle tissues, erythrocytes (red blood cells), and certain other cells.
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What is the pathway of pyruvate in ethanol fermentation?
In ethanol fermentation, pyruvate is converted into ethanol. This pathway is observed in specific organisms like yeast and certain bacteria.
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In what industries or processes is ethanol fermentation commonly used?
Ethanol fermentation is used in the production of beverages (such as alcoholic drinks) and in baking bread, among other applications.
175
What occurs during anaerobic glycolysis and lactic acid fermentation?
During intense physical activity, when the muscles require more oxygen than can be supplied, anaerobic glycolysis and lactic acid fermentation occur. This is because the oxygen demand exceeds the capacity of the blood system, lungs, and cells to deliver enough oxygen to the muscles.
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What happens to lactate produced during anaerobic glycolysis?
Lactate produced during anaerobic glycolysis is rapidly removed from the muscles and converted back into glucose through a process called gluconeogenesis in the liver.
177
What causes muscle soreness after a workout?
Muscle soreness after a workout is caused by microscopic damage to the muscle fibers that occurred during exercise, not lactic acid buildup.
178
What is the burning sensation felt during intense exercise related to?
The burning sensation felt during intense exercise is related to changes in pH levels in the muscle cells. This sensation occurs as a natural response in our body to protect us from overexertion and potential harm.
179
What is the process of anaerobic glycolysis also known as?
Anaerobic glycolysis is also known as lactic acid fermentation.
180
What enzyme is involved in the conversion of pyruvate to lactate?
The enzyme involved in the conversion of pyruvate to lactate is lactate dehydrogenase.
181
Why is pyruvate converted to lactate during anaerobic glycolysis?
Pyruvate is converted to lactate during anaerobic glycolysis due to the lack of oxygen. This conversion helps regenerate NAD from NADH, allowing glycolysis to continue.
182
What is the fate of lactate produced during anaerobic glycolysis?
The lactate produced during anaerobic glycolysis is carried away from the muscle cells to the liver, where it is converted back into glucose through gluconeogenesis.
183
Why is the conversion of pyruvate to lactate not a sustainable long-term solution?
The conversion of pyruvate to lactate is not a sustainable long-term solution because it produces a small amount of ATP compared to full glucose oxidation, and the body relies on oxygen-dependent processes for efficient energy production.
184
Why do cells like red blood cells rely on anaerobic glycolysis for energy production?
Cells like red blood cells rely on anaerobic glycolysis because they lack mitochondria, which are responsible for reoxidizing NADH involved in energy production.
185
What role does lactate play in anaerobic glycolysis?
Lactate is produced during anaerobic glycolysis as a byproduct. It is a normal component found in the blood, especially from red blood cells, and is later converted back into glucose in the liver through gluconeogenesis.
186
How do red blood cells adapt to the absence of mitochondria?
Red blood cells adapt to the absence of mitochondria by relying on anaerobic glycolysis to produce energy. This pathway allows them to generate ATP without the need for oxygen or mitochondrial metabolism.
187
What happens to the lactate produced by red blood cells during anaerobic glycolysis?
The lactate produced by red blood cells is transported to the liver, where it undergoes gluconeogenesis, a process that converts lactate back into glucose.
188
Why do cancer cells have a high demand for glucose?
Cancer cells have a high demand for glucose because it serves as their main source of energy to fuel their growth and support various metabolic processes.
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How do cancer cells efficiently take in glucose?
Cancer cells express special receptors called glut 1 and glut 3 on their cell surface, which allow them to take in glucose more efficiently compared to other cells.
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How are the glut 1 and glut 3 receptors in cancer cells different from the glut 4 receptor found in muscles and fat cells?
Unlike the glut 4 receptor, which depends on insulin to facilitate glucose uptake, the glut 1 and glut 3 receptors in cancer cells can take in glucose without the need for insulin.
191
What advantage do cancer cells gain from the efficient glucose uptake?
The efficient glucose uptake by cancer cells gives them easier access to glucose, particularly after consuming a meal with carbohydrates. This provides them with more energy to support their growth and metabolic processes.
192
How do the glut 1 and glut 3 receptors contribute to the energy needs of cancer cells?
The presence of glut 1 and glut 3 receptors on the cell surface of cancer cells allows them to uptake glucose independently of insulin, ensuring a constant supply of glucose for their energy demands.
193
Why is the high uptake of glucose in cancer cells utilized in positron emission tomography (PET)?
The high uptake of glucose in cancer cells is utilized in PET scans to investigate the activity and location of cancer cells in the body.
194
How do cancer cells appear in PET scans?
In PET scans, cancer cells appear as bright spots because they absorb specially labeled glucose molecules at a higher rate compared to normal cells.
195
Why are PET scans not always performed on patients unless necessary?
PET scans can be expensive, so they are not always performed on patients unless there is a specific need to investigate the activity and location of cancer cells.
196
What is the purpose of using labeled glucose analogs in PET scans?
Labeled glucose analogs are used in PET scans to detect their uptake by tissues, including cancer cells. These analogs are absorbed but not metabolized, allowing them to highlight the areas of increased glucose uptake in the body.
197
What information can be obtained from PET scans?
PET scans provide information about the activity and location of cancer cells in the body, helping in the diagnosis, staging, and monitoring of cancer.
198
Why do cancer cells have a significantly higher rate of glycolytic enzymes compared to normal cells?
One hypothesis is that cancer cells require a lot of energy for their growth, and the upregulation of glycolytic enzymes provides the necessary metabolites for other important pathways, such as the pentose phosphate pathway.
199
What is the role of the pentose phosphate pathway in cancer cells?
The pentose phosphate pathway, which can be fueled by intermediates of glycolysis, is crucial for DNA and RNA synthesis in rapidly dividing cells like cancer cells. It also generates NADPH+H+ that helps improve the cancer cell's resistance against the immune system.
200
How can inhibiting glycolysis be a potential strategy to combat cancer cells?
Inhibiting glycolysis using medications and drugs can starve cancer cells and reduce their spread, as they heavily rely on glucose for energy production.
201
How can adjusting the patient's diet play a role in fighting cancer cells?
Reducing glucose consumption, especially from fast sugars found in candies, sweets, and sugary beverages, can create competition between cancer cells and vital organs and tissues that also require glucose for energy.
202
Why can substances that inhibit key steps in glycolysis effectively kill cancer cells?
Tumor cells often have increased expression of lactate dehydrogenase (LDH) to support their rapid growth. Inhibiting key steps in glycolysis can limit the energy production of cancer cells, leading to their death.
203
Why is lactate considered an important factor in predicting the overall survival of cancer patients?
Lactate production is increased in cancer cells due to their abundance of glycolytic enzymes. Lactate has been shown to promote cancer growth, metastasis, and resistance to treatment, making it an important factor in predicting patient outcomes.
204
What is the Warburg effect, and how does it relate to lactate accumulation?
The Warburg effect refers to the phenomenon where cancer cells accumulate lactate even in the presence of oxygen. This glycolytic metabolism leads to increased lactate production in cancer cells.
205
How does lactate contribute to cancer growth and metastasis?
Lactate can activate proteinases that help cancer cells spread to other parts of the body, promoting metastasis. It also contributes to immune evasion and the secretion of VEGF, which stimulates the formation of new blood vessels, providing nutrients and oxygen to the tumor.
206
What role does lactate play in resistance to radiation therapy?
High levels of lactate have been associated with resistance to radiation therapy, suggesting that lactate accumulation may contribute to the reduced effectiveness of this treatment method.
207
How can monitoring lactate levels provide insights into cancer prognosis?
Monitoring lactate levels in cancer patients can provide valuable information about tumor progression, potential metastasis, immune response, and response to treatment, helping to assess the prognosis and guide treatment decisions.
208
What is ethanol fermentation, and which organisms use this process?
Ethanol fermentation is a process used by yeast and bacteria to produce ethanol. Yeast and certain bacteria carry out this fermentation process.
209
What happens during the first step of ethanol fermentation, and what enzyme is involved?
In the first step of ethanol fermentation, pyruvate is converted into ethanol. The enzyme responsible for this step is called pyruvate decarboxylase, which removes a carboxyl group from pyruvate.
210
How is carbon dioxide involved in ethanol fermentation, and what effects does it have?
Carbon dioxide is produced in the first step of ethanol fermentation. It creates carbonation in beer, giving it a bubbly texture, and causes dough to rise when baking bread.
211
What is the role of acetaldehyde in ethanol fermentation?
Acetaldehyde is formed as an intermediate in ethanol fermentation and undergoes further reduction to produce ethanol.
212
Why do yeast and bacteria carry out ethanol fermentation, and what is the purpose of reoxidizing NAD?
Yeast and bacteria lack mitochondria, just like humans, so they need a way to reoxidize NAD to continue breaking down sugars and obtain energy. Ethanol fermentation allows them to achieve this.
213
Why is the regulation of glycolysis important?
The regulation of glycolysis is important for maintaining stable ATP levels and providing enough intermediates for biosynthesis.
214
How do ATP consumption and NADH regeneration contribute to the regulation of glycolysis?
Cells balance the production and consumption of ATP and regenerate NADH, which is crucial for energy production, to regulate the rate of glycolysis.
215
What is allosteric regulation, and how does it affect glycolysis?
Allosteric regulation involves the binding of certain molecules to enzymes in the glycolytic pathway, such as hexokinase, PFK1, and pyruvate kinase, influencing their activity and regulating glycolysis.
216
How do the concentration of key metabolites in the cell affect glycolysis?
The concentration of key metabolites reflects the balance between ATP production and consumption and the need for glycolytic intermediates for biosynthesis, thereby influencing the regulation of glycolysis.
217
How do hormones like insulin, glucagon, and epinephrine impact glycolysis?
Hormones can affect glycolysis over a slightly longer time scale by influencing the expression of glycolytic enzymes. Insulin, glucagon, and epinephrine can impact the overall glycolytic activity in the cell through their effects on gene expression and enzyme levels.
218
Where does glycolysis take place in human cells?
Glycolysis takes place in the cytosol of all human cells.
219
Which tissues and cell types in mammals rely on glycolysis as their main source of energy?
Red blood cells, retina, kidney medulla, brain, and sperm rely on glycolysis as their main source of energy.
220
What is the role of glycolysis in breaking down glucose?
Glycolysis is a fundamental pathway for breaking down glucose in cells.
221
What are the two main phases of glycolysis?
The two main phases of glycolysis are the preparatory phase and the payoff phase.
222
What is the outcome of the payoff phase of glycolysis?
The payoff phase of glycolysis results in the production of ATP and NADH+H+, which are important energy molecules.
223
How is glycolysis regulated in our cells?
Glycolysis is tightly regulated by signaling molecules and hormones within our cells.
224
What is the role of glycolysis in synthesizing important substances in our body?
Glycolysis plays a crucial role in producing intermediate molecules that are used for synthesizing fats, amino acids, and other important substances in our body.
225
What is fermentation, and why is it important?
Fermentation is the breakdown of glucose or other organic nutrients to obtain energy in the absence of oxygen. It is important for cells to generate ATP, the energy currency of the cell.
226
What is anaerobic glycolysis, and what is its outcome in human cells?
Anaerobic glycolysis is the breakdown of glucose in human cells in the absence of oxygen, preventing the re-oxidation of NADH+H+. It results in the production of lactate.
227
What is the purpose of ethanol fermentation in yeast and bacteria?
Ethanol fermentation occurs in yeast and bacteria as a way for these microorganisms to obtain energy by breaking down glucose into ethanol (alcohol).
228
Why is anaerobic glycolysis particularly important in cancer cells?
Anaerobic glycolysis is important in cancer cells as it provides them with the energy they need to grow and survive.
