Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

biochem sem 2 > week 13 > Flashcards

week 13 Flashcards

1
Q

Why is glucose considered a central fuel for our bodies?

A

Glucose is an essential source of energy for our bodies. It can be fully broken down to provide a significant amount of energy. Moreover, glucose can be stored efficiently in a polymer form, allowing organisms and tissues to meet their energy needs by using glucose alone.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How does the breakdown of glucose differ from the breakdown of fat in terms of oxygen requirements?

A

The breakdown of glucose requires less oxygen compared to the breakdown of fat. While fat provides more energy in the form of calories, it needs more oxygen to be converted into energy. This distinction is important because the type of energy our cells use depends on the prevailing conditions. When there is an abundance of nutrients or limited oxygen, our primary metabolic pathway is glycolysis, which breaks down glucose.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Why is glycolysis important in situations where there is an abundance of nutrients or limited oxygen?

A

Glycolysis is important in such situations because it allows for the breakdown of glucose to produce energy with less reliance on oxygen. When there is an abundance of nutrients or limited oxygen availability, our cells prioritize glycolysis as the primary metabolic pathway to generate energy from glucose.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How is glucose stored in our bodies?

A

Glucose can be stored efficiently in a polymer form. In plants, it is stored as starch, which serves as a source of nutrients during digestion. In our bodies, glucose is stored as glycogen primarily in the liver, providing a readily available reserve of glucose for later use.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Which tissues rely predominantly on glucose for their energy needs?

A

There are several tissues in our bodies that rely mainly on glucose for energy. The liver plays a significant role in storing and releasing glucose for energy. Red blood cells and certain other cells also primarily depend on glucose for their metabolic needs.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the versatility of glucose in our bodies?

A

Glucose is a versatile molecule that can be used to create a wide range of important molecules in our bodies. It serves as a building block for amino acids, membrane lipids, and components of DNA and RNA, among others. This versatility allows glucose to contribute to various metabolic processes and the synthesis of essential biomolecules.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How does Escherichia coli, a type of bacteria, utilize glucose?

A

Escherichia coli, commonly found in the gastrointestinal tract, has the ability to convert glucose into the specific molecules it requires for growth. This showcases the remarkable adaptability of glucose and its utilization in different metabolic processes within organisms.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the two main pathways for glucose utilization?

A

The two main pathways for glucose utilization are glycolysis and the pentose phosphate pathway.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is glycolysis?

A

Glycolysis is a process in which glucose is converted into pyruvate.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the pentose phosphate pathway?

A

The pentose phosphate pathway is an alternative pathway that utilizes glucose to produce riboses, which are important components of RNA, DNA, and other essential molecules in our body.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How is glucose stored in the body?

A

Glucose is stored in the body in the form of glycogen, a polymer that serves as a reservoir for glucose for later use.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the role of glucose in the synthesis of polymers?

A

Glucose is involved in the synthesis of various polymers, including the extracellular matrix and cell wall polysaccharides.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the key functions of the pentose phosphate pathway?

A

The pentose phosphate pathway produces riboses for the synthesis of RNA, DNA, and other essential molecules in the body.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Can you summarize the major pathways of glucose utilization?

A

Glucose is primarily used in glycolysis to produce pyruvate. It can also be utilized through the pentose phosphate pathway to produce riboses. Glucose is stored as glycogen and is involved in the synthesis of various polymers in the body.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the main purpose of glycolysis?

A

The main purpose of glycolysis is to produce energy in the form of ATP and NADH+H+ from glucose.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is ATP and what role does it play in cellular processes?

A

ATP is a molecule that stores and releases energy. It is composed of three phosphate groups, ribose (a sugar molecule), and adenine (a component of DNA and RNA). ATP provides the energy necessary for various cellular processes, such as muscle contraction.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are the end products of glycolysis?

A

The end products of glycolysis are pyruvate, ATP, and NADH+H+.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How is the energy captured during glycolysis?

A

Some of the energy released during glycolysis is captured in the form of ATP and NADH+H+.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What happens to pyruvate after glycolysis?

A

Pyruvate can undergo further oxidation in the presence of oxygen. It can also serve as a precursor for the synthesis of other important molecules in the body.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Can you summarize the importance of glycolysis?

A

Glycolysis is a process that converts glucose into pyruvate, generating energy in the form of ATP and NADH+H+. ATP provides energy for cellular processes, while pyruvate can be used for further energy production or as a precursor for biosynthesis.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Where does glycolysis take place in the human body?

A

Glycolysis takes place in every cell of the human body, but it occurs at a particularly high rate in the brain and muscles.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Why is glycolysis particularly active in the brain and muscles?

A

The brain requires a lot of energy for neuronal signaling, while muscles need energy to maintain contractions and perform their functions.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Where specifically does glycolysis occur within the cell?

A

Glycolysis occurs in the cytosol, which is the fluid part of the cell.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is gluconeogenesis and where does it take place?

A

Gluconeogenesis is the synthesis of glucose from pyruvate. It also occurs in the cytosol.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

How does glycolysis regulate the use or synthesis of glucose in cells?

A

Glycolysis has three regulatory reactions that determine the direction of the conversion process, ensuring whether glucose is used or synthesized within the cells.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Can you summarize the main points about glycolysis and gluconeogenesis?

A

Glycolysis occurs in all cells, with higher rates in the brain and muscles, and takes place in the cytosol. Gluconeogenesis, the synthesis of glucose from pyruvate, also occurs in the cytosol. Glycolysis has three regulatory reactions that control the conversion of substrates and determine the use or synthesis of glucose in the cells.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

How can glycolysis be divided into different phases?

A

Glycolysis can be divided into two phases: the preparatory phase and the payoff phase.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What happens in the preparatory phase of glycolysis?

A

In the preparatory phase, some energy is invested to prepare the glucose molecule for further breakdown and energy production.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

How many reactions are involved in the preparatory phase of glycolysis?

A

The preparatory phase consists of the first five reactions in the glycolysis pathway.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What role does ATP play in the preparatory phase?

A

In the first and third reactions of the preparatory phase, two ATP molecules are used up. This investment of ATP helps prepare the glucose molecule for further breakdown.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Why might it seem counterintuitive to invest energy in the preparatory phase of glycolysis?

A

It might seem counterintuitive because the overall goal of glycolysis is to produce energy, yet in the preparatory phase, some energy is actually invested.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What is the purpose of the preparatory phase in glycolysis?

A

The purpose of the preparatory phase is to prime the glucose molecule for subsequent breakdown and energy production in the payoff phase of glycolysis.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What is the purpose of the payoff phase in glycolysis?

A

The purpose of the payoff phase in glycolysis is to generate energy.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What specific molecules are produced in the payoff phase of glycolysis?

A

The payoff phase produces ATP and NADH+H+.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

In which reactions of glycolysis can you observe the production of ATP?

A

The production of ATP can be observed in the 7th and 10th reactions of glycolysis.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

What is the significance of ATP in cellular functions and processes?

A

ATP is an energy-rich molecule that is vital for various cellular functions and processes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

What is the role of the NADH+H+ cofactor in the payoff phase?

A

The NADH+H+ cofactor is generated in the 6th reaction of the payoff phase and plays a crucial role in energy transfer and cellular redox reactions.

38
Q

How do ATP and NADH+H+ contribute to cellular processes?

A

ATP provides the energy needed for cellular activities, while NADH+H+ participates in cellular respiration and serves as an electron carrier in metabolic reactions.

39
Q

Why do phosphorylated intermediates play an important role in glycolysis?

A

Phosphorylated intermediates are important in glycolysis because they remain inside the cell and can be used for various cellular functions, saving energy for the cell.

40
Q

What is the advantage of phosphorylation in glycolysis?

A

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.

41
Q

How does phosphorylation affect enzyme reactions in glycolysis?

A

Phosphorylation of molecules lowers the activation energy and increases the specificity of the enzymes that act upon them. This enhances the efficiency of enzymatic reactions.

42
Q

What are the benefits of phosphorylated intermediates in glycolysis?

A

The benefits of phosphorylated intermediates include their inability to easily transport out of the cell, energy conservation, release of potential energy when bonds are broken, and enhanced enzyme efficiency through lowered activation energy and increased specificity.

43
Q

What is the role of hexokinases in glycolysis?

A

Hexokinases are enzymes that transfer a phosphate group from ATP to the 6th carbon atom of glucose in an important step of glycolysis.

44
Q

Why is the transfer of the phosphate group by hexokinases considered an irreversible step?

A

The transfer of the phosphate group is irreversible because cell membranes lack transporters for phosphate sugar molecules, ensuring that once glucose is phosphorylated, it remains inside the cell for cellular processes.

45
Q

How does the phosphorylation of glucose by hexokinases affect glucose concentration inside the cell?

A

The phosphorylation of glucose lowers its concentration inside the cell, allowing more glucose to be transported from the blood.

46
Q

How is hexokinase negatively regulated?

A

Glucose-6-phosphate, the product of the hexokinase reaction, negatively regulates hexokinase through a feedback mechanism.

47
Q

What is the role of magnesium ions in the hexokinase reaction?

A

Magnesium ions serve as cofactors for hexokinase. They form a complex with ATP, reducing the negative charges on the phosphate group and facilitating the nucleophilic attack of the oxygen atom in the glucose molecule.

48
Q

What is the significance of the induced fit conformational change in hexokinase?

A

The induced fit conformational change brings the glucose molecule and the ATP-magnesium complex closer together, facilitating the reaction. It also prevents water from entering the enzyme’s active site and potentially hydrolyzing the ATP, ensuring the reaction proceeds as intended.

49
Q

What is the purpose of the first step in glycolysis, which is the phosphorylation of glucose?

A

The purpose of this step is to trap glucose inside the cell and lower the concentration of glucose outside the cell, ensuring sufficient glucose uptake for energy production.

50
Q

What molecule provides the energy for the phosphorylation of glucose?

A

ATP provides the energy needed for the phosphorylation of glucose.

51
Q

How does the oxygen atom of glucose participate in the phosphorylation reaction?

A

The oxygen atom at the 6th carbon of glucose attacks the last phosphate group of ATP, leading to the phosphorylation of glucose.

52
Q

What is the role of Mg2+ in the phosphorylation reaction?

A

Mg2+ bound to ATP helps shield the negative charges on ATP, facilitating the attack of the oxygen atom and promoting the phosphorylation of glucose.

53
Q

What is the specific subtype of hexokinase called that is primarily found in the liver?

A

The specific subtype is called glucokinase.

54
Q

How does glucokinase differ from other hexokinase isoforms?

A

Glucokinase has a higher Km value, indicating a lower affinity for glucose compared to other hexokinase isoforms. This allows the liver to prioritize glucose storage as glycogen and ensure other tissues receive sufficient energy before the liver stores excess glucose.

55
Q

When is glucokinase typically activated, and what signals its activation?

A

Glucokinase is typically activated after a meal when there is an abundance of glucose available, signaling the need for storage.

56
Q

What is the purpose of the second step in glycolysis, known as phosphohexose isomerization?

A

The purpose of this step is to make the subsequent step easier and require less energy by converting glucose 6-phosphate into fructose 6-phosphate through intramolecular rearrangement.

57
Q

What enzyme catalyzes the conversion of glucose 6-phosphate to fructose 6-phosphate?

A

The enzyme phosphohexose isomerase catalyzes the conversion of glucose 6-phosphate to fructose 6-phosphate.

58
Q

How does phosphohexose isomerase achieve the conversion of glucose 6-phosphate to fructose 6-phosphate?

A

Phosphohexose isomerase rearranges the structure of the molecule, opening and closing the ring structure in a specific way, resulting in the conversion of glucose 6-phosphate to fructose 6-phosphate.

59
Q

How does the conversion of glucose 6-phosphate to fructose 6-phosphate benefit the subsequent reactions in glycolysis?

A

The rearrangement performed by phosphohexose isomerase makes the structure of fructose 6-phosphate more favorable for the subsequent reactions in glycolysis, making them easier to proceed and requiring less energy.

60
Q

What type of catalysis is involved in the mechanism of this conversion?

A

The mechanism of this conversion involves acid-base catalysis, where certain molecules act as catalysts to facilitate the reaction.

61
Q

What is the final result of the phosphohexose isomerization step?

A

The final result is the conversion of glucose 6-phosphate to fructose 6-phosphate, setting the stage for the further steps in glycolysis.

62
Q

What is the purpose of the third step in glycolysis, known as the second priming phosphorylation?

A

The purpose of this step is to further activate glucose and prepare it for the subsequent reactions in glycolysis. It is an important and irreversible reaction considered the committed step of glycolysis.

63
Q

Which molecule acts as a feed-forward activator for the enzyme phosphofructokinase-1 in this step?

A

Fructose 6-phosphate acts as a feed-forward activator for phosphofructokinase-1.

64
Q

What is the product of the second priming phosphorylation step?

A

The product is fructose 1,6-bisphosphate, which contains two phosphate groups attached.

65
Q

What role do the phosphate groups in fructose 1,6-bisphosphate play in glycolysis?

A

The phosphate groups allow for the formation of two three-carbon sugars with one phosphate group each, enabling energy production in later steps of glycolysis.

66
Q

Why is the second priming phosphorylation step considered the committed step of glycolysis?

A

It is considered the committed step because once fructose 1,6-bisphosphate is formed, it is committed to proceeding through the rest of the glycolysis pathway.

67
Q

How is the activity of phosphofructokinase-1 regulated in this step?

A

The activity of phosphofructokinase-1 is regulated through allosteric regulation. Activators such as AMP, ADP, and ribulose 5-phosphate enhance its activity, while inhibitors such as ATP, phosphoenolpyruvate, and citrate suppress its activity.

68
Q

How does the regulation of the second priming phosphorylation step ensure efficient management of glucose concentration and energy utilization within the cell?

A

The regulation allows the cell to respond to signals of energy availability and demand. Activators signal low energy levels, promoting the activity of phosphofructokinase-1, while inhibitors indicate abundant energy availability, suppressing its activity. This ensures efficient management of glucose concentration and energy utilization within the cell.

69
Q

Apart from glycolysis, what are the alternative fates of glucose within the cell?

A

Glucose can be stored as glycogen or converted into fatty acids through the breakdown of pyruvate into acetyl coenzyme A, regardless of the cell’s immediate energy needs.

70
Q

What is the purpose of the fourth step in glycolysis, the aldol cleavage of fructose 1,6-bisphosphate?

A

The purpose of this step is to split fructose 1,6-bisphosphate into two three-carbon sugars, dihydroxyacetone phosphate and glyceraldehyde 3-phosphate.

71
Q

Which enzyme is responsible for the aldol cleavage of fructose 1,6-bisphosphate?

A

The enzyme aldolase is responsible for the cleavage of fructose 1,6-bisphosphate.

72
Q

What are the two molecules formed as a result of the cleavage of fructose 1,6-bisphosphate?

A

The two molecules formed are dihydroxyacetone phosphate and glyceraldehyde 3-phosphate.

73
Q

What is the difference between dihydroxyacetone phosphate and glyceraldehyde 3-phosphate?

A

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.

74
Q

Is the aldol cleavage of fructose 1,6-bisphosphate thermodynamically favorable?

A

No, the reaction is not thermodynamically favorable, as the delta G is positive.

75
Q

How are the concentrations of dihydroxyacetone phosphate and glyceraldehyde 3-phosphate regulated in the cell?

A

The concentrations of dihydroxyacetone phosphate and glyceraldehyde 3-phosphate are kept low in the cell by rapid utilization. This shift towards their production helps drive the reaction forward.

76
Q

What is the significance of the cleavage of fructose 1,6-bisphosphate in glucose breakdown?

A

The cleavage of fructose 1,6-bisphosphate into dihydroxyacetone phosphate and glyceraldehyde 3-phosphate is an essential part of glucose breakdown. These products can be used for various metabolic processes, such as the synthesis of glycerol, which is used for the storage of fat as triacylglycerides.

77
Q

How does the synthesis of triacylglycerides from glucose contribute to obesity?

A

The consumption of sugary foods, which can contribute to the production of the fat components derived from glucose metabolism, has been linked to the rise in obesity rates. Glucose can be converted into triacylglycerides by synthesizing both the glycerol backbone and the fatty acids derived from pyruvate conversion to acetyl-CoA.

78
Q

What does the interconnectedness of these processes highlight?

A

The interconnected processes of glucose metabolism and the synthesis of molecules like triacylglycerides emphasize the importance of understanding the relationships between glucose metabolism and various physiological outcomes in our bodies.

79
Q

What is the purpose of creating two identical molecules, dihydroxyacetone phosphate and glyceraldehyde 3-phosphate, in glycolysis?

A

The purpose is to ensure efficient continuation of the glycolysis process. These molecules are isomers with the same composition but different structures.

80
Q

What would happen if dihydroxyacetone phosphate was further oxidized instead of creating identical molecules?

A

Further oxidation of dihydroxyacetone phosphate would lead to different reactions and pathways compared to glyceraldehyde 3-phosphate. This would disrupt the efficiency of the metabolic pathway.

81
Q

Why is it important for the metabolic pathway to create two identical molecules of glyceraldehyde 3-phosphate?

A

Creating two identical molecules ensures consistency and efficiency in the subsequent reactions of glycolysis.

82
Q

How does the completion of the preparative phase of glycolysis relate to creating identical molecules?

A

Creating two identical molecules of glyceraldehyde 3-phosphate marks the completion of the preparative phase of glycolysis.

83
Q

Why is the concentration of glyceraldehyde 3-phosphate kept low?

A

The concentration of glyceraldehyde 3-phosphate is kept low to promote the occurrence of this reaction, as it is not thermodynamically favorable otherwise.

84
Q

What is the purpose of the payoff phase in glycolysis?

A

The purpose is to obtain energy in the form of ATP and NADH+H+.

85
Q

What happened in the preparatory phase that impacts the payoff phase?

A

In the preparatory phase, two identical molecules of glyceraldehyde 3-phosphate were created, which affects the subsequent reactions in the payoff phase.

86
Q

How does the number of reactions in the payoff phase differ from the preparatory phase?

A

The remaining reactions in the payoff phase occur twice, resulting in twice as much ATP and cofactors being produced.

87
Q

Why is it important to consider the number of reactions in the payoff phase when calculating total ATP production?

A

Considering the number of reactions in the payoff phase is important because it directly influences the total ATP production during glycolysis.

88
Q

How does the payoff phase contribute to overall energy production in glycolysis?

A

The payoff phase generates ATP and NADH+H+, contributing to the overall energy production in glycolysis.

89
Q

What is the role of the enzyme dehydrogenase in the 6th step of glycolysis?

A

The enzyme dehydrogenase catalyzes the oxidation of glyceraldehyde 3-phosphate in the 6th step of glycolysis.

90
Q

What are the cofactors required by dehydrogenases to carry out the reaction?

A

Dehydrogenases require NAD or FAD as cofactors to carry out the reaction.

91
Q

What is the product of the oxidation of glyceraldehyde 3-phosphate in this step?

A

The product is NADH+H+, which is the reduced form of the cofactor.

biochem sem 2 (7 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions