Topic 5: Energy Reactions In Cells

Question 1

What is the definition of cell metabolism?

Answer 1

Highly integrated network of chemical reactions that occur within cells

Question 2

What are the functions of cell metabolism?

Answer 2

Cells metabolise nutrients to provide:

• Energy for cell function and synthesis of ATP
• Building block molecules that are used in synthesis of cell components needed for the growth, repair and division of the cell
• Organic precursor molecules that are used to allow the inter conversion of building block molecules
• Biosynthetic reducing power used in the synthesis of cell components

Question 3

What is a catabolic pathway?

Answer 3

• Breaking down larger molecules into smaller ones (intermediary metabolites)
• Releases large amounts of free energy
• Oxidative -> releases H atoms / reducing power

Question 4

What is an anabolic pathway?

Answer 4

• Synthesizing larger important cellular components from intermediary metabolites
• Uses energy released from catabolism (ATP)
• Reductive (uses H+ released in catabolism)

Question 5

What is the relationship between catabolism and anabolism?

Answer 5

• Anabolism synthesizes larger important cellular components from intermediary metabolites produced from catabolism
• Anabolism uses energy released from catabolism
• Anabolism uses reductive power released by catabolism

Question 6

Why do cells need a continuous supply of energy?

Answer 6

There is a limited amount of ATP and carriers,so a continuous cycle is needed.

Question 7

What is the role of redox reactions in metabolism?

Answer 7

• Oxidation reactions releases chemical bond energy and reducing power
• Reducing power is converted to ATP by oxidative phosphorylation
• Energy and reducing power are used to drive the synthesis of new molecules or to produce work
• Reducing power and energy transferred between those pathways using carriers

Question 8

What is the biological role of ATP?

Answer 8

Energy currency

Question 9

What is the role of phosphorylated compounds containing high energy of hydrolysis?

Answer 9

Phosphoenolpyruvate and 1,3-biophosphoglycerate is important in producing ATP a from ADO in glycolysis via substrate level phosphorylation.

Question 10

What is the biological role of creatine phosphate?

Answer 10

When ATP levels are high, phosphate bond energy may be stored by forming creatine phosphate. If ATP concentration falls suddenly, the reaction reverses and creatine phosphate forms ATP. Hence, creatine phosphate is used as a store of free energy that can be used immediately.

Question 11

What are the roles of high and low energy signals in the regulation of metabolism?

Answer 11

• When concentration of ATP is high, high energy signals activate anabolic pathways to use ATP and synthesize cellular components
• When concentration of ATP is low, low energy signals activate catabolic pathways to break down larger molecules into intermediary metabolites to produce ATP