10. Metabolism

Question 1

Define metabolism

Answer 1

Metabolism - all of the chemical reactions that are happening inside an organism (despite unicellular or multicelluar)

Question 2

What are the two large subgroups of metabolism?

Answer 2

• Anabolic metabolism - consumes E to build large molecules from small components (ex protein synthesis)
• Catabolic metabolism - releases E when complex molecules are broken down into monomers (ex respiration)
• cross talk between the two metabolic processes - due to release / use of E

Question 3

What is a metabolic pathway?

Answer 3

Metabolic pathway - process when a starting molecule is altered in a series of steps to make a final product - each step is catalysed by an enzyme

• Altering structure - function

Question 4

Why does metabolism produce heat?

Answer 4

• The First Law of Thermodynamics: within an isolated system E cannot be created nor destroyed but it can be transferred and transformed
• The Second Law of Thermodynamics: every E transfer or transformation increases the amount of disorder (entropy) in the Universe (due to loss of E as thermal E - heat lost to the environment) (ex in picture - E from cell lost as heat - input of E into environment)

Question 5

What is the difference between the two cells in mitosis?

Answer 5

What is the difference between the two cells in mitosis?

• The first one goes from spherical to oval and divides into neat spherical shapes - healthy cell
• The second one in the division produces blebs - additional bodies - shape not perfectly round - indication of smth going wrong - maybe mutation
• Round spherical shape - most efficient in SA:V which is important for cells - excretion of waste/heat through membrane

Question 6

Explain a spontaneous reaction

Answer 6

• energetically favourable - occur on their own
• increase in entropy -> no input of E required
• spontaneous doesn’t mean it happens quickly (but can occur quickly)

Question 7

How is E available for work inside a cell called? Explain how it can be calculated

Answer 7

Question 8

What can cells do with the E from exergonic reactions?

Answer 8

• anabolism - ex peptide bonds in am a chains
• transport - ex Na-K protein pumps - against conc gradient
• mechanical processes - kinetic E - muscle contraction
• mediated by hydrolysis of ATP

Question 9

From where does E in ATP come from?

Answer 9

• NOT high E bonds in phosphates
• products of ATP hydrolysis are of lower free E than ATP (reactant)