1. Lecture 13: Metabolic pathways and energy production
Chemistry - FALL 2016
Course lecturer :
Jasmin Šutković
10 th January 2017

2. Contents Flow of energy ATP Metabolism How Enzymes work
International University of Sarajevo
Flow of energy
ATP
Metabolism
How Enzymes work
Cellular respiration

3. Energy: the capacity to do work -kinetic energy: the energy of motion
Flow of Energy
Energy: the capacity to do work
-kinetic energy: the energy of motion
-potential energy: stored energy
Energy can take many forms: chemical, mechanical, electric current, heat, light

5. ATP - Energy Currency of Cells
ATP is the molecule that cells use to store, transfer, and provide energy
The energy from ATP is used to fuel anabolic reactions
recall: for growth, repair, and reproduction
ATP = Adenosine TriphosPhate
Adenosine (same molecule from DNA and RNA) +
Three inorganic phosphates (functional group PO4)

6. ATP - Energy Currency of Cells
ATP = adenosine triphosphate
the energy “currency” of cells
ATP structure:
ribose, a 5-carbon sugar
adenine
three phosphates

7. Photo Courtest of Dr. O’Steen

9. ATP - Energy Currency of Cells
ATP - 1 PO4 = ADP (Adenosine Diphosphate)
ADP - 1 PO4 = AMP (Adenosine Monophosphate)
ADP + 1 PO4 = ATP 9

10. ATP is a molecule that is used as an Energy Currency in cells
ATP’s can be broken down to provide energy for endergonic reactions
Cells use energy to build ATP’s
Enzymes of allow cells to efficiently build ATP’s - Cells can make ATP’s for less energy than ATP’s can provide

11. ATP - Energy Currency of Cells
ATP stores energy in the covalent bonds between phosphates:
Phosphates are highly negative, therefore:
the phosphates repel each other
much energy is required to keep the phosphates bound to each other
Energy is released when the bond between two phosphates is broken

12. Energy Currency of Cells
When the bond between phosphates is broken:
ATP ADP + Pi
energy is released
ADP = adenosine diphosphate
Pi = inorganic phosphate
This reaction is reversible...

13. ATP/ADP Cycling

14. ATP regulates enzyme activity
Other Functions of ATP
ATP regulates enzyme activity
Phosphorylation and dephosphorylation - process of adding or removing phosphate groups - can activate or deactivate enzymes
ATP serves as a source of phosphate groups 14

15. Three rules to be considered an enzyme
Enzymes
Enzymes: molecules that catalyze - speed up - biochemical reactions in living cells
Three rules to be considered an enzyme
Most are proteins (some RNA enzymes)
Lower the energy of activation required for a reaction to occur
Are not changed or consumed by the reaction
Cofactors, Coenzymes 15

16. Metabolism Enzymes catalyze cellular chemical reactions
Metabolism - the chemical reactions in a cell:
Two categories of cellular chemical reactions:
Anabolic Reactions
Build larger molecules for growth, repair, reproduction
Dehydration Synthesis Reactions
require energy and nutrients
Catabolic Reactions
Breakdown larger molecules
Hydrolysis Reactions
mobilize nutrients for energy making it available to the cell

17. Metabolism
Metabolism is the sum total of all anabolic and catabolic reactions that occur in the cell
The metabolism of cells is carried out and controlled by the enzymes
There are catabolic enzymes – those that cleave larger molecules into smaller ones
Ex. Hydrolysis Reactions
There are also anabolic enzymes – those that assemble smaller molecules into larger ones
Ex. Dehydration Reactions

18. Enzymes interact with substrates.
substrate: molecule that will undergo a reaction
active site: region of the enzyme that binds to the substrate
Binding of an enzyme to a substrate causes the enzyme to change shape, producing a better induced fit between the molecules.

19. Enzymes lower the activation energy of biochemical reactions.
How Enzymes Work
Enzymes lower the activation energy of biochemical reactions.
Enzymes make it easier for chemical reactions to occur:
by destabilizing the bonds in the substrate
by bringing substrates together so they react
by decreasing entropy - disorder - in the system
Enzymes make the chemical reactions possible in the cell’s environment
Enzymes make cells very efficient 19

21. Enzymes make cells very efficient
How Enzymes Work
Enzymes make cells very efficient
Through enzymes, cells can carry out anabolic and catabolic reactions and end up with a net profit of energy.
Metabolic reactions and
Cellular respiration 21

22. The Energy is in the form of ATP
Cellular Respiration
Cellular Respiration is a metabolic pathway that breaks down glucose and extracts the energy to produce energy
C6H12O6 + 6O H2O + 6CO2 + Energy
Glucose Oxygen Water Carbon Dioxide
The Energy is in the form of ATP

23. Metabolic Pathways
Metabolic Pathways are series of chemical reactions carried out by separate enzymes
It is a sequence of chemical reactions where each reaction is controlled by a separate enzyme
The product of one enzyme serves as the substrate for the enzyme of subsequent reaction in the metabolic pathway

24. The metabolism of cells is carried out and controlled by ENZYMES
There are catabolic enzymes – those that cleave larger molecules into smaller ones
Ex. Hydrolysis Reactions
There are also anabolic enzymes – those that assemble smaller molecules into larger ones
Ex. Dehydration Reactions