1. An Introduction to. Metabolism
An Introduction to Metabolism Campbell- Chapter 6 (old) Chapter 8 (new)

5. Introduction to Metabolism

6. Metabolism is the sum of an organism’s chemical reactions
Metabolism is an emergent property of life that arises from interactions between molecules within the cell

7. BIOCHEMICAL PATHWAY VIDEO
A metabolic pathway begins with a specific molecule and ends with a product
The product of one reaction is substrate of the next
Each step is catalyzed by a specific enzyme
BIOCHEMICAL PATHWAY VIDEO

8. ENZYMES THAT WORK TOGETHER IN A PATHWAY CAN BE
Concentrated in specific location
Covalently bound in complex
Soluble with free floating
intermediates
Attached to a membrane in sequence

9. CATABOLIC PATHWAY (CATABOLISM) Release of energy by the breakdown of complex molecules to simpler compounds EX: digestive enzymes break down food ANABOLIC PATHWAY (ANABOLISM) consumes energy to build complicated molecules from simpler ones EX: linking amino acids to form proteins

10. Forms of Energy ENERGY = capacity to cause change
Energy exists in various forms (some of which can perform work)
Energy can be converted from one form to another

11. KINETIC ENERGY – energy associated with motion
HEAT (thermal energy) is kinetic energy associated with random movement of atoms or molecules
POTENTIAL ENERGY = energy that matter possesses because of its location or structure
CHEMICAL form of potential energy stored in chemical bonds in molecules

12. Diving converts
potential energy to
kinetic energy.
On the platform, the diver has
more potential energy.
In the water, the diver has less potential energy.
Climbing up converts kinetic energy of muscle movement to potential energy.

13. THERMODYNAMICS = the study of energy transformations
CLOSED system (EX: liquid in a thermos) = isolated from its surroundings
OPEN system energy + matter can be transferred between the system and its surroundings
Organisms are open systems

14. The First Law of Thermodynamics
= energy of the universe is constant
Energy can be transferred and transformed
Energy cannot be created or destroyed
The first law is also called the principle of CONSERVATION OF ENERGY

15. The Second Law of Thermodynamics
During every energy transfer or transformation
entropy (disorder) of the universe INCREASES
some energy is unusable, often lost as heat

16. ORGANISMS are energy TRANSFORMERS!
Second law of thermodynamics
First law of thermodynamics
Chemical
energy
Heat
CO2
H2O
ORGANISMS are energy TRANSFORMERS!

17. Thursday October 5, 2017
Check-out a Campbell book today Continue- Introduction to Metabolism Chapter 6 (old) or 8 (new) with Daily Lecture & Review/Reflection HW Component- work on it nightly Anticipate Quizzes

18. Equation that describes energy of a system. ∆G = ∆H - T∆S https://www
Equation that describes energy of a system ∆G = ∆H - T∆S Free-Energy Change (G) can help tell which reactions will happen
∆G = change in free energy ∆H = change in total energy (enthalpy) or change ∆S = entropy T = absolute temperature in degrees Kelvin

19. Exergonic and Endergonic Reactions in Metabolism
EXERGONIC reactions (- ∆G)
Release energy
are spontaneous
ENDERGONIC reactions (+ ∆G)
Absorb energy from their surroundings
are non-spontaneous

20. Exergonic Reaction Only processes with a negative ∆G are spontaneous
Spontaneous processes can be harnessed to perform work

21. Overall, the coupled reactions are exergonic
Concept 8.3: ATP powers cellular work by coupling exergonic reactions to endergonic reactions
In the cell, the energy from the exergonic reaction of ATP hydrolysis can be used to drive an endergonic reaction
Overall, the coupled reactions are exergonic

22. ATP provides energy for cellular functions
ATP (adenosine triphosphate) is the cell’s renewable and reusable energy shuttle
ATP provides energy for cellular functions
Energy to charge ATP comes from catabolic reactions
Adenine
Phosphate groups
Ribose

23. Adenosine triphosphate (ATP)+ P P +
Energy i
Inorganic phosphate
Adenosine diphosphate (ADP)

24. -adding phosphate group stores energy; -removing it releases energy
ATP
Energy for cellular work
provided by the loss of phosphate from ATP
Energy from catabolism
(used to charge up ADP into ATP
ADP + P i

25. Reactants: Glutamic acidP i P
Motor protein
Protein moved
Mechanical work: ATP phosphorylates motor proteins
Membrane
protein
ADP
ATP + P i P P i
Solute
Solute transported
Transport work: ATP phosphorylates transport proteins P
NH2 +
NH3
Glu + P i
Glu
Reactants: Glutamic acid
and ammonia
Product (glutamine)
made
Chemical work: ATP phosphorylates key reactants

26. Every chemical reaction between molecules involves
bond breaking and bond forming
ACTIVATION ENERGY = amount of energy required to get chemical reaction started
Activation energy is often supplied in the form
of heat from the surroundings
Free energy animation
IT’S LIKE PUSHING A
SNOWBALL UP A HILL . . .
Once you get it up there,
it can roll down by itself

27. The Activation Energy BarrierD
Transition state A B EA
Free energy C D
Reactants A B
DG < O C D
Products
Progress of the reaction

28. CATALYST = a chemical agent that speeds up a reaction without being consumed by the reaction ENZYMES = biological catalysts Most enzymes are PROTEINS Exception = ribozymes (RNA)

29. ENZYMES work by LOWERING ACTIVATION ENERGY;
Course of
reaction
without
enzyme EA
without
enzyme
EA with
enzyme
is lower
Reactants
Free energy
Course of
reaction
with enzyme
DG is unaffected
by enzyme
Products
Progress of the reaction
ENZYMES work by LOWERING ACTIVATION ENERGY;

30. ENZYMES LOWER ACTIVATION ENERGY BY:
Orienting substrates correctly
Straining substrate bonds
Providing a favorable microenvironment
Enzymes change ACTIVATION ENERGY but NOT energy of REACTANTS or PRODUCTS

31. ~Happy Thursday~ 1. Turn in your “self-prescribed” homework page (last daily) 2. Corrections are due today by 5:15 pm. 3. Metabolism WS is due Friday 3. Free Energy POGIL in groups

32. ENZYMES Most are proteins Lower activation energy Specific
Shape determines function
Re-usable
Unchanged by reaction

33. The REACTANT that an enzyme acts on = SUBSTRATE
Enzyme + substrate = ENZYME-SUBSTRATE COMPLEX
Region on the enzyme where the substrate binds = ACTIVE SITE
Substrate held in active site by WEAK interactions (ie. hydrogen and ionic bonds)
ENZYMES are UNCHANGED & REUSABLE

34. TWO MODELS PROPOSED
LOCK & KEY Active site on enzyme fits substrate exactly
INDUCED FIT Binding of substrate causes change in active site so it fits substrate more closely

35. Enzyme Activity can be affected by:
General environmental factors, such as temperature, pH, salt concentration, etc.
Chemicals that specifically influence the enzyme
See a movie
Choose narrated

36. TEMPERATURE & ENZYME ACTIVITY
Each enzyme has an optimal temperature at which it can function (Usually near body temp)

37. Higher temperatures = more collisions among the molecules so increase rate of a reaction BUT. .
Above a certain temperature, activity begins to
decline because the enzyme begins to denature.
So rate of chemical reaction increases with temperature up to optimum, then decreases

38. pH and ENZYME ACTIVITY Each enzyme has an optimal pH at which it can function
Extremes in pH and temp can DENATURE enzymes -causing them to unwind/lose their 3-D TERTIARY structure -breaks hydrogen, ionic bonds; NOT covalent peptide bonds

39. Many enzymes require helpers:
COFACTORS = non-protein enzyme helpers
EX: Zinc, iron, copper
(minerals)

40. COENZYMES = organic enzyme helpers Ex: vitamins

41. SUBSTRATE CONCENTRATION & ENZYME ACTIVITY←
V MAX
Adding substrate increases activity up to a point

42. REGULATION OF ENZYME PATHWAYS
GENE REGULATION cell switches on or off the genes that code for specific enzymes

43. ~Happy Tuesday~ 1. Turn in your enzyme HW 2. Complete Enzyme PPT 3
~Happy Tuesday~ 1. Turn in your enzyme HW 2. Complete Enzyme PPT 3. Metabolism/enzymes questions- due Thursday 4. Complete Pre-Lab; Read through Lab/watch Bozeman Catalase Lab

44. REGULATION OF ENZYME PATHWAYS
FEEDBACK INHIBITION end product of a pathway interacts with and “turns off” an enzyme earlier in pathway
prevents a cell from wasting chemical resources by synthesizing more product than is needed
FEEDBACK INHIBITION

45. NEGATIVE FEEDBACK Switches off pathway when product is plentiful
Common in many enzyme reactions
Saves energy: don’t make it if you don’t need it B A C D
Enzyme 1
Enzyme 2
Enzyme 3
Negative feedback
Example: sugar breakdown generates ATP; excess ATP
inhibits an enzyme near the beginning of the pathway

46. POSITIVE FEEDBACK (less common)
The end product speeds up production W X Y Z
Enzyme 4
Enzyme 5
Enzyme 6
Positive feedback
EXAMPLE: Chemicals released by platelets that accumulate
at injury site, attract MORE platelets to the site.

47. REGULATION OF ENZYME ACTIVITY
ALLOSTERIC REGULATION protein’s function at one site is affected by binding of a regulatory molecule at another site
Allosteric regulation can inhibit or stimulate an enzyme’s activity
Allosteric enzyme inhibition

48. SOME ALLOSTERIC ENZYMES HAVE MULTIPLE SUBUNITS
Each enzyme has active and inactive forms
The binding of an ACTIVATOR stabilizes the active form
The binding of an INHIBITOR stabilizes the inactive form

49. COOPERATIVITY = form of allosteric regulation that can amplify
enzyme activity
Binding of one substrate to active site of one subunit locks all subunits in active conformation

50. Enzyme Inhibitors
COMPETITIVE inhibitor REVERSIBLE; Mimics substrate and competes with substrate for active site on enzyme
ENZYME ANIMATION

51. Enzyme Inhibitors
NONCOMPETITIVE inhibitors bind to another part of an enzyme, causing the enzyme to change shape and making the active site less effective
ENZYME ANIMATION