Energy and Metabolism Chapter 8

1
Energy and MetabolismChapter 8
2
Energy

3
Energy
4
Energy
5
Metabolism

• All chemical reactions carried out by the cell

6
Metabolism

• Catabolic reactions
• Break down large molecules into smaller
  substances
• Releases energy or is exergonic

7
Metabolism

• Anabolic reactions
• Synthesis of large molecules from smaller
  substances
• Requires energy or is endergonic

8
Metabolism

• Biochemical pathways
• Reactions in a cell that occur in sequence
• Product of one reaction becomes substrate in
  next reaction
• Pathways are highly regulated coordinated
• Feedback inhibition
• End product of a reaction inhibits the pathway
  from producing more.

9
Energy
10
Energy

• Bioenergetics
• Analysis of how energy powers activities of
  living systems
• Growth, order, reproduction, responsiveness
  regulation
• Require energy to happen

11
Energy

• Energy
• Capacity to do work
• Kinetic energy
• Energy of motion
• Potential energy
• Energy of position or stored energy

12
Energy

• Kinetic energy
• Potential energy

13
Energy

• Most of the work done by living organisms is the
  transformation of potential energy to kinetic
  energy
• Thermodynamics 
• Study of energy heat changes

14
Energy

• Sun main source of energy
• Energy from sun is used to combine smaller
  molecules to make larger molecules
• Energy is then stored in the chemical bond

15
Energy

• Redox(oxidation-reduction) reactions
• Transfer of an electron or electrons
• Play a key role in flow of energy in biological
  systems
• An electron is passed from one atom to another
  energy is passed

16
Law of thermodynamics

• Laws of thermodynamics govern all energy changes
  in the universe.
•  First law of thermodynamics
• Energy cannot be created or destroyed
• It can change from one form to another.
  (potential to kinetic)
• Total amount of energy stays the same

17
First law

• In living organisms
• Eating transfers energy from bonds in food to
  organism
• Potential energy is transferred to kinetic energy

18
First Law

• Heat random motion of molecules
• Heat can be lost during conversions
• Sun replaces energy that is lost as heat

19
Second law

• Second law of thermodynamics
• Transformation of PE to heat (random motion of
  molecules).
• Entropy (disorder) in universe is increasing

20
Second law

• Energy transformations tend to proceed
  spontaneously
• Convert matter from a more ordered state to a
  less ordered
• More stable state.

21
Second law

• Entropy(s) Disorder in a system
• Enthalpy (H) heat content
• Free energy(G) Amount of energy available to do
  work in any system.
• Amount of energy available to break then make
  other chemical bonds

22
Second law

• GGibbs free energy
• ?G ??H - T?S (TKelvin temp)
• ?G is positive than products have more energy
  than reactants
• Due to more energy in bonds or less randomness
• Endergonic reaction

23
Endergonic reaction
24
Second law

• ?G is negative products have less energy than
  reactants
• H is lower (bond energy) or
• S is greater- more randomness
• Exergonic any reaction that releases energy

25
Exergonic reaction
26
Exergonic reactions
27
Energy
28
ATP

• ATP powers energy requiring processes in cell
• 1. Chemical work (making polymers)
• 2. Transporting substances across the membranes
• 3. Mechanical work
• Muscle movement, cilia

29
ATP

• Structure of ATP
• Ribose sugar
• Adenine
• 3 phosphate attached in a row

30
ATP
31
ATP
32
ATP

• ATP
• ADP
• Losses a inorganic phosphate
• Hydrolysis
• 7.3kcal/mole of energy is released.

33
Activation Energy

• Energy needed to initiate a reaction
• Exergonic endergonic reactions both require
  activation energy.
• Reactions with higher AE tend to move forward
  more slowly

34
(No Transcript)
35
Enzymes

• Catalyst in living organisms
• Large three-dimensional globular protein

36
Enzymes

• Substrate Molecule that is going to undergo the
  reaction
• Active sites Specific spots on enzyme that
  substrates bind to.
• Enzyme-substrate complex enzymes are bound to
  substrates with a precise fit.
• Induced fit when the substrate causes the enzyme
  to adjust to make a better fit
• ES ES E P

37
(No Transcript)
38
Enzymes

• Only small amounts are necessary
• Can be recycled
• Specific
• Speeds up reactions
• Different types of cells have different enzymes
• Determine course of chemical reactions in the cell

39
Enzyme examples

• Lipase, protease
• Carbonic anhydrase
• CO2 H2O H2CO3
• Lactate dehydrogenase
• Lactate to pyruvate
• Pyruvate dehydrogenase
• Enzyme that starts the Kreb cycle

40
Enzymes

• Most enzymes are proteins
• RNA has been shown to catalyze some reactions
• Ribozymes
• RNA catalysts are specific speed up reactions

41
Enzymes

• Factors that affect rate of enzyme-catalyzed
  reactions
• 1. Concentration of the enzyme substrate
• 2. Factors that affect the 3-D shape of the
  enzyme
• Temperature, pH, salt concentration regulatory
  molecules

42
Enzymes

• Inhibitor
• Binds enzyme prevents it from working
• Occurs at end of a pathway to stop reactions
• Two types of inhibitors
• Competitive
• Noncompetitive

43
Enzymes

• Allosteric site
• On/off switch for enzyme
• Allosteric site usually at a different location
  than active site
• Allosteric inhibitor
• Binds at allosteric site stops enzyme activity
• Activitors
• Bind increases activity

44
(No Transcript)
45
Enzymes

• Cofactor
• Assists enzyme function (Zn, Mg, Cu)
• Coenzymes
• Cofactors that are not proteins but are organic
  molecules
• Help transfer electrons energy associated with
  electrons
• Vitamins are coenzymes
• NAD is an important coenzyme