Ground Rules for Metabolism - PowerPoint PPT Presentation

1 / 23
About This Presentation
Title:

Ground Rules for Metabolism

Description:

Ground Rules for Metabolism Starr/Taggart s Biology: The Unity and Diversity of Life, 9e Chapter 6 – PowerPoint PPT presentation

Number of Views:347
Avg rating:3.0/5.0
Slides: 24
Provided by: Matti193
Category:

less

Transcript and Presenter's Notes

Title: Ground Rules for Metabolism


1
Ground Rules for Metabolism
  • Starr/Taggarts
  • Biology
  • The Unity and Diversity of Life, 9e
  • Chapter 6

2
Key Concepts
  • Cells engage in metabolism
  • Metabolic reactions lead to energy loss to the
    environment
  • Energy losses and energy gains must be balanced
  • Cells maintain greater or lesser amounts of
    certain substances as required for metabolism

3
Key Concepts
  • Metabolic reactions release usable energy from
    substances to other reactions that require energy
  • Action of specific enzymes increase the rate of
    specific chemical reactions
  • ATP transports usable energy from one reaction
    site to another by the transfer of a phosphate
    group

4
Energy and the Underlying Organization of Life
  • Metabolism
  • Cells capacity to
  • Acquire energy
  • Build
  • Break apart
  • Release substances
  • Defining Energy
  • Potential Energy
  • Kinetic Energy
  • Heat (Thermal) Energy
  • Chemical Energy

5
Defining Energy
  • First Law of Thermodynamics
  • Energy cannot be created or destroyed
  • Second Law of Thermodynamics
  • Total amount of energy in the universe is flowing
    from higher to lower quality
  • Entropy
  • Systems disorder

6
Total Energy Content
  • Energy content of any system with the environment
    remains constant

7
Energy Inputs Coupled with Outputs
  • Exergonic reaction
  • Net loss of energy
  • Endergonic reaction
  • Net increase of energy
  • Cells couple reactions

8
Phosphorylation
  • Transfer of a phosphate group to a molecule

9
How Does ATP Give Up Energy?
  • 5-carbon sugar, base, and triphosphate tail
  • Enzymes can break bond between outermost P and
    tail, then attach P to another substance
    energizing it

10
Electron Transfers Oxidation-Reduction Reactions
  • Oxidation - removal of electrons
  • Reduction - addition of electrons

11
Electron Transport System
  • Array of enzymes coenzymes that transfer
    electrons
  • In cell membranes
  • Mitochondria
  • Chloroplasts

12
Which way will a reaction run?
  • Nearly all chemical reactions in cells are
    reversible

A B lt----------gt C
Substrates
Product
13
Chemical Equilibrium
  • High reactant concentration - runs strongly
    forward
  • Equilibrium - rate of forward and back reactions
    the same
  • High product concentration - runs strongly in
    reverse

14
Metabolic Pathways
  • Ordered
  • Enzyme mediated
  • Biosynthetic or Degradative

15
Enzyme Structure and Function
  • Catalysts speed the rate of chemical reactions
  • Not permanently altered or used up
  • Reversible reactions
  • Selective for the substrates

16
Enzyme - Substrate Interactions
  • Activation energy

17
Factors Influencing Enzyme Activity
  • Temperature
  • pH
  • Salinity
  • Ranges are specific

18
Control of Enzyme Function
  • Allosteric control
  • Binding of substances on enzyme other than the
    active site
  • Can activate
  • Can inhibit

19
Feedback Inhibition
  • Shutting down of activity
  • Product produced shuts down reaction
  • Binds to allosteric site

20
In Conclusion
  • Sum of metabolism underlies the survival of
    living things
  • The First and Second Laws of Thermodynamics
    affect life
  • Energy can be converted from one form to another
    but cannot be destroyed
  • Energy flows from higher to lower quality
  • Cells balance energy output with input

21
In Conclusion
  • Most metabolic reactions proceed in one direction
    but some are reversible
  • Reversible reactions tend toward equilibrium
  • Metabolic reactions can release or require energy
  • Exergonic reactions end with loss of energy
  • Endergonic reactions end with a net gain of energy

22
In Conclusion
  • Cells couple exergonic and endergonic reactions
  • ATP is the main energy carrier in cells
  • ATP forms when a phosphate is donated to ADP
  • Metabolic pathways are orderly enzymatically
    driven reactions
  • Enzymes are catalysts, lower activation energy,
    and bind substrates

23
In Conclusion
  • Enzymes are temperature, pH, and salinity
    specific
  • Cofactors affect enzymes
  • Energy conversions in cells involve a flow of
    electrons
  • developed by M. Roig
Write a Comment
User Comments (0)
About PowerShow.com