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Transcript

Energy, Metabolism, and Enzymes

Lecture Goals:

  • Examine cellular metabolism and its components
  • Understand the mechanisms of biological reactions
  • Examine the role of enzymes in biological reactions

Course Competencies: 11. Describe the laws of thermodynamics and their relationship to the energy dynamics of living things. (V)12. Explain the importance of enzymes to metabolic processes and their mode of action. (V) 13. Explain the importance of adenosine triphosphate (ATP) to living things. (V)

Click the sound button for audio!

"Ameboid Protozoa: Amoeba proteus" by bccoer is marked with CC0 1.0.

Life's Need for Energy

Reactions

Enzymes and Energy

Presentation Links

Sources and Types of Energy

"File:Adenosine-diphosphate-3D-balls.png" by Jynto (talk) is marked with CC0 1.0.

Life's Need for Energy

  • Energy cannot be created or destroyed
    • First law of thermodynamics
  • The energy living things use has to come from and go somewhere.
  • How organisms acquire energy varies:
    • Autotroph: gains energy through photosynthesis or chemosynthesis
    • Heterotroph: gains energy be eating other living things
    • Decomposer: gains energy from breaking down organic matter
    • Detritovore: gains energy from eating dead organism and waste

Recall Theme of Life: Life depends on a continuous input and transfer of energy.

"0302 Phospholipid Bilayer" by OpenStax is licensed under CC BY 4.0.

Life's Need for Energy

Metabolism is all of the chemical reactions occuring in a living thing.

  • Chemical reactions either require energy or release energy (typically the transfer of electrons)
2 origins of biological energy:
  • Photosynthesis - energy originates from light from the sun and is converted to biological energy (ATP)
  • Chemosynthesis - energy originates from chemical bonds (often methane or sulfide based) and is converted to biological energy (ATP)

Metabolism

Life's Need for Energy

ATP is the form of biological energy used by all living things.

  • Nucleic acid
    • Ribose sugar
    • 3 phosphate groups (triphosphate)
    • Nitrogenous base (adenine)
  • Phosphate bonds store chemical energy

Adenosine Triphosphate

"File:230 Structure of Adenosine Triphosphate (ATP)-01.jpg" by OpenStax College is licensed under CC BY 3.0.

Life's Need for Energy

Watch: Amoeba Sisters Video

Life's Need for Energy

Anabolic

  • Small molecules assemble into larger ones
  • Requires energy
  • Tip to remember: anabolic adds

Metabolic Pathways

Catabolic

  • Large molecules break down into small ones
  • Releases energy
  • Tip to remember: catabolic cuts

"fig 6.5" by OpenStax is licensed under CC BY 4.0.

Test your Knowledge

Life's Need for Energy

Entropy

  • All things naturally move toward disorder
    • Second law of thermodynamics
    • Maintaining order requires energy
  • Recall - order is a characteristic of life
    • Life requires energy to maintain order
Energy isn't created nor destroyed, only transferred.
  • Different forms of energy
  • Not all energy is automatically usable by all living things
  • Life needs to access energy in order to change it into a usable form

Laws and Concepts of Energy that Apply to Life

Watch: Crash Course video (until 2:30)

"fig 6.5" by OpenStax is licensed under CC BY 4.0.

Check your notes

02:00

Check your notes, can you define:

  • Metabolism
  • Anabolic pathway
  • Catabolic pathway
  • Entropy

Types of Energy

Potential energy is stored energy.Four types of potential energy:

  • Chemical - stored in the chemical bonds between atoms and molecules (very important for living things!)
  • Nuclear - energy stored within the nucleus of an atom (what holds the protons and neutrons together)
  • Gravitational - energy stored in an object's height
  • Elastic/mechanical - energy stored by tension (like a rubberband)

Potential Energy

Types of Energy

Watch: Chemical Energy Videos

Types of Energy

Watch: Nuclear Energy Video

Types of Energy

Watch: Gravitational Energy Video

"Rollarcoaster" by AESanfacon is licensed under CC BY-SA 2.0.

Types of Energy

Watch: Elastic Energy Video

Types of Energy

Kinetic energy is motion energy.5 types of kinetic energy:

  • Radiant - energy from electromagnetic waves (in other words light)
  • Thermal - energy from the speed of atoms or molecules that are moving (heat)
  • Motion - energy from the speed of anything larger than atoms or molecules that are moving
  • Sound - energy of compression/refraction waves (vibrations)
  • Electrical - energy of electrons moving through metal

Kinetic Energy

Types of Energy

Activity: Potential vs Kinetic Energy

Virtual Pendulum Lab

  • Click the "energy" tab in the Virtual Pendulum Lab to examine the relationship between potential and kinetic energy
  • Also available in Chapter 6, Section 2 of the textbook

Types of Energy

calories vs kilocalories vs Calories

  • calorie - energy required to raise the temperature of 1 mL of water by 1 degree Celsius
  • 1,000 calories = 1 kcal = 1 Calorie
  • Nutrition is discussed in kilocalories or Calories
Average human body needs between 2000-2500 kcal.
  • All of your cells need that much energy by breaking chemical bonds (like in food molecules) in order to maintain their metabolism

Measuring Energy

Test your Knowledge

Can you explain what each arrow means in terms of cell metabolism and/or what each nutrient does for the body using what we have learned in class thus far?

Check your notes

02:00

Check your notes, can you:

  • List the four types of potential energy
  • List the five types of kinetic energy
  • Differeniate between cal vs kcal vs Cal

Reactions

Oxidation Reaction

  • "Loses" electrons
  • Atom was oxidized
    • Named because oxygen is usually the electron taker between two atoms
Reduction Reaction
  • "Gains" electrons
  • Atom was reduced
    • Named because the charge became more negative because it now has more electrons

Redox Reactions: The Movement of Electrons

OIL RIG: oxidation is loss (of electrons), while reduction is gain (of electrons).

https://www.reagent.co.uk/blog/what-is-reduction-in-chemistry/

Reactions

Enthalpy - total energy present with a system (such a chemical bond)

  • All energy transfers involve losing some energy into an unusable form such as heat, resulting in entropy
  • Life needs a continuous input of energy since some energy is always "lost" (no longer in a useable form)
Free energy - energy available for a chemical reaction after we account for entropyFree energy equation: ΔG = ΔH − TΔS Change in free energy = Change in total energy - Temperature(Change in entropy)

Enthalpy, Entropy, and Free Energy

Reactions

Free energy equation: ΔG = ΔH − TΔS Change in free energy = Change in total energy - Temperature(Change in entropy)

  • Endergonic reaction
    • Positive ∆G - reaction uses energy
    • Anabolic pathways contain endergonic reactions
  • Exergonic reaction
    • Negative ∆G - reaction releases energy
    • Catabolic pathways contain exergonic reactions

Endergonic and Exergonic Reactions

https://www.thoughtco.com/endergonic-vs-exergonic-609258

Test your Knowledge

Reactions

Chemical reactions are either...

  • Spontaneous
    • Happens without external energy input
    • Example: exergonic reactions
  • Non-spontaneous
    • Requires external energy input
    • Example: endergonic reactions
Note: All chemical reactions can run in both directions.

Spontaneous and Non-Spontaneous Reactions

https://www.khanacademy.org/science/biology/energy-and-enzymes/free-energy-tutorial/a/gibbs-free-energy

Reactions

Every chemical reaction needs a small amount of energy to begin. This energy is called the activation energy.Enzymes serve as biological catalysts to speed up chemical reactions by lowering activation energy!

Activation Energy

Activation Energy

Activation Energy

https://www.khanacademy.org/science/biology/energy-and-enzymes/free-energy-tutorial/a/gibbs-free-energy

Reactions Summary

Activation Energy, Reaction Types, and Enzymes

"Fig 6.9" by OpenStax is licensed under CC BY 4.0.

Check your notes

02:00

Check your notes, can you define:

  • Oxidation
  • Reduction
  • Endergonic reactions
  • Exergonic reactions
  • Activation energy

Enzymes

Watch: How Enzymes Work

Enzymes

  • Made from proteins
  • Acts as a biological catalyst - help speed up a chemical reaction by lowering the reaction's activation energy
  • Contains an active site
    • Where the chemical reaction takes place
    • Shaped so that only a specific molecule can bind (the substrate)
  • Substrate temporarily binds to the active site and undergoes a reaction
  • After the reaction, the substrate is released and the enzyme returns to its original state

Structure and Function

https://www.khanacademy.org/science/ap-biology/cellular-energetics/enzyme-structure-and-catalysis/a/enzymes-and-the-active-site

Enzymes

Some molecules are inhibitors.

  • Stop or slow the function of enzymes
2 types of inhibitors:
  • Competitive
    • Physically block the active site
  • Non-competitive
    • Bind to the enzyme at a non-active site, causing a shape change that removes the active site
    • Substrate can no longer bind to the active site

Enzyme Inhibitors

"File:Competitive&NonCompetitive Enzyme Inhibition.jpg" by California16 is licensed under CC BY-SA 4.0.

Enzymes

Some molecules are activators.

  • Increase the activation or speed of the enzyme
  • Can be an organic or inorganic molecule
    • If organic, typically called a co-enzyme
    • If inorangic, typically called a co-factor
How do activators work?
  • Bind to the enzyme, causing a shape change that reveals the active site
  • Substrate can now bind to the active site!

Enzyme Activators

https://www.khanacademy.org/science/biology/energy-and-enzymes/enzyme-regulation/a/enzyme-regulation

Check your notes

02:00

Check your notes, can you define:

  • Enzymes
  • Active site
  • Substrate
  • Inhibitors
  • Co-enzymes

Recommended Textbook Reading

OpenStax Biology 2e: Chapter 6

Not required, but highly recommended (it can be very helpful to see the material again but phrased a little differently!)