Ph and biological systems
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pH and Biological Systems. Dr. Nicholas Buker. Module Learning Goals. Review of acids and bases Understand the pH scale and calculations Grasp buffers and their function Study protein folding and observe denaturation Recognize the importance of buffers in biological systems

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pH and Biological Systems

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Ph and biological systems

pH and Biological Systems

Dr. Nicholas Buker


Module learning goals

Module Learning Goals

  • Review of acids and bases

  • Understand the pH scale and calculations

  • Grasp buffers and their function

  • Study protein folding and observe denaturation

  • Recognize the importance of buffers in biological systems

  • Discuss and demonstrate the bicarbonate buffering system in our bodies


Review acids and bases defined

Review: Acids and Bases Defined

  • BrØnsted-Lowry: Acids donate protons (H+ ions) into solution and bases accept protons

  • In solution, protons combine with water molecules to form hydronium ions (H3O+)

    acid base

Review of acids and bases


Review strong and weak acids

Review: Strong and Weak Acids

  • Strong acids dissociate nearly completely in solution

  • Weak acids partially dissociate in solution

  • Notice the difference in arrows used

    acid base

Review of acids and bases


Review conjugate acids and bases

Review: Conjugate Acids and Bases

  • The acidic and basic products are called conjugate acids and bases

  • Strong acids have very weak conjugate bases

  • Weak acids have conjugate bases strong enough to drive the reaction somewhat in the reverse direction

    acid base conjugateconjugate

    acid base

Review of acids and bases


The ph scale and calculations

The pH scale and Calculations

  • Logarithmic scale of acidity/basicity

  • pH < 7 is acidic, pH = 7 is neutral and pH < 7 is basic

  • [H3O+] > [OH-] acidic and [OH-] > [H3O+] basic

pH scale and calculations


Buffer solutions

Buffer Solutions

  • Solutions that change pH only slightly when acid or base is added using LeChatelier’s Principle

  • Ideally composed of roughly equal amounts of a weak acid and its conjugate base

  • Added acid is neutralized by the conjugate base

  • Added baseis neutralized by the weak acid

Buffers and their function


Protein folding

Protein Folding

  • Proteins begin as long chains that fold into very complex shapes

  • Process is driven primarily by IMF’s

  • The shape is critical to protein function

  • If the protein is misshapen, it will not function

Protein folding and observe denaturation


Protein denaturation

Protein Denaturation

  • Folded proteins are delicate and many things can cause misfolding, including pH changes

  • This process is known as denaturation and it can be lethal to organisms

Protein folding and observe denaturation


The bicarbonate buffer system

The Bicarbonate Buffer System

  • Blood pH is maintained around 7.4 using a buffer of carbonic acid (H2CO3) and the bicarbonate ion (HCO3-)

  • If blood is too acidic (acidosis), kidneys retain the basic bicarbonate ions

  • If blood is too basic (alkalosis), kidneys expel the basic bicarbonate ions

Buffers in biological systems


Why do we need buffers

Why do we need buffers?

  • Strenuous activity creates CO2 which make the blood more acidic

  • Most foods are acidic and some are very acidic

  • Human ceviche?

Buffers in biological systems


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