3/12/25 bio notes

Introduction to Scientific Communication

• Scientists often struggle with conveying scientific concepts to the public.

• There can be misunderstandings about scientific data among non-experts.

• Example of confusion around fish population assessments based on egg counts.

Understanding Fish Population Dynamics

• Misinterpretation of fish reproductive biology:

  • One egg does not equal one adult fish; not all eggs survive to adulthood.

  • High rates of mortality at each life stage:

    • Eggs to larvae, larvae to juveniles, juveniles to adults.

  • Importance of recognizing these dynamics for accurate fish population health assessments.

Energy Transformation in Physics

• Basics of energy types:

  • Potential energy: stored energy, at rest.

  • Kinetic energy: energy of motion, requires ATP (adenosine triphosphate).

• Introduction to the Laws of Thermodynamics:

  • First Law: Energy cannot be created or destroyed; it only changes forms.

  • Second Law: Energy transformations are not 100% efficient; some energy is lost to disorder (entropy).

  • Example illustrating inefficiency: a cow consumes grass, but not all energy is converted to meat.

Concepts of Entropy

• Entropy refers to the tendency toward disorder in the universe.

• Practical analogy: neglecting to clean results in disorder akin to increasing entropy.

Role of Enzymes in Metabolism

• Proteins as enzymes:

  • Enzymes have specific three-dimensional shapes determined by genetic material.

  • Specificity: each enzyme acts on specific substrates (reactants).

  • Enzyme activity is influenced by conditions that can denature proteins.

Metabolic Reactions and Energy

• Overview of metabolism:

  • Anabolic reactions: build molecules, require energy (positive free energy).

  • Catabolic reactions: break down molecules, release energy (negative free energy).

• Relationship between catabolism and anabolism:

  • Energy released from catabolic reactions can fuel anabolic reactions.

Energy in Reactions

• Understanding delta G (Gibbs free energy):

  • Negative delta G: energy produced during reactions.

  • Positive delta G: energy consumed to create products.

Biological Functional Groups and Structures

• Importance of phosphate groups in biological molecules:

  • Phospholipids and nucleic acids contain phosphate groups critical for function.

Enzymes and Reaction Rates

• Concept of activation energy:

  • The energy required to reach a transition state for a reaction.

  • Enzymes lower activation energy, speeding up reactions.

  • Visual analogy: a hill vs. a mountain representing activation energy barriers.

Specificity of Enzymes

• Enzymes are often highly specific for one substrate:

  • Active site: the specific region where the substrate binds.

  • Analogy: enzyme as a lock, substrate as a key.

• The effect of temperature on enzyme activity:

  • Increased temperature leads to quicker reactions due to faster molecule movement and collision rates.

Enzyme Activators

• Activators and enzyme functionality:

  • Activators enhance enzyme activity, shifting them from an inactive to an active state.

  • Cofactors and coenzymes:

    • Cofactors: inorganic components aiding enzyme function (e.g., metals).

    • Coenzymes: organic molecules that assist enzymes (e.g., vitamins).