Chapter 1 - Evolution and the Foundations of Biology

Unifying Themes in Biology

  1. Levels of Classification

  2. Transmission of Genetic Information

  3. Transfer and Transformation of Energy and Matter

  4. Interactions between Organisms and with the Environment

  5. Evolution


Levels of Classification

Biosphere [entire global system] > Ecosystem [physical interaction, with the environment] > Community [biological interactions, between species] > Population [one species, can include subspecies] > Individual [one organism] > Organ > Tissue [Collection of cells all doing the same function, can be multiple types of cells] > Cell [basic unit of life] > Organelle > Molecule [macromolecules, movement of ions, etc.]

*Viruses go against the usual definition of what is alive


Ways of Understanding Organization

Reductionism - Reducing a complex system down to its simplest parts and studying and defining those, and then recombining to learn the whole function


Systems Biology - An exploration of many combined interactions which create the emergent properties of a system


Emergent Properties - Properties which emerge due to the interaction between various components * Increases with complexity


2 Basic Forms of Cells:

Eukaryotic - Plants, animals, fungi [multi- or single- celled organisms]

Prokaryotic - Bacteria, archaea [single-celled organisms]

*Eukaryotic cells have membrane-bound organelles, Prokaryotic cells do NOT

Transmission of Genetic Information

Deoxyribonucleic Acid (DNA)

  • Unit of inheritance, a chromosome

  • Encodes hundreds of thousands of genes per molecule

Genes encode:

  • The information required for the reproduction of a species

  • The molecules required for the ongoing functioning of a living cell

Nucleotide - C, G, A, T/U in DNA/RNA


Genes (usually) encode for proteins

  • Gene Expression - Genes directing the production of a cellular product

Proteins serve several different functions within a cell, including as enzymes, structure, messenger markers, etc.


Sometimes gene expression doesn’t form proteins:

  • Can remain as mRNA

  • Can become a polypeptide chain, not functional as a protein on its own

  • Etc.


Interactions Between Species

  • Individuals from different species interact with one another as part of their ecosystem

  • Symbiosis - Interactions between organisms; can be neutral, positive, or negative


Human Interactions Alter Environments

  • Climate Change

  • Habitat Destruction

  • Species Endangerment and Loss of Diversity

  • Alterations in Ocean Currents

  • Economic Losses


Evolution


Evolution - The concept that all current life on Earth is descended from common ancestor(s)


Unity - The sharing of traits between organisms descended from a single ancestor


Diversity - Certain heritable traits are inherited after their divergence from a common ancestor


Species - A population or group of populations that can successfully interbreed and produce viable and fertile offspring

✩ This definition does not include/consider asexual reproducing species, such as bacteria


Charles Darwin (1809 - 1882)

  • Wrote On the Origin of Species by Means of Natural Selection (1859)

  • Ideas/Theories:

    • Descent with Modification - Species arise from ancestors that differ from them

    • Natural Selection of evolutionary adaptations


Darwin’s Theory of Evolution

Observations:

  1. Individuals within a population have varying heritable traits

  2. Populations can produce more offspring than can survive to reproduce themselves

  3. Species are adapted to their environment

Theory: Those individuals with favorable traits are selected for by their environment [natural selection]


Classifying Diversity

  • Organisms are classified within a hierarchy due to their degree of similarity

  • The lower (or later) the divergence occurs, the more closely related the two organisms are


✩ Writing scientific names: Capitalized genus, lowercase species, all italicized

Mnemonic Device - Dear King Phillip Came Over For Good Soup


✩ 3 Domains Of Life

✩ 4 Kingdoms of Eukarya

  1. Kingdom Plantae

  2. Kingdom Fungi

  3. Kingdom Animalia

  4. Protists

Connection of Structure and Function

  • Found at all levels of complexity

  • Due to natural selection for optimal function

  • When paired with symbiotic relationships, extreme adaptations can arise