Biology: Evolution and Key Properties of Life

Themes of Biology

• Energy and Matter relates to how organisms obtain, process, and transform energy and matter for their needs.
• Information involves the storage, transmission, and expression of genetic information within and between organisms.
• Organization refers to the hierarchical structure of life, from molecules to ecosystems.
• Interactions: Involve the relationships and communication between organisms and their environment, both internal and external.
• Evolution encompasses the change over time in the genetic makeup of populations. This change is driven by natural selection, which favors advantageous traits in an ever-changing environment.

Concepts in Biology

• Natural Selection: The process where organisms with advantageous traits are more likely to survive and reproduce, passing these advantageous traits to their offspring.
• Gene: A segment of DNA that codes for a specific protein or a functional RNA molecule. Genes play a vital role in determining an organism's traits.
• Common Ancestry: All living organisms share a common ancestor. This concept suggests that all life on Earth is interconnected and has evolved over time from a single origin.
• DNA is a molecule that carries genetic information. The sequence of nucleotides in DNA determines the genetic code.
• Genome: The complete set of genetic information in an organism.
• Gene Expression: the process by which the information encoded in a gene is used to synthesize a functional gene product, like a protein.
• Producers: Organisms like plants that capture light energy and convert it into chemical energy through photosynthesis. Producers are the foundation of food chains.
• Consumers: Organisms that obtain energy by eating other organisms. Consumers depend on producers for their energy.
• Decomposers: Organisms that break down dead organic matter, releasing nutrients back into the environment. This process is essential for nutrient recycling.
• Ecosystem: A community of living organisms and their physical environment.
• Chemical Energy: Stored in the bonds of molecules. Plants produce chemical energy through photosynthesis, and it is released when the bonds are broken.

Understanding Biological Processes

• Metabolism: The sum of all chemical reactions that occur within an organism, including energy conversion and production of essential molecules.
• Feedback Regulation: A process where a change in a system triggers a response that either amplifies or counteracts the initial change.
• Photosynthesis: The process by which plants use light energy to convert carbon dioxide and water into glucose (sugar) and oxygen.
• Energy Flow: The transfer of energy through an ecosystem, starting with producers and flowing to consumers and decomposers.
• Nutrient Cycling: The movement and transformation of nutrients through an ecosystem, including processes like decomposition and the absorption of nutrients by organisms.

The Scientific Method

• Control Group: A standard of comparison in an experiment that does not receive the experimental treatment.
• Hypothesis: A testable explanation or prediction for an observed phenomenon.
• Variable: A factor that can be changed in an experiment to test its effect on the outcome.

Biological Classification

• Taxonomy: The science of classifying and naming organisms, based on their similarities and relationships.

Interplay of Biological Systems

• Internal Interactions: Processes that occur within an organism, such as cell signaling and the regulation of bodily functions.
• External Interactions: Interactions between organisms and their environment, such as predation, competition, and symbiosis.

Levels of Biological Organization

• Ecosystem: Incorporates all living organisms and their physical environment in a specific area
• Community: A group of different populations of species inhabiting a specific area.
• Population: A group of individuals of the same species living in the same place at the same time.
• Organism: A complete living being, composed of different organ systems working together.
• Organ System: A group of organs that work together to perform a specific function, such as the digestive system or the respiratory system.
• Organ: A structure made up of different tissues that work together to perform a specific function.
• Tissue: A group of similar cells that work together to perform a specific function.
• Cell: The basic unit of life, capable of carrying out all the processes necessary for life.
• Molecule: A group of atoms held together by chemical bonds.

Key Biological Concepts

• DNA is the genetic material of all living organisms. DNA contains the instructions for building and maintaining an organism.
• Genes are segments of DNA that code for a specific protein or functional RNA molecule.
• Mutations: permanent changes in the DNA sequence. These mutations can be beneficial, harmful, or neutral.
• Evolution is the process of descent with modification. It is the unifying theme of all biology.
• Energy transformation in organisms occurs through metabolic processes.
• Producers capture light energy and convert it into chemical energy in the form of sugars.
• Consumers obtain energy by feeding on other organisms.

Important Notes:

• All living organisms share a common ancestor, and all life on Earth is interconnected.
• The diversity of life on Earth is a product of evolution.
• Organisms are organized in a hierarchy of levels, from molecules to ecosystems
• Biological systems (cells, organs, organisms, ecosystems) are characterized by interactions both internal and external.

Evolution

• Organisms are modified descendants of common ancestors
• Natural selection drives evolution
• Nature selects certain traits for survival, while others become less prevalent
• Evolution explains the wide diversity of traits across species
• Similar traits between different species can be explained by a shared common ancestor
• DNA is the universal genetic language shared by all organisms
• There is unity in the diversity of life, as seen in the similar skeletons of different animals

What is life?

• 5 unifying themes of biology:
  • Organization
  • Information
  • Energy and Matter
  • Interactions
  • Evolution
• Properties of life:
  • Order
  • Evolutionary Adaptation
  • Regulation
  • Energy Processing
  • Growth and Development
  • Response to the Environment
  • Reproduction

Information

• Information is encoded in the sequence of nucleotides
• There are 4 nucleotides in DNA: A, T, C, and G
• Nearly every cell of the human body contains DNA
• DNA is found in the nucleus of cells: an organelle
• Genes are units of inheritance, located on the DNA
• Genome refers to all the genetic information an organism inherits from its parents
• A single molecule of DNA contains many genes
• Genes are segments of DNA that code for molecules, usually proteins
• Gene expression is the process of using a gene to make a protein or other cellular product
• The sequence of nucleotides in DNA is important, and a change in the sequence could affect the product

Organization

• Levels of organization:
  • Biosphere
  • Ecosystems
  • Communities
  • Populations
  • Organisms
  • Organs
  • Tissues
  • Cells
  • Organelles
  • Molecules

Biosphere

• All life on Earth and all the places where life exists
• Extends from the sediment below the ocean floor to the atmosphere kilometers above the surface

Ecosystems

• All components in a particular environment
• Examples include: meadows, forests, grasslands, deserts, coral reefs
• Includes both living organisms and their nonliving surroundings: soil, water, atmospheric gases, and light

Communities

• The variety of organisms inhabiting a particular ecosystem
• Examples include: plants, animals, fungi, bacteria

Populations

• All the individual organisms of the same species that are living within a specific area
• Individuals within the same population can interbreed

Organisms

• An individual living thing
• Examples: individual plants, animals, fungi, and bacteria

Organs

• A body part that has a specific function
• Examples: leaves, stems, and roots in a plant
• Made up of tissues

Tissues

• Groups of cells working together to perform a specific function
• Example: tissue that converts light energy into chemical energy in the processes called photosynthesis

Cells

• Some organisms are unicellular, meaning they have one cell that performs all the functions of the organism.
• Some organisms are multicellular, meaning they have many cells
• Multicellular organisms have specialized cells that perform specific roles
• Cells are made up of organelles

Organelles

• A functional component of cells
• Example: Chloroplast's function is to produce energy from sunlight

Molecules

• A chemical structure consisting of two or more atoms
• Example: Chlorophyll molecules are found in chloroplast organelles

Scientific Inquiry

• Scientific Method:
  • Make Observations
  • Ask Questions
  • Form a Hypothesis
  • Conduct an Experiment
  • Analyze Results
• Good experiments test only 1 variable at a time
• Variables are factors that can change in an experiment
• Controlled experiments:
  • Experimental group
  • Control Group
• Controlled variables ensure only the variable being tested is influencing the results

Classification of Life

• Taxonomy is the science of classifying organisms
• Hierarchy of classification:
  • Domain
  • Kingdom
  • Phylum
  • Class
  • Order
  • Family
  • Genus
  • Species

Domains

• Domain: Bacteria
  • Consists of single-celled prokaryotic organisms
  • Prokaryotic cells do not have membrane-enclosed organelles such as a nucleus
• Domain: Archaea
  • Consists of single-celled prokaryotic organisms
  • Prokaryotic cells do not have membrane-enclosed organelles such as a nucleus
• Domain: Eukarya
  • Consists of eukaryotic organisms
  • Includes single-celled and multicellular organisms
  • Eukaryotic cells DO have membrane-enclosed organelles such as a nucleus