Diversity of life
Diversity of Life
Learning Objectives
1. Unifying Themes of Biology
Organization: Refers to the order within living systems, from molecules to ecosystems.
Example: Cellular organization, where cells form tissues, tissues form organs, etc.
Information: Biological information is stored in DNA, which contains the instructions for life.
Example: Genetic information passed from parents to offspring.
Energy and Matter: All living organisms require energy to survive and interact with their environment.
Example: Photosynthesis in plants, where light energy is converted into chemical energy.
Interactions: Living organisms interact with each other and their environments in various ways.
Example: Predator-prey relationships.
Evolution: The process by which populations change over time through natural selection and adaptation.
Example: The development of antibiotic resistance in bacteria.
2. Properties of Life
Recognizing life involves identifying characteristics shared by all living organisms:
Metabolism: The sum of all chemical reactions in a living organism, e.g., cellular respiration.
Reproduction: The ability to produce offspring, e.g., sexual and asexual reproduction.
Growth and Development: Changes that an organism undergoes in its lifecycle, e.g., metamorphosis in frogs.
Homeostasis: The maintenance of stable internal conditions, e.g., temperature regulation in mammals.
Response to stimuli: The reaction to environmental changes, e.g., plant growth towards light.
3. Prokaryotes vs. Eukaryotes
Prokaryotes: Simple, unicellular organisms without a nucleus.
Example: Bacteria and Archaea.
Characteristics: Peptidoglycan cell wall, smaller (0.1 - 5.0 µm), and reproduce asexually (binary fission).
Eukaryotes: Complex cells with a nucleus and membrane-bound organelles.
Example: Plants, animals, fungi, and protists.
Characteristics: Larger (10 - 100 µm), can be unicellular or multicellular, and reproduce sexually or asexually.
4. Genetic Information Expression and Transmission
Central Dogma of Molecular Biology: Describes the flow of genetic information within a biological system.
Stages:
Transcription: DNA is transcribed into mRNA.
Translation: mRNA is translated into proteins.
Example: Synthesis of insulin from the insulin gene.
Exceptions: Some viruses (retroviruses) use reverse transcription to replicate, which deviates from the standard flow.
5. Role of DNA in Growth and Development
DNA serves as the blueprint for the development of organisms, dictating cellular functions and processes.
Example: In humans, genes influencing height and eye color determine growth patterns and physical traits.
6. Definitions
Genomics: The study of the complete set of genes (genome) in an organism.
Proteomics: The study of the entire set of proteins expressed by a genome.
Transcriptomics: The analysis of the transcriptome, the complete set of RNA transcripts produced by the genome at a specific time.
Bioinformatics: The use of software and computational tools to manage, analyze, and interpret biological data, especially genomic and proteomic information.
7. Evolutionary Unity and Diversity
Evolution explains how organisms have diverged over time from common ancestors while also exhibiting similarities.
Example: The similarities in forelimb structure between humans, whales, and bats, indicating a common evolutionary origin.
8. Biological Organization and Domains of Life
Levels of Biological Organization:
Molecule
Cell
Tissue
Organ
Organ system
Organism
Population
Community
Ecosystem
Biosphere
Three Domains of Life:
Bacteria: Prokaryotic and unicellular.
Archaea: Prokaryotic and unicellular, often extremophiles.
Eukarya: Eukaryotic, encompasses all eukaryotes.
9. Energy Flow and Matter Cycling in the Environment
Energy flow through ecosystems starts with primary producers (e.g., plants) converting solar energy into chemical energy.
Matter cycles through the ecosystem, involving processes such as decomposition, nutrient uptake by plants, and energy transfer through food chains.
10. Feedback Regulation
Feedback regulation refers to a process where the output of a system inhibits or enhances its own production.
Example: In the regulation of body temperature, if the body overheats, mechanisms such as sweating are activated to cool it down.
11. Natural Selection
Natural selection is the process by which organisms better adapted to their environment tend to survive and produce more offspring.
Examples include:
Peppered Moths: Darker moths became more common in polluted areas because they were less visible to predators.
Darwin’s Finches: Variation in beak size among finches in response to available food sources.
Inquiry of Science
1. Forming and Testing a Hypothesis
A hypothesis is a testable prediction about the outcome of an experiment. Formulation involves observation and prior knowledge leading to a question.
2. Conducting Experiments and Scientific Inquiry
Experiments are designed to test hypotheses, involving clearly defined methods and measurements to derive conclusions from collected data.
3. Identifying Variables and Controls
Variables: Factors that can change in an experiment.
Independent Variable: The factor that is manipulated.
Dependent Variable: The factor that is measured.
Controls: Elements that remain constant to ensure that the results are due solely to the independent variable.
4. Distinguishing Between Theory and Hypothesis
A hypothesis is a proposed explanation made on the basis of limited evidence; a theory is a well-substantiated explanation acquired through the scientific method and repeatedly tested and confirmed through observation and experimentation.