Chapter 1: Lecture Outline and Important Terminology

Characteristics of Life

All living organisms share fundamental properties that distinguish them from non-living matter. Understanding these characteristics is essential for studying biology.

• Emergent Properties: New properties that arise at each level of biological organization due to the arrangement and interactions of parts.

• Fundamental Unit: The cell is the basic unit of life.

• Organization:

  • Biosphere: The global sum of all ecosystems.

  • Ecosystem: A community of living organisms interacting with their environment.

  • Community: All populations of different species living in an area.

  • Population: Individuals of the same species living in a specific area.

  • Organism: An individual living entity.

  • Organ System: Groups of organs working together.

  • Organ: A structure composed of tissues performing specific functions.

  • Tissue: Groups of similar cells performing a function.

  • Cell: The smallest unit of life.

  • Molecule: Chemical structures consisting of two or more atoms.

  • DNA: Deoxyribonucleic acid, the molecule carrying genetic information.

  • Gene: A segment of DNA that codes for a protein.

  • Genome: The complete set of genes or genetic material in an organism.

  • Proteome: The entire set of proteins expressed by a genome.

Use of Energy

Living organisms require energy to maintain order, grow, and reproduce. Energy is processed and transformed through various biological mechanisms.

• Metabolism: The sum of all chemical reactions in an organism.

• Chemical Reaction: Processes that change one set of chemicals into another.

• Cellular Respiration: The process by which cells convert glucose and oxygen into energy ().

• Photosynthesis: The process by which plants convert light energy into chemical energy ().

• Energy Flow: Movement of energy through an ecosystem.

• Chemical Cycling: The recycling of elements such as carbon and nitrogen within ecosystems.

Homeostasis

Homeostasis refers to the ability of organisms to maintain a stable internal environment despite changes in external conditions.

• Response to Environment: Organisms detect and respond to stimuli.

• Tropism: Directional growth responses to environmental stimuli (positive/negative).

Reproduction

Reproduction is the process by which organisms produce new individuals, ensuring the continuation of species.

• Asexual Reproduction: Offspring arise from a single organism, inheriting the genes of that parent only.

• Sexual Reproduction: Offspring are produced by the fusion of gametes from two parents.

• Fertilization: The union of sperm and egg to form a zygote.

• Zygote: The fertilized egg cell.

Growth and Development

Organisms grow and develop according to specific genetic instructions and environmental influences.

• Growth: Increase in size and number of cells.

• Development: Changes in an organism as it matures.

• Maturity: The stage at which an organism can reproduce.

• Adaptation: Inherited characteristics that enhance survival and reproduction.

• Metamorphosis: A dramatic change in form during development (e.g., caterpillar to butterfly).

• Phenotypic Plasticity: The ability of an organism to change its phenotype in response to environmental conditions.

• Acclimatization: Short-term physiological adjustments to environmental changes.

• Learning: Behavioral changes based on experience.

• Natural Selection: The process by which organisms better adapted to their environment tend to survive and produce more offspring.

Viruses and Cells

Cells are the basic units of life, while viruses are non-living entities that require host cells to reproduce.

• Prokaryotic Cells: Cells without a nucleus (e.g., bacteria, archaea).

• Eukaryotic Cells: Cells with a nucleus and membrane-bound organelles (e.g., plants, animals, fungi, protists).

Three Domains of Life

All living organisms are classified into three domains based on genetic and cellular differences.

Scientific Inquiry and Evolution

Biology relies on scientific methods to understand life, and evolution explains the diversity of organisms.

• Hypothesis: A testable explanation for observations.

• Scientific Theory: A well-substantiated explanation of natural phenomena (e.g., theory of evolution).

• Evolution: The process by which populations change over time through genetic variation and natural selection.

• Classification: Organizing living things into groups based on similarities.

Levels of Biological Organization

Biological systems are organized into hierarchical levels, each with emergent properties.

Key Terms and Concepts

• Autotrophy: Organisms that produce their own food (e.g., plants via photosynthesis).

• Heterotrophy: Organisms that obtain energy by consuming other organisms.

• Unicellular: Consisting of a single cell.

• Multicellular: Consisting of multiple cells.

• Adaptation: Trait that increases an organism's fitness.

• Natural Selection: Mechanism of evolution where individuals with advantageous traits survive and reproduce.

Example: Photosynthesis and Cellular Respiration

Photosynthesis and cellular respiration are complementary processes in the flow of energy through ecosystems.

• Photosynthesis: Converts light energy into chemical energy in plants.

• Cellular Respiration: Releases energy from food molecules in all organisms.

Equations:

• Photosynthesis:

• Cellular Respiration:

Additional info:

• Evolution is a scientific theory that explains how all living organisms descended from a common ancestor.

• Natural selection can lead to adaptation by favoring beneficial traits.

• Fungi belong to the domain Eukarya.