Introduction to Life Science

Introduction to Life Science

• Life science is the study of living things
• Lesson topics include the concept of life, theories of the origin of life, and unifying themes of life
• Learning outcomes include discovering the origin of life, learning about unifying themes of life, and creating an ecosystem

Concept of Life

• Life is defined as any system capable of performing functions like eating, metabolizing, excreting, breathing, moving, growing, reproducing, and responding to external stimuli
• Life properties include a definite form and limited size, a limited lifespan, being made up of one or more cells, using only chemical energy, and having adaptation

Characteristics of Life

• Nutrition: Metabolism, the sum total of chemical reactions in an organism
• Movement: Ability of an organism to move
• Respiration: Anabolism, building up process
• Excretion: Process of removing waste and excess water from the body
• Growth: Increase in size and number
• Sensitivity: Ability to respond to environmental stimuli
• Reproduction: Ability of living things to produce new individuals closely resembling them

Two Types of Cell Organisms

• Unicellular Organisms: Made up of a single cell that carries out all necessary functions (e.g., Paramecium, Amoeba, Bacteria, Yeast)
• Multicellular Organisms: Use many different cells to function (e.g., Insects, Humans, Plants)

Theories on the Origin of Life

• Special Creation Theory: Life was created by a divine being or supernatural power

• Spontaneous Generation Theory: Living organisms arise from non-living things

  • Francesco Redi (1668): Experiment disproved spontaneous generation of maggots, showing they came from fly eggs
  • John Needham (1745): Challenged Redi's work, arguing boiling could kill microorganisms
  • Lazzaro Spallanzani: Designed experiments showing only exposed broth produced microorganisms
  • Louis Pasteur: Further experiments disproved spontaneous generation, demonstrating contamination came from the air

• Other Theories:

  • Beneath the Ice: Ice protected early compounds, allowing interaction to create life
  • Lightning: Produced simple sugars and amino acids from simple elements
  • Panspermia: Life came from outer space
  • RNA World Theory : RNA was the first genetic material

Unifying Themes of Life

• Biological Systems: Living things function as an integrated system that cannot be separated from non-living things
• Cellular Basis of Life: Cells are the fundamental units of life
• Form and Function: Organism's structures fit with its functions
• Reproduction and Inheritance: Traits of parents are passed to offspring
• Interaction with the Environment: Survival depends on interactions with the environment
• Energy and Life: Organisms use energy for processes; autotrophs use photosynthesis, and heterotrophs consume other organisms
• Regulation/Homeostasis: Maintaining a stable internal environment
• Adaptation: Ability to adjust to changing environments, fundamental to survival
• Evolution: Change over time, leading to biodiversity
• Biology and Society: Science changes the lives of organisms, impacts medicine, agriculture, environment, humans
• Further study considers how modern biology changes everyday human life