What is Life? BIOL 120 Study Notes

What is Life?

• BIOL 120 - Fundamentals of Biology: Ecology and Evolution (Course context)
• Date reference in transcript: 27 August 2025

Announcements and Course Information

• eBook for the course: issues can be fixed at the library at no extra cost
• Written Assignment #1: Due Wednesday, August 27th at 11:59 PM
• Pre-Semester Questionnaire: Due Friday, August 29th at 11:59 PM
• Written Assignment #2: Due Wednesday, September 3rd at 11:59 PM
• Excel courses: Free access to LinkedIn Learning for IC students; self-paced Excel modules available

Class Schedule and Meeting Times

• Lecture schedule (as per transcript):
  • Lectures: Monday, Wednesday, and Friday
• Section 01: 10:00 AM - 10:50 AM
• Section 02: 11:00 AM - 11:50 AM
• Labs: Start week of August 25th (THIS WEEK!)

Sections and Instructors (Course Sections)

• Section 03: Mondays 1:00 PM - 3:30 PM, CNS 102, Dr. Chad Nihranz, TA Alex
• Section 04: Tuesdays 9:10 AM - 11:40 AM, CNS 102, Dr. Chad Nihranz, TA Annie
• Section 05: Tuesdays 1:00 PM - 3:30 PM, CNS 102, Dr. Cynthia Becker Kili
• Section 06: Wednesdays 1:00 PM - 3:30 PM, CNS 102, Dr. Cynthia Becker Anya
• Section 07: Wednesdays 1:00 PM - 3:30 PM, CNS 105, Dr. Leann Kanda
• Section 08: Thursdays 1:00 PM - 3:30 PM, CNS 105, Dr. Susan Swensen
• Section 09: Thursdays 1:00 PM - 3:30 PM, CNS 102, Dr. Dave Gondek

Section Access Links (iClicker)

• Section 01: join.iclicker.com/HHGH
• Section 02: join.iclicker.com/XCFS

What is Biology?

• The study of life across multiple subfields:
  1. Molecular Biology: Studies molecular mechanisms within cells, including DNA, RNA, and protein synthesis
  2. Cell Biology: Studies the structure and function of cells, the basic units of life
  3. Genetics: Explores how traits are inherited through genes and the role of genetic variation in evolution
  4. Anatomy and Physiology: Looks at the physical structure (anatomy) and functions (physiology) of organisms
  5. Microbiology: Studies microorganisms (bacteria, viruses, fungi, protozoa)
  6. Ecology: Examines how organisms interact with each other and their environments
  7. Evolutionary Biology: Investigates how species evolve over time through natural selection and other processes

The Seven Characteristics of Life

• Living organisms share seven characteristics:
  • Order
  • Reproduction
  • Growth and development
  • Energy processing
  • Regulation
  • Response to environment
  • Adapt to environment

Order

• Life is characterized by highly ordered structures

Reproduction

• Organisms reproduce their own kind
• Sexual reproduction concepts:
  • Male sperm and female gametes combine to form a zygote
  • Examples shown: pollen grains, ovary, stigma, pollination
  • Embryo formation in sexual reproduction
• Asexual reproduction concepts:
  • Examples shown: Hydra; budding; new buds; development of new individuals
• Additional illustrations referenced:
  • Hydras (jelly-like organisms)
  • Pollination and pollen/ovule structures
  • Rhizome and taproot diagrams as examples of growth/reproduction modes

Hybrids (Examples of Crosses)

• Hybrid organisms discussed: Mule, Liger, Zonkey, Tigon
• These illustrate cross-species or cross-genus reproduction outcomes

Growth and Development

• DNA is inherited and controls growth and development of all organisms
• Core molecular processes:
  • Replication
  • Transcription
  • Translation
  • (Mention of reverse transcription in some contexts)
• Basic DNA structure and readability:
  • DNA base pairs: A 00T,
    G G (note: actual pairing shown as A
    ightleftharpoons T,
    ightleftharpoons C) [textual note: A pairs with T; G pairs with C]
• Additional references in the transcript to polymerase activity and the flow from DNA to RNA to protein

Energy Processing

• Organisms take in energy and use it to power activities
• Energy flow pyramid (typical terrestrial food web snapshot):
  • Producers (autotrophs): $100\%$ of available energy
  • Primary consumers: $10\%$ of energy transferred from producers
  • Secondary consumers: $1\%$
  • Tertiary consumers: $0.1\%$
  • Decomposers: role in recycling energy and materials (no fixed percentage listed in slide)
• Note: Percentages reflect typical energy transfer efficiency between trophic levels

Regulation (Homeostasis)

• Organisms maintain a beneficial internal environment (homeostasis)
• Example: Thermoregulation vs Thermoconformity
  • Thermoregulator: regulates internal body temperature
  • Thermoconformer: internal temperature follows the environment

Response to Environment

• All organisms respond to environmental stimuli
• Conceptual label in slide: "Responses to Stimuli" under the SCIENCE TAKE/ONGScience framing

Adapt to Environment

• Natural selection favors individuals with traits that increase reproductive success in their environments
• Examples of adaptations listed:
  • Thick fur protects against sun/temperature
  • Hump stores fat/energy reserves
  • Long, thick eyelashes keep sand out
  • Leathery mouth helps eat spiky plants
  • Wide, padded feet prevent sinking and protect against heat
  • Highly concentrated urine and dry feces minimize water loss

Evolutionary Timeline and Major Transitions

• Broad idea: life forms evolve via adaptations across deep time
• Domains and major lineages:
  • Eukaryotes
  • Archaea
  • Bacteria
• Notable milestones shown in transcript (approximate framing):
  • Prokaryotes precede eukaryotes
  • LUCA (Last Universal Common Ancestor) ~ between $3.6\text{ to }4.3\text{ billion years ago}$
  • Cambrian Explosion as a major diversification event within the animal lineage
  • Mass extinctions and subsequent radiations (illustrated in the timeline with various groups such as echinoderms, fish, amphibians, reptiles, birds, mammals, etc.)
• A visual timeline lists major categories like Eukaryotes, Archaea, Bacteria, and various animal phyla appearing through deep time

Diversity of Life and Three Domains

• Life is organized into three domains:
  • Bacteria
  • Archaea
  • Eukarya (which includes protists, fungi, plants, animals)
• LUCA: Last Universal Common Ancestor, estimated to be from roughly $3.6\text{ to }4.3\text{ billion years ago}$
• Examples of members within each domain highlighted in slides:
  • Bacteria: diverse prokaryotes (green non-sulfur bacteria, Gram-positive, purple bacteria, cyanobacteria, etc.)
  • Archaea: including Methanosarcina, Methanobacterium, Methanococcus, Thermococcus, Halobacteria, and others
  • Eukarya: animals (ciliates, flagellates), green plants, fungi, algae, microsporidia, etc.

Prokaryotic vs Eukaryotic Cells

• Prokaryotic cells (Bacteria and Archaea):
  • DNA free-floating in cytoplasm
  • No membrane-bound organelles
  • Small size: approximately 0.5–2 microns
• Eukaryotic cells (plants, animals, fungi, algae, protozoans):
  • Membrane-bound organelles
  • Nucleus containing DNA
• Key conclusion: Cells are the fundamental unit of life; all living things are composed of cells

Cell Theory and Historical Context

• Core statements highlighted in slides:
  • Cells form a unifying structural basis of organization
  • Cells come from preexisting cells (cell reproduction)
• Historical note: First descriptions and study of cells are often tied to plants

Dated Assignments and Course Tasks

• Written Assignment #1: due Wednesday, August 27th – 5 points
• Pre-semester Questionnaire: due Friday, August 29th – 5 points
• Lab 1: due at end of your lab period – 20 points
• Written Assignment #2: due Wednesday, September 4th – 5 points
• Canvas Quiz #1: due Wednesday, September 4th – 5 points

Quick Reference: Key Terms and Concepts to Remember

• Life characteristics: $ext{Order}, ext{Reproduction}, ext{Growth and development}, ext{Energy processing}, ext{Regulation}, ext{Response to environment}, ext{Adapt to environment}$
• DNA processes: replication, transcription, translation, (reverse transcription in some contexts)
• DNA base pairs: $A \leftrightarrow T,\quad G \leftrightarrow C$
• Energy transfer efficiency across trophic levels: 100\%
  ightarrow 10\%
  ightarrow 1\%
  ightarrow 0.1\%
• Homeostasis: regulation of internal environment; thermoregulation vs thermoconformity
• LUCA: Last Universal Common Ancestor; approximate age range $3.6\text{ to }4.3\text{ billion years ago}$
• Three domains: Bacteria, Archaea, Eukarya
• Prokaryotes vs Eukaryotes: differences in DNA location, organelles, and cell size

Connections to Foundational Principles and Real-World Relevance

• Evolutionary biology explains why traits persist or disappear through natural selection, genetic variation, and adaptation to environments
• Understanding cellular organization underpins modern medicine, microbiology, genetics, and biotechnology
• Energy flow and trophic efficiency inform ecology, farming, and conservation decisions
• The three-domain system (Bacteria, Archaea, Eukarya) frames current microbiology and the study of life’s diversity

Ethical, Philosophical, and Practical Implications

• Implications of understanding life’s diversity for bioethics, environment, and policy decisions
• Recognizing the deep time scale of life emphasizes stewardship of ecosystems
• Knowledge of cellular mechanisms underpins medical advances and biotechnological innovations