Concepts of Biology: Course Overview

• Concepts of Biology, also called Ngā Huatau o te Koiora

Lectures

• Attending lectures is encouraged as up to 4.5% of the final grade comes from engaging in lectures
• Lecture material is assessed through three in-person tests held during normal lecture time, accounting for 33% of the final grade

Moodle Quizzes

• Weekly lecture quizzes contribute 10% to the final grade
• Quizzes are open for multiple weeks with unlimited attempts allowed during that period
• The highest grade is recorded
• Some quiz questions appear in tests
• Quizzes are designed for self-assessment to aid studying

Workshops and Labs

• Workshops and labs require in-person attendance and are not recorded
• Sign-up for workshops and labs is available on Moodle and must be completed before Friday
• Labs account for 29%, and workshops for 16%, of the final grade
• Classes for workshops and labs start next week

Assessment Schedule

• Three lecture tests: 33% of grade, dates are March 25, May 6, and May 29
• Eight workshops: 16% of grade, held during weeks of March 3, March 10, March 24, March 31, April 28, May 12, and May 19
• Lecture activities: 4.5% of grade, occur every lecture
• Nine Moodle quizzes: 4.5% of grade, available weekly on Moodle
• Eight lab tests: 24% of grade, held weekly in the lab
• Lab practical exam: 5% of grade, taking place during the week of May 27
• Group video assignment: 13% of grade, with a draft due April 26 and the final submission on May 9

Staying Updated

• Moodle is the primary platform for resources and messages
• Check Moodle every week for updates and reminders

Course Outline

• The course outline has information on assessment, rooms, times, and covered topics

Lecture Participation

• Lecture participation enables attendance marking and contributes towards the final grade
• The QR code gives access to Moodle to mark presence
• QR codes are shown at the start of each lecture to check in
• Scanning in for 15 out of 21 lectures results in earning a 4.5% grade

Learning Outcomes

• Explain why life likely arose on the subsurface of the planet, linking evidence to life's necessities.
• Provide evidence for the RNA world view.
• Explain when the oxygen revolution occurred, and clarify its importance.
• Describe the endosymbiotic theory for the origin of eukaryotes and the supporting evidence.

Terminology

• Key terms include: abiotic, anaerobic, aerobic, autotroph, heterotroph, eukaryote, prokaryote, inorganic, organic, and protocells.

Origins of Life

• Key theories are panspermia (extra-terrestrial origin), special creation (spiritual or religious view), and biochemical origins

Origin of Cellular Life

• Early Earth was anoxic and much hotter
• First biochemical compounds were from abiotic systems

Biochemical Origins of Life

• Multiple experiments have replicated the origin of life, identifying themes and what's needed for life to begin

What Life Requires

• Biogenic elements: C, H, O, combined to form molecules
• Energy: needed to make a system work
• Aggregation: organic molecules form something (clumps or clusters)
• Replication: protocells to make more copies to reproduce

Experimental Evidence

• Organic molecules can be created given the right conditions
• A gas mixture of a hypothesised atmosphere was exposed to electricity forming amino acids
• This led to the theorisation of primordial soup
• Current hypothesis is that life originated subsurface of the earth

Subsurface Hypothesis

• Life originated far from the Earth's surface, likely around hydrothermal vents
• Recent experiments have found both amino acids and cell membranes can occur spontaneously around hydrothermal vents
• Hydrothermal vents provide a mineral-rich environment, chemical and heat energy, UV-ray protection, and environmental stability
• Evidence from both microbial fossils, and protocells

Surface vs Subsurface

• Dramatic changes to temperature and mixing via meteor impacts, dust clouds, and storms

Self-Replication

• RNA was the main molecule for self-replication, rather than DNA

Central Dogma

• DNA contains genetic information (cookbook), our genes (recipes)
• RNA copies DNA (photocopies the recipes) and enables the creation of molecules (cook and kitchen hand) through translation
• Proteins: drive the bodies functions using called amino acids as ingredients to make the final dish

RNA World

• RNA predates DNA
• RNA carries information
• RNA is more versatile than DNA
• RNA can bind to molecules and itself
• RNA functions like enzymes
• This fulfills the requirement of RNA being self-replicating

Transition to Prokaryotes

• First organisms were bacteria, followed by archaea, around 3.5 BYA
• Bacteria and archaea are prokaryotes and have simple cells
• They have a lipid bilayer, DNA, ribosomes, and a cell wall

Oxygen Revolution

• Early life was anaerobic so didn't release oxygen
• Cyanobacteria evolved photosythnesis producing O2 gas approximately 2.7 BYA
• Oxygen concentrations raised to 1 part per million, released by cyanobacteria
• First O2 bonded with iron in rocks causing them to rust, accumulating on the sea floor making them incapable of accepting more oxygen
• Oxygen started to accumulate in the air as a result
• Oxygen in the atmosphere resulted in mass extinction of prokaryote life

Transition to Eukaryotes

• Next step in evolution was the formation of more complex cells, or eukaryotes
• This occurred through endosymbiosis (endo means inside, symbiosis means to live together)
• One cell (host) engulfed another cell
• The engulfed cell was not digested or broken down
• The engulfed cell produced something beneficial to the hose
• The engulfed cell becomes permanently incorporated into the host

Endosymbiotic Theory Evidence

• Mitochondria (and chloroplasts) are similar to prokaryotes
• They have their own DNA and ribosomes
• They have a double membrane
• Independent replication takes place
• Binary fission takes place

Complex Life

• Multicellular life (algae) arose 1.8 to 2 BYA
• Animals much later, around 600 to 535 MYA
• Animal evolution coincided with the second oxygen event
• Oxygen levels rose to almost present day
• Life was aquatic until ~500 MYA when plants colonized the land
• Animals moved onto land around ~365 MYA

Summary

• Life on Earth began through biochemical processes in the oceans near hydrothermal vents
• RNA may be the first molecule for genetic information storage and replication
• Life likely started with simple protocells with RNA
• Prokaryotes came before eukaryotes, endosymbiosis was important for eukaryotic evolution
• Earth was originally anoxic, changing during the oxygen revolution around 2.5 BYA