BIO105 Introductory Biology, Wed., Sept., 9th, David Champlin, USM

Overview

David Champlin lays out BIO105’s progression from atoms and biological chemistry to cells and metabolism, using reductionism—the study of a cell by examining its parts—as the organizing approach. He previews aquaporin as a recurring example of protein structure and function, then introduces the periodic table, atomic structure, ions, isotopes, electron shells, and how shared electrons form water molecules.

Key takeaways

BIO105’s first exam sequence moves from atoms and biological chemistry through macromolecules and membranes to cells and metabolism, with chapter 7 on membranes taught before chapter 6 on cells.
Aquaporin connects several course topics: it is a membrane protein with a water-selective channel, and a mutation that blocks the channel can impair eye lubrication and contribute to glaucoma in mice.
In the sodium chloride example, sodium loses one electron and chlorine gains it; their resulting +1 and −1 charges make them ions, while their proton counts still identify their elements.
Isotopes of the same element have the same number of protons but different numbers of neutrons: carbon-12, carbon-13, and carbon-14 have 6, 7, and 8 neutrons, respectively.
Champlin presents full outer electron shells as the reason noble gases are relatively unreactive and electron sharing as the basis for the bonds in water.
Students who miss class are expected to study the recording, submit notes by email within one week, and use their notes as a tool for recalling course material.

Chapters

0:00 Attendance, Recordings, and Notes for BIO105

Students who miss class must take notes from the recording and email photos or a PDF of those notes within one week.
Attendance is intended to keep students participating; Champlin asks students facing serious illness or caregiving issues to let him know.
Class recordings may be deleted as the semester progresses, so Champlin encourages students who attend to take notes as a study guide.

4:15 Chapter 2 Reading, Practice Quizzes, and Biology Opportunities

Students should read chapter 2, record questions while studying, and bring them to class; a 10-point multiple-choice quiz will cover two short videos.
Champlin frames practice quizzes as preparation for the format of course exams, which cover much more material than the focused quizzes.
A biology-program information session with pizza is scheduled for 12:30 in room 1, Pace Smith; students can explore lab, field, and career-path opportunities.

9:44 Open Questions and the Course’s Biology Roadmap

Students are encouraged to interrupt with questions, including questions about material they find confusing or material beyond the current lesson.
The course covers roughly the first 20 textbook chapters, generally in sequence, while chapter 1 serves as an overview students can ask about as needed.
Champlin plans to supplement the textbook with his own explanations, particularly where he considers its treatment of biology or evolution unclear.

13:00 Reductionism: Building from Chemistry to Cells and Metabolism

Chapters 2–5 introduce biological chemistry and progressively larger molecules; chapter 7 covers cell-membrane molecules before chapter 6’s focused treatment of cells.
Champlin describes reductionism as taking a cell apart to study its components, down to atoms, rather than assuming the whole is more than the sum of its parts.
The first exam follows the transition from molecular building blocks to the cell and then to metabolism and energy flow.

16:50 Aquaporin: A Water Channel Built into Cell Membranes

Aquaporin is a protein embedded in the cell membrane; its donut-shaped channel allows water to pass in either direction without actively pumping it.
Champlin says typical cells contain tens of thousands of aquaporins, with tear-gland cells relying on them to move water into tears.
The channel selectively passes water, and specific amino acids lining its pore help determine how water moves through it.

23:20 Cell Membranes, Aquaporin Mutations, and Biological Scale

Cell membranes surround cells across life and are made of phospholipids; membrane proteins such as aquaporin regulate movement across that boundary.
A mouse with a mutation affecting aquaporin can develop early glaucoma because water movement needed to keep the eye’s lens wet is disrupted.
The Boston-scale analogy makes molecular size tangible: if a cell spanned the Boston metro area, water would be basketball-sized and an aquaporin would be about the size of a delivery truck.

32:20 Atoms as the Building Blocks of Biological Molecules

Chapter 2 starts with atoms as the components of water, phospholipids, and proteins; Champlin compares them to Lego blocks used to construct larger molecules.
He emphasizes oxygen, carbon, hydrogen, and nitrogen as especially common elements in living organisms, while noting that calcium and sodium also have essential biological roles.
The periodic table organizes elements by atomic number and recurring chemical properties.

34:40 Atomic Number and the Periodic Table’s Organization

An element’s atomic number is its number of protons: hydrogen has 1, helium 2, and carbon 6.
Changing an atom’s proton count changes its element, which is why the atomic number identifies the element rather than merely labeling it.
The periodic table’s columns group elements with recurring chemical similarities, a pattern chemists began recognizing in the 19th century.

37:00 Why Noble Gases Are Unreactive

Helium, neon, and argon belong to the noble-gas column and are gases at room temperature that generally do not react readily.
Champlin gives a laboratory example: manufacturers can replace air in bottles of sensitive powdered chemicals with an inert gas to limit reactions with oxygen.
He previews the explanation that a full outer electron shell makes these elements less likely to form chemical bonds.

40:10 Protons, Neutrons, and Electrons in an Atom

Atoms have a nucleus containing positively charged protons and neutral neutrons, with negatively charged electrons around the nucleus.
Protons determine the element; protons and neutrons account for nearly all atomic mass, while electrons have negligible mass by comparison.
Champlin sets the biological focus at atoms and these subatomic particles, noting that biology rarely needs to go down to quarks or leptons.

44:00 How Sodium and Chlorine Form Charged Ions

When sodium chloride dissolves in water, sodium transfers one electron to chlorine, producing sodium with a +1 charge and chloride with a −1 charge.
A neutral sodium atom has 11 protons and 11 electrons; after losing one electron it has 10 electrons, while chlorine gains one.
A charged atom is an ion: positive ions are cations and negative ions are anions; electron changes occur in the outermost orbitals.

50:55 Carbon Isotopes and the Role of Electrons in Reactions

Carbon-12 has 6 protons and 6 neutrons; carbon-13 and carbon-14 retain 6 protons but have 7 and 8 neutrons, respectively.
Different neutron counts produce isotopes; some isotopes are radioactive and can be used to date biological samples, rocks, and other materials.
Champlin emphasizes electrons as central to bonding: metabolism rearranges the bonds between atoms in molecules.

55:30 Electron Shells Explain Water’s Covalent Bonds

Electrons fill shells around the nucleus; in Champlin’s introductory model, the first shell holds 2 electrons and the next shells relevant to common biological elements hold 8.
Noble gases such as helium and neon are unreactive because their outermost shells are full; oxygen, with 6 outer-shell electrons, can become more stable by sharing electrons.
In water, oxygen shares electrons with two hydrogen atoms, filling the outer-shell positions described in the lecture and forming a stable molecule.

Summary, takeaways, and chapters were generated by AI from the video's transcript and may contain errors. The video belongs to its creator, The New Evolution for Everyone.