Lec 12 Teaching Prep: Part 1 - Recap, Mechanism Reel, Cell Palette

Lecture 12 Teaching Prep. Part 1. The recap. The mechanism real and the cell palette.

Hey Michael, welcome to your prep for lecture 12. This is Thursday, May 7th,

and there are three things to hold in your head as you walk in. First, today is the pivot.

The mechanism unit ended Tuesday with the mixing continuum. Today we leave mechanism behind

and ask the next question. How do these mechanisms get arranged in space and stripes,

bars and spots? That pivot is the through line. Second, the deck has four short embedded videos.

They're not filler. The opening three are LEC 11 reinforcement and a bridge into today.

The middle one is a touring math explainer. The fourth is a 14-second zebrafish stripe formation

time lapse and it is the conceptual heart of the cell rules block. Third, you're sharing this

lectures content with LEC 13 next Tuesday. Some material that lives in day two has been pulled

forward today one to land you at 60 minutes today. You are not running long because you stole

content. You are running on time because the pivot from day one to day two is now cleaner.

Part one of your prep covers the opening through the cell palette TPS. About 12 to 14 minutes of class time.

Part two covers the Walpert versus Turing dichotomy through the zebrafish stripe formation video.

Part three covers the reaction diffusion intuition through the exit ticket. Let's start. Your title slide

is up. Wait for the room to settle. Make eye contact with the back row before you say a word.

Then deliver the opening. Good morning. LEC 12 color patterns. On Tuesday, we ended with the mixing

continuum, the synthesis of the entire color mechanism unit. Today we leave mechanism and ask

the question that comes next. Once a mechanism is in place, how does the body decide where to put it?

Pause. Then advance. Slide one is the Tuesday recap. The six photographs from the mixing continuum,

each with a one or two sentence reminder of why that organism sits where it does on the continuum.

Turaco at position one. Pure pigment. Tantajer at two. Plus reflective backing. Pepilio at three.

Plus structural amplifier. Green parod at four. Plus structural producer. Peacock at five.

Pigment a structure. Morpho at six. Pure structure. Walk it briskly. Two minutes maximum.

Don't reteach the continuum. Just have students name the diagnostic for each panel. Bleach the

Turaco color survives. Grind the Morpho color is gone. The recap is about reactivating Tuesday's

cognition, not deepening it. Then deliver the closing line. Mechanism is set. Today, how does it

get arranged in space and stripes, bars and spots? That sentence is the pivot. Say it at full energy.

Then advance. Slide two is the Cuddlefish camouflage video. Roger Hanlon, TDXWIT's whole, 60 seconds.

Here's the move. Hit play. Don't talk over the first 10 seconds. Let the underwater seaweed

cephalopod land. Then say something close to this. Last week, we talked about chromatophores as

units of color. Here is what they look like in action. Cephalopod chromatophores expand and contract

in milliseconds. Same machinery as the Salopris and Tree Frog from Tuesday, just on a faster clock.

Pause. Let the rest play. Total time on this slide, 90 seconds. Slide three is the Chameleon

Iridifor video. 90 seconds total. The Morpho butterfly intro at the front of the clip is at

LEC 11 callback. Then the side by side Iridifor lattice expansion is the money shot. Don't lecture

during it. Just point and say, watch the lattice spacing change. Cells expand. Lattice spacing

increases. Reflected wavelength shifts red. Pause two seconds. That is structural color modulated

by cell biology. Pure LEC 9 and 10 physics with LEC 11 cellular control. Slide four is the bird

of Paradise courtship video. 90 seconds. This is the bridge slide. After the superb bobped

smiley face dance plays, deliver the bridge line. The bob is using mechanism, structural color

in the throat shield, super black background feathers, and a precisely arranged spatial pattern.

The pattern is the signal. Then deliver the three questions set up. How does the male assemble

those colors? LEC 8 through 11. We did that. How does the body know to put those patches where they are?

Today, why does the female care? LEC 14 through 16 function unit coming up. Pause. Then advance.

Total time on these three video slides is about six minutes. Watch the clock. If you are running

long after slide four, drop slide four entirely on Tuesday and just say in passing, I had a beautiful

bob video for you. See it on Bruin Learn. Slide five is the three questions. The agenda slide. Read it.

Don't dwell. The three questions are what patterns exist, where do the cells come from, and how do

cells self-organize? Below them, the arc note. Mechanism, last week. Arrangement today. Function, next week.

Total time 45 seconds. Slide six is the grand tour of pattern diversity. Eight photographs.

Tiger, zebra, leopard, giraffe, cuddlefish, dart frog, bicyclists, peacock eyespot. Don't lecture.

Point at things. Move quickly. Then deliver the closing line at full energy. Every one of these

started as an un-patterned embryo. Pause. Let that hang. Then advance. Total time 90 seconds.

Slide seven is the naming pattern slide. The taxonomy table on the left. The taxon-specific

terminology warning on the right. Walk through the table once. Stripe, bar, spot, a cellus,

reticulation, vermiculation. Don't memorize it. Tell the room. Don't memorize this. Use it as a

reference. The reason it matters is not the categories. It is the move that comes next.

Endler 1978. Pattern is measurable. Spot size, spacing, contrast, orientation. Modern tools,

mica toolbox, and patTR3D do the same job in software. For the project, you should think about

pattern in measurable terms, not just verbal categories. That is the important pedagogical move on

the slide. Total time two minutes. Slide eight is the cell palette. The chromata-4 diagram.

This is the unit bridge slide. Each cell type was introduced earlier in the course.

Melanaphore in LEC-8. Santa IV in LEC-8. I rid a IV in LEC-9 and 10. Errithre IV in LEC-8.

Today we treat them as spatial agents, units that get placed somewhere in the skin. Then deliver

the asymmetry. Mammals and birds carry only melanocytes. Pattern complexity reflects palette size.

Fish and herps with the full-four cell palette get a vastly larger pattern phenotype space. Pause.

That asymmetry is going to come back when we hit Murray's scaling rule later in the lecture.

Don't preview it now. Just plant the seed. Total time two and a half minutes. Slide nine is the

first TPS. Predict the cell stack for three organisms. Emperor Angelfish, leopard, dart frog.

Three minutes total. 90 seconds discussion. 60 seconds cold cold. Walk among them. Listen. Almost

everyone will get the leopard right. Melanocytes only. Most will get the Angelfish full palette.

The dart frog is the discriminator. The expected answer is the three layer chromata-4 unit from

LEC-11. Zanthophore on top. I writ a four-middle. Melanophore deep. If a pair gives you that answer,

validate it visibly. They have transferred LEC-11 onto a new species. After the cold call,

deliver the reveal. The dart frog and the Emperor Angelfish use the same chromata-4 stack.

The leopard uses one cell type. The cell palette doesn't predict the pattern. The rules of cell

placement do. That is where Turing comes in. Pause. Then advance. End of part one. You are about

14 minutes into the lecture. On time. Take a breath. Part two starts with the central dichotomy of

the lecture, Walpert versus Turing.