Updates:

• Last week’s quiz average: 78%

• Pediducer grades are posted

• We will try to finish up genetic disease presentations today. Those who have already presented, I need you all to individually send me emails detailing the amount of work put into your project by each group member (See RUBRIC!)

• At the end of class, if we have time, I want to touch base with everyone on Semester Projects

Light and Colors

•Building and confirming tools for inquiry

Reminder…• OIL RIG:

–Oxidation Is Loss (of electrons)–Reduction Is Gain (of electrons)

• Whenever something is reduced, something else is oxidized! These do not happen alone!

What is ‘color’

•Is there a difference between your

•shirt and a neon light?

Some Dye Structures

Crystal Violet

Yellow Napthol Green

FDC Blue1

FDC Red 3

FDC Yellow5

What do you know about…

Think With Me…• Why do you see (different) colors when • chemicals are flamed?

• Why different colors?

• Assertion I – unlike planets, electrons are • only allowed discrete energies

• Assertion II – energies that don’t take • electrons to an “allowed” place are ignored

Hydrogen Atom Simulator

•http://chemsite.lsrhs.net/FlashMedia/html/flashEMR.htm

•Also in Further Explorations

•Predict what happens to an arbitrary energy photon

•Predict what happens to one that matches a difference between current and potential orbital

Think With Me…• Why do you see (different) colors when • chemicals are flamed?

• Why different colors?

• Assertion I – unlike planets, electrons are • only allowed discrete energies

• Assertion II – energies that don’t take • electrons to an “allowed” place are ignored

Types of evidence/arguments

• Empirical--you saw it, touched it, etc.

• Reasoned argument from documented/identified assumptions & previous knowledge

• Repeatedly established by others

• Never: Assertions by authority regardless of the nature (or volume) of that authority

How are these different?

• Using a thermometer to test temperature

• Pointing a stick, say magic words, wait for rain

• Using pH paper to count protons

• Using Ba(OH)2 ‘test’ for CO2

• Counting ‘geigs’ with a Geiger counter

Principles ofspectrophotometry

• Absorption?

• Re-emitted?

• What will density do to readings?

The Parts

Set for infinite absorbance

(blocked path)

Set wavelength

Set zero absorbance

Tool using

• We have chalk at each station

• Place these in the specs (IN THE TUBE!)

• Look at the beam inside!

• Slowly (and carefully) move the wavelength • selector

• What do you see?

• Reset spec to ‘correct’ wavelength

Calibrating your eye

• Graph paper page I-9

• Predict: how will a blue liquid absorb? A green one?

Do it• Tubes in the rack

• Find the absorbance of each color at each wavelength

• MOVE to the next wavelength

Data350 430 500 590 630 660

Violet

Blue

Green

Yellow

Red

Chlorophyll

Page I-1 in lab manual

Do it• Tubes in the rack

• Find the absorbance of each color at each wavelength

• MOVE to the next wavelength

•Protocol for chlorophyll on 11-3 (Exercise 2) Make absorption closer to 1, not 2 (page 11-4)

Remember ‘density’?• What would you have to do to make a dye so

that there were half as many collisions between dye molecules and the beam of light?

• Build a solution with ¼ absorbance of the stock solutions

• Confirm

• Is it consistent with all wavelengths?

Photosynthesis

• 6CO2 + 6H2O C6H12O6 + 6O2

Light

Photosynthesis: Intro

Photosynthesis: Intro

Photosynthesis: Intro

Flight of the

electron

Photosynthesis: Intro

Fashioning an Assay• How can you tell if photosynthesis is

happening?

• What are the inputs? The products?

– How can you test for these?

• Protocol on 11-4; Exercise 4

• More information on 12-2

Next week!• You’ll take the data you

have from this week to create a red-passing, blue-passing or green-passing solution

• This will be used to test whether different portions of the visible spectrum are equally potent for photosynthesis

Sadava, Life, Fig. 8-6

Homework

•Table & Graph of absorbance data

•including your ‘predictions’

•Dilution worksheet (fine to do in-class)

What’s in a leaf

• Predict: what will we find when we grind up a leaf?

• Protocol: p. 11-3– Graph absorption of spinach extract– ‘ultra’-violet light it (high or low energy)?– Note!! These wavelengths re-do your DNA!!

Thinking it through

• Is the reddish light emitted being used for photosynthesis?

• What would happen if we applied a drug that BLOCKED electron transport?

Graphing

• Create a graph, table for HW• See rubric!!!

The Joy of Dilution• What fraction of molecules

would you have to remove for there to be 1/2 as many collisions between beam & dye?

• OK, build a solution with 1/4 absorbance of stock; confirm

• Tubes will be covered