Today is Wednesday,October 30th, 2013

Pre-Class:Why are plants green?

(Or why are the green parts of them green, at least?)

Other stuff:Turn in your homework if you did it on paper.

Grab a [small] paper towel for your pair.

In This Lesson:Photosynthesis(Lesson 2 of 3)

Today’s Agenda

• Photosynthesis• Photosynthesis• And maybe flamingos.

http://www.harunyahya.com/kids/pictures/wallpaper1024/flamingo.jpg

ATP Review

• Think of ATP (Adenosine Triphosphate) as a molecule like a chocolate bar.– “Not another analogy!”

• The cell can break off a square to make it ADP.– That releases energy.

• The cell can put a square on (add a phosphate group to ADP, making ATP), but that’s hard to do.– You’d need to melt it down in an oven and re-form it.– That absorbs (uses) energy.

Simple Diagram(worth sketching…no, really)

http://mrsec.wisc.edu/Edetc/nanoquest/molecular_motor/images/atpenergy.jpg

Watching Plants Grow

• First, where is this in my book?– P. 204 and following…

• As usual, here are the historic figures related to Photosynthesis:– Van Helmont– Priestley– Ingenhousz– [your name here]

1600s: Jan van Helmont• Belgian physician – tries to figure out if plants

take mass from soil to grow so large.• Measured soil, planted a seed, and watered

it.• Then he waited five years (!). The soil

weighed the same as it did five years earlier.• CONCLUSION– The plant is using water (hydrate) to grow. (it’s

also using CO2 but he didn’t catch that part)– Jan van Helmont also coined the word “gas.”

http://2.bp.blogspot.com/_XU9nEwykZRc/SkO5s53xzgI/AAAAAAAAACU/gUPGWU3wpbo/s320/van_Helmont.jpg

Floating head! Spooky…

1700s: Joseph Priestley

• English minister – noticed that a candle will go out if you put a glass jar over it.– Flames need oxygen as fuel.

• However, if you put a leaf in there (he used mint), the candle burns longer.

• CONCLUSION– Plants produce oxygen.– Priestley also named rubber. Hmmph.

http://explorepahistory.com/images/ExplorePAHistory-a0h1r8-a_349.jpg

‘allo guv’nah!!

Aside: Great Moments in Science

• Turns out that Priestley wasn’t the first to discover oxygen, though he got all the credit.

• Previously, Carl Scheele discovered oxygen and seven other elements, unfortunately receiving credit for none of them.

• Also unfortunate: Scheele had a habit of tasting all the chemicals with which he worked.– He was found dead at the age of 43

surrounded by several toxic chemicals.

1700s: Jan Ingenhousz

• Dutch scientist – noticed that air bubbles only form around aquatic (underwater) plants when they are in sunlight.– The air bubbles are oxygen from

photosynthesis.• No bubbles formed in darkness.• CONCLUSION– Plants need sunlight to make oxygen.

http://0.tqn.com/d/chemistry/1/0/W/1/1/Jan_Ingenhousz.jpg

I am grayscale.

2013: You.

• Here’s an interesting question:– Suppose you put soil and some water in a clear jar.– Then you plant a seedling in that soil.– Then you put a lid on the jar, sealing the air.– Lastly, you set it on a windowsill so it gets a

normal amount of light and heat.• What happens?

The Magic Photosynthesis Machine

YE OLDEPHOTOSYNTHESI

SMACHINE

?INPUT OUTPUT

?

Photosynthesis: An Outline

• Photosynthesis is basically this:

• 6CO2 + 6H2O + [LIGHT] C6H12O6 + 6O2

– In other words, it’s a conversion of light energy to chemical energy.

– Plants use it to convert and store energy.

• What you should do is this:– Write down the chemical formula.

– Write down the formula in English.

– Draw the formula in mini-diagrams.• (2 minutes to work)

Photosynthesis

• First, some review: (whiteboards)– In which organelle does photosynthesis occur?– What is a pigment?– What’s the name of the pigment inside

chloroplasts?– What color is it?• Chlorophyll appears green to us because it is reflecting

green light. Therefore, it’s absorbing every other color but green*.

*Disclaimer

• Technically, when a color is transmitted to us, only a complementary color is absorbed:

Wavelength Absorbed - nm

Color of Light Absorbed

Complementary Color Transmitted

400-435 Violet Yellow-Green

435-480 Blue Yellow

480-490 Blue-Green Orange

490-500 Green-Blue Red

500-560 Green Purple

560-580 Yellow-Green Violet

580-595 Yellow Blue

595-650 Orange Blue-Green

650-750 Red Green-Blue

The Big Aside

• TED: David Gallo – Underwater Astonishments• Other people’s colors– Do I See Colors The Same Way You Do?– A Bee’s Eye View article

• Ishihara Test• Stop sign color experiment and night vision– TED: Beau Lotto – Optical Illusions

• Primary colors• Upside-down perception• Vision correction

Ishihara Test

http://www.toledo-bend.com

Ishihara Test

http://www.toledo-bend.com

Perception

• The image of the world around you strikes the retina in the back of the eye upside-down.– Your brain “flips” the image for you. Kinda.

http://www.diycalculator.com/imgs/cvision-upside-down.gif

Vision Correction

http://www.d.umn.edu/~jfitzake/Lectures/DMED/Vision/Optics/Figures/RefractiveErrors.gif

The ChloroplastSketch it like you mean it!

Grana

Chloroplast Structure(It’s not just an oval)

• Two membranes– The inside of the inner membrane is called the

stroma.• Stacks of “disk-like structures.” (Holt: Biology)

– The disks are called thylakoids.– The stacks are called grana (singular: granum).– Contain chlorophyll (pigment).• Light hits chlorophyll and chlorophyll reacts!

RapidTrivia!

• It’s time for something new I’m going to try.• Grab your whiteboards, grab your markers, and get

your partner’s attention.• I’m going to post a series of trivia questions about

today’s topics or recent ones, including an off-topic bonus question.

• Write down your answers QUICKLY!– Got the right answer? Fantastic, give yourself a star.– Got the wrong answer? Write down the topic of the

question and review it later.• Unless it’s the off-topic bonus question.

Question #1

• What is the name of the innermost “space” of the chloroplast?– Stroma

Question #2

• What is the name of the disk-like structures inside the chloroplasts? (just the disks, not the stacks!)– Thylakoids

Question #3

• What are the two products of the photosynthesis reactions?– Sugar (glucose) and oxygen

Question 4*

• Why did bald eagles become so endangered in the mid-20th century?– DDT (dichlorodiphenyltrichloroethane)

*Off-topic

“Illuminating Photosynthesis”

• Before we get to pigments and the “nuts and bolts” of this whole process, we’re going to see a really nice animation of the whole process in general.

• Please take the time to read through it carefully – this will help!

• It’s available here:– http://www.pbs.org/wgbh/nova/methuselah/phot_flash.html

Photosynthesis: Pigments

• There are three main pigments:– Chlorophyll A– Chlorophyll B– Carotenoids– There are also Anthocyanins – they help make

leaves change color in the fall.

• “Hard to place” fact:– Chlorophyll reflects green light!

Carotenoids: A Brief Aside

• In plants:– Carrots– Oranges– Fall leaves

• In animals:– Flamingos– Zebra Finches– Et cetera

http://www.rbgsyd.nsw.gov.au/__data/assets/image/0011/88535/Taeniopygia_guttata_Zebra_Finch_620.JPG

I know you think my beak is

attractive.

Back on topic…

http://www.pearsonsuccessnet.com/snpapp/iText/products/0-13-115075-8/text/chapter8/08images/08-02.gif

Chloroplasts

http://www.school.net.th/library/create-web/10000/science/10000-6528/pic2.jpeg

Chloroplasts

http://www.vialattea.net/spaw/image/biologia/May2005/thylakoids2.jpg

Let’s summarize…

Let’s summarize…

Photosynthesis Lab Gizmo!

• Today we’re going to look at a photosynthesis gizmo. Also please complete the Photosynthesis Lab Gizmo quiz on Quia.

• [Log-in Instructions]

Photosynthesis Reactions

• There are two overall parts of Photosynthesis:– The Light Reactions (or Light-Dependent Reactions)• [because the plant needs light for them]

– The Calvin Cycle (or Light-Independent Reactions)• Also called “The Dark Reactions”• [because the plant doesn’t need light for them]

Light Reactions

• Where: The thylakoid membrane.• Needs: Light and Water (H2O)• Makes: ATP and protons (H+)• Waste: Oxygen– Note: Even though oxygen is waste, it’s still a

product.

Photosynthesis Reactions

6CO2 + 6H2O C6H12O6 + 6O2

Light Reactions

Light Reactions

Light Reactions• Three Steps:– Light excites chlorophyll’s electrons (makes them

go to higher energy).– Electrons travel down the thylakoid membrane as

they lose energy. (leave some space in your notes)– The electrons power the thylakoid to make ADP

into ATP. (leave some space in your notes)• This thing is called the electron transport chain, by the

way, and it’s much like electricity flowing through a strand of holiday lights.

e-

Electron Transport Chain

http://bioweb.wku.edu/courses/Biol120/images/non-cyclic1.jpg

e-

H+

STROMA SPACE

THYLAKOID SPACE

ETC

• And what do those electrons power?– Electrons power a proton pump which brings protons

into the thylakoid space.• And then…– Protons passively diffuse out through a protein/enzyme

complex called ATP Synthase.• ATP Synthase “harvests” the motion of diffusion to

synthesize ATP from ADP and free phosphate groups.– Much like a hydroelectric dam harvests water flow.

The Calvin Cycle/Dark Reactions

• Where: The Stroma• Needs: ATP and protons (H+) [from the Light

Reactions] and CO2 [from the air]• Makes: Glucose (sugar/carbohydrate)

• Side note: named after Melvin Calvin.

Photosynthesis Reactions

6CO2 + 6H2O C6H12O6 + 6O2

Light Reactions

Light Reactions

Calvin Cycle

Calvin Cycle

Summary

• The light reactions use sunlight to make ATP (and some by-products).

• The dark reactions use that ATP to make glucose.

Closure

• Let’s do a WhipAround, shall we?• Write down one new vocabulary word from

today or yesterday and its definition.– Stand up once you’re done.

Water Weed Lab• This is a written lab report.– Specific requirements and a rubric are listed on the reverse of your lab

sheet.• You will be taking a virtual look at an aquatic plant (Elodea) and

analyzing photosynthetic rate as a function of three particular conditions:– Light Level– Light Color– CO2 Level

• You will need to create a graph for your final lab report.– The graph can be created in Excel, by hand, or with an online graphing

tool.• Create-a-Graph (in Biology Links – Various Units section)• http://nces.ed.gov/nceskids/createagraph/default.aspx

• TIP: Select “X5” to run the simulator faster.

Closure

• TED: Amanda Ooten – The Simple Story of Photosynthesis and Food