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Today is Thursday,

October 29

th

, 2015

Pre-Class:

Why are plants green?

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

Other stuff:

Grab a [small] paper towel for your pair. In This Lesson:

Photosynthesis (Lesson 2 of 3)

(2)

Today’s Agenda

• Photosynthesis

• Photosynthesis

• And maybe flamingos.

(3)

By the end of this lesson…

• You should be able to identify the general input and output of the photosynthesis reactions.

(4)

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.

(5)

Simple Diagram

(worth sketching…no, really)

(6)

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

(7)

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.

Importantly, plants gain their mass largely from CO2, not from water.

Jan van Helmont also coined the word “gas.”

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

Floating head! Spooky…

(8)

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!!

(9)

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

(10)

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.

(11)

2015: 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.

(12)

The Magic Photosynthesis Machine

YE OLDE

PHOTOSYNTHESIS

MACHINE

?

INPUT OUTPUT

?

(13)

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)

(14)

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

(15)

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

• Vision anomalies

(16)

Ishihara Test

(17)

Ishihara Test

(18)

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.

(19)

Vision Correction

(20)

The Chloroplast

Sketch it like you mean it!

(21)

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).

(22)

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.

(23)

Question #1

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

(24)

Question #2

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

(25)

Question #3

• What are the two products of the photosynthesis reactions?

(26)

Question 4*

• Why did bald eagles become so endangered in the mid-20th century?

DDT (dichlorodiphenyltrichloroethane)

(27)

“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:

(28)

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:

(29)

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.
(30)

Back on topic…

(31)

Chloroplasts

(32)

Chloroplasts

(33)
(34)
(35)

Photosynthesis Lab Gizmo!

• Today we’re going to look at a photosynthesis gizmo. Also please complete the

Photosynthesis Lab Gizmo quiz on Quia.

(36)

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”

(37)

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.

(38)

Photosynthesis Reactions

6CO

2

+ 6H

2

O

C

6

H

12

O

6

+ 6O

2 Ligh t R eac tions Ligh t R eactio ns
(39)

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.

(40)

-Electron Transport Chain

http://bioweb.wku.edu/courses/Biol120/images/non-cyclic1.jpg e -H+ STROMA SPACE THYLAKOID SPACE
(41)

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.

(42)

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)

(43)

Photosynthesis Reactions

6CO

2

+ 6H

2

O

C

6

H

12

O

6

+ 6O

2 Ligh t R eac tions Ligh t R eactio ns Calv in Cy cle Calv in Cy cle
(44)

Summary

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

• The dark reactions use that ATP to make glucose.

(45)

Closure

• First, 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. • Now the Water Weed Lab.

(46)

Closure

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

References

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