ATP & Photosynthesis

Honors Biology

ATP

• All cells need __________for life. • Some things we use energy for are:• Moving• Thinking• Sleeping• Breathing• Growing• Reproducing

ENERGY

The principal chemical compound used by living things to store energy is: adenosine triphosphate (ATP).

Adenine Ribose 3 Phosphate groups

Labeled Sketch:

Energy Storage/ Energy Release

Energy

EnergyAdenosine diphosphate (ADP) + Phosphate Adenosine triphosphate (ATP)

Partiallychargedbattery

Fullychargedbattery

Energy can be stored by adding a phosphate group to ADP, creating ATP, called phosphorylation.

Breaking the phosphate chemical bond in ATP releases energy, changing the ATP back into ADP.

ATP:• ATP is used for active transport,

movement of cell organelles and other basic functions (mitosis, etc)

• Glucose: sugar molecule that stores 90 times more energy than ATP. Glucose is used to regenerate ATP.

Comparison of burning a marshmallow at a campfire vs in your body.

When sugar burned in fire:

Both have in common (Similarities)

When sugar burned in body

Energy is released quickly as heat and light

-Glucose and oxygen are reactants.-Carbon dioxide and water are products. -Both release energy.

Energy is stored in small ATP molecules for slow use

Why do we use ATP? Why not just get energy from sugar directly?

• ATP is small units of energy. Sugar is a very high energy molecule (if you burn it all at once…spontaneous combustion!)

Analogy:

• Power lines= sugar = tons of energy• Wall socket = ATP = smaller units of energy

Basic Equation

6CO2 + 6H2O C6H12O6 + 6O2

Photosynthesis• Process by which plants use water, carbon

dioxide, and energy from sunlight to produce sugar (and oxygen).

Photosynthesis Experiments• 1600’s – Van Helmont

Determined that mass gained during plant growth does NOT come from the soil. He concluded it must come from the water he added.

• 1700’s – PreistlyDetermined that plants release oxygen

• 1700’s – IngenhouszBuilding on Preistly’s work, he determined that oxygen was only produced in the presence of light.

Chemical Equation6CO2 + 6H2O C6H12O6 + 6O2 + ATP + NADPH

Photosynthesis Equation in Detail

Glucose continues to be processed into ATP.

How do plants USE these raw materials?

Oxygen released for use in aerobic

reactions

ATP utilized as energy for reactions

NADPH used to convert oxidized molecules such

as carbon dioxide

Light and Pigments

-Why are most plants green?

-Are there plants / photosynthetic organisms that are other colors?

-Why? The answer lies in:1) Light Spectra2) Pigments

Light and PigmentsWhat is the light spectra?

Visible light is just a small part of the electromagnetic spectrum

Light and PigmentsThe longest wavelengths have the lowest energies. (radio)

As wavelengths decrease, the energy increases. (gamma)

Light and PigmentsDifferent colors correspond to

different wavelengths

The colors of the rainbow are ROY G BIV:

red orange yellow green blue indigo violet.

red has the longest wavelength, and the lowest energyviolet has the shortest wavelength, and the highest energy

Homework

Seeing colorThe color an object appears depends on the

colors of light it reflects.

For example, a red book only reflects red light:

Whitelight

Only red light is reflected

Homework

A white hat would reflect all seven colors:

A pair of purple pants would reflect purple light (and red and blue, as purple is made up of red and blue):

Purple light

Whitelight

Homework

Using colored light

If we look at a colored object in colored light we see something different.

Whitelight

Shorts look blue

Shirt looks red

Homework

In different colors of light these clothes would look different:

Redlight

Shirt looks red

Shorts look black

Bluelight

Shirt looks black

Shorts look blue

Light and Pigments

Plants gather light spectra with light absorbing

molecules called PIGMENTS

The major pigment used by plants is chlorophyll

There are two main chlorophyll types a and b

Light and PigmentsChlorophyll a and b absorb

light very well in the violet/blue and orange/red

parts of the spectrum.

But very poorly in the green part of the spectrum.

This makes most plants green (remember, to see a

color it needs to be reflected)

Light and PigmentsOther pigments are also present in plants that use other wavelengths

These include:

- Beta-carotene (orange)

- Xanthophyll (Lutein) (yellow)

Light and PigmentsAutumn Leaves

There is so much chlorophyll, it masks other pigment colors.

Light regulates chlorophyll production, so shorter days means less chlorophyll is produced, and the green color

fades.

Anthocynanins, producing red color, are produced during the

breakdown of chlorophyll.

Overview of Reactions1) The Light Reaction

ReactantsH2O Light

NADP+ ADP + P Products

ATP NADPH O2

2) The Calvin Cycle(AKA The Dark Reaction)

ReactantsCO2 ATP

NADPHProducts

Sugar NADP+ ADP + P

Location of ReactionsThylakoid: Sac-like photosynthetic membranes, location of the light reaction

Granum: A collection or stack of thylakoids

Stroma: Gel-like space outside the thylakoid, location of the Calvin Cycle

ChloroplastWater

O2

Sugars

CO2

Light-Dependent Reactions

CalvinCycle

NADPHATP

ADP + PNADP+Chloroplast

Location of Reactions

Thylakoid Stroma

Photophosphorylation

Definition: Using light energy to phosphorylate ADP to make ATP

Light Reaction Overview1. Photosystem II absorbs light energy2. This light energy increases the energy

level of electrons in pigments3. Enzyme on the thylakoid breaks up

water into 2 electrons, 2 H+, 1 Oxygen4. The electrons replace those lost in the

pigment5. Oxygen is released out of the chloroplast6. H+ stays inside the thylakoid membrane

Light Reaction Overview

Animation

Light Reaction Overview1. Electron Transport Chain2. Electrons leave photosystem II, and are

accepted by plastoquinone3. Plastoquinone passes the electrons to

the proton pump in b6-f complex4. The proton pump moves protons (H+)

from the stroma into the thylakoid5. The thylakoid now has a high

concentration of H+ compared to the stroma

Light Reaction Overview

Animation

What is NADPH / NADP+ ?

NADPH is a co-enzyme that is an electron carrier.

It exists in two forms:

NADPH has the electron

NADP+ lacks the electron

Light Reaction Overview1. Photosystem I absorbs light energy2. This light energy increases the energy

level of electrons passed from photosystem II

3. Electrons pass through ferrodoxin to NADP reductase enzyme

4. NADP reductase transfers electrons to NADP+ and H+ to form NADPH

5. NADPH is used in the Calvin Cycle

Light Reaction Overview

Animation

Light Reaction Overview1. ATP Formation2. High concentration of H+ has been built

up in the thylakoid3. The thylakoid membrane contains ATP

synthase, which allows H+ to pass through

4. As H+ passes through, it spins ATP synthase, binding ADP and P, creating ATP

5. ATP is used in the Calvin Cycle

Light Reaction Overview

Animation

The Calvin CycleWhere does the Calvin Cycle take place? In the StromaDoes the Calvin Cycle require light? No. It’s also called ‘light-independent’

Why do plants need the Calvin Cycle? The ATP and NADPH produced in the light

reactions are unstable. The Calvin Cycle creates longer lasting compounds (sugars)

Calvin Cycle Overview1. Carbon Dioxide enters from the atmosphere,

combines with RuBP, a 5 carbon molecule, using the enzyme RuBisCo

2. This 6 carbon molecule is unstable, and breaks into (2x) 3-PGA

3. ATP and NADPH turn 3-PGA into a more stable G3P

4. Most of the G3P is converted back to RuBP, using ATP

5. 1 of 6 G3P molecules is used to make sugar

Calvin Cycle Overview

Animation 1

Animation 2