ATP & Photosynthesis

ATP & Photosynthesis Honors Biology

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

Adenine Ribose 3 Phosphate groups The principal chemical compound used by living things to store energy is: adenosine triphosphate (ATP). Labeled Sketch:

Energy Storage/ Energy Release Energy Adenosine diphosphate (ADP) + Phosphate Energy Adenosine triphosphate (ATP) Partially charged battery Fully charged battery 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.

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

Photosynthesis Basic Equation • Process by which plants use water, carbon dioxide, and energy from sunlight to produce sugar (and oxygen). 6CO2 + 6H2O  C6H12O6 + 6O2

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 – Preistly • Determined that plants release oxygen • 1700’s – Ingenhousz • Building on Preistly’s work, he determined that oxygen was only produced in the presence of light.

Photosynthesis Equation in Detail Chemical Equation 6CO2 + 6H2O  C6H12O6 + 6O2 + ATP + NADPH Glucose continues to be processed into ATP. ATP utilized as energy for reactions NADPH used to convert oxidized molecules such as carbon dioxide Oxygen released for use in aerobic reactions How do plants USE these raw materials?

Light and Pigments • Why are most plants green? • Are there plants / photosynthetic organisms that are other colors? • -Why? The answer lies in: Light Spectra Pigments

Light and Pigments What is the light spectra? Visible light is just a small part of the electromagnetic spectrum

Light and Pigments The longest wavelengthshave the lowest energies. (radio) As wavelengths decrease, the energy increases. (gamma)

Light and Pigments Different colors correspond to different wavelengths The colors of the rainbow are ROY G BIV: red orange yellow green blue indigo violet. redhas the longest wavelength, and the lowest energy violet has the shortest wavelength, and the highest energy

Homework Seeing color The color an object appears depends on the colors of light it reflects. For example, a red book only reflects red light: White light Only red light is reflected Homework

A pair of purple pants would reflect purple light (and red and blue, as purple is made up of red and blue): Purple light A white hat would reflect all seven colors: Homework White light

Using colored light If we look at a colored object in colored light we see something different. Shirt looks red White light Homework Shorts look blue

In different colors of light these clothes would look different: Red light Shirt looks red Shorts look black Shirt looks black Blue light Homework 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 Pigments Chlorophyll 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 Pigments Other pigments are also present in plants that use other wavelengths These include: • Beta-carotene (orange) • Xanthophyll (Lutein) (yellow)

Light and Pigments Autumn 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 Reactions • 1) The Light Reaction • Reactants • H2O Light • NADP+ ADP + P • Products • ATP NADPH O2 • 2) The Calvin Cycle • (AKA The Dark Reaction) • Reactants • CO2 ATP NADPH • Products • Sugar NADP+ ADP + P

Location of Reactions Thylakoid: 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

Water CO2 Sugars O2 Location of Reactions Chloroplast Chloroplast NADP+ ADP + P Light- Dependent Reactions Calvin Cycle ATP NADPH Stroma Thylakoid

Photophosphorylation Definition: Using light energy to phosphorylate ADP to make ATP

Light Reaction Overview • Photosystem II absorbs light energy • This light energy increases the energy level of electrons in pigments • Enzyme on the thylakoid breaks up water into 2 electrons, 2 H+, 1 Oxygen • The electrons replace those lost in the pigment • Oxygen is released out of the chloroplast • H+ stays inside the thylakoid membrane

Light Reaction Overview Animation

Light Reaction Overview • Electron Transport Chain • Electrons leave photosystem II, and are accepted by plastoquinone • Plastoquinone passes the electrons to the proton pump in b6-f complex • The proton pump moves protons (H+) from the stroma into the thylakoid • The thylakoid now has a high concentration of H+ compared to the stroma

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 Overview • Photosystem I absorbs light energy • This light energy increases the energy level of electrons passed from photosystem II • Electrons pass through ferrodoxin to NADP reductase enzyme • NADP reductase transfers electrons to NADP+ and H+ to form NADPH • NADPH is used in the Calvin Cycle

Light Reaction Overview • ATP Formation • High concentration of H+ has been built up in the thylakoid • The thylakoid membrane contains ATP synthase, which allows H+ to pass through • As H+ passes through, it spins ATP synthase, binding ADP and P, creating ATP • ATP is used in the Calvin Cycle

The Calvin Cycle Where does the Calvin Cycle take place? In the Stroma Does 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 Overview • Carbon Dioxide enters from the atmosphere, combines with RuBP, a 5 carbon molecule, using the enzyme RuBisCo • This 6 carbon molecule is unstable, and breaks into (2x) 3-PGA • ATP and NADPH turn 3-PGA into a more stable G3P • Most of the G3P is converted back to RuBP, using ATP • 1 of 6 G3P molecules is used to make sugar

Calvin Cycle Overview Animation 1 Animation 2

ATP & Photosynthesis