Chapter 5: Photosynthesis

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Chemicals present to initiate the Calvin cycle:

- CO2 (Carbon Dioxide) -RuBisCO (An enzyme) -RuBP (Ribulose Bisphosphate)

Chlorophyll A

-All photosynthetic organisms have it -Humans see as the common GREEN color associated with plants -Absorbs wavelengths from either end of the visible spectrum (blue and red), but not from green.

Lightdependent reactions steps

-Light energy is absorbed by a chlorophyll molecule and is passed along a pathway to other chlorophyll molecules. -The energy culminates in a molecule of chlorophyll found in the reaction center. -The energy "excites" one of its electrons enough to leave the molecule and be transferred to a nearby primary electron acceptor. - A molecule of water splits to release an electron, which is needed to replace the one donated. -Oxygen and hydrogen ions are also formed from the splitting of water.

Electromagnetic spectrum facts

-Longer the wavelength/more stretched out = Less energy -Short/tight waves = Most energy Ex: St. Bernard = Chill Chihuahua = Crackhead

The Calvin cycle reactions can be organized into three basic stages:

1. Fixation 2. Reduction 3. Regeneration.

Photosynthesis takes place in 2 stages:

1. Light-Dependent Reactions 2. Calvin Cycle ****The two reactions use carrier molecules to transport the energy from one to the other****

Cellular respiration equation

6O2 + C6 H12 O6 → 6CO2 + 6H2O

Reduction reaction

A chemical change in which electrons are gained, either by the removal of oxygen, the addition of hydrogen, or the addition of electrons

Photosystem

A grouping of pigment molecules and proteins that exist in the membranes of thylakoids. Photosystem = where lightdependent reactions begin ***EUKARYOTES two photosystems exist, the first is called photosystem II

Pigment

A molecule that absorbs light

Photon

A particle of light - a quantity or "packet" of light energy.

Photosynthesis process

STARTING REACTANTS: Requires sunlight, carbon dioxide, and water RESULTS: Releases oxygen and produces carbohydrate molecules, most commonly glucose.

The energy that these molecules carry is stored in a bond that holds a single atom to the molecule

ATP = phosphate atom NADPH = hydrogen atom. **When these molecules release energy into the Calvin cycle, they each LOSE atoms to become the lower-energy molecules ADP and NADP+**

Reduction reaction explanation

ATP and NADPH use their stored energy to convert the three-carbon compound, 3-PGA, into another three-carbon compound called G3P. The molecules of ADP and NAD+, resulting from the reduction reaction, return to the light-dependent reactions to be re-energized.

What are the two energy-carrying molecules of the light-dependent reactions?

ATP and NADPH.

Carotenoids

Accessory pigments that broaden the spectrum of colors that can drive photosynthesis.

Chlorophyll B

An accessory photosynthetic pigment that transfers energy to Chlorophyll A *Absorbs blue and red-orange light) and the carotenoids

Chloroplast

An organelle found in plant and algae cells where photosynthesis occurs ***Chloroplasts have a double (inner and outer) membrane.***

A bacterium that lives near a thermal sea vent is able to transform inorganic compounds into an energy source. This organism would be classified as a(n) _____________________

Autotroph

How do prokaryotes, such as cyanobacteria, carry out photosynthesis?

Because they lack membrane-bound organelles, prokaryotic photosynthetic autotrophic organisms have infoldings of the plasma membrane for chlorophyll attachment and photosynthesis.

Photosynthesis equation

Carbon dioxide + Water + Sun's energy = Glucose (Sugar) + Oxygen OR 6CO2 + 6H2O + light energy → C6H12O6 + 6O2

Carbon atoms used to build carbohydrate molecules comes from

Carbon dioxide, the gas that animals exhale with each breath.

Photosynthesis

Certain organisms convert solar energy (sunlight) into chemical energy, which is then used to build carbohydrate molecules

In ALL autotrophic EUKARYOTES, photosynthesis takes place inside an organelle called the __________________

Chloroplast

Pigment facts

Different kinds of pigments exist, and each absorbs only certain wavelengths (colors) of visible light. Pigments reflect the color of the wavelengths that they cannot absorb.

Photosystem II and I (II Comes FIRST)

From photosystem II, the excited electron travels along a series of proteins. This electron transport system (chain) uses the energy from the electron to pump hydrogen ions into the interior of the thylakoid. A pigment molecule in photosystem I accepts the electron.

Because the carbohydrate molecule has six carbon atoms....

It takes six turns of the Calvin cycle to make one carbohydrate molecule (one for each carbon dioxide molecule fixed).

In plants, photosynthesis takes place primarily in the _________________

Leaves, specifically the mesophyll

Lightdependent reactions facts

MAIN PURPOSE: To convert light energy into chemical energy. -This chemical energy will be used by the Calvin cycle to fuel the assembly of sugar molecules.

In plants, chloroplast-containing cells exist in the _____________

Mesophyll

Autotroph (Producers)

Organism that can produce its own food. *Plants are the best-known autotrophs, but others exist, including certain types of bacteria and algae.

Heterotrophs (Consumers)

Organisms incapable of photosynthesis that must therefore obtain energy and carbon from food by consuming other organisms. *Humans and all animals are heterotrophs

Photosynthesis produces _____________ as a byproduct, and respiration produces _____________ as a byproduct.

Oxygen Carbon Dioxide

Calvin Cycle

Reactions of photosynthesis that use the energy stored by the lightdependent reactions to form glucose and other carbohydrate molecules.

Carbon fixation explanation

RuBisCO catalyzes a reaction between CO2 and RuBP, which forms a six-carbon compound that is immediately converted into two three-carbon compounds. *CO2 is "fixed" from its inorganic form into organic molecules.

Stomata

Small, regulated openings of the leaf where the gas exchange of carbon dioxide and oxygen occurs.

Granum

Stack of thylakoids

Thylakoids

Stacked, disc-shaped structures inside the chloroplast, used to convert light energy to chemical energy. **Located within the chloroplasts**

Calvin Cycle simplified

Stage 1. Enzyme RuBisCO incorporates carbon dioxide into an organic molecule Stage 2. The organic molecule is reduced Stage 3. RuBP (the molecule that starts the cycle) is regenerated so the cycle can continue.

Lightdependent reactions

TAKES PLACE IN THYKALOID MEMBRANE 1. Chlorophyll absorbs energy from sunlight 2. Converts it into chemical energy with the use of water. 3. Oxygen released from the hydrolysis of water as a byproduct.

More on Calvin Cycle

Takes six turns of the Calvin cycle to fix six carbon atoms from CO2. These six turns require energy input from 12 ATP molecules and 12 NADPH molecules in the reduction step and 6 ATP molecules in the regeneration step.

Wavelength

The distance between two consecutive, similar points in a series of waves, such as from crest to crest or trough to trough *The wavelength of a single wave is the distance between two consecutive points along the wave.

Reduction

The gain of an electron by an atom or molecule.

Carbon fixation

The initial incorporation of carbon into organic compounds.

The Energy Cycle

The movement of energy into and out of the earth system.

Clorophyll

The pigment through which the entire process of photosynthesis begins. *Chlorophyll is responsible for the green color of plants* **Located within the thylakoids**

Absorption spectrum

The range of a pigment's ability to absorb various wavelengths of light.

Electromagnetic spectrum

The range of all possible wavelengths of radiation. *Each wavelength corresponds to a different amount of energy carried.

Stroma

The space surrounding the granum

Photoautotrophs

Type of autotroph that uses sunlight and carbon from carbon dioxide to synthesize chemical energy in the form of carbohydrates. *Plants, algae, and certain bacteria, called cyanobacteria, are photoautotrophs that can carry out photosynthesis.

Mesophyll

the tissue in the interior of the leaf where photosynthesis occurs.


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