Chloroplasts and Photosynthesis Flashcards
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Questions and Answers

What is the role of chloroplasts?

Convert light energy to chemical energy through photosynthesis.

What is chlorophyll?

A pigment that traps light energy; appears green; inside the thylakoid membrane.

What are carotenoids?

Orange and yellow pigments that absorb light.

Describe the membrane structure of chloroplasts.

<p>Enclosed by two membranes with a third internal membrane structure.</p> Signup and view all the answers

What is the stroma?

<p>Fluid-filled space inside the inner membrane; contains enzymes; contains internal membrane system of thylakoids.</p> Signup and view all the answers

What is the thylakoid lumen?

<p>The innermost compartment of the chloroplast; fluid-filled space inside the thylakoids.</p> Signup and view all the answers

What is photosynthesis?

<p>The process by which light energy is transformed into chemical energy; carbohydrate and oxygen are created.</p> Signup and view all the answers

What is the overall reaction for photosynthesis?

<p>6 CO2 + H2O --&gt; glucose + 6 O2; CO2 is reduced.</p> Signup and view all the answers

Where are chloroplasts found?

<p>Inside leaf cells of the mesophyll - layer that includes air spaces and water vapor.</p> Signup and view all the answers

Describe the organization of the thylakoid membrane.

<p>Organized into stacks called grana; pigments and electron acceptors are embedded.</p> Signup and view all the answers

What are thylakoids?

<p>Interconnected, flat, disc-like sacs suspended in the stroma.</p> Signup and view all the answers

What are grana?

<p>A stack of thylakoid sacs.</p> Signup and view all the answers

What is the thylakoid membrane?

<p>Encloses thylakoids; involved in ATP synthesis.</p> Signup and view all the answers

What are pigments?

<p>Substances that absorb light at distinct wavelengths.</p> Signup and view all the answers

Describe the structure of chlorophyll.

<p>Porphyrin ring made up of smaller joined rings of C and N; absorbs light energy; contains Mg in center; long hydrocarbon side chain.</p> Signup and view all the answers

How do chlorophyll A and B differ?

<p>Chlorophyll a has a methyl terminal group, appears bright green, while chlorophyll b has a carbonyl group, appears green/yellow.</p> Signup and view all the answers

What is the strongest biological oxidizing agent?

<p>p680+.</p> Signup and view all the answers

What is the strongest biological reducing agent?

<p>p700 activated with light.</p> Signup and view all the answers

What are antenna complexes?

<p>&quot;Satellite dishes&quot; made of chlorophyll and other pigments; trap photons; found in thylakoid membrane.</p> Signup and view all the answers

What happens to light energy when it reaches the reaction center?

<p>An electron is promoted to a higher energy level and can now be donated to an electron acceptor.</p> Signup and view all the answers

How are photosystems I and II connected?

<p>Through the electron transport chain.</p> Signup and view all the answers

An electron that enters the ETC comes from?

<p>p680 molecules in the reaction center of photosystem II.</p> Signup and view all the answers

Where is the proton gradient located?

<p>Across the thylakoid membrane; pH in thylakoid lumen = 5, pH in stroma = 8.</p> Signup and view all the answers

The ETC is coupled to the movement of protons across the thylakoid membrane because?

<p>Energy released by electrons traveling down the ETC is used to pump protons into the thylakoid lumen.</p> Signup and view all the answers

Where does the production of ATP take place?

<p>In the stroma.</p> Signup and view all the answers

Where does the Calvin cycle take place?

<p>In the stroma.</p> Signup and view all the answers

What is photolysis?

<p>Incoming light &quot;splits water&quot; into an oxygen molecule and 2 H+; generates protons that perpetuate the pH gradient.</p> Signup and view all the answers

What drives ATP synthase activity in photosynthesis?

<p>The ATP synthase.</p> Signup and view all the answers

Where does ATP synthase project into?

<p>The stroma.</p> Signup and view all the answers

Study Notes

Chloroplasts and Photosynthesis

  • Chloroplasts convert light energy into chemical energy through photosynthesis.
  • Chlorophyll is the green pigment located inside the thylakoid membrane that traps light energy.
  • Carotenoids are orange and yellow pigments that absorb light and transfer energy to chlorophyll a.
  • Chloroplast membranes consist of an inner membrane, outer membrane with pores, and thylakoid membrane enclosing the thylakoid lumen.
  • The stroma is a fluid-filled space in the chloroplast that contains enzymes and the internal thylakoid membrane system; comparable to the mitochondrial matrix.
  • The thylakoid lumen is the innermost compartment of chloroplasts, filled with fluid.
  • Photosynthesis transforms light energy into chemical energy, creating carbohydrates and oxygen.
  • The overall photosynthesis reaction is: 6 CO2 + H2O → glucose + 6 O2; CO2 is reduced in this process.
  • Chloroplasts are primarily found in mesophyll cells of leaves, which contain air spaces and water vapor.
  • The thylakoid membrane organizes into stacks called grana, where pigments and electron acceptors are embedded.
  • Thylakoids are disc-like sacs suspended in the stroma, interconnected for efficient functioning.
  • Grana refer to the stacked structures of thylakoid sacs.
  • The thylakoid membrane encloses the thylakoids and is crucial for ATP synthesis.
  • Pigments absorb light at distinct wavelengths and play key roles in photosynthesis.
  • Chlorophyll is structured with a porphyrin ring that absorbs light and contains magnesium, with a long hydrocarbon side chain for membrane anchoring.
  • Chlorophyll A and B differ by their terminal group: A has a methyl group and appears bright green, while B has a carbonyl group and appears green/yellow.
  • P680+ is the strongest biological oxidizing agent, while P700, activated by light, is the strongest biological reducing agent.
  • Antenna complexes, made of chlorophyll and other pigments, act like "satellite dishes" for trapping photons, located in the thylakoid membrane with a reaction center at their core.
  • Resonance transfer occurs in the reaction center, where energy from absorbed photons is passed among pigments until reaching the reaction center.
  • The reaction center consists of a special chlorophyll pair, absorbing at the longest wavelengths and promoting an electron to a higher energy state for donation to an electron acceptor.
  • Photosystems I and II are connected via the electron transport chain (ETC).
  • Electrons entering the ETC originate from P680 molecules in the reaction center of photosystem II.
  • A proton gradient exists across the thylakoid membrane, with pH in the thylakoid lumen at 5 and in the stroma at 8.
  • The ETC is coupled with proton movement across the thylakoid membrane, as energy released by electrons is used to pump protons into the thylakoid lumen.
  • ATP production occurs in the stroma, utilizing ATP synthase activity.
  • The Calvin cycle, responsible for carbon fixation, takes place in the stroma.
  • Photolysis is the process where light energy splits water into an oxygen molecule and two protons, aiding proton gradient maintenance.
  • ATP synthase activity in photosynthesis is driven by the proton motive force and its projection into the stroma.

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Explore the fundamentals of photosynthesis with these flashcards focused on chloroplasts and their components. Learn about chlorophyll, carotenoids, and the conversion of light energy to chemical energy. Perfect for students looking to enhance their understanding of plant biology.

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