adaptations of chloroplasts for photosynthesis Flashcards
What is the structure of chloroplasts?
Chloroplasts have a double membrane (outer chloroplast envelope), an extensive system of internal membranes called thylakoids, and a fluid-filled space (stroma) surrounding them.
What is the role of thylakoids in chloroplasts?
Thylakoids are stacked into grana and contain chlorophyll, which absorbs light for photosynthesis. Their large surface area enhances light absorption.
How do chloroplasts maximize light absorption?
Chloroplasts have photosystems embedded in the thylakoid membranes, which contain pigment molecules that absorb light. The stacked arrangement of thylakoids (grana) increases the surface area for light absorption.
How do chloroplasts produce ATP during photosynthesis?
Chloroplasts use photophosphorylation to produce ATP. This process requires a proton gradient that develops in the thylakoid membrane, with the small volume of the thylakoid space allowing a rapid build-up of the proton gradient.
What is the role of the stroma in chloroplasts?
The stroma contains the enzymes required for the Calvin Cycle, along with substrates and products of the cycle. The concentration of these enzymes and substrates speeds up the reactions.
How do chloroplasts efficiently perform the Calvin Cycle?
The ATP and reduced NADP produced in the thylakoids are readily available in the stroma, where the Calvin Cycle takes place. The proximity of these molecules to the enzymes involved speeds up the cycle.
What evidence is there of active photosynthesis in chloroplasts?
Starch grains or lipid droplets may be present in the stroma of chloroplasts that are photosynthesizing rapidly, indicating the production of energy-rich compounds.
How do thylakoids support ATP production?
The small volume inside the thylakoids means that the proton gradient needed for ATP production can form quickly after the absorption of light photons, allowing for efficient ATP synthesis.
