Chloroplasts

Definition

Chloroplasts are organelles found in eukaryotic cells that conduct photosynthesis, capturing light energy to produce glucose and oxygen. They contain their own DNA and are believed to have originated from cyanobacteria through endosymbiosis.

5 Must Know Facts For Your Next Test

1. Chloroplasts have a double membrane structure comprising an outer membrane and an inner membrane.
2. They contain thylakoids arranged in stacks called grana where the light-dependent reactions of photosynthesis occur.
3. The stroma, the fluid inside chloroplasts, contains enzymes essential for the Calvin cycle (light-independent reactions).
4. Chloroplasts possess their own circular DNA and ribosomes similar to those found in prokaryotes.
5. They play a crucial role in producing ATP and NADPH during photosynthesis, which are then used in carbohydrate synthesis.

Review Questions

• What is the primary function of chloroplasts in eukaryotic cells?
• How do chloroplasts contribute to protein synthesis within the cell?
• Explain the significance of chloroplast DNA in understanding its evolutionary origin.

Related terms

Mitochondria:

Organelles responsible for producing ATP through cellular respiration.

Thylakoid:

Membrane-bound compartments inside chloroplasts where light-dependent reactions take place.

Endosymbiotic Theory:

Theory suggesting that certain organelles, like mitochondria and chloroplasts, originated as free-living bacteria engulfed by larger cells.