Question: Explain the structure of a chloroplast, please

Laura Newton answered on 16 Jun 2015:

Hey!

Chloroplasts are round or oval shaped and have two membranes around their outside, these are called the chloroplast envelope. Inside them there is another membrane that folds around a lot and forms lots of little discs called thylakoids. When these discs are stacked on top of each other they are called grana. When the membrane connects different grana to each other it is called lamellae.

Inside the thylakoid membranes are photosystem I and photosystem II, two complexes of proteins which can convert sunlight into the energy needed to make bonds. Specifically they make a molecule called ATP. Surrounding the thylakoid membranes is the stroma, a liquid that contains a lot of enzymes including the ones that use the ATP molecules from the photosystems to make glucose – the sugar the plant needs to grow. This is called the Calvin cycle.

Hope that answers your question.
Best wishes,
Laura