Question Video: Recalling the Structures Contained Within A Chloroplast Biology • Second Year of Secondary School

Video Transcript

Which of the following statements correctly links the grana to the thylakoids? (A) Circular grana come together in stacks to form a single thylakoid. (B) Disklike structures called thylakoids form stacks called grana. Or (C) a single thylakoid cell is formed of multiple grana components.

Let’s review the structures within a chloroplast to answer this question. Chloroplasts are cell organelles that are surrounded by two membranes. The inside of a chloroplast is filled with a fluid matrix called the stroma. The stroma contains many enzymes along with the DNA of the chloroplast and ribosomes. It also contains disklike structures called thylakoids. These thylakoids, which are one of the key terms used in our question, form stacks of around 15 or more disks. A stack of thylakoids is called a granum or plural grana. This is the other key term that’s been used in the question.

The grana are interconnected by thin membranous folds called lamellae or a singular lamella. Within each thylakoid is an aqueous space called the lumen. So now we know the relationship between thylakoids and the grana, which is (B). Disklike structures called thylakoids form stacks called grana.