AP Bio 2.10 Origins of Cell Compartmentalization

chloroplast and mitochondria

• have double sets of membrane

  • internal membrane makes up the thylakoids within a chloroplast

  • internal convoluted and folded up membrane within the mitochondria

• divide independently

• have their own sets of DNA

• are inherited independently

  • inherited from the biological mother

• have their own ribosomes

origins of compartmentalization

• 2.5 billion years ago, all living things were prokaryotes

  • did not have compartmentalization

• little cell is wrapped in a vesicle which becomes its internal membrane

  • big cell provides its external membrane

• these little cells evolved into mitochondria and chloroplasts through endocytosis

• phagocytosis: folding in the membrane to take in a large particle or large molecule and forming a vesicle around it

  • particular type of endocytosis

• the resulting organisms evolved into eukaryotes with compartmentalization/internal membrane-bound structures

origin of mitochondria

• occurred about 2.5 billion years ago

• aerobic respiration: can take carbohydrates from the environment and use some oxygen in such a way that it can make large amounts of ATP

  • highly efficient ATP phosphorylation reactions

• big cell folded in the smaller cell that is good at aerobic respiration through phagocytosis

  • big cell provides a stable environment

  • little cell provides a steady supply of ATP

origin of chloroplast

• around the same time (2.5 billion years ago), cyanobacterium was good at taking in carbon dioxide, and using sunlight and water in its environment to produce glucose

• larger cell took in the cyanobacterium via phagocytosis, wrapped it in a vesicle, and brought it inside

  • big cell provides a stable environment

  • little cell provides a steady supply of glucose