Unit 2: Topic 11 - Origins of Cell Compartmentalization

Question 1

According to the endosymbiotic theory, how did cells develop membrane-bound organelles?

Answer 1

According to the endosymbiotic theory, membrane-bound organelles were actually once independent prokaryotic cells that got taken in by larger cells. The cells ended up forming a symbiotic relationship where the small cell would provide energy and other functions, and the larger cell would provide resources and protection. Evidence for this theory comes in the form of mitochondria and chloroplast having their own DNA and being able to multiply on their own.

Question 2

What are the differences in compartmentalization between prokaryotic and eukaryotic cells

Answer 2

Prokaryotic cells have no membrane-bound organelles, while eukaryotic cells do. Instead, prokaryotic cells have internal regions with specialized structures and functions. For example, instead of having a nucleus with a nuclear membrane, prokaryotic cells have a nucleoid which is just a general area where the genetic material of the prokaryotic cell is located.

Question 3

What are the difference in internal membranes between prokaryotic and eukaryotic cells?

Answer 3

Eukaryotic cells have internal membrane-bound organelles, and prokaryotic cells don’t. By creating membrane-bound organelles, the cell becomes efficient by having organelles that are efficient at specific functions. For example, the mitochondria specialize in ATP production and have folds that increase the organelle’s surface area to volume ratio, which increases ATP production. Since prokaryotes don’t have membrane-bound organelles, they tend to be less complex than eukaryotes and less efficient.

Question 4

How are mitchondria and chloroplasts similar to their past prokaryotic ancestors?

Answer 4

Both mitochondria and chloroplasts have their own genetic information contained within them and are able to replicate through a process similar to the binary fission of their prokaryotic ancestors. The ancestors also likely had similar qualities as their current versions. The prokaryotic ancestor of the mitochondria was likely very efficient at producing ATP, and the prokaryotic ancestor of the chloroplast was likely able to use light energy to produce ATP.