3.2.6 The Origin of Mitochondria and Chloroplasts

Question 1

review

Answer 1

• Strong evidence suggests that mitochondria and chloroplasts—both membrane-bound organelles that occur in eukaryotic cells—evolved as independent prokaryotic organisms that later came to occupy eukaryotic organisms. The process is called endosymbiosis.

Question 2

phagocytosis

Answer 2

• when extensions of the plasma membrane surround and engulf food particles

Question 3

endocytosis

Answer 3

• A food particle, such as a living prokaryotic cell, will become surrounded with cell membrane

Question 4

Which membrane of mitochondria is thought to be eukaryotic in origin?

Answer 4

• the outer membrane

Question 5

The _________ membranes of mitochondria and chloroplasts have several enzymes and electron transport molecules that resemble those found in the plasma membrane of modern prokaryotes, presumably as a result of their endosymbiotic origin.

Answer 5

• inner

Question 6

Chloroplasts and mitochondria are thought to have arisen evolutionarily through endosymbiosis. Which of the following would provide the best evidence of endosymbiosis?

Answer 6

• identifying a protein that is common to both chloroplasts and bacteria

Question 7

The function of chloroplasts is most closely related to which cellular organelle?

Answer 7

• mitochondria

Question 8

True or false?

Mitochondria are thought to have arisen from an ancestral aerobic heterotrophic prokaryote.

Answer 8

• true

Question 9

Which organelle(s) of eukaryotic cells probably descended from endosymbiotic bacteria?

Answer 9

• Both mitochondria and chloroplasts

Question 10

How are present-day mitochondria similar to prokaryotic cells?

Answer 10

• The shape and structure of their ribosomes are homologous