Unit 2: Endosymbiosis

Question 1

mitochondria and chloroplasts can only form out of _______

Answer 1

other existing mitochondria or chloroplast. That is why scientists think they evolved from bacteria

Question 2

What is the endosymbiosis theory mainly concerned with?

Answer 2

certain organelles within eukaryotes originated from free-living bacteria that were engulfed by ancestral eukaryotic cells.

Question 3

What is the endosymbiosis theory mainly concerned with?

Answer 3

Origin of mitochondria and chloroplasts

Question 4

Which type of bacterium is believed to have evolved into mitochondria?

Answer 4

Aerobic bacterium related to rickettsias

Question 5

How many base pairs are there in the genome of human mitochondria?

Answer 5

16,569

Question 6

What is the primary amino acid at the start of mitochondrial and chloroplast proteins?

Answer 6

fMet

Question 7

Which molecule encodes the genes for ribosomal RNA in chloroplasts?

Answer 7

The chloroplast genome encodes genes for ribosomal RNA (rRNA), including each of the four subunits (23S, 16S, 4.5S, and 5S).

Question 8

What is secondary endosymbiosis?

Answer 8

Engulfing eukaryotic cell containing a chloroplast

Question 9

What is the function of RUBISCO encoded by the chloroplast genome?

Answer 9

RUBISCO is responsible for adding CO2 to ribulose bisphosphate during the Calvin cycle.

Question 10

What is the evidence that mitochondria and chloroplasts evolved from bacteria?

Answer 10

(1) They can arise only from preexisting mitochondria and chloroplasts.

(2) They have their own genome, which resembles that of bacteria, not nuclear genome.

(3) Both have their own protein-synthesizing machinery, and it more closely resembles that of bacteria than eukaryotes.

(4) The first amino acid of their transcripts is always fMet