3.1.2 Prokaryotes vs. Eukaryotes

Question 1

note

Answer 1

• A comparison of the prokaryotic cell versus the eukaryotic cell yields several key differences in cell appearance and structure.
• In terms of evolutionary history, the term “prokaryotic” translates literally as “before the kernel/nucleus.” Prokaryotes, which lack a nucleus, have a relatively long evolutionary history.
• The term “eukaryotic” translates as “true nucleus.” The term indicates that eukaryotes have a nucleus, a relatively recent evolutionary invention.

Question 2

Prokaryotic cells

Answer 2

• are between 1-10 microns in size. Illustration (a) on the left depicts a prokaryotic cell.
• The DNA is not enclosed in a nucleus.
• Prokaryotic DNA is a template for RNA synthesis. RNA directs protein synthesis. Prokaryotes have relatively few organelles, but do have ribosomes.

Question 3

eukaryotic cells

Answer 3

• are between 10–100 microns in size. Illustration (a) shows a eukaryotic cell.
• The DNA of a eukaryote is contained in the nucleus. The DNA molecule exists as a double helix, and the chromosome that the DNA is packaged in occurs in a rod-like form.
• Eukaryotic DNA is a template for RNA synthesis, and RNA directs protein synthesis. Eukaryotes have many organelles, including ribosomes.

Question 4

Prokaryotic and eukaryotic nuclear DNA are both

Answer 4

• organized into chromosomes

Question 5

With the use of electron microscopes, scientists discovered key differences between eukaryotes and prokaryotes. One difference was

Answer 5

• the presence versus absence of membrane-bound organelles

Question 6

True or false?
Robert Brown is attributed with the discovery of the nucleus in eukaryotic cells. He called the nucleus the cell’s “kernel”.

Answer 6

• true

Question 7

One micron is equal to ____________.

Answer 7

• one millionth of a meter (1/1,000,000 m)

Question 8

Which of the following is present in prokaryotic cells but not eukaryotic cells?

a. mitochondria
b. cilia
c. nucleoid
d. cell wall

Answer 8

• nucleoid