Chapter 11.1.1 (Exam 2) Cell Division

Question 1

What are the 4 main steps in cell division across all organisms?

Answer 1

Cell division signals

DNA replication

DNA segregation

Cytokinesis

Question 2

Describe cell division in prokaryotes.

Answer 2

Cell division (binary fission) results in reproduction of the entire single-celled organism

Cell division signals are usually external factors such as nutrient concentration and environmental condition

Question 3

Describe the DNA that is present in prokaryotes.

Answer 3

Most prokaryotes have one chromosome, a single molecule of DNA

Often circular, but folded

Question 4

What are the two important regions of the DNA in a prokaryote?

Answer 4

ori—where replication starts (origin)

ter—where replication ends (terminus)

Question 5

How does prokaryotic DNA replicate?

Answer 5

Replication occurs as the DNA moves through a protein replication complex

Question 6

Describe DNA segregation in prokaryotes.

Answer 6

When replication is complete, ori regions move to opposite ends of the cell, segregating the daughter chromosomes

Question 7

Describe cytokinesis in prokaryotes.

Answer 7

Cell membrane pinches in; protein fibers form a ring (Z-ring)

New cell wall materials are synthesized, resulting in separation of the two cells

Question 8

Describe the different cell division signals for unicellular eukaryotes.

Answer 8

Like prokaryotes, they divide when nutritional and environmental conditions are optimal

Question 9

Describe the different cell division signals for multicellular eukaryotes.

Answer 9

Cell division signals occur internally and are related to the needs of the entire organism

Internal environmental conditions are often suitable for cell division, but division may not always occur

Question 10

Describe DNA replication in eukaryotes.

Answer 10

Eukaryotes have more than one chromosome

Replication starts at many origins on the chromosome

Replication is limited to one part of the cell cycle

Question 11

Describe DNA segregation in eukaryotes.

Answer 11

Mitosis separates the newly replicated chromosomes into two new nuclei

One copy of each chromosome ends up in each daughter cell

Question 12

What is cytokinesis in eukaryotes dependent on?

Answer 12

Cytokinesis proceeds differently in animal and plant cells because plants have cell walls