Cytokinesis — Science definition

The final step of division, in which the cytoplasm splits to form two separate daughter cells.

Where it is taught

In use

Mitosis divides the nucleus, but one step remains: cytokinesis, in which the rest of the cell pinches in two, splitting the cytoplasm so that each new nucleus ends up in its own separate cell.

Mitosis & the Cell Cycle

Questions using cytokinesis

Problem 1

In the standard model without new copying errors, what is the main result of mitosis followed by cytokinesis?
  1. Two genetically identical daughter cells
  2. Four sex cells with half the DNA
  3. A cell with double the normal chromosome number
  4. A finished protein
Answer and explanation

Two genetically identical daughter cells

Mitosis produces two daughter cells genetically identical to the parent, used for growth and repair.

Problem 2

A diploid cell has 12 chromosomes before replication. How many chromosomes does each daughter cell normally have after mitosis and cytokinesis? Explain the reasoning in your own words.
Answer and explanation

Each daughter normally has 12 chromosomes in this model.

Replication makes sister chromatids without changing the stated chromosome number.

Normal separation gives each daughter the original set size.

Response criteria

  • Use the stated conditions.
  • Show the evidence or calculation.
  • Explain the conclusion and any stated limitation.

Problem 3

A diploid model starts with 10 chromosomes. Track chromosomes, chromatids and daughter-cell chromosome number through replication and normal mitosis/cytokinesis.
Answer and explanation

After S phase there are 10 replicated chromosomes and 20 chromatids; during separation each former chromatid becomes a chromosome. Each daughter receives 10 chromosomes, preserving diploidy in the model.

After S phase there are 10 replicated chromosomes and 20 chromatids; during separation each former chromatid becomes a chromosome. Each daughter receives 10 chromosomes, preserving diploidy in the model.

Response criteria

  • Use the stated measurements or conditions, with correct units.
  • Connect the result to the biological mechanism or evidence relationship.
  • Identify the assumption, model limit or further evidence requested.

Problem 4

Independent chapter check: A diploid model starts with 10 chromosomes. Track chromosomes, chromatids and daughter-cell chromosome number through replication and normal mitosis/cytokinesis.
Answer and explanation

After S phase there are 10 replicated chromosomes and 20 chromatids; during separation each former chromatid becomes a chromosome. Each daughter receives 10 chromosomes, preserving diploidy in the model.

After S phase there are 10 replicated chromosomes and 20 chromatids; during separation each former chromatid becomes a chromosome. Each daughter receives 10 chromosomes, preserving diploidy in the model.

Response criteria

  • Use the stated measurements or conditions, with correct units.
  • Connect the result to the biological mechanism or evidence relationship.
  • Identify the assumption, model limit or further evidence requested.

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