Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
The cell cycle is an ordered sequence of events involving cell growth and division. It consists of Interphase (, , ), Mitosis ( phase), and Cytokinesis.
During the phase (Synthesis), DNA replication occurs. The amount of DNA doubles from to , although the chromosome number remains diploid ().
Mitosis is the division of the nucleus into two genetically identical daughter nuclei. It consists of four stages: Prophase, Metaphase, Anaphase, and Telophase ().
Cyclins are a group of proteins used to ensure that tasks are performed at the correct time and that the cell only moves to the next stage of the cycle when it is appropriate. They bind to enzymes called cyclin-dependent kinases ().
Mutagens, oncogenes, and metastasis are involved in the development of primary and secondary tumors. Oncogenes are genes that have the potential to cause cancer when mutated.
Cytokinesis occurs after mitosis. In animal cells, a cleavage furrow forms as the plasma membrane is pulled inwards by a ring of contractile proteins. In plant cells, vesicles fuse to form a cell plate which eventually becomes a new cell wall.
The Mitotic Index is a measure of the proliferation status of a cell population, defined as the ratio between the number of cells in mitosis and the total number of observed cells.
📐Formulae
💡Examples
Problem 1:
A student examines a microscope slide of a cancerous tissue sample. Out of total cells, are in Prophase, are in Metaphase, are in Anaphase, and are in Telophase. Calculate the Mitotic Index of this tissue.
Solution:
Explanation:
To find the Mitotic Index, we sum all cells currently undergoing any stage of mitosis (Prophase through Telophase) and divide by the total number of cells identified in the sample (including those in Interphase).
Problem 2:
If a diploid cell has a chromosome number of , determine the number of chromosomes and the number of DNA molecules (chromatids) present during the phase and after Anaphase.
Solution:
In : Chromosomes = , DNA molecules = . After Anaphase (in each resulting cluster): Chromosomes = , DNA molecules = .
Explanation:
During the phase, DNA replicates, doubling the DNA molecules to , but they remain attached at the centromere, so the chromosome count stays at . In Anaphase, sister chromatids separate, briefly doubling the chromosome count in the cell to ( moving to each pole).