What is Mitosis?
Mitosis is the part of the eukaryotic cell cycle where a cell duplicates its chromosomes and splits its nucleus into two identical daughter nuclei. It follows interphase and is essential for growth, tissue repair, and asexual reproduction.
Mitosis is the phase of the cell cycle in which a eukaryotic cell duplicates its chromosomes and divides its nucleus into two genetically identical daughter nuclei, following interphase (G1, S, G2).
- 1.Interphase (G1, S, G2) — The cell grows and replicates its DNA in preparation for division.
- 2.Prophase — Chromatin condenses into visible chromosomes; spindle fibers form.
- 3.Metaphase — Chromosomes align at the cell's equatorial plate.
- 4.Anaphase — Sister chromatids are pulled to opposite poles.
- 5.Telophase — Nuclear envelopes reform around each set of chromosomes.
- 6.Cytokinesis — The cytoplasm divides, producing two identical daughter cells.
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Step-by-step worked examples
A cell cycle lasts 20 hours total, with mitosis (M phase) taking up 5% of that time. How long is M phase?
T = 20 hours, p = 5% Duration = T × p/100 = 20 × 5/100 = 1 hour
If G1, S, and G2 (interphase) together take 23 hours of a 24-hour cycle, what percent of the cycle is interphase?
Interphase = 23 hours, Total = 24 hours Percent = 23/24 × 100 ≈ 95.8%
A somatic cell with 46 chromosomes undergoes mitosis. How many chromosomes are in each daughter cell, and are they identical?
Mitosis produces 2 daughter cells from 1 parent cell Each daughter gets one full copy of the genome Each daughter cell has 46 chromosomes, genetically identical to the parent
Flashcards
Quick quiz
Q1.During which phase does DNA replication occur?
Q2.Sister chromatids separate and move to opposite poles during…
Q3.A 24-hour cell cycle spends 10% of its time in mitosis. How long is mitosis?
Q4.What is the main purpose of mitosis?
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Common mistakes
Confusing mitosis with the entire cell cycle. — Correct: Mitosis (M phase) is just one part; most of the cycle is interphase (G1, S, G2).
Thinking chromosomes replicate during mitosis. — Correct: DNA replication happens in S phase, before mitosis begins.
Mixing up chromatids and chromosomes. — Correct: Sister chromatids are joined copies of one chromosome; they become separate chromosomes only after anaphase.
Confusing mitosis and meiosis outcomes. — Correct: Mitosis makes 2 identical diploid cells; meiosis makes 4 genetically varied haploid gametes.
FAQ
What is mitosis?
Mitosis is the cell cycle phase where a eukaryotic cell duplicates its chromosomes and divides into two genetically identical daughter cells.
What is the formula to calculate the duration of a cell cycle phase?
Phase duration = Total cycle time × (percent of the cycle in that phase ÷ 100).
What are examples of cell cycle phases?
Interphase (G1, S, G2) for growth and DNA replication, followed by mitosis (prophase, metaphase, anaphase, telophase) and cytokinesis.
How do you calculate how long mitosis takes in a cell cycle?
Multiply the total cell cycle length by the percentage of time spent in M phase (typically ~5-10%).