Mitosis vs Meiosis
Mitosis and meiosis are the two types of nuclear division in eukaryotic cells. Mitosis involves 1 division that produces 2 genetically identical diploid daughter cells for growth and tissue repair, whereas meiosis involves 2 divisions (meiosis I and II) that produce 4 genetically distinct haploid gametes for sexual reproduction.
- Mitosis
- One nuclear division that produces two daughter cells genetically identical to the parent, each with the same (diploid) chromosome number. It underlies growth, tissue repair, and asexual reproduction.
- Meiosis
- Two successive nuclear divisions (meiosis I and II) following a single DNA replication, producing four genetically distinct haploid daughter cells. It makes gametes for sexual reproduction.
- Diploid (2n) vs Haploid (n)
- Diploid cells contain two sets of chromosomes (one from each parent); haploid cells contain a single set. Meiosis halves the chromosome number from diploid to haploid, which fertilization then restores.
Mitosis (2n → 2n) vs Meiosis (2n → n) & Ribosome Protein Synthesis
1. Interphase (DNA Replication)
Diploid parent cell (2n = 46 in humans). DNA replicates so each chromosome consists of two identical sister chromatids; subcellular organelles (mitochondria, ribosomes) also double.
Diploid germ cell (2n = 46). DNA replicates once to form homologous pairs of doubled chromosomes ready for two rounds of division.
Key Concepts & Exam Definitions (5)
- Mitosis
- One nuclear division that produces two daughter cells genetically identical to the parent, each with the same (diploid) chromosome number. It underlies growth, tissue repair, and asexual reproduction.
- Meiosis
- Two successive nuclear divisions (meiosis I and II) following a single DNA replication, producing four genetically distinct haploid daughter cells. It makes gametes for sexual reproduction.
- Diploid (2n) vs Haploid (n)
- Diploid cells contain two sets of chromosomes (one from each parent); haploid cells contain a single set. Meiosis halves the chromosome number from diploid to haploid, which fertilization then restores.
- Homologous chromosomes
- A matching pair of chromosomes, one inherited from each parent, carrying the same genes at the same loci. They pair up (synapsis) only in meiosis I, which is why meiosis reduces the chromosome number and mitosis does not.
- Crossing over & independent assortment
- Crossing over swaps DNA segments between homologous chromosomes in prophase I; independent assortment randomly orients each homologous pair in metaphase I. Together they are the main sources of the genetic variation produced by meiosis.
Quick-Fire Flashcards (5)
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How many daughter cells does each process make, and how many divisions?
Compare the daughter cells of mitosis vs meiosis (ploidy and genetics).
When and where does crossing over occur?
What is the key event that makes meiosis I 'reductional'?
What is each process used for in the body?
Exam-Style Questions & Mark Schemes (3)
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- Q1
A human cell with 46 chromosomes undergoes meiosis. How many chromosomes will each resulting daughter cell have, and how many cells are produced?
Click “Check Mark Scheme” to compare your answer, Each of the 4 daughter cells has 23 chromosomes. Meiosis halves the chromosome number (from diploid 2n=46 to haploid n=23) and its two divisions produce four cells. This halving is why fertilization can restore the diploid number of 46.
- Q2
Explain why meiosis produces genetic variation but mitosis does not.
Click “Check Mark Scheme” to compare your answer, Meiosis includes crossing over (exchange of DNA between homologous chromosomes in prophase I) and independent assortment (random orientation of homologous pairs in metaphase I), which reshuffle alleles so each gamete is unique. Mitosis has neither event and simply copies the parent cell, so its daughter cells are genetically identical.
- Q3
In which division do sister chromatids separate: mitosis, meiosis I, or meiosis II?
Click “Check Mark Scheme” to compare your answer, Sister chromatids separate in mitosis and in meiosis II. In meiosis I, it is the homologous chromosomes that separate (sister chromatids stay together), which is the step that reduces the chromosome number from diploid to haploid.
Common Exam Questions (6)
What is the difference between mitosis and meiosis?
Mitosis has 1 nuclear division and produces 2 genetically identical diploid (2n) daughter cells for growth, repair, and asexual reproduction. Meiosis has 2 nuclear divisions and produces 4 genetically unique haploid (n) gametes for sexual reproduction.
How many divisions are in meiosis?
Meiosis consists of 2 consecutive nuclear divisions: meiosis I (which separates homologous chromosome pairs and halves the chromosome number) and meiosis II (which separates sister chromatids), resulting in 4 daughter cells.
Is haploid mitosis or meiosis?
Meiosis produces haploid (n) cells containing a single set of chromosomes (23 chromosomes in human gametes). Mitosis preserves the chromosome number of the parent cell.
Does mitosis make diploid cells?
Yes. In diploid organisms such as humans, mitosis of a somatic cell (2n = 46) produces two diploid daughter cells, each containing 46 chromosomes identical to the parent cell.
How many chromosomes do daughter cells have after meiosis?
Daughter cells produced by meiosis are haploid, containing half the chromosome number of the parent cell (23 chromosomes in human sperm and egg cells, so that fertilisation restores the diploid number of 46).
Why does meiosis produce genetic variation?
Meiosis generates genetic variation through two mechanisms in meiosis I: crossing over between non-sister chromatids of homologous chromosomes at chiasmata during prophase I, and independent assortment (random orientation) of homologous pairs along the equator during metaphase I.
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Related study guides
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