Correct option is C
Neurospora crassa (Fungi) is an ideal model system for studying the segregation of alleles during meiosis because it exhibits a linear arrangement of ascospores within the ascus. This allows direct observation of the products of meiosis and mitosis in a sequential order, making it possible to determine at which stage (Anaphase I or Anaphase II) allelic segregation has occurred.
- Neurospora crassa:
- It undergoes ordered tetrad analysis, which allows researchers to track the segregation of alleles.
- The arrangement of meiotic products (ascospores) in a linear order reflects the order of chromosome segregation.
- This model system provides insights into crossing-over and chromosomal behavior during meiosis.
Thus, Neurospora crassa is widely used to determine whether allele segregation occurs at Anaphase I (homologous chromosome separation) or Anaphase II (sister chromatid separation).
Information Booster
- Meiosis Overview: Meiosis consists of two divisions—Meiosis I (reductional division) and Meiosis II (equational division).
- Anaphase I vs. Anaphase II:
- Anaphase I: Homologous chromosomes segregate.
- Anaphase II: Sister chromatids segregate.
- Tetrad Analysis in Neurospora:
- The ordered tetrads of Neurospora crassa allow precise tracking of allele segregation.
- First-Division Segregation (FDS): If alleles separate at Anaphase I, all spores of the same type are grouped together.
- Second-Division Segregation (SDS): If alleles separate at Anaphase II, crossover events can be detected by mixed spore arrangements.
Additional Information
Option (1) Arabidopsis thaliana (Incorrect)
- A model plant used in genetics, but not ideal for directly observing meiotic segregation due to its random spore arrangement.
Option (2) Drosophila melanogaster (Incorrect)
- A widely used genetic model, but meiosis occurs in specialized germ cells, making direct observation of allelic segregation difficult.
Option (4) Saccharomyces cerevisiae (Incorrect)
- A model yeast used in genetics and meiosis studies, but it undergoes unordered tetrad formation, making it less suitable for tracking specific segregation events.
