GENETIC SYSTEM OF NEUROSPORA fnl .pptx.ppsx

Nope

1. TOPIC : GENETIC SYSTEM OF
NEUROSPORA
MSC Biotechnology 1St Sem
SPCA College
Submitted to : Dr. Prerna Soni
Presented by : Somnath sahu

2. Cell
NucleusChromosom
e
DNA
gene
1. Life Cycle and Reproduction
2.Tetrad Analysis and Genetic Mapping
3. Neurospora in Genetic Research
4. Genome Structure and Functional
Genomics
5. Applications and Future Directions
6. Question
Synopsis :

3. Overview & History
Neurospora, a genus of widespread species, produces bakery mold, or red bread mold. It
has been used extensively in genetic and biochemical investigations.
1. Early Discovery- 1887: Neurospora crassa was first described by the American mycologist
Edgar B. Speare. The fungus was initially found in bread mold.
2. Development as a Model Organism- 1940s: Neurospora gained prominence as a model
organism for genetic research. This shift was driven largely by the work of George Beadle
and Edward Tatum.
*Beadle and Tatum's Experiment (1941): They used Neurospora to investigate the
relationship between genes and enzymes, leading to their formulation of the one gene-one
enzyme hypothesis. This work demonstrated that each gene controls the production of a
specific enzyme, marking a foundational moment in molecular biology.

4. 1) Life Cycle and Reproduction
•Asexual Reproduction & Haploid Life Cycle :
Neurospora can reproduce asexually through the production of conidia (asexual spores).
Conidia are formed on specialized hyphae called conidiophores and can germinate to form
new mycelia.
Neurospora primarily exists in a haploid state, meaning it has one set of chromosomes,
which simplifies genetic analysis. This allows mutations to be expressed directly without the
complications of dominant and recessive alleles.
•Sexual Reproduction:
Sexual reproduction involves two mating types, designated as "A" and "a." The process
begins with the fusion of compatible hyphae (each of branching filaments that make up the
mycelium of a fungus) from different mating types, leading to the formation of a diploid
nucleus (zygote).

5. The diploid nucleus undergoes meiosis to
produce four haploid (tetrad) nuclei, which
then undergo mitosis, resulting in eight
ascospores arranged linearly within an
ascus.
The ordered nature of these ascospores is
crucial for genetic analysis, particularly
tetrad analysis.

6. 2.Basic Structure
*Hyphal Structure: Neurospora is a filamentous fungus, meaning it grows in long, thread-like structures
called hyphae. Hyphae are tubular cells that form a network known as mycelium.
•Septate Hyphae: The hyphae of Neurospora are typically septate, meaning they are divided by
cross-walls called septa. These septa have pores that allow the flow of cytoplasm and organelles
between cells.
•Mycelium: The network of hyphae constitutes the mycelium, which infiltrates the substrate (e.g.,
decaying organic matter) to absorb nutrients.
*Cell Structure:
Cell Wall: Neurospora, like other fungi, has a cell wall made of chitin. This provides structural support
and protection.
Glucans: In addition to chitin, the cell wall of Neurospora contains various types of glucans, primarily β-
glucans. These polysaccharides contribute to the cell wall's structural matrix and flexibility.
Chitin: The primary component of the Neurospora cell wall is chitin, a long-chain polymer of N-
acetylglucosamine, a derivative of glucose. Chitin is a crucial structural polysaccharide in fungi,
providing rigidity and strength to the cell wall.

7. Proteins and Glycoproteins: The cell wall also contains
structural proteins and glycoproteins, which may be
involved in cell wall assembly, stability, and interactions
with the environment.
Cytoplasm: The cytoplasm contains various organelles
such as the nucleus, mitochondria, and endoplasmic
reticulum. The cytoplasm flows through the hyphal cells,
aiding in nutrient transport and growth.
•

8. 2) Tetrad Analysis and Genetic Mapping
• Linear Asci (arrangement of ascospores):

I. The linear arrangement of ascospores within an ascus allows for
precise mapping of genetic loci.
*A locus (or loci) is the actual location of the gene on a region of a
chromosome.
*Ascospores are sexual spores.
*(Ascus is the largest cell in the entire life cycle of Neurospora ; it is
where the transient diploid nucleus
undergoes meiosis and a postmeiotic mitosis.The eight haploid
nuclei are then sequestered into eight linearly
ordered ascospores.)
II. During meiosis, crossing over can occur, leading to recombination
between homologous chromosomes.
This results in different combinations of alleles among the
ascospores.

9. • First and Second Division
Segregation:
i) 1st Division segregation
I. No crossing-over
II. Segregation of alleles occurs during the
first division of meiosis III. Ascospores are
arranged in 4:4 pattern
III. Ascus with this type of arrangement is
known a Parental Ditype
ii) 2nd Division segregation
I. Crossing-over occurs
II. Segregation of alleles occurs during the
2nd division of meiosis
III. Ascospores are arranged in 2:2:2:2
pattern ,Such ascus is known as tetratype
IV. Four different segregation pattern
occurs
V. It depends upon the orientaion of the
recombinant chromatids
during anaphase II.
This information is used to calculate the
distance between genes and the
centromere, an essential aspect of genetic
mapping.

10. 3. Neurospora in Genetic Research
A)Historical Contributions:
* Beadle and Tatum's Experiments: o The pioneering experiments by Beadle and Tatum using Neurospora crassa
led to the formulation of the "one gene-one enzyme" hypothesis, establishing the direct link between genes and
their enzymatic functions and the production of enzymes.
B)Model for Eukaryotic Genetics:
The ease of genetic manipulation, combined with a well-characterized genome, makes Neurospora an excellent
model for studying eukaryotic genetics. The organism's genetic toolkit includes techniques for targeted gene
deletion, gene silencing (RNAi), and CRISPR-Cas9 genome editing.
4. Genome Structure and Functional Genomics
•Genome Sequencing:
The genome of Neurospora crassa has been fully sequenced, revealing approximately 10,000 genes distributed
across seven chromosomes. Comparative genomics with other fungi has identified conserved and unique genes,
providing insights into fungal biology and evolution.
•Functional Genomics:
Large-scale functional genomics projects have been undertaken to understand the role of each gene in
Neurospora. Techniques such as transcriptomics, proteomics, and metabolomics are employed to study gene
expression and function at a systems level.
•Gene Knockouts and Phenotypic Analysis:
Systematic gene knockout libraries have been created, allowing researchers to investigate the phenotypic effects
of deleting individual genes. These studies help in deciphering gene function and their interactions in complex
biological networks.

11. 5. Applications and Future Directions
• Biotechnology:
* Neurospora is used in industrial biotechnology for the production of enzymes, biofuels, and other valuable
metabolites.
* The genetic tools available for Neurospora make it a versatile platform for synthetic biology applications.
• Ecological and Evolutionary Studies:
*Neurospora species are found in diverse environments, and their genetic diversity is studied to understand fungal
ecology and evolution.
*Population genetics and phylogenetic studies provide insights into the adaptation of Neurospora to different ecological
niches.
• Human Health:
* While Neurospora itself is not pathogenic, the study of its genetic system has implications for understanding human
diseases, particularly those related to circadian rhythms and metabolic disorders. 8. Conclusion
• Neurospora remains an important model organism in genetics, offering insights into basic biological processes that are
applicable to more complex organisms. Its simple genetic system and ease of manipulation make it a powerful tool for
research in genetics, biochemistry, and molecular biology.
6. Question :- i) In Neurospora ascus, the 8 ascospores show 2a:4A:2aarrangement.
It suggests

a. No crossing over between centromere & gene
b.1st division segregation
c. 2nd division segregation
d. Can't say

ii) In Neurospora ascus, the 8 ascospores show 4A:4a arrangement. it suggests
a. No crossing over between centromere & gene
b. 1st division segregation
C. 2nd division segregation
d. Both a & b

12. Referen
ces
1. Davis, R. H. (2000). Neurospora: Contributions of a Model
Organism.
Oxford University Press.
2. https://youtu.be/30yMV2yehqo?si=YnNihhsjZipd86Vh
3. https://www.researchgate.net/figure/Life-cycle-of-
Neurospora- crassa-Depending-on-environmental-conditions-
the-vegetative_fig1_51763764
4. Slideshare
5. Chatgpt

13. How does not completing a prescribed
course of antibiotics demonstrate the
principles of natural selection and
mutation in the development of
antibiotic resistance in bacteria?
Antibiotic resistance can arise when
patients do not complete their
prescribed course of antibiotics.
For instance, if a patient takes
antibiotics for only 3 out of 5
prescribed days, some bacteria may
survive. These surviving bacteria
can mutate, developing resistance
to the antibiotic.
Answer:
THINK
ABOUT
IT!

14. THANK
YOU