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Semester 1: M.Sc. Biotechnology Syllabus 2023-2024
Genes and chromosomes, Co-linearity of Genes and Proteins, Genetic code. Identification of DNA as the genetic material. The complexity of eukaryotic genome introns, exons, repetitive DNA sequence, gene duplication and pseudogenes
M.Sc. Biotechnology Syllabus 2023-2024
M.Sc. Biotechnology
Core Paper-2 MOLECULAR GENETICS
1
Periyar University
MOLECULAR GENETICS
Genes and Chromosomes
Definition of Genes
Genes are functional units of heredity made of DNA, which encode for proteins and determine traits.
Structure of Chromosomes
Chromosomes are long DNA molecules organized into structures. They contain genes and are found in the nucleus of eukaryotic cells.
Types of Chromosomes
Chromosomes can be classified as autosomes (non-sex chromosomes) and sex chromosomes. The number and structure vary among species.
Co-linearity of Genes and Proteins
Definition of Co-linearity
Co-linearity refers to the direct correspondence between the sequence of nucleotides in DNA and the sequence of amino acids in proteins.
Evidence of Co-linearity
Studying various organisms has demonstrated a conservation of gene structure that corresponds to protein structure.
Genetic Code
Definition of Genetic Code
The genetic code is a set of rules that defines how the information in DNA is translated into proteins.
Characteristics of Genetic Code
The genetic code is universal, redundant, and non-overlapping, consisting of codons, which are sequences of three nucleotides.
Identification of DNA as the Genetic Material
Historical Experiments
Experiments by Griffith, Avery, and Hershey-Chase demonstrated that DNA is the carrier of genetic information.
Research Findings
Further research clarified the mechanisms by which DNA replicates, mutates, and expresses genes.
Complexity of Eukaryotic Genome
Introns and Exons
Eukaryotic genes are often interrupted by non-coding sequences called introns, while exons are the coding regions that are expressed.
Repetitive DNA Sequences
These are sequences that occur in multiple copies within the genome, including satellite DNA and transposable elements, serving various functions.
Gene Duplication
Gene duplication events can lead to evolutionary innovations, allowing for functional diversification of genes.
Pseudogenes
Pseudogenes are non-functional sequences that resemble functional genes, often resulting from duplication or mutation.
Gene expression and regulation in prokaryotes and eukaryotes. Mutation Spontaneous and virus induced mutation, Radiation induced mutation. Chromosomal Abnormalities and associated genetic diseases, Techniques in the study of chromosomes and their applications, Recombination models
Gene expression and regulation in prokaryotes and eukaryotes
Gene Expression in Prokaryotes
In prokaryotes, gene expression is primarily controlled at the level of transcription. The process is relatively simple, as prokaryotic cells lack a nucleus. Transcription occurs in the cytoplasm, and mRNA is synthesized directly from the DNA template. Key components include promoters, operons, and transcription factors. The lac operon is a classic example, demonstrating how genes can be co-regulated in response to environmental changes.
Gene Expression in Eukaryotes
Eukaryotic gene expression is more complex due to the presence of a nucleus and chromatin structure. Transcription occurs in the nucleus, where mRNA is synthesized and then processed through capping, polyadenylation, and splicing before being transported to the cytoplasm. Regulation occurs at multiple levels including chromatin remodeling, transcriptional regulation, post-transcriptional modifications, and translational control.
Mutation
Mutations are changes in the DNA sequence and can be classified as spontaneous or induced. Spontaneous mutations occur naturally and can arise from errors during DNA replication or from natural cellular processes. Induced mutations result from external factors such as radiation or chemical exposure. Viral infections can also lead to mutations by integrating viral DNA into the host genome.
Types of Induced Mutations
Radiation can induce mutations through several mechanisms including direct damage to DNA or generating reactive oxygen species that subsequently damage DNA. Virus-induced mutations can occur through mechanisms like transduction where viruses carry and integrate host genes into their own genome, potentially altering gene expression and function.
Chromosomal Abnormalities
Chromosomal abnormalities refer to changes in chromosome number or structure. These can include aneuploidy, where there is an abnormal number of chromosomes, and structural alterations like deletions, duplications, inversions, or translocations. Such abnormalities can lead to genetic diseases such as Down syndrome, Turner syndrome, and chronic myelogenous leukemia.
Techniques in Chromosomal Studies
Techniques for studying chromosomes include karyotyping, fluorescence in situ hybridization (FISH), and comparative genomic hybridization (CGH). These methods help in identifying chromosomal abnormalities and understanding the genetic basis of diseases. Karyotyping allows visualization of chromosomal structure, while FISH provides insights into specific gene locations.
Recombination Models
Recombination is the process by which genetic material is rearranged during meiosis. Homologous recombination, which occurs between similar DNA sequences, is crucial for genetic diversity and repair of damaged DNA. Various models explain recombination processes, including the double-strand break model and the synthesis-dependent strand annealing model, each providing insights into genetic variability and evolution.
DNA Damage and Repair - Internal and external agents causing DNA damages, Mechanisms of DNA damage transition, transversion, frameshift, nonsense mutations, Repair mechanisms Photo reactivation, excision repair, mismatch repair, post replication repair, SOS repair, Transposons and its mechanisms, control consequences and application
DNA Damage and Repair
Internal and External Agents Causing DNA Damage
DNA damage can occur due to internal factors like reactive oxygen species, replication errors, and spontaneous hydrolysis. External agents include UV radiation, ionizing radiation, and chemical mutagens.
Mechanisms of DNA Damage
DNA damage can manifest as transitions, transversions, frameshift mutations, and nonsense mutations. Transitions involve purine to purine or pyrimidine to pyrimidine changes. Transversions are purine to pyrimidine changes. Frameshift mutations result from insertions or deletions, while nonsense mutations create premature stop codons.
Repair Mechanisms
Repair mechanisms include photo reactivation, excision repair, mismatch repair, post-replication repair, and SOS repair. Photo reactivation repairs UV-induced thymine dimers. Excision repair removes damaged bases. Mismatch repair corrects replication errors. Post-replication repair addresses lesions that escape earlier repair. SOS repair activates in response to extensive damage.
Transposons and Its Mechanisms
Transposons are mobile genetic elements that can insert themselves into different genomic locations. They can disrupt genes, leading to mutations. Their movements can be classified into cut-and-paste and replicative transposition.
Control, Consequences and Application
Controlling DNA damage is crucial for maintaining genetic stability. Consequences of unrepaired DNA damage include cancer and hereditary diseases. Applications include gene therapy, biotechnology, and understanding evolutionary processes.
Allele and genotype frequencies, Random mating population, Hardy-Weinberg principle, complications of dominance, special cases of random mating multiple alleles, autosomal and X-linked frequencies. Inbreeding, genetics and evolution, random genetic drift, Karyotyping and usefulness of chromosomes in understanding Genetic variation, Genetics of eukaryotes gene linkage and chromosome mapping
M.Sc. Biotechnology Syllabus 2023-2024
M.Sc. Biotechnology
Core Paper-2 MOLECULAR GENETICS
1
Periyar University
MOLECULAR GENETICS
Allele and Genotype Frequencies
Allele frequency refers to how often an allele appears in a population. Genotype frequency is the proportion of different genotypes in a population. These frequencies are crucial for understanding genetic diversity and evolution.
Random Mating Population
In random mating populations, individuals mate without regard to their genetic backgrounds. This leads to a balanced frequency of alleles across generations.
Hardy-Weinberg Principle
The Hardy-Weinberg principle provides a baseline to study genetic variation. It states that allele and genotype frequencies will remain constant in a population under certain conditions, including no mutation, migration, selection, and random mating.
Complications of Dominance
Dominance complicates the expression of alleles. Complete dominance, incomplete dominance, and codominance affect phenotype expressions and the resulting genotypic ratios.
Special Cases of Random Mating
Special cases include populations with multiple alleles, leading to more complex frequency calculations. Overdominance can favor heterozygotes.
Multiple Alleles
Multiple alleles exist when more than two alleles are present for a genetic trait. This contributes to the genetic variation and can complicate allele frequency calculations.
Autosomal and X-linked Frequencies
Autosomal traits are affected equally by both sexes, while X-linked traits can show different frequencies in males and females due to the presence of one X chromosome in males.
Inbreeding
Inbreeding increases the chance of recessive traits being expressed. It also affects allele frequencies and can lead to inbreeding depression.
Genetics and Evolution
Genetics plays a fundamental role in evolution. Changes in allele frequencies due to natural selection drive evolutionary processes.
Random Genetic Drift
Genetic drift is the change in allele frequencies due to random sampling effects. It can have significant effects in small populations.
Karyotyping and Usefulness of Chromosomes in Understanding Genetic Variation
Karyotyping helps visualize chromosomes in a cell. It is useful for identifying chromosomal abnormalities that can lead to genetic disorders.
Genetics of Eukaryotes, Gene Linkage and Chromosome Mapping
In eukaryotes, genes can be linked on the same chromosome. Mapping these genes helps understand inheritance patterns and genetic disorders.
Extra chromosomal heredity Biology of Plasmids, their discovery, structure and types. Replication and partitioning, Incompatibility and copy number control-natural and artificial plasmid transfer and their applications- Genomics and Modern methodologies in understanding genome -Human Genome Project, DNA markers -VNTR, STR, microsatellite, SNP and their detection techniques
Extra chromosomal heredity
Plasmids
Plasmids are small, circular DNA molecules found in bacteria and some eukaryotes. They are separate from chromosomal DNA and can replicate independently. Plasmids often carry genes that confer advantageous traits, such as antibiotic resistance.
Discovery of Plasmids
Plasmids were first discovered in the early 1950s. Their role in microbial genetics was highlighted by researchers studying antibiotic resistance. The presence of plasmids in various bacterial species illustrated genetic variability and adaptability.
Structure of Plasmids
Plasmids generally consist of a circular double-stranded DNA structure. They have an origin of replication, one or more genes, and regulatory sequences. The size of plasmids varies, typically ranging from a few kilobases to several hundred kilobases.
Types of Plasmids
Plasmids can be classified based on their functions: 1. Conjugative plasmids - required for bacterial conjugation. 2. R plasmids - carry antibiotic resistance genes. 3. Col plasmids - produce bacteriocins to inhibit closely related bacteria. 4. Virulence plasmids - contain genes that enhance pathogenicity.
Plasmid Replication and Partitioning
Plasmid replication involves bidirectional replication from the origin of replication, ensuring that plasmid copies are distributed to daughter cells during cell division. Partitioning mechanisms ensure equal distribution of plasmids.
Incompatibility and Copy Number Control
Plasmids can be incompatible if they belong to the same compatibility group and cannot coexist in the same cell. Copy number control mechanisms regulate the number of plasmid copies within a cell, often influenced by their replication origins.
Natural and Artificial Plasmid Transfer
Natural plasmid transfer occurs through processes like conjugation, transformation, and transduction. Artificial methods, such as electroporation and microinjection, facilitate plasmid transfer in laboratory settings.
Applications of Plasmids
Plasmids have several applications in biotechnology and genetic engineering, including gene cloning, protein expression, and the development of genetically modified organisms (GMOs). They are essential tools for researchers in molecular biology.
Genomics and Modern Methodologies
Genomics involves the study of genomes, including aspects of structure, function, and evolution. Modern methodologies include next-generation sequencing, CRISPR technology, and bioinformatics to analyze genetic data.
Human Genome Project
The Human Genome Project was an international research initiative aimed at sequencing the human genome. Completed in 2003, it provided valuable information on human genetics and laid the foundation for advances in medicine and biotechnology.
DNA Markers
DNA markers are specific sequences in the genome that can be used for identification. Common types include: 1. VNTR (Variable Number Tandem Repeats) - variations in repeated DNA sequences. 2. STR (Short Tandem Repeats) - shorter repeat sequences used in forensic analysis. 3. Microsatellites - repeating sequences of 1-6 base pairs. 4. SNP (Single Nucleotide Polymorphisms) - single base pair variations.
Detection Techniques
Detection techniques for DNA markers include PCR (Polymerase Chain Reaction) for amplifying specific sequences, DNA sequencing for obtaining sequence data, and gel electrophoresis for separating DNA fragments. Each technique has unique applications in research and diagnostics.
