BIO301 Final Term Current Papers 2023

Types of mutation: Followings are the types of mutations. ➢ Points Mutations ➢ Variations in chromosomes number ➢ Variations in chromosomes structure

➢ Point mutation Base Pair Substitutions Silent, Missense, Nonsense , Base pair insertions/deletions ,Triplet Repeats ,Frameshift ➢ Variation in Chromosome Number Aneuploidy, Hyperploidy, Hypoploidy , Euploidy , Monoploidy, Diploidy, Polyploidy ➢ Variation in chromosome structure Deletions, Translocations ,Duplications ,Inversions ,Mutations and effects DNA polymorphism DNA polymorphism is a sequence difference compared to a reference standard present in at least 1–2% of a population. DNA Polymorphism may be single nucleotide or thousands of BASES Polymorphisms can be due to a single base or thousands of bases. DNA Polymorphism may or may not have phenotypic effects Polymorphisms may or may not have phenotypic effects. DNA POLYMORPHISM - SNP DNA Polymorphism are found throughout the genomes Polymorphisms are found throughout the genome. Polymorphic sequence can serve as marker If the location of a polymorphic sequence is known, it can serve as a marker for locating other genes or genetic regions. Polymorphic markers have different versions Each polymorphic marker has different versions or alleles. Polymorphisms can be silent, or be exhibited at levels of Proteins *The principle of Southern blotting* involves the transfer of DNA fragments from a gel onto a nitrocellulose or nylon membrane, which is then hybridized with a labeled DNA probe that is complementary to the target sequence of interest. The labeled probe hybridizes specifically to the target sequence, allowing it to be visualized and detected.

*Diploid cells and haploid cells*

Diploid cells are body cells. They are called as (2n) cells. Examples: skin cells, brain cells, bone cells, blood cells. In humans, ~ 220 types of somatic cells. Haploid cells Sex cells produce gametes. Gametes are haploid (n) cells. Sperms and ova are gametes which are produced in males and females respectively.

*Organic method of DNA extraction*

There are several organic methods for DNA extraction, but a commonly used protocol is the phenolchloroform method. Here's a brief overview of the steps involved:

Cell lysis: Cells are first lysed to release the DNA. This can be done using a variety of methods, such as mechanical disruption (e.g. grinding or homogenization), enzymatic digestion, or detergent-based lysis.

Removal of proteins: The lysate is treated with a protease (such as proteinase K) to digest the proteins that are present in the sample. This step helps to remove any proteins that could interfere with DNA isolation.

Phenol-chloroform extraction: Phenol and chloroform are organic solvents that can be used to separate DNA from other cellular components. In this step, an equal volume of phenol-chloroform is added to the sample and mixed thoroughly. The mixture is then centrifuged, which causes the phases to separate. The aqueous (top) layer contains the DNA, while the organic (bottom) layer contains other cellular components.

How protein can be denatured from DNA extraction ?

Proteins can be denatured by SDS or by heat.

*Applications of VNTR*

Microbiology DNA fingerprinting Genetic diversity Forensics Mapping of genomes Breeding patterns of wild or domesticated animals

*Meiosis I – Reductional division*

Meiosis I results in two haploid daughter cells. It is called the reductional division. Homologous chromosomes separate. *Meiosis II:* Second cell division where sister chromatids separate. As a result of meiosis II, two haploid cells become four haploid cells. Meiosis II behaves like mitosis, where no reduction in chromosomes number.

*Mono-allelic, di-allelic and poly-allelic*

30% genes in humans are di-allelic - they exist in two forms. 70% are mono-allelic; they exist only in one form. Few are poly-allelic.

Environmental effects on allelic expression

Allele expression may be affected by environmental conditions Examples:

• Coat color in arctic foxes
• Himalayan rabbits
• Siamese cats

Explanation ch allele affected by temp >33 C tyrosinase enzyme inactivates and reduces melanin pigment.

*HGNC rules*

">" indicates a substitution at DNA level (like c.76A>T) "_" (underscore) indicates a range of affected residues, separating the first and last residue