Maxam–Gilbert sequencing is a method of DNA sequencing developed by Allan Maxam and Walter Gilbert in 1976–1977. This method is based on nucleobase-specific partial chemical modification of DNA and subsequent cleavage of the DNA backbone...

Practice life sciences questions using real examples from 2012.

Humans inherit two alleles for each gene, and their interaction determines how traits are expressed—homozygous if both alleles are the same, and heterozygous if they differ. In complete dominance, one allele masks the other; in...

Dominant trait needs only 1 affected allele, whereas recessive trait needs both allele. Normally a dominant trait will be seen in all generations, but a recessive trait may skip generations. We can have X-linked dominant or autosomal...

What will be the blood type of the probable progenies of blood type AB and blood type O parents? Let's solve this problem in the scenarios below: What will be the phenotype from a father with heterozygous type A, and a mother with...

The CRISPR-Cas9 system, adapted from a bacterial defense mechanism, uses Cas9 nuclease and a guide RNA (gRNA) to target and cut specific DNA sequences for genome editing. Cas9, guided by the gRNA, binds to complementary DNA and creates...

Abscissic acid induces seed dormancy which is relieved by Gibberilin. Then, Auxin and cytokinin promotes growth of the plant, and finally ethylene induces flowering and senescence. Two hormones important for seed dormancy are Gibberin...

According to Bergmann, in cold regions animals have larger body, with less SA:Volume ratio which helps them to avoid heat loss. According to Allen they have short tail, ears and snout. According to Gloger animals in cold regions are...

To determine if two genes are linked, observe the variation in offspring numbers—if all genotypes occur equally, the genes are not linked. If offspring counts differ, the most frequent genotypes represent parental types, and the less...

A three-point linkage cross helps determine gene order and distances between three linked genes using observed recombination frequencies. The process involves identifying parental types (most frequent), double crossovers (DCO) (least...

Summarized tips for Pedigree analysis

Multiple allele traits are controlled by a single gene with more than two allele variants, as seen in the ABO blood group system, which involves the alleles IA, IB, and i. The six possible genotypes result in four blood types, with IA...

A dihybrid cross is a breeding experiment between P generation (parental generation) organisms that differ in two traits. The individuals in this type of cross are homozygous for a specific trait. Traits are characteristics that are...

The ABO gene on chromosome 9 encodes enzymes that determine an individual’s blood group by modifying the H antigen into A or B antigens via glycosyltransferases. The A allele produces an enzyme that adds N-acetylgalactosamine (GalNAc),...

In biology, altruism refers to behaviour by an individual that increases the fitness of another individual while decreasing the fitness of the other. The individual performing the act is called as an altruist and the individual...

Taxonomy is the practice of categorizing and naming of species. The official "scientific name" of an organism consists of its Genus and its Species Identifier in a naming system called binomial nomenclature. The current taxonomic system...

Photoperiodism is a plant's ability to respond to the length of day and night, regulating processes like flowering based on a critical day length. Plants are classified as long day, short day, or day-neutral based on how they respond to...

The SOS response is a bacterial mechanism activated by DNA damage, involving the RecA protein and regulated by the LexA repressor. Upon DNA damage, RecA binds to single-stranded DNA, becomes activated, and promotes LexA self-cleavage,...

A species is a group of closely related organisms capable of interbreeding and producing fertile offspring, and speciation is the evolutionary process by which new species arise. Speciation can occur through anagenesis (gradual...

Symbiosis is a close and evolved interaction between species, which can be obligate (necessary for survival) or facultative (optional). It includes various types: mutualism (both benefit), commensalism (one benefits, the other is...

Isoelectric focusing (IEF) is a high-resolution technique for separating proteins based on their isoelectric points, utilizing electric fields to focus molecules into sharp zones within a pH gradient. The pH gradient, created using...

Proteins, composed of amphoteric amino acids, can carry different net charges depending on the pH of their environment. The pH at which a protein has no net charge is called its isoelectric point (pI), and this varies between proteins...

SDS–PAGE is a widely used technique for qualitative analysis of protein mixtures, particularly during protein purification. Proteins are denatured using SDS and β-mercaptoethanol, which linearize the molecules and impart a uniform...

COVID-19, caused by the novel coronavirus SARS-CoV-2, emerged in China and rapidly escalated into a global pandemic, as declared by the WHO on March 11, 2020. While most patients recover, the disease poses higher risks for the elderly...