Cell division is necessary for growth and reproduction in organisms. Mitosis aids cell growth and development by dividing somatic cells. In contrast, meiosis causes the division of germ cells and plays an essential role in sexual reproduction. Due to their unique functional requirements, mitosis and meiosis differ from each other in multiple aspects.
Before the start of mitosis and meiosis I, the cell synthesizes DNA, resulting in two homologous copies of each chromosome. DNA synthesis is...

Pathogens spread from their reservoirs to susceptible hosts through three main routes: contact transmission, vehicle transmission, and vector transmission. Each route involves distinct mechanisms of transfer.Contact TransmissionThis category includes direct contact, indirect contact, and droplet transmission:Direct contact involves immediate physical interaction between individuals—such as a handshake—which can spread pathogens like Streptococcus pyogenes, the bacterium responsible for...

Yellow fever is a viral hemorrhagic disease caused by the yellow fever virus (YFV), a member of the Flaviviridae family. It is transmitted primarily by Aedes and Haemagogus mosquitoes in tropical and subtropical regions of Africa and South America. After transmission through a mosquito bite, the virus initially replicates in skin-resident immune cells such as dendritic cells and macrophages. These cells then migrate to the lymph nodes, where viral replication increases, eventually leading to...

Cytomegalovirus (CMV) disease is caused by human cytomegalovirus, a double-stranded DNA virus of the Herpesviridae family. While primary CMV infection is often asymptomatic in immunocompetent individuals, the virus can cause severe disease in neonates and immunocompromised patients. CMV is the most common cause of congenital viral infection in the United States, and a major pathogen in solid organ and hematopoietic stem cell transplant recipients.CMV is transmitted via bodily fluids, sexual...

Malaria pathogenesis in humans reflects a delicate interplay between parasite biology and host response. Clinical illness reflects a host’s immune response to the parasite’s asexual replication cycle, which is often asymptomatic in individuals with partial immunity. From the parasite's perspective, transmission between mosquito and human with minimal host pathology is evolutionarily advantageous. Among the six Plasmodium species infecting humans, P. falciparum and P. vivax dominate in global...

Toxoplasmosis, a zoonotic disease caused by the protozoan Toxoplasma gondii, poses significant public health challenges globally due to its high seroprevalence and varied clinical manifestations. As an obligate intracellular parasite, T. gondii can infect all warm-blooded vertebrates, but felids are its only definitive hosts, shedding unsporulated oocysts into the environment. Humans typically acquire the infection through ingestion of tissue cysts in undercooked meat or oocysts from...