Author Archives: Gagana BR

The Nucleus of a Eukaryotic Cell and Chromatin Organization

By | August 20, 2021

The nucleus of a eukaryotic cell is essential for the storage and utilization of genetic information. The contents of the nucleus are enclosed by a complex nuclear envelope that separates the nucleus from the cytoplasm. The nucleus of a non-mitotic cell contains: Chromosomes, highly extended nucleoprotein fibers, also called chromatin. An irregularly shaped electron-dense structure,… Read More »

Lysosomes – Digestive Organelle of an Animal Cell

By | July 27, 2021

A lysosome has approximately 50 different hydrolytic enzymes. These enzymes are produced by the endoplasmic reticulum and targeted lysosomes. Lysosome enzymes can digest every type of biological macromolecule. All the enzymes of the lysosome share significant properties – their optical activity at an acid pH and thus are acid hydrolases. The pH optimum of these… Read More »

Golgi Complex – The Protein Assembly Center of the Cell

By | July 26, 2021

The Golgi complex has a characteristic morphology – flattened, disklike, membranous cisternae with dilated rims, and associated tubules. The cisternae have a diameter of 0.5 to 1 micrometer, stacked in an ordered manner and a Golgi stack contains fewer than eight cisternae. There are several thousand distinct types of stacks depending on the cell type.… Read More »

Endoplasmic Reticulum – The Lipid and Protein Processing Machinery of the Cell

By | July 23, 2021

The endoplasmic reticulum (ER) is divided into – smooth endoplasmic reticulum (SER) and rough endoplasmic reticulum (RER). ER consists of a system of membranes that enclose a space or lumen, that separates it from the cytosol. The composition of the luminal or cisternal space inside the ER membranes is quite different from the cytosolic space.… Read More »

Why are potassium ions more permeable than sodium ions?

By | July 20, 2021

Ion channels have three important properties: They are selective to specific ions They open and close to specific stimuli such as electrical, chemical, or mechanical signals They conduct ions across the membrane. The fastest flow of ions across channels is comparable to the fastest turnover of enzymes such as carbonic anhydrase or catalase. The turnover… Read More »

The Nervous System: Basic Properties of Nerve Cells

By | July 20, 2021

The fundamental unit of the nervous system is not just neurons but also glia! However, the neurons have features that would allow them to communicate with each other, including long-distance communication. These features are: The morphological and functional asymmetry of neurons – dendrites with specialized receptors and the transmitting potential of axon forms the basis… Read More »

Deforestation: Everything One Should Know!

By | July 15, 2021

Forests and the present state of deforestation Forests, home to about 50% of species on land, are useful for – Provision of accessible fresh water Climate mitigation Provision of life saving medicines for various diseases Mitigation of natural hazards Provision of oxygen Maintenance of soil integrity Storage of carbon from the atmosphere Maintenance of food… Read More »

Enhancers and Genetics

By | July 10, 2021

Enhancers They are short DNA fragments with several prominent features such as: driving the expression of the target gene, orientation relative to a target gene promoter, functionally independent of genomic distance, sensitivity towards DNase treatment (since its neucleosome free region), functional influence over chromatin architecture by allowing binding of transcription co-activators and histone acetylation, and… Read More »

Global Warming and Climate Change: Everything One Should Know!

By | July 9, 2021

The heatwaves struck Europe, South Asia, Australia, and North America such that the weather records got smashed in the summer of 2019. The Intergovernmental Planet for Climate Change (IPCC) released a report that human-induced activities are causing a major shift in the earth’s climate. We have warmed the earth by 1 degree Celsius since pre-industrial… Read More »

DNA methylation systems

By | July 9, 2021

The E. coli strains used in the laboratory for cloning and DNA isolation contain three site-specific DNA methylation systems. Modification of DNA using these methylation systems protects the potential restriction enzyme recognition sites from cleavage. This genetic engineering technique sheds light on the sensitivity of restrictions endonuclease towards DNA methylation. Such DNA methylation systems are:… Read More »