A prokaryote is a simple, unicellular organism that lacks an organized nucleus or other membrane-bound organelle. Learning Objective Describe the structure of prokaryotic cells Key Points Prokaryotes lack an organized nucleus and other membrane-bound organelles. Prokaryotic DNA is found in a central part of the cell called the nucleoid. The cell wall of a prokaryote…
Bacteria cells function quite differently from human cells, from the function of the cell as a whole, right down to the individual structures in each cell. Bacteria exist in nature as individual cells. While some bacteria work together in a group, no bacteria forms multicellular tissues. Bacteria have organized structures within the cell, but do not have membrane-bound…
It began with what can only be described as an ingenious invention. It’s a fold-out sheet, with sticky tabs at the front and back, like a flattened starfish. The tabs stick to the loo seat. When in place, it forms a kind of hammock onto which the specimen is presented, ready for sampling. I slipped on the rubber gloves to prepare for the procedure. Once I had left…
It turns out, there are more reasons to love bacteria than to fear them — the latest being a the discovery of a new bacteria-based antibiotic that allows scientists to fight infections that kill hundreds of thousands of people each year! But there’s more to bacteria than their antibiotic qualities. Check out these nine facts — some of them may surprise you: This fact…
In case, the second best phylum shows ≥30% NOGs matching with the NOGs of the best matched phylum, the best phylum is selected by comparing the NOGs of the query genome with the classes present in both the phyla. The class with maximum number of NOGs matches is selected as the best class and its corresponding phylum is selected as the best phylum. In case, the top…
As gut bacteria garner more attention every day, scientists are starting to make forays into uncharted waters: the microbes of marine mammals. The collection of benign bacteria living within our bodies, our “microbiota, ” helps us digest food, ward off infection, and has even been linked to mood and behavior. Research on microbial communities has branched out from…
Fourteen years ago, during the darkest moments of the “stem-cell wars” pitting American scientists against the White House of George W. Bush, one group of advocates could be counted on to urge research using cells from human embryos: parents of children with type 1 diabetes. Motivated by scientists who told them these cells would lead to amazing cures, they spent…
Prokaryotic cells fall into a size range of about 1–5µm and hence can be observed clearly by microscopes. However, some prokaryotic cells may be larger than this. A prokaryotic cell contains external and internal structures. Capsule, flagella, axial filaments, fimbriae, and pili are present external to the cellwall, while interior of the bacterial cell contains cytoplasm…
Microorganisms sense and adapt to changes in their environment. When favored nutrients are exhausted, some bacteria may become motile to seek out nutrients, or they may produce enzymes to exploit alternative resources. One example of an extreme survival strategy employed by certain low G+C Gram-positive bacteria is the formation of endospores. This complex developmental…
Gut bacteria can alter cancer risk up or down “Gone are the days of one organism, one disease. We’re really looking at how a whole community of microbes influences disease risk, ” Hullar said. “For example, scientists are looking at how the metabolism of the microbiome — all of the members of the microbial community — influences its host, ” she said. Researchers are…
Physiological groups of soil microorganisms were investigated in a forest ( Pinus pinaster Sol.) to asses their response to wildfire-induced soil changes. Microbial fluctuations were recorded 1 month and 1 year after the fire, both in the field and during controlled soil incubations. In both the burned and the unburned soil, starch-mineralizing microbes predominated…
Pili-plural for pilus-are hairlike appendages found on the surface of many bacteria. Pili are fragile and need to be constantly replaced. The pili (plural) or pilus (singular)is a biological molecule that is on the surface of many bacteria. It is sometimes described as a hair structure. The term pilus comes from the latin word thread or fiber. All of the pili are…
Note that this definition has two issues. There is no universally accepted definition of life. There is no universally accepted size threshold for being called a microbe (to my knowledge). I would go with a threshold of about $10^{-5}$ meters. Is a virus a microbe? A virus IS and IS NOT alive depending on the definition. Note btw, that the definition of what is alive…
STEC O157 strains of bovine origin (n = 102) that varied by source, and epidemiologically unrelated human clinical STEC O157 strains (n = 91) were used for polymorphism discovery (Additional data file 1) [, –]. Each strain was characterized as STEC O157 by an enzyme-linked immunosorbent assay using an O157 monoclonal antibody and multiplex PCR for stx1 , stx2 , eae…
