These stunning images show the phwoar-some power of some of Americas most extreme weather. Camille Seaman’s wondrous work features huge super cells, crashing lightning and gale-force winds.
The roaming photographer has chased storms across the US from Iowa to Wyoming and from Minnesota to Texas. Her favorite places to chase are Kansas, Nebraska and South Dakota - notorious hotspots for spectacular storms. (Caters News)
Apoptosis or programmed cell death is an essential part of life. For example, it’s critical to human development. Where would we be if every fetal cell survived? Some cells must die to form, say, our fingers and toes; others must perish to shape our functional brains.
Cells frequently commit suicide for the good of the whole. They may become apoptotic in response to viruses or gene mutations in order to prevent further damage. Menstruation relies upon programmed cell death.
Apoptosis may be necessary, but it’s not necessarily pretty. Above is a scanning electron micrograph of several cultured HeLa cancer cells. The cell at the center is undergoing apoptosis. During the process, the cell’s cytoskeleton breaks up, causing the outer membrane to bulge and decouple. The resulting wart-like structures are called blebs, which eventually break off and are consumed by phagocytic cells for recycling.
The hairy extensions are filopodia, extremely tiny extensions of cytoplasm used by cells for sensing, migration and cell-cell interactions.
Images: Scanning electron micrographs (SEM) of mitochondria
Most people know it as the powerhouse of the cell, or where most of a cell’s ATP (the chemical currency of cells) is made. Most cells will have one or two of these structures within them, but depending on what the cell’s job is can impact directly the amount of mitochondria it contains.
The inner mitochondrial membrane is the location of the electron transport chain. Here, a system of proteins undergo a series of redox reactions which allow a proton gradient to be formed. Due to the chemiosmotic effect, the power of this gradient can be harnessed by proteins by allowing a stead flow of protons down the gradient, in which ATP is formed.
There is a substantial amount of evidence that suggests mitochondria were originally a species of free ancient-bacteria that were engulfed by early cells. This was suggested as they have their own DNA and replicate independently of the host as well as their outer membranes resembling more eukaryotic membranes, while the inner membrane resembles a bacterial membrane.