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Intro to Prokaryotes and Viruses. Adam Bede has been added to your Reading List! Some viruses only infect bacteria, some only infect plants, and many only infect animals. However, a virus can evolve to jump into humans. This often happens with influenza: for example bird flu or swine flu which originated in birds and pigs and managed to infect humans.
The life cycle of a virus can be divided into the following stages: entry of the virus into the host cell; replication of the viral genome; production of new viral proteins; assembly of those viral proteins into new viruses and then release from the host cell either by killing the cell or by budding off the host cell membrane ready to infect new cells.
Researchers at IMB are working on ways to be able to capture and identify bacteria from infections within hours—this currently takes days. Researchers are re-engineering the lethal design of bacteria and viruses to find ways to stop their infectious cycles. Vaccines show the immune system important parts of the virus so that the immune system can prepare the tools to fight the real virus effectively—vaccines trick the immune system into responding like it has previously seen the virus.
But the immune system also makes killer cells, which stop viral replication by killing any infected host cells. There are many potential vaccine candidates in the pipeline globally, made using a wide range of new technologies. These vaccine technologies include the use of subunit vaccines: researchers make viral proteins and put them into the body, so that the immune system makes antibodies against those viral proteins.
Other technologies trick the body to make those viral proteins itself, these include delivery of RNA in liposomes or DNA plasmids in nanoparticles, as well as modified safe viruses and existing vaccines. By studying virus life cycles and how viruses are detected by the immune system, we can discover new ways to target the virus and treat viral disease even without a vaccine.
Severe cases of viral pneumonia often end up with an associated bacterial infection. So, despite COVID being caused by a virus, antibiotics are really important to treat the associated bacterial infections.
As antibiotic-resistant bacteria are an increasing global problem, researchers at IMB are investigating the surface activity of bacteria at molecular level and have discovered how they elude the human immune system.
They are also looking at developing new therapies to treat resistant bacteria, and working to help r esearchers around the world discover new antibiotics. Skip to menu Skip to content Skip to footer. Site search Search. Site search Search Menu. In our oceans, there are 10 billion times more bacteria than there are stars in the universe.
The millions of viruses in the world laid end to end would stretch for million light years. Bacteria are free-living cells that can live inside or outside a body.
Bacteria reproduce mainly by binary fission Bacteria reproduce mainly by binary fission—replicating their DNA so they have two copies on opposite sides of the cell, then growing a new cell wall down the middle to produce two daughter cells. The cellular structures responsible for the synthesis of proteins are called ribosomes. The bacterial flagellum is smaller and simpler in structure and is made up of a protein called flagellin.
It is proton-gradient driven, capable of rotary movement and attachment to host cells and other surfaces. Rod-like structures named pili are present in some bacteria. These play a role in transferring DNA molecules to other bacterias and are also used for locomotion.
Eukaryotic flagella are ATP-driven, allowing them to perform a bending movement. Archaea may also have most of these cell surface features, but their versions of each feature are typically different from those of bacteria. They are small protein particles surrounded by a protein coat that instead replicate inside of the cells they infect. They range in size from nm.
Viruses are not capable of movement, and they are incapable of replicating outside of a host cell. They also do not possess a metabolic pathway. Examples are the viruses showing icosahedral symmetry.
Their genomic material can also be either single-stranded or double-stranded in nature and are either linear or circular. An important example of retroviruses is the human immunodeficiency virus HIV. Homeostasis reflects the ability of an organism to maintain a relatively stable metabolism and to function normally despite many constant changes in its environment. The changes that are part of normal metabolism may be internal or external, and the organism must respond appropriately. This is accomplished by the use of control systems comprised of three parts: receptor, control center, and effector.
A receptor is a body structure that detects changes in a variable, which can either be a chemical or a process that is regulated. Receptors typically are comprised of nerve cells e. Another example of a receptor is the retina of your eye, which detects changes in the level of light the stimulus that enters the eye.
The control center is the structure that interprets input from the receptor and initiates changes through the effector. Most often, the control center is a portion of the nervous system or an endocrine gland. License: Public Domain. A homeostatic mechanism involving the nervous system provides a relatively quick means of responding to change.
Your endocrine system equips you with a more sustained response, generally lasting several hours or even days through the release of hormones.
For example, parathyroid hormone regulates your blood calcium levels in a process that is paramount to the functioning of your muscles and nerve cells. Sometimes the receptor, control center, and effector are all located in the same organ. A good example of this is your pancreas , which acts as a receptor when it detects an increase in blood glucose, and also acts as the effector when it releases insulin.
An effector is a structure that brings about changes to alter the stimulus. Most body structures can serve as effectors.
The most common effectors are muscles and glands. For example, smooth muscles in the walls of bronchioles regulate airflow into and out of the lungs. Most of the processes in your body are controlled by negative feedback. In this type of homeostatic control, the resulting action will always be in the opposite direction of the stimulus. Homeostatic mechanisms modulate blood pressure, blood glucose levels, body temperature, body fluid composition, heart rate, among many others.
They enable the body to constantly be in a steady-state and to respond to ever-changing circumstances. Through homeostasis, for instance, the body can return the breathing pattern to normal after exercise. An example of homeostasis in the human body is the release of insulin by the pancreas when the glucose levels get too high.
The maintenance of blood pressure is another, already mentioned, one. A third common example is a human body retaining a temperature of The body can control it by making or releasing heat.
A good way to think about negative feedback is the maintaining of constant body temperature. On a very cold day , a decrease in body temperature is detected by the sensory receptors of the skin , which send nerve impulses to the hypothalamus a component of the brain.
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