What do bacterial cells do

The flagella beat in a propeller-like motion to help the bacterium move toward nutrients; away from toxic chemicals; or, in the case of the photosynthetic cyanobacteria; toward the light.

Nucleoid - The nucleoid is a region of cytoplasm where the chromosomal DNA is located. It is not a membrane bound nucleus, but simply an area of the cytoplasm where the strands of DNA are found. Most bacteria have a single, circular chromosome that is responsible for replication, although a few species do have two or more. Smaller circular auxiliary DNA strands, called plasmids, are also found in the cytoplasm. Pili - Many species of bacteria have pili singular, pilus , small hairlike projections emerging from the outside cell surface.

These outgrowths assist the bacteria in attaching to other cells and surfaces, such as teeth, intestines, and rocks. Without pili, many disease-causing bacteria lose their ability to infect because they're unable to attach to host tissue. Specialized pili are used for conjugation, during which two bacteria exchange fragments of plasmid DNA.

Ribosomes - Ribosomes are microscopic "factories" found in all cells, including bacteria. Proteins are the molecules that perform all the functions of cells and living organisms. Bacterial ribosomes are similar to those of eukaryotes, but are smaller and have a slightly different composition and molecular structure. Bacterial ribosomes are never bound to other organelles as they sometimes are bound to the endoplasmic reticulum in eukaryotes, but are free-standing structures distributed throughout the cytoplasm.

There are sufficient differences between bacterial ribosomes and eukaryotic ribosomes that some antibiotics will inhibit the functioning of bacterial ribosomes, but not a eukaryote's, thus killing bacteria but not the eukaryotic organisms they are infecting. License Info. Image Use. Custom Photos. Site Info. Contact Us. The Galleries:.

Photo Gallery. Silicon Zoo. Chip Shots. DNA Gallery. Amino Acids. Religion Collection. Cocktail Collection. Screen Savers. Win Wallpaper. Mac Wallpaper. Movie Gallery. Bacteria Cell Structure They are as unrelated to human beings as living things can be, but bacteria are essential to human life and life on planet Earth.

Send us an email. Many bacteria are beneficial to humans. We harness their power to curdle milk into yogurt and ferment cabbage into kimchi.

Some species even do their work inside us. According to the Microbiology Society, there are about 10 times as many bacterial cells as human cells inside a person's body, and many of these live in the digestive tract. These bacteria get a constant stream of nutrients from the human gut. In return, they help break down foods that human digestive enzymes can't. Bacteroides thetaiotaomicron , for example, helps break down complex carbohydrates. Bacteria on the skin can also produce byproducts that keep harmful bacteria away, according to a paper in the journal Nature Reviews Microbiology.

The benign bacterium Corynebacterium accolens , for example, inhibits the growth of the pneumonia-causing S. Some skin bacteria can be both helpful and harmful. Staphylococcus epidermidis is a spherical bacterium that commonly colonizes the skin but can cause infection if it gets inside the human body.

However, S. Some bacteria, like S. But when these bacteria find their way into the body, especially in people who are immunocompromised , they can cause fatal infections.

Staph infections can cause sepsis full-body inflammation in response to infection , pneumonia , endocarditis inflammation of the heart and heart valves and osteomyelitis inflammation of the bone , according to the CDC. Other bacteria are almost always harmful to humans. Cholera, a diarrheal disease that kills about 95, people worldwide each year, is caused by V. The bacterium Yersinia pestis , spread by fleas that bite rodents, was responsible for the Black Death.

And Bacillus anthracis can form almost indestructible anthrax spores that lurk in soil and can cause deadly disease if inhaled or consumed. Some of the most common problematic bacteria infect people through spoiled food. Salmonella bacteria cause an illness called salmonellosis, marked by diarrhea, stomach cramping and fever. Though most people recover after four to seven days, salmonellosis can be serious, and even fatal, in both young children and older people, according to the CDC.

While many strains live harmlessly in human intestines, others cause diarrheal illness. Like salmonellosis, E. Another common bacterium that can be harmful to people is Helicobacter pylori.

About half of people carry these bacteria in their stomachs, according to the Mayo Clinic. Most people never show any ill effects of this infection, but in some cases, the bacteria cause peptic ulcers , or painful sores in the lining of the stomach. It's not entirely clear how the bacteria spread, but risk factors include crowded livi. Bacterial vaginosis is a condition in which anaerobic bacteria bacteria that do not use oxygen in their metabolism overtake Lactobacillus , a type of beneficial bacteria, in the vagina.

Symptoms include vaginal itching, gray or green discharge, a fishy odor and pain during urination, according to the Mayo Clinic. It's not clear what causes bacterial vaginosis, according to the Mayo Clinic. Some people are likely susceptible because their vaginal environment is not as comfortable for the Lactobacillus bacteria that make up a healthy vaginal microflora.

Douching or having sex with a new partner or with multiple sexual partners can be a risk factor, possibly because these activities disrupt the usual bacterial communities in the vagina. Bacteria commonly associated with bacterial vaginosis include Gardnerella vaginalis , Prevotella species, Mobiluncus species and Atopobium vaginae , according to the CDC. If untreated, bacterial vaginosis is a risk factor for preterm birth and can make a person more susceptible to contracting sexually transmitted infections.

Bacterial vaginosis can be treated with antibiotics. Sterilization techniques and antibiotic medications have led to a significant drop in deaths from bacterial diseases. However, the overuse of antibiotics is making bacterial infection harder to treat. As the bacteria mutate, they become more resistant to existing antibiotics, making infections harder to treat. Bacteria transform naturally, but the overuse of antibiotics is speeding up this process. For this reason, scientists and health authorities are calling on doctors not to prescribe antibiotics unless it is necessary, and for people to practice other ways of preventing disease, such as good food hygiene, hand washing, vaccination, and using condoms.

Recent research has led to a new and growing awaress of how the human body interacts with bacteria, and particularly the communities of bacteria living in the intestinal tract, known as the gut microbiome, or gut flora. In , researchers published findings suggesting that women with obesity were more likely to have a particular kind of bacteria, Selenomonas noxia S. They suggest that this may have a psychological impact. Over 2, years ago, a Roman author, Marcus Terentius Varro, suggested that disease may be caused by tiny animals that floated in the air.

He advised people to avoid marshy places during building work because they might contain insects too small for the eye to see that entered the body through the mouth and nostrils and cause diseases. In the 17th century, a Dutch scientist, Antonie van Leeuwenhoek created a single-lens microscope with which he saw what he called animalcules, later known as bacteria. He is considered to be the first microbiologist. In the 19th century, the chemists Louis Pasteur and Robert Koch said that diseases were caused by germs.

This was known as the Germ Theory. In the , the scientist Paul Ehrlich announed the development of the first antibiotic , Salvarsan. He used it to cure syphilis. He was also the first scientist to detect bacteria by using stains. In time, this work is expected to shed new light a wide range of health conditions. Gut bacteria receive a great deal of attention, but scientists are beginning to invest more time in studying gut viruses.

A new study finds fresh…. In this Special Feature, we examine how and why financial precarity is often linked with prolonged exposure to toxic chemicals that have ill effects…. A new mouse study finds that fasting can neutralize some infections. It seems that healthy gut bacteria out-compete Salmonella for nutrients during a…. Staph infection is contagious. A person can pass it on through close contact or shared objects. It can live on other objects for 24 hours. Learn more. A study shows that a substance in the drink kefir can help combat disease-causing, antibiotic resistant bacteria by disrupting their communication.

What are bacteria and what do they do? Medically reviewed by Jill Seladi-Schulman, Ph. What are bacteria? Types Structure Feeding Where do they live? Reproduction and transformation Uses Hazards Resistance The gut microbiome History Bacteria are microscopic, single-celled organisms that exist in their millions, in every environment, both inside and outside other organisms.

Share on Pinterest Bacteria are single-celled organisms. Where do they live? Share on Pinterest Bacteria can thrive even in extreme environments, such as glaciers. Reproduction and transformation. Share on Pinterest Cheesemaking involves bacteria.