Prokaryotes are single-celled organisms that do not have a membrane-bound nucleus. They live in a very diverse range of habitats and help many organisms digest food. Using DNA technology, Carl Woese found that there are two main branches of prokaryotes: Bacteria and Archaea. By comparing rRNA (ribosomal) scientists have found that archaebacteria are more related to eukaryotes than prokaryotes.
Archaea have different cell walls, membrane lipids, genetics, and metabolism compared to bacteria. Archael cell wells do not have peptidoglycan, a protein in bacteria cell walls. Archaea were first found in harsh environments like salt lakes, swamps and hot springs, however, scientists are finding them to be more common than first thought. Methanogens
These convert hydrogen gas and carbon dioxide into methane gas. Oxygen is poisionous, so they can only live where there is no oxygen. These are responsible for the methane that bubbles out at sites such as swamps, called marsh gas. They also thrive in the intestines of cows and termites. Halophiles
These archaea love salt and live in live in salty environments like the Great Salt Lake and the Dead Sea. Thermoacidophiles
These archae live in very acidic environments at hot temperatures, like at the hot springs of Yellowtone National Park. Some live at deep sea vents called black smokers, where they are the autototrophs that make up the base of the food chain there.
Most prokaryotes are bacteria. They come in 4 basic shape. Rod shaped bacteria are called bacilli, sphere-shaped are cocci, and spiral shaped bacteria are called spirilla. When cocci occur in chains, they are called streptocci, while when they occur in clusters they are called staphylocci. This grouping is also the source of the common names strept-throat and staph infection.
Gram Staining is a technique that can determine the amount of peptidoglycan in a cell wall. Gram-negative bacteria becomes pink and has a very thin peptidoglycan layer. These contain endotoxins Gram-positive bacteria turn purple and therefore have more peptidoglycan. These contain exotoxins. These tend to be simpler than their counterparts. Proteobacteria
This is one of the largest and most diverse groups of bacteria. Many live symbiotically with other organisms. Nitrogen fixing bacteria (genus Rhizobium) lives in the roots of legumes. These bacteria convert nitrogen in the atmostphere to ammonia, which plants can use. Some proteobacteria form nitrates from ammonia in the soil. Nitrates are then converted into nitrates by other bacteria, which plants can use. Some proteobacteria cause disease, like spotted fever and stomach ulcers. Others live within the intestines of animals and help in the breakdown of food. Gram-Positive Bacteria
Most members of the Gram-positive group are gram-positive, but some genetically similar gram negative are put into this category. Members include the bacteria that causes strep throat, the toxins used in botox, the bacteria that turns milk to yogurt, and anthrax. Actinomycetes are Gram-positive bacteria that form branching filaments of colonies. Many make antibiotics, chemicals that kill neighboring fungi and bacteria.
Cyanobacteria
These bacteria use photosynthesis to make energy. They give off oxygen as a waste product. Some grow in filaments, and others form specialized cells called heterocysts. Heterocysts have enyzymes for fixing nitrogen. Cyanobacteria are numerous and were the Earth’s first oxygen-producing organisms. They lack chloroplasts.
Spirochetes
These are gram-negative, spiral-shaped bacteria. They live freely or as pathogens, some causing STI’s or STD's (sexually transmitted infections or sexually transmitted diseases respectively) like syphilis.
Chlamydia
Gram negative, cocci shaped pathogens of this group only live inside animal cells. These cell walls do not have peptidoglycan and are also responsible for spreading STI’s.
23.2 Biology of Prokaryotes
Most members of Bacteria and Archaea have a cell wall. Bacterial cell walls have petidoglycan. Archaeal cells contain pseudomurein in their cell walls. Both bacterial and archael cell membranes are lipid bilayers. Phyotosynthetic bacteria have cell membranes whose internal folding are called thylakoids and act it like chloroplasts. Prokaryotic DNA is a single closed loop of double-stranded DNA attached at one point to the cell membrane. Some prokaryotes also have plasmids, which are small, circular, self-replicating loops of double-stranded DNA. Many bacteria have an outer covering of polysaccharides called a capsule. It helps protect bacteria from white blood cells. It is made of a fuzzy coat of sticky sugars called a glycocalyx. Pili are short, hairlike structures that help connect bacteria together and other surfaces. Some gram-positive bacteria can form a thick-coated, resistant structure called an endospore when environmental conditions become harsh. When conditions are favorable, the endospores become bacteria. Most prokaryotes use flagella to avoid danger. Some do not have flagella but can move by forming a layer of slime.
Some bacteria are heterotrophs and get their carbon from other organisms. Autotrophs get their carbon from inorganic molecules of carbon dioxide. If they use light, they are called phototrophs, and if they use chemicals in their environment they are called chemotrophsPhotoheterotrophs use light energy but also get their carbon from other organisms. Chemoautotrophs are mainly nitrogen fixing.
Prokaryotes live in certain habitats based on their abilities. Many are obligate anaerobes that cannot live where there is oxygen. Facultative anaerobes can live with oxygen, but prefer without. Prokaryotes that need oxygen to live are called obligate aerobes. Psychrophilic prokaryotes love cold conditions. Mesophiles thrive at the same middle temperatures humans do, and thermophiles resist being destroyed by heat. Acid-loving prokaryotes are called acidophiles.
Prokaryotes usually reproduce by binary fission (asexual)/ Prokaryotes can exchange pieces of DNA without reproducing; this is called recombination.Prokaryotes can get DNA from prokaryotes by: Transformation, when a prokaryote takes DNA from its environment, Conjugation, when two prokaryotes bind together and transfer DNA through a sex pilus, and Transduction, when a virus obtains a small part of DNA from the host. The host bacteria then replicates with the virus DNA as part of its own. This is important in the creation of antibiotics for humans by using artificial plasmids and chromosomes called bacterial artificial chromosomes (BAC’s).
23.3 Bacteria and Humans
Pathology is the study of disease. Pathogens cause disease. Some bacteria cause disease by making poisons, called toxins. Exotoxins are toxic substances that bacteria secrete into their environment. These are found often In Gram-positive bacteria. Endotoxins, used by many Gram-negative bacteria, are toxic substances that are only released when the cell dies. Antibiotics interfere with cellular activities to stop bacteria growth. Antibiotics that can kill more than one type of organism are called broad-spectrum antibiotics. Over time, bacteria may develop resistance. Mutations that take place would allow the mutant strain to evolve and survive. Because antibiotics have been overprescribed and misused, many resistance genes are now present on plasmids called R-plasmids, which can pass easily between bacteria.
Bacteria are becoming more difficult to treat and more common than they have been in the past. A disease that can pass from animals to humans is called a zoonosis. Lyme disease and others are spreading more as humans take up land that originally wasn’t touched. Bacteria can also be found on mishandled or undercooked food, like E coli. By refrigerating and properly storing foods, and washing your hands, the prevalence of foodborne illness can be decreased.
Bacteria are used to make many foods, like cheese, sour cream, and yogurt. Heat loving prokaryotes help biotechnologists to copy pieces of DNA rapidly. Bacteria can hurt and help agriculture. Some plants now contain toxins that kill bugs. Bioremediation is the process of using bacteria to break down pollutants.
23.1 Bacteria
Prokaryotes are single-celled organisms that do not have a membrane-bound nucleus. They live in a very diverse range of habitats and help many organisms digest food. Using DNA technology, Carl Woese found that there are two main branches of prokaryotes: Bacteria and Archaea. By comparing rRNA (ribosomal) scientists have found that archaebacteria are more related to eukaryotes than prokaryotes.
Archaea have different cell walls, membrane lipids, genetics, and metabolism compared to bacteria. Archael cell wells do not have peptidoglycan, a protein in bacteria cell walls. Archaea were first found in harsh environments like salt lakes, swamps and hot springs, however, scientists are finding them to be more common than first thought.
Methanogens
These convert hydrogen gas and carbon dioxide into methane gas. Oxygen is poisionous, so they can only live where there is no oxygen. These are responsible for the methane that bubbles out at sites such as swamps, called marsh gas. They also thrive in the intestines of cows and termites.
Halophiles
These archaea love salt and live in live in salty environments like the Great Salt Lake and the Dead Sea.
Thermoacidophiles
These archae live in very acidic environments at hot temperatures, like at the hot springs of Yellowtone National Park. Some live at deep sea vents called black smokers, where they are the autototrophs that make up the base of the food chain there.
Most prokaryotes are bacteria. They come in 4 basic shape. Rod shaped bacteria are called bacilli, sphere-shaped are cocci, and spiral shaped bacteria are called spirilla. When cocci occur in chains, they are called streptocci, while when they occur in clusters they are called staphylocci. This grouping is also the source of the common names strept-throat and staph infection.
Gram Staining is a technique that can determine the amount of peptidoglycan in a cell wall.
Gram-negative bacteria becomes pink and has a very thin peptidoglycan layer. These contain endotoxins
Gram-positive bacteria turn purple and therefore have more peptidoglycan. These contain exotoxins. These tend to be simpler than their counterparts.
Proteobacteria
This is one of the largest and most diverse groups of bacteria. Many live symbiotically with other organisms. Nitrogen fixing bacteria (genus Rhizobium) lives in the roots of legumes. These bacteria convert nitrogen in the atmostphere to ammonia, which plants can use. Some proteobacteria form nitrates from ammonia in the soil. Nitrates are then converted into nitrates by other bacteria, which plants can use. Some proteobacteria cause disease, like spotted fever and stomach ulcers. Others live within the intestines of animals and help in the breakdown of food.
Gram-Positive Bacteria
Most members of the Gram-positive group are gram-positive, but some genetically similar gram negative are put into this category. Members include the bacteria that causes strep throat, the toxins used in botox, the bacteria that turns milk to yogurt, and anthrax. Actinomycetes are Gram-positive bacteria that form branching filaments of colonies. Many make antibiotics, chemicals that kill neighboring fungi and bacteria.
Cyanobacteria
These bacteria use photosynthesis to make energy. They give off oxygen as a waste product. Some grow in filaments, and others form specialized cells called heterocysts. Heterocysts have enyzymes for fixing nitrogen. Cyanobacteria are numerous and were the Earth’s first oxygen-producing organisms. They lack chloroplasts.
Spirochetes
These are gram-negative, spiral-shaped bacteria. They live freely or as pathogens, some causing STI’s or STD's (sexually transmitted infections or sexually transmitted diseases respectively) like syphilis.
Chlamydia
Gram negative, cocci shaped pathogens of this group only live inside animal cells. These cell walls do not have peptidoglycan and are also responsible for spreading STI’s.
23.2 Biology of Prokaryotes
Most members of Bacteria and Archaea have a cell wall. Bacterial cell walls have petidoglycan. Archaeal cells contain pseudomurein in their cell walls. Both bacterial and archael cell membranes are lipid bilayers. Phyotosynthetic bacteria have cell membranes whose internal folding are called thylakoids and act it like chloroplasts. Prokaryotic DNA is a single closed loop of double-stranded DNA attached at one point to the cell membrane. Some prokaryotes also have plasmids, which are small, circular, self-replicating loops of double-stranded DNA. Many bacteria have an outer covering of polysaccharides called a capsule. It helps protect bacteria from white blood cells. It is made of a fuzzy coat of sticky sugars called a glycocalyx. Pili are short, hairlike structures that help connect bacteria together and other surfaces. Some gram-positive bacteria can form a thick-coated, resistant structure called an endospore when environmental conditions become harsh. When conditions are favorable, the endospores become bacteria. Most prokaryotes use flagella to avoid danger. Some do not have flagella but can move by forming a layer of slime.
Some bacteria are heterotrophs and get their carbon from other organisms. Autotrophs get their carbon from inorganic molecules of carbon dioxide. If they use light, they are called phototrophs, and if they use chemicals in their environment they are called chemotrophs Photoheterotrophs use light energy but also get their carbon from other organisms. Chemoautotrophs are mainly nitrogen fixing.
Prokaryotes live in certain habitats based on their abilities. Many are obligate anaerobes that cannot live where there is oxygen. Facultative anaerobes can live with oxygen, but prefer without. Prokaryotes that need oxygen to live are called obligate aerobes. Psychrophilic prokaryotes love cold conditions. Mesophiles thrive at the same middle temperatures humans do, and thermophiles resist being destroyed by heat. Acid-loving prokaryotes are called acidophiles.
Prokaryotes usually reproduce by binary fission (asexual)/ Prokaryotes can exchange pieces of DNA without reproducing; this is called recombination. Prokaryotes can get DNA from prokaryotes by: Transformation, when a prokaryote takes DNA from its environment, Conjugation, when two prokaryotes bind together and transfer DNA through a sex pilus, and Transduction, when a virus obtains a small part of DNA from the host. The host bacteria then replicates with the virus DNA as part of its own. This is important in the creation of antibiotics for humans by using artificial plasmids and chromosomes called bacterial artificial chromosomes (BAC’s).
23.3 Bacteria and Humans
Pathology is the study of disease. Pathogens cause disease. Some bacteria cause disease by making poisons, called toxins. Exotoxins are toxic substances that bacteria secrete into their environment. These are found often In Gram-positive bacteria. Endotoxins, used by many Gram-negative bacteria, are toxic substances that are only released when the cell dies. Antibiotics interfere with cellular activities to stop bacteria growth. Antibiotics that can kill more than one type of organism are called broad-spectrum antibiotics. Over time, bacteria may develop resistance. Mutations that take place would allow the mutant strain to evolve and survive. Because antibiotics have been overprescribed and misused, many resistance genes are now present on plasmids called R-plasmids, which can pass easily between bacteria.
Bacteria are becoming more difficult to treat and more common than they have been in the past. A disease that can pass from animals to humans is called a zoonosis. Lyme disease and others are spreading more as humans take up land that originally wasn’t touched. Bacteria can also be found on mishandled or undercooked food, like E coli. By refrigerating and properly storing foods, and washing your hands, the prevalence of foodborne illness can be decreased.
Bacteria are used to make many foods, like cheese, sour cream, and yogurt. Heat loving prokaryotes help biotechnologists to copy pieces of DNA rapidly. Bacteria can hurt and help agriculture. Some plants now contain toxins that kill bugs. Bioremediation is the process of using bacteria to break down pollutants.