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Prokaryotes are the most numerous organisms on Earth

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Presentation on theme: "Prokaryotes are the most numerous organisms on Earth"— Presentation transcript:

1 Prokaryotes are the most numerous organisms on Earth
Bacteria Prokaryotes are the most numerous organisms on Earth

2 Prokaryotes Prokaryotes: are single-celled organisms that do not have a membrane-bound nucleus They live in every environment on Earth They are a major source of food for many organisms They also help many organisms digest food

3 General Characteristics
Unicellular Prokaryotic Nutrition modes: mainly absorption, some photosynthetic, some chemosynthetic Anaerobic and aerobic species Reproduction: fusion or budding microscopic

4 Carl Woese Discovered in the late 1970’s that prokaryotes made up 2 of the 3 domains of life Categorized based on ribosomal RNA analysis

5 2 Major Domains Archaea: means “archaic” or “ancient” Bacteria:

6 Domain Archaea Not like bacteria, but more like Eukaryota
Differ from bacteria in the make up of their cell wall, membrane lipids, their genetics & metabolism Cell walls do not have peptidoglycan (a protein-carbohydrate compound) Cell walls have different amino acids and different types of lipids

7 Truth about Archaea Archaea were first discovered in extreme environments like swamps, salt lakes and hot springs Recently, scientists found Archaea genetic materials in samples of surface water from the North Pacific & Antarctic Oceans So, Archaea may be more common that once thought.

8 3 Broad Groups of Archael Bacteria
Methanogens Halophiles Thermoacidophiles

9 1. Methanogens Named for their unique way of getting energy
Convert H2 gas & CO2 into methane gas (CH4) Live in anaerobic environments)-like swamp bottoms (marsh gas), sewage, intestinal tracts of humans, cows, & termites Oxygen is poisonous to them A cow can belch 200 & 400 L Of Methane per day

10 The methane that bubbles out at marshes are called marsh gas

11 2. Halophiles “Salt Lovers”-live in high salt concentrations like the Great Salt Lakes & Dead Sea High salt concentrations would kill most bacteria but favor the growth of halophiles b/c they have adapted to live in very salty water Aerobic organisms

12 Ex: Great Salt Lakes Ex: Dead Sea

13 3. Thermoacidophiles Live in very acidic environments that have very high temperatures (ph less than 2) with temperatures (230 F); Found in hot springs (Yellowstone National Park), volcanic vents, hydrothermal vents of the ocean Requires sulfur anaerobes

14 Hot Springs at Yellow Stone National Park
Hydrothermal Vent

15 Domain Bacteria Most well known prokaryotes General Characteristics
1. Largest group of bacteria 2. Occur in many shapes and sizes 3. Have distinct biochemical and genetic characteristics

16 Domain Bacteria Occur in different shapes and sizes
Identified by basic shapes Sphere: Coccus [round] Rods: Bacillus [Rod Shaped] Spirals: Spirillum

17 Three Bacterial Cell Shapes

18 Bacterial cells are also classified by their arrangements
Diplo – Two Staphlyo – Clusters Strepto – Long Chain Bacteria can occur in pairs diplo- bacilli or cocci Staphylococci cause “staph” infections Streptococcus cause infections such as “strep” throat

19 Some well known Bacteria
Streptococcus mutans causes tooth decay by converting sugars to an acid That erodes the tooth Clostridium botulinum produces a poison causing food poisoning Treponema pallidum causes syphilis

20 Gram Stain Used to group bacteria into 2 groups based on the structure of their cell walls 1. Gram-positive bacteria: appears purple because they retain the crystal violet stain Are simpler and have more peptidoglycan The stain retains purple dye and appear purple

21 Gram-negative bacteria
2. Gram-negative bacteria: appears pink because the cell becomes counterstained by the safranin red stain Gram negative bacteria have cell walls that are complex and have small amounts of peptidoglycan It takes up the the red dye of the Gram stain making it look pink

22 Peptidoglycan Cell Wall Peptidoglycan Cell Wall

23 Important Bacterial Groups 5 major phyla (actually 12 phyla exist)
1. Cyanobacteria 2. Spirochetes 3. Gram-Positive Bacteria 4. Proteobacteria 5. Chlamydia

24 Important Bacterial Groups 5 major phyla (actually 12 phyla exist)
1. Phylum Cyanobacteria: (blue green bacteria) Photosynthestic Encased in a jelly like substance-live in colonies Some are made of chains of cells with special enlarged cells called heterocysts (fixes nitrogen into ammonia which plants use)

25 Environmental note: Anabaena loves phosphates and nitrates-undergoes a population bloom (eutrophication)-following the bloom many die and become decomposed by heterotrophic bacteria which consume large amounts of oxygen causing fish kills

26 Important Bacterial Groups 5 major phyla (actually 12 phyla exist)
2. Phylum Spirochetes: Gram negative, spiral-shaped bacteria Some are aerobic, some anaerobic Moves by means of a cork-screw like rotation Live freely, symbiotically, or as parasites Treponema pallidum causes syphilis Borrelia burgdorferi causes limes disease

27 Important Bacterial Groups 5 major phyla (actually 12 phyla exist)
3. Phylum Gram Positive Bacteria Not all are gram positive Some gram negative in this group share molecular similarities Makes yogurt Found in oral cavity and human intestines Causes tooth decay Makes antibiotics (actinomycetes)

28 Members include: streptococcal species, causes strep throat
Clostridium botulinum: makes toxins in botulism (used medically to treat painful muscle spasms and frown lines on the face) Anthrax is caused by the rod Bacillus anthracis which is used as a biological weapon

29 Important Bacterial Groups 5 major phyla (actually 12 phyla exist)
4. Phylum Proteobacteria: Largest & most diverse bacteria Divided into several subdivisions: A. Enteric Bacteria Gram negative, heterotrophic, found in animal intestinal tracts, aerobic or anaerobic, Escherichia coli (E.coli) found in human intestines; makes vitamin K, aids in the break down of nutrients, Salmonella-disease causing protobacteria

30 C. Other Proteobacteria:
B. Chemoautotrophs: Gram negative, extracts energy from minerals Lives symbiotically Rhizobium and Azotobacter-fix nitrogen in the soil. Live in nodules inside the roots of legumes which is important to the success of plants Called Nitrogen Fixation C. Other Proteobacteria: Some cause disease like Rocky Mountain Spotted Fever Helicobacter plyori causes stomach ulcers Agrobacterium causes tumors in plants

31 Important Bacterial Groups 5 major phyla (actually 12 phyla exist)
5. Chlamydia Gram-negative-coccoid bacteria Live only inside animal cells (rely for protection and nutrients) The cell walls do not have peptidoglycan Chlamydia tramchomatis causes chlamydia---an STD

32 The importance of bacteria
Soybeans have nodules on their roots that convert nitrogen gas to ammonia that is used by the plant Foods & Medicines some foods would not exist without bacteria Swiss cheese Crispy Pickles vinegar sauerkraut Distinctive flavors Nitrogen fixing bacteria

33 Biology of Prokaryotes

34 Structure & Function


36 Nutrition & Metabolism
Nutrition & Metabolism Prokaryotes have many ways of getting carbon and energy from the environment Heterotroph Photoheterotroph Uses light energy but gets its carbon from other organisms Chemoheterotroph Obtains both energy and carbon from other organisms Autotrophs Photoautotroph Uses light energy and gets carbon from CO2 Chemoautotroph Extracts energy from inorganic compounds and uses CO2 as a carbon source

37 Reproduction: binary fission
Prokaryotes reproduce asexually by binary fission

38 ANTIBIOTICS Antibiotics affect bacteria with certain cellular activities Penicillin: blocks the ability to build new cell wall material Tetracycline: blocks protein synthesis Antibiotics are made naturally by some fungi & bacteria They kill neighboring bacteria or fungi that compete for resources

39 Antibiotic Resistance
A big worry for modern medicine Bacteria may become resistant to antibiotics by Mutations in bacterial DNA give bacterium resistance Mutant bacteria multiply & take over the population and stop the antibiotic’s curing power

40 Viruses In 2003, some people in China started showing symptoms of a new illness. These symptoms were similar to those of pneumonia. The condition was highly infectious. Soon, scientists found that the disease was caused by a virus. They called the disease severe acute respiratory syndrome, or SARS

41 What is a Virus? You’ve probably had the flu—influenza—at some time during your life. Nonliving particles called viruses cause influenza. Viruses are composed of nucleic acids enclosed in a protein coat and are smaller than the smallest bacterium Viruses are interesting to scientists because they cause many diseases and are useful tools for genetic research

42 Did You Know… Viruses are not alive because they lack some of the key characteristics of living organisms 1. They do not have cytoplasm or organelles 2. They cannot carry out cellular functions like metabolism and homeostasis 3. They do not grow as cells do by dividing into two 4. They cannot reproduce outside a host cell 5. They must enter a living cell and use the host cell’s ribosomes, ATP, enzymes, and other molecules to reproduce

43 Virus Size and Structure
Viruses are some of the smallest particles that are able to cause disease They vary in size and shape

44 The arrangement of proteins give different shapes to viruses
Viral Shapes Consist of an inner core of nucleic acid surrounded by 1 or 2 protein coats or capsid The human flu virus may have another layer called a viral envelope surrounded by an outer-coat Contains DNA & RNA but never both


46 Shapes Viral coat is called capsids
Nucleic acid Viral coat is called capsids Polyhedral viruses (polio virus) resembles small crystals Tobacco mosaic viruses-small cylinders T-4 –looks like a lunar landing module Capsid

47 Shapes Some viruses have a bilipid membrane called an envelope that surrounds the capsid The envelope is formed from the nuclear membrane or the cell membrane of the host cell as the viral capsid buds from the host cell

48 Classification of Viruses
By whether they have RNA or DNA as their gnome and whether their gnome is double stranded or linear or circular. Based on the nature of the capsid and on the presence or absence of an envelope ex: SARS is a coronavirus. Corona is the Latin word for “crown” –the envelope protein looks like a crown

49 How are they named? Poliovirus Viruses are not given names
AIDS VIRUS Viruses are not given names Often named after the disease they cause EXAMPLE: RABIES VIRUS

50 How are they named? Code Numbers are used to name several viruses infecting the same host Example: T-1  T-7 7 viruses that infect the intestinal bacteria E.coli (T stands for Type) Others are named for the organ or tissue they infect EXAMPLE: ADENOVIRUSES adenoid tissue in the back of the throat

51 How are they named? Bacteriophage is a virus that infects bacteria T-4

52 Attachment to a Host Before a virus can replicate, it must enter a host cell virus recognizes and attaches to a host cell when one of its proteins interlocks with a molecular shape that is the receptor site on the host cell’s plasma membrane.

53 Lytic Cycle: To Break Down
1. Attachment 2. Entry: once inside the virus destroys the host DNA 3. Replication: it reprograms the cells metabolic activity to copy the virus genes 4. Assembly: nucleic acid & coats are assembled into new viruses 5. Release: host cell breaks open & new virus particles are released

54 A. Attachment B. Entry C. Replication E. Lysis and Release D. Assembly

55 Lysogenic Cycle Begins like the Lytic Cycle Instead of destroying the host cell the DNA becomes part of the host New DNA does not interfere with normal functions of the host cell 4. Every time the host cell reproduces, virus is reproduced 5. Can continue undetected for many years, but can pop out at any time then the virus starts killing the host cells.


57 Where are Viruses found?
Viruses are found everywhere… Some have been linked to cancers, animals, in plants Ex: Tobacco mosaic virus

58 Tobacco Mosaic Virus First plant virus to be identified
There are more than 400 viruses that infect a variety of plants Virus can stunt the growth or yield a loss in the host plants Plant viruses require wounds, or insect bites to enter and infect the host

59 Tobacco Mosaic Virus

60 Some Other Well known Viruses

61 Small Pox 30% of infected die
Vaccines not administered to public since 1970’s No treatment, only preventative vaccine Used as a biological weapon The last case of smallpox in the United States was in 1949

62 Hepatitis Is an inflammation of the liver
Can be caused by 5 different viruses Hepatitis A & E: can be spread by fecal contaminated food and water Hepatitis B, C, & D are spread by sexual contact, by contact with infected blood an serum, and by the use of contaminated needles Symptoms: fever, nausea, jaundice, and liver failure Caused by Hepatitis B

63 Influenza A, B, & C Influenza types A or B viruses cause epidemics of disease almost every winter. In the U.S. influenza epidemics can cause illness in 10% to 20% of people average 36,000 deaths and 114,000 hospitalizations per year

64 Influenza Pandemic of 1918

65 AIDS Virus HIV is the virus that causes AIDS.
AIDS is a serious condition in which the body's defenses against some illnesses are broken down.

66 Herpes Virus The virus Herpes simplex causes the common sexually transmitted disease genital herpes There are two types of Herpes Simplex, and both can cause genital herpes Most babies are born through c-section

67 HPV Genital Warts:one of the most common types of sexually transmitted diseases Virus that causes them called the human papillomavirus

68 Bubonic Plague During the 1300s - a massive epidemic swept through Europe, killing one-third of the population by some estimates, and subsequently changing the course of European history. Referred to as The Black Death, Caused from being bitten by a rodent flea that is infected with the disease

69 Polio Virus Phase 3: Muscle weakness and muscle paralysis, difficult swallowing, nasal voice, difficulty breathing It enters through the mouth & is contagious. Phase 1: Fever, headache, sore throat, spewing, malaise(general bodily weakness and discomfort). Phase 2: Meningitis, fever, severe headaches, stiff neck and back, muscle pain.

70 When first introduced into the United States, SARS was thought to be a chemical weapon.
Originated in Asia in 2003 Stands for Acute Respiratory Syndrome and can be contracted by close person to person contact.

71 West Nile Virus Virus carried by mosquitoes causing EEE.
The most serious outbreak causes inflammation of the brain in humans and horses, as well as mortality in certain domestic and wild birds

72 Ebola Virus Ebola Virus, common name for several strains of virus, three of which are known to cause hemorrhagic fever in humans, which is characterized by massive bleeding and destruction of internal tissues.

73 Chicken Pox Chicken pox is a rash illness caused by a virus.
Chicken pox usually occurs in childhood. More than 90% of Chicken pox cases occur in children less than 12 years of age.

74 Chicken pox and shingles are caused by the same varicella-zoster herpesvirus
The virus multiplies in the lungs and travels to blood vessels in the skin Shingles The painful shingles rash, caused By a herpes virus, is limited to an Area of the skin innervated by a Particular nerve branch Ex: on the side of the chest

75 Anthrax Caused by the bacteria Bacilli
Anthrax most commonly found in wild &domestic lower animals (cattle, sheep, goats, camels, antelopes They ingest spores from soil It can occur in humans when they are exposed to infected animals Or when anthrax spores are used as a bio-terrorist weapon

76 Yellow Fever Yellow fever is a serious viral infection, transmitted by mosquitoes in tropical regions There are no medicines that are effective against this virus

77 Emerging Viral Diseases
Are illnesses caused by new or reappearing infectious agents that typically exist in animal population—often in isolated habitats—and can infect humans who interact with these animals. Ex: Ebola virus also called hemorrhagic fever

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