relationships of viruses & bacteria to...

Relationships of Viruses & Bacteria to Disease

Virtual Science University

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Relationships of Viruses & Bacteria to Disease

Texas TEK B.4 (C) Student will compare the structures and functions of viruses to cells and describe the role of viruses in causing diseases and conditions such as acquired immune deficiency syndrome, common colds, smallpox, influenza, and warts.Texas TEK B.4 (D) Identify and describe the role of bacteria in maintaining health such as in digestion and in causing disease such as in streptococcus infections and diptheria.

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Glossary • Virus is a nonliving infectious substance

that can invade and destroy a cell. It is made up of a nucleic acid and a protein coat.

• Protein Coat is also known as a capsid and may contain either RNA or DNA.

• Bacteria are the organisms that compose the Kingdom Eubacteria and the Kingdom Archaebacteria.

• Pilli are shorter and thicker outgrowths that some bacteria have which are used to attach to surfaces or to other cells.

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Glossary • Flagella or Flagellum are simple

structures composed of a single protein fiber that spins like a corkscrew to move the bacterial cell.

• Coccus is a round-shaped bacterial cell.• Spirilla are bacterial cells that are spiral-

shaped bacteria. A few of these bacteria form strands.

• Bacillus is a rod-shaped bacterial cell.• Strepto is a prefix attached to bacterial

species that form filaments.• Staphylo is a prefix attached to bacterial

species that form clusters.

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Glossary • Pathogens are infectious agents. They

are Viruses or other microorganisms that cause disease.

• Toxins are substances that are produced by one organism that are poisonous to another organism.

• Antibiotics are substances that can inhibit the growth or kill some microorganisms.

• Binary Fission is a form of asexual-reproduction in single celled organisms in which one cell divides into two cells of the same size.

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Glossary

• Conjugation is a process in bacteria by which two microorganisms exchange genetic material.

• Decomposers are organisms such as bacteria and fungi that remove or feed on dead organisms.

• Endospores are thick-walled protective spores that form inside a bacterial cell and can resist very harsh conditions.

• Nitrogen Fixation is a process by which nitrogen is fixed and gaseous nitrogen is converted into NH3.

• Chemosynthesis is the process of obtaining energy by removing electrons from inorganic molecules.

• Cyanobacteria, -as Anabaena are bacteria that undergo photosynthesis and can fix nitrogen.

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Structure of a Virus• The Capsid or Virus Protein

Coat – may contain DNA or RNA,

but not both. • One of those Viruses that

contain RNA is HIV or Human Immunodeficiency Virus – which causes AIDS.

• Other RNA containing Viruses – Influenza Viruses – Rabies Virus

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Structure of a Virus• Those containing DNA

are those Viruses that cause – Warts – Chicken Pox– Mononucleosis

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Structure of a Virus• Many Viruses such as

Influenza have a membrane or envelope surrounding the capsid.

• The envelope helps the Virus enter cells.

• It consists of proteins, lipids, and glycoproteins which are proteins with attached carbohydrate molecules.

• Some Viruses also have specific enzymes.

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Viral Reproduction• Two Cycles of Viral Reproduction

– Lytic Cycle - Considered as the main method of viral reproduction because it ends in the lysis of the infected cell releasing the progeny viruses that will in turn spread and infect other cells.

– Lysogenic Cycle - In the Lysogenic Cycle, a bacteriophage enters a cell and remains inactive in the host’s genome until an external stimulus causes the virus to enter the lytic cycle.

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Lytic & Lysogenic Cycle

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Lytic Cycle• Stages of the lytic cycle are:

– Attachment – the virus attaches itself to the host cell.

– Injection - the virus inserts its genetic material into the host cell.

– Integration - the genetic material tells the cell what to do.

– Replication – the host cell builds parts of the virus.

– Assembly - the cell assembles the replicated parts into progeny viruses.

– Lysis- the cell breaks open and each replicated virus can now infect other cells.

• Some Viruses, though, can leave the infected cell not through lysis but rather by budding.

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http://www.biology-online.org/dictionary/Attachment

http://www.biology-online.org/dictionary/Attachment

Lysogenic Cycle• Bacteriophage's nucleic acid

fuses together with the hosts nucleic acid, so that genetic information of the virus is transmitted through daughter cells.

• Viral replication cycle in which the virus's nucleic acid is integrated into the host cells chromosome

• A provirus is formed and replicated each time the host cell reproduces

• The host cell is not killed until the lytic cycle is activated

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Bacteria• Bacteria are the organisms that compose the

Kingdom – Eubacteria and Archaebacteria

• There are seven ways in which bacteria differ from eukaryotes– Cell Size– Chromosomes– Reproduction– Movement– Metabolic Diversity– Multicellular– Internal Compartmentalization

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Bacteria differ from Eukaryotes

• Cell Size – Bacteria range in size

between .5 micrometers and 5 micrometers, while most eukaryotic cells range between 10 and 100 micrometers.

– There are however very large bacteria that are as big as 750 micrometers.

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Bacteria Cell Size Eukaryotes Cell Size

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Bacteria differ from Eukaryotes• Chromosomes

– Bacteria chromosomes are made up of a single piece of DNA

– Eukaryotic chromosomes are linear pieces of DNA that are associated with proteins.

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Bacteria Chromosomes Eukaryotes Chromosomes

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Bacteria differ from Eukaryotes• Reproduction

– Bacteria reproduce by• Binary Fission

– Pinch into two cells

– Eukaryotic Cells reproduce by• Mitosis

– the chromosomes pull apart to opposite poles and then divided into two new cells

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Bacteria Reproduction Eukaryotes Reproduction

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Bacteria differ from Eukaryotes• Movement

– Bacteria• Flagellum is made up of a single fiber of

protein that spins like a corkscrew• Some Bacteria have pilli which are

outgrowths that allow bacteria to attach to other surfaces

– Eukaryotic • Flagella are more complex microtubules

that whip back and forth rather than spin

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Bacteria Movement Eukaryotes Movement

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• Metabolic Diversity–Bacteria

• can perform many anaerobic and aerobic processes

–Eukaryotes • are mostly aerobic

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• Multicellular –Most Bacteria are unicellular –Eukaryotes are multi-cellular

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Bacteria Unicellular Eukaryotes Multicellular

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• Internal Compartmentalization– Bacteria are

prokaryotes and have no internal compartments or membrane systems

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Bacteria Which are Photosynthesizers

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Bacteria Which Are Chemoautotrophs

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Bacteria Which Are Heterotrophs

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Bacteria Which Are Pathogenic

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Doctor’s Corner

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Important Diseases Caused by Bacteria

• Disease Illness Description Bacterium Transmission

• Anthrax Fever Bacillus anthracis Inhalation of Severe Difficulty Spores Breathing

• Bubonic Plague Fever, Swollen Yersinia pestis Bite of an Lymph Notes Infected Flea

• Cholera Severe Diarrhea Vibro cholerae Drinking and Vomiting Contaminated Water

• Dental Cavities Destruction of Streptococcus Dense collection Composition of Tooth Mutans of bacteria

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Important Diseases Caused by Bacteria

• Disease Illness Description Bacterium Transmission

• Lyme Disease Rash, Pain, Borrelia burgdorferi Bite of an Swelling in joints Infected Tick

• Tuberculosis Fever, Cough Mycobacterium Inhalation Difficulty breathing tuberculosis

• Typhus Headache, High Rickettsia prowazeki Bite of

Fever Infected Flea or Louse

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Contact Information

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1-877-920-5550

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