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Prokaryotes Virus APBio

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Information about Prokaryotes Virus APBio

Published on February 28, 2008

Author: MrDPMWest

Source: slideshare.net

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Prokaryotes and Viruses

Prokaryotic Domains Single-cell microbes Lack most organelles (membrane bound) Inhabit diverse environments Differences between Bacteria and Archaea Structural and biochemical features Archaea have histones (just like Eukarya) Differences in cell walls, plasma membrane composition, ribosomes, and RNA polymerases

Single-cell microbes

Lack most organelles (membrane bound)

Inhabit diverse environments

Differences between Bacteria and Archaea

Structural and biochemical features

Archaea have histones (just like Eukarya)

Differences in cell walls, plasma membrane composition, ribosomes, and RNA polymerases

The Sizes of Microorganisms 1 µ m Eukaryotic Cells (10-100 µ m) Prokaryotic Cells (0.2-10 µ m) Staphylococcus Cyanobacterium Escherichia coli Viruses (0.05-0.2 µ m)

Classifying Prokaryotes Is Difficult Features used in prokaryotic classification: Shape Means of locomotion Pigments Nutrient requirements Colony appearance Gram staining characteristics Nucleotide sequences

Features used in prokaryotic classification:

Shape

Means of locomotion

Pigments

Nutrient requirements

Colony appearance

Gram staining characteristics

Nucleotide sequences

Three Common Bacterial Shapes (a) (b) (c)

Bacterial Characteristics Shape - cocci, bacilli, spirilla Cell wall - peptidoglycan Capsules or slime layer - polysaccharide or protein chains Pili - protein form of attachment Flagella - used to propel by rotation Endospores (some bacteria) Contain nucleic acid surrounded by a protein coat Form in inhospitable environments Reside dormant until favorable environment; Can last for years Great mechanism for continuing species

Shape - cocci, bacilli, spirilla

Cell wall - peptidoglycan

Capsules or slime layer - polysaccharide or protein chains

Pili - protein form of attachment

Flagella - used to propel by rotation

Endospores (some bacteria)

Contain nucleic acid surrounded by a protein coat

Form in inhospitable environments

Reside dormant until favorable environment; Can last for years

Great mechanism for continuing species

 

Diverse Metabolisms Anaerobic Metabolism Some bacteria live without oxygen (and are poisoned by it) e.g. Tetanus bacteria Some bacteria can switch between aerobic and anaerobic respiration e.g. Escherichia coli in our large intestines

Anaerobic Metabolism

Some bacteria live without oxygen (and are poisoned by it)

e.g. Tetanus bacteria

Some bacteria can switch between aerobic and anaerobic respiration

e.g. Escherichia coli in our large intestines

Diverse Metabolisms Where bacteria get their energy Familiar organic compounds Sugars, carbohydrates, fats, and proteins Compounds poisonous to humans Petroleum, methane, benzene, toluene Inorganic molecules Hydrogen, sulfur, ammonia, iron, nitrite Some bacteria get energy from sunlight Cyanobacteria perform photosynthesis Sulfur bacteria use H 2 S instead of water in photosynthesis

Where bacteria get their energy

Familiar organic compounds

Sugars, carbohydrates, fats, and proteins

Compounds poisonous to humans

Petroleum, methane, benzene, toluene

Inorganic molecules

Hydrogen, sulfur, ammonia, iron, nitrite

Some bacteria get energy from sunlight

Cyanobacteria perform photosynthesis

Sulfur bacteria use H 2 S instead of water in photosynthesis

Binary Fission Asexual cell division produces identical copies Binary fission can occur every 20 minutes Rapid reproductive rate allows for rapid evolution Mutations in DNA replication are rapidly spread

Asexual cell division produces identical copies

Binary fission can occur every 20 minutes

Rapid reproductive rate allows for rapid evolution

Mutations in DNA replication are rapidly spread

 

Exchange of Genetic Material Conjugation allows for DNA transfer between donor and recipient Sex pilus connects donor to recipient cell forming a cytoplasmic bridge Conjugation can occur between different species Small circular DNA molecules ( plasmids ) carry genes from donor to recipient

Conjugation allows for DNA transfer between donor and recipient

Sex pilus connects donor to recipient cell forming a cytoplasmic bridge

Conjugation can occur between different species

Small circular DNA molecules ( plasmids ) carry genes from donor to recipient

Conjugation: Prokayotic “Mating” Sex Pilus Donor Recipient

Benefits of Bacteria Cyanobacteria Photosynthesis Pioneers in primary succession Chemosynthesis - nutrient cycles and plants Symbiosis - living together Ruminants’ digestive tracts Nitrogen fixing in certain legumes Bacteria on the human body Biodegradation - oil Food production - cheese, yogurt, sauerkraut Decomposers

Cyanobacteria

Photosynthesis

Pioneers in primary succession

Chemosynthesis - nutrient cycles and plants

Symbiosis - living together

Ruminants’ digestive tracts

Nitrogen fixing in certain legumes

Bacteria on the human body

Biodegradation - oil

Food production - cheese, yogurt, sauerkraut

Decomposers

Bacterial Pathogens Small number of species cause disease Survey of human bacterial diseases Anaerobes - toxins (tetanus, botulism) Allergic reactions - Streptococcus pneumoniae Pneumonia "Flesh-eating" bacteria Black Death, tuberculosis Sexually transmitted diseases Gonorrhea Syphilis

Small number of species cause disease

Survey of human bacterial diseases

Anaerobes - toxins (tetanus, botulism)

Allergic reactions - Streptococcus pneumoniae

Pneumonia

"Flesh-eating" bacteria

Black Death, tuberculosis

Sexually transmitted diseases

Gonorrhea

Syphilis

The Prokaryote Flagellum (b)

Bacterial Habits Habitats Bacteria inhabit nearly every habitat Bacteria are specialists

Habitats

Bacteria inhabit nearly every habitat

Bacteria are specialists

Archaea Unique lipid membranes, cell walls, and rRNA Methanogens Convert CO 2 to methane Swamps, hot springs, vent communities, cow stomachs Halophiles - survive concentrated salt environment Thermoacidophiles - thrive in hot, acidic environment

Unique lipid membranes, cell walls, and rRNA

Methanogens

Convert CO 2 to methane

Swamps, hot springs, vent communities, cow stomachs

Halophiles - survive concentrated salt environment

Thermoacidophiles - thrive in hot, acidic environment

Some Prokaryotes Thrive in Extreme Conditions

Nitrogen-Fixing Bacteria on Root Nodules (a) (b)

Nonliving Parasitic Molecules Viruses Nucleic acid molecule surrounded by a protein coat Bacteriophages; viruses that infect bacteria Survey of human viral diseases Viroids Short strands of RNA without a protein coat Cause disease mostly in plants; affect some crops Prions Proteinaceous infectious particle Human prion diseases

Viruses

Nucleic acid molecule surrounded by a protein coat

Bacteriophages; viruses that infect bacteria

Survey of human viral diseases

Viroids

Short strands of RNA without a protein coat

Cause disease mostly in plants; affect some crops

Prions

Proteinaceous infectious particle

Human prion diseases

Viruses Two major components constitute a virus Single or double-stranded DNA or RNA as hereditary material Protein coat May be surrounded by an envelope formed from the plasma membrane of the host cell Cannot grow or reproduce on their own and are parasites of living cells Have a specialized protein coat that enables entry into a host cell…

Two major components constitute a virus

Single or double-stranded DNA or RNA as hereditary material

Protein coat

May be surrounded by an envelope formed from the plasma membrane of the host cell

Cannot grow or reproduce on their own and are parasites of living cells

Have a specialized protein coat that enables entry into a host cell…

Viruses Viral genetic material “hijacks” host cell to produce new viral components Viral components assemble rapidly into new viruses and burst from host cell

Viral genetic material “hijacks” host cell to produce new viral components

Viral components assemble rapidly into new viruses and burst from host cell

Viral Structure and Replication (a) Glycoproteins Envelope (lipid bilayer) Protein Coat Core Proteins Reverse Transcriptase Viral RNA in protein coat Spikes Herpes Viruses HIV (b)

Viruses Come in Many Shapes Rabies Measles Bacteriophage Herpes Tobacco Mosaic

Viruses Are Host-Specific Each viral type specialized to attack specific host cell Bacteriophages can treat bacterial diseases Rise in bacterial antibiotic resistance makes standard drugs less effective Bacteriophages specifically target host bacteria Bacteriophages are harmless to human body cells

Each viral type specialized to attack specific host cell

Bacteriophages can treat bacterial diseases

Rise in bacterial antibiotic resistance makes standard drugs less effective

Bacteriophages specifically target host bacteria

Bacteriophages are harmless to human body cells

Viruses Are Host-Specific In multicellular organisms viruses specialize in attacking particular cell types Cold viruses attack membranes of respiratory tract Measles viruses infect the skin Rabies viruses attack nerve cells

In multicellular organisms viruses specialize in attacking particular cell types

Cold viruses attack membranes of respiratory tract

Measles viruses infect the skin

Rabies viruses attack nerve cells

Viruses Are Host-Specific Some viruses linked to cancer (e.g. T-cell leukemia, liver cancer, cervical cancer) Herpes virus attacks mucous membranes of mouth and lips (causing cold sores) Other herpes virus type causes genital sores HIV virus attacks specific white blood cell type, causing AIDS

Some viruses linked to cancer (e.g. T-cell leukemia, liver cancer, cervical cancer)

Herpes virus attacks mucous membranes of mouth and lips (causing cold sores)

Other herpes virus type causes genital sores

HIV virus attacks specific white blood cell type, causing AIDS

Some Viruses Infect Bacteria Bacterium Newly forming bacteriophages

How Viruses Replicate: HIV (a) cytoplasm nucleus DNA vRNA mRNA 1a. Virus attaches to receptor 2. Viral reverse transcriptase makes DNA using viral RNA 1b. Core disintegrates; viral RNA enters the cytoplasm 3a. DNA enters nucleus & chromosomes 3b. DNA transcribed into mRNA & viral RNA, which move to cytoplasm

How Viruses Replicate: HIV (b) 4. Viral proteins made using mRNA 5. Viral proteins & RNA assembled 6. Viruses bud from plasma membrane

How Viruses Replicate: Herpes (a) (cytoplasm) envelope coat DNA nucleus DNA mRNA 1. Virus enters cell by endocytosis 3. Viral DNA transcribed to mRNA, which moves to cytoplasm 2a. Viral envelope merges with nuclear membrane 2b. Protein coat disintegrates; viral DNA copied & enters nucleus

How Viruses Replicate: Herpes (b) nucleus mRNA (cytoplasm) envelope coat DNA DNA mRNA 4. MRNA makes proteins, which enter nucleus 5. New viruses assembled & bud from nucleus, get envelope from inner nuclear membrane 6. Newly formed viruses leave the cell by exocytosis

Viral Infections Are Difficult to Treat Antibiotics against bacteria are infective against viruses Antiviral drugs may also kill host cells Viruses “hide” within cells, are hard to detect Viruses have high mutation rates Mutations can confer resistance to antiviral drug Resistant viruses spread and multiply, rendering drug ineffective

Antibiotics against bacteria are infective against viruses

Antiviral drugs may also kill host cells

Viruses “hide” within cells, are hard to detect

Viruses have high mutation rates

Mutations can confer resistance to antiviral drug

Resistant viruses spread and multiply, rendering drug ineffective

Viroids Viroids are infectious particles with only short RNA strands (no protein coat) Able to enter host cell nucleus and direct new viroid synthesis A number of crop diseases are caused by viroids e.g. cucumber pale fruit disease, avocado sunblotch, potato spindle tuber disease

Viroids are infectious particles with only short RNA strands (no protein coat)

Able to enter host cell nucleus and direct new viroid synthesis

A number of crop diseases are caused by viroids

e.g. cucumber pale fruit disease, avocado sunblotch, potato spindle tuber disease

Prions A mutated protein that acts as an infectious agent Fatal degenerative disease discovered in New Guinea tribe (Fore) in 1950 Kuru causes loss of coordination, dementia, death Kuru in the Fore tribe was transmitted by ritual cannibalism of the dead

A mutated protein that acts as an infectious agent

Fatal degenerative disease discovered in New Guinea tribe (Fore) in 1950

Kuru causes loss of coordination, dementia, death

Kuru in the Fore tribe was transmitted by ritual cannibalism of the dead

Prions Other diseases like kuru include: Creutzfeldt-Jacob (CJD) disease in humans Scrapie in sheep Bovine spongiform encephalopathy (BSE or “Mad Cow Disease”) in cattle These diseases create holes in brain tissue

Other diseases like kuru include:

Creutzfeldt-Jacob (CJD) disease in humans

Scrapie in sheep

Bovine spongiform encephalopathy (BSE or “Mad Cow Disease”) in cattle

These diseases create holes in brain tissue

Prions: Puzzling Proteins

The End

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