Prokaryotes Virus APBio
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Transcript of Prokaryotes Virus APBio
Chapter 19Chapter 19Prokaryotes and Prokaryotes and VirusesViruses
Chapter 19 2
Prokaryotic DomainsProkaryotic DomainsSingle-cell microbesSingle-cell microbes
Lack most organelles (membrane bound)Lack most organelles (membrane bound)
Inhabit diverse environmentsInhabit diverse environments
Differences between Bacteria and ArchaeaDifferences between Bacteria and Archaea• Structural and biochemical featuresStructural and biochemical features
– Archaea have histones (just like Eukarya)Archaea have histones (just like Eukarya)– Differences in cell walls, plasma membrane Differences in cell walls, plasma membrane
composition, ribosomes, and RNA polymerasescomposition, ribosomes, and RNA polymerases
Chapter 19 3
The Sizes of MicroorganismsThe Sizes of Microorganisms11µµmm
Eukaryotic CellsEukaryotic Cells(10-100 (10-100 µµm)m)
Prokaryotic CellsProkaryotic Cells(0.2-10 (0.2-10 µµm)m)
StaphylococcusStaphylococcus
CyanobacteriumCyanobacterium
Escherichia coliEscherichia coli
VirusesViruses(0.05-0.2 (0.05-0.2 µµm)m)
Chapter 19 4 Classifying Prokaryotes Is DifficultClassifying Prokaryotes Is Difficult
Features used in prokaryotic Features used in prokaryotic classification:classification:• ShapeShape•Means of locomotionMeans of locomotion• PigmentsPigments• Nutrient requirementsNutrient requirements• Colony appearanceColony appearance• Gram staining characteristicsGram staining characteristics• Nucleotide sequencesNucleotide sequences
Chapter 19 5
Three Common Bacterial ShapesThree Common Bacterial Shapes
(a)(a)(a)(a) (b)(b)(b)(b)
(c)(c)(c)(c)
Chapter 19 6
Bacterial CharacteristicsBacterial CharacteristicsShape - cocci, bacilli, spirillaShape - cocci, bacilli, spirilla• Cell wall - peptidoglycanCell wall - peptidoglycan• Capsules or slime layer - polysaccharide or protein Capsules or slime layer - polysaccharide or protein
chainschains• Pili - protein form of attachmentPili - protein form of attachment• Flagella - used to propel by rotationFlagella - used to propel by rotation
Endospores (some bacteria)Endospores (some bacteria)• Contain nucleic acid surrounded by a protein coatContain nucleic acid surrounded by a protein coat• Form in inhospitable environmentsForm in inhospitable environments• Reside dormant until favorable environment; Can Reside dormant until favorable environment; Can
last for yearslast for years• Great mechanism for continuing speciesGreat mechanism for continuing species
Chapter 19 7
Chapter 19 8 Diverse MetabolismsDiverse Metabolisms
Anaerobic MetabolismAnaerobic Metabolism• Some bacteria live without oxygen (and are Some bacteria live without oxygen (and are
poisoned by it)poisoned by it)– e.g. Tetanus bacteriae.g. Tetanus bacteria• Some bacteria can switch between aerobic Some bacteria can switch between aerobic
and anaerobic respirationand anaerobic respiration– e.g. e.g. Escherichia coliEscherichia coli in our large intestines in our large intestines
Chapter 19 9 Diverse MetabolismsDiverse Metabolisms
Where bacteria get their energyWhere bacteria get their energy• Familiar organic compoundsFamiliar organic compounds
– Sugars, carbohydrates, fats, and proteinsSugars, carbohydrates, fats, and proteins• Compounds poisonous to humansCompounds poisonous to humans
– Petroleum, methane, benzene, toluenePetroleum, methane, benzene, toluene• Inorganic moleculesInorganic molecules
– Hydrogen, sulfur, ammonia, iron, nitriteHydrogen, sulfur, ammonia, iron, nitrite
Some bacteria get energy from sunlightSome bacteria get energy from sunlight• CyanobacteriaCyanobacteria perform photosynthesis perform photosynthesis• Sulfur bacteria use HSulfur bacteria use H22S instead of water in S instead of water in
photosynthesisphotosynthesis
Chapter 19 10 Binary FissionBinary Fission
Asexual cell division produces identical Asexual cell division produces identical copiescopies
Binary fission can occur every 20 Binary fission can occur every 20 minutesminutes
Rapid reproductive rate allows for rapid Rapid reproductive rate allows for rapid evolutionevolution•Mutations in DNA replication are rapidly Mutations in DNA replication are rapidly
spreadspread
Chapter 19 11
Chapter 19 12 Exchange of Genetic MaterialExchange of Genetic Material
ConjugationConjugation allows for DNA transfer allows for DNA transfer between donor and recipientbetween donor and recipient
Sex pilusSex pilus connects donor to recipient connects donor to recipient cell forming a cytoplasmic bridgecell forming a cytoplasmic bridge
Conjugation can occur between Conjugation can occur between different speciesdifferent species
Small circular DNA molecules (Small circular DNA molecules (plasmidsplasmids) ) carry genes from donor to recipientcarry genes from donor to recipient
Chapter 19 13
Conjugation:Conjugation:Prokayotic “Mating”Prokayotic “Mating”
Sex PilusSex PilusSex PilusSex Pilus
DonorDonorDonorDonor
RecipientRecipientRecipientRecipient
Chapter 19 14
Benefits of BacteriaBenefits of BacteriaCyanobacteriaCyanobacteria• PhotosynthesisPhotosynthesis• Pioneers in primary successionPioneers in primary succession
Chemosynthesis - nutrient cycles and plantsChemosynthesis - nutrient cycles and plantsSymbiosis - living togetherSymbiosis - living together• Ruminants’ digestive tractsRuminants’ digestive tracts• Nitrogen fixing in certain legumesNitrogen fixing in certain legumes• Bacteria on the human bodyBacteria on the human body
Biodegradation - oilBiodegradation - oilFood production - cheese, yogurt, sauerkrautFood production - cheese, yogurt, sauerkrautDecomposersDecomposers
Chapter 19 15
Bacterial PathogensBacterial PathogensSmall number of species cause diseaseSmall number of species cause diseaseSurvey of human bacterial diseasesSurvey of human bacterial diseases• Anaerobes - toxins (tetanus, botulism)Anaerobes - toxins (tetanus, botulism)• Allergic reactions - Allergic reactions - Streptococcus Streptococcus
pneumoniaepneumoniae– PneumoniaPneumonia– "Flesh-eating" bacteria"Flesh-eating" bacteria• Black Death, tuberculosisBlack Death, tuberculosis• Sexually transmitted diseasesSexually transmitted diseases
– GonorrheaGonorrhea– SyphilisSyphilis
Chapter 19 16
The ProkaryoteThe ProkaryoteFlagellum (b)Flagellum (b)
Chapter 19 17
Bacterial HabitsBacterial Habits
HabitatsHabitats
• Bacteria inhabit nearly every habitatBacteria inhabit nearly every habitat
• Bacteria are specialistsBacteria are specialists
Chapter 19 18
ArchaeaArchaea
Unique lipid membranes, cell walls, and Unique lipid membranes, cell walls, and rRNArRNA
MethanogensMethanogens• Convert COConvert CO22 to methane to methane• Swamps, hot springs, vent communities, cow Swamps, hot springs, vent communities, cow
stomachsstomachsHalophiles - survive concentrated salt Halophiles - survive concentrated salt environmentenvironment
Thermoacidophiles - thrive in hot, acidic Thermoacidophiles - thrive in hot, acidic environmentenvironment
Chapter 19 19
Some ProkaryotesSome ProkaryotesThrive in Extreme ConditionsThrive in Extreme Conditions
Chapter 19 20
Nitrogen-Fixing BacteriaNitrogen-Fixing Bacteriaon Root Noduleson Root Nodules
(a)(a)(a)(a)
(b)(b)(b)(b)
Chapter 19 21
Nonliving Parasitic MoleculesNonliving Parasitic MoleculesVirusesViruses• Nucleic acid molecule surrounded by a protein Nucleic acid molecule surrounded by a protein
coatcoat• Bacteriophages; viruses that infect bacteriaBacteriophages; viruses that infect bacteria• Survey of human viral diseasesSurvey of human viral diseases
ViroidsViroids• Short strands of RNA without a protein coatShort strands of RNA without a protein coat• Cause disease mostly in plants; affect some cropsCause disease mostly in plants; affect some crops
PrionsPrions• Proteinaceous infectious particleProteinaceous infectious particle• Human prion diseasesHuman prion diseases
Chapter 19 22 VirusesViruses
Two major components constitute a virusTwo major components constitute a virus• Single or double-stranded DNA or RNA as Single or double-stranded DNA or RNA as
hereditary materialhereditary material• Protein coat Protein coat
– May be surrounded by an envelope formed May be surrounded by an envelope formed from the plasma membrane of the host cellfrom the plasma membrane of the host cell
Cannot grow or reproduce on their own Cannot grow or reproduce on their own and are parasites of living cellsand are parasites of living cells
Have a specialized protein coat that Have a specialized protein coat that enables entry into a enables entry into a hosthost cell… cell…
Chapter 19 23 VirusesViruses
Viral genetic material “hijacks” host cell Viral genetic material “hijacks” host cell to produce new viral componentsto produce new viral components
Viral components assemble rapidly into Viral components assemble rapidly into new viruses and burst from host cellnew viruses and burst from host cell
Chapter 19 24
Viral Structure and ReplicationViral Structure and Replication(a)(a) (b)(b)
GlycoproteinsGlycoproteinsGlycoproteinsGlycoproteins
EnvelopeEnvelope(lipid bilayer)(lipid bilayer)
EnvelopeEnvelope(lipid bilayer)(lipid bilayer)
ProteinProteinCoatCoat
ProteinProteinCoatCoat
CoreCoreProteinsProteins
CoreCoreProteinsProteins
ReverseReverseTranscriptaseTranscriptase
ReverseReverseTranscriptaseTranscriptase
Viral RNA inViral RNA inprotein coatprotein coatViral RNA inViral RNA inprotein coatprotein coat
SpikesSpikesSpikesSpikes
Herpes VirusesHerpes VirusesHIVHIVHIVHIV
Chapter 19 25
Viruses Come in Many ShapesViruses Come in Many Shapes
RabiesRabiesRabiesRabies
MeaslesMeaslesMeaslesMeasles
BacteriophageBacteriophageBacteriophageBacteriophage
HerpesHerpesHerpesHerpes
TobaccoTobaccoMosaicMosaic
TobaccoTobaccoMosaicMosaic
Chapter 19 26 Viruses Are Host-SpecificViruses Are Host-Specific
Each viral type specialized to attack Each viral type specialized to attack specific host cellspecific host cell
Bacteriophages can treat bacterial diseases Bacteriophages can treat bacterial diseases • Rise in bacterial antibiotic resistance makes Rise in bacterial antibiotic resistance makes
standard drugs less effectivestandard drugs less effective• Bacteriophages specifically target host Bacteriophages specifically target host
bacteriabacteria• Bacteriophages are harmless to human body Bacteriophages are harmless to human body
cellscells
Chapter 19 27 Viruses Are Host-SpecificViruses Are Host-Specific
In multicellular organisms viruses In multicellular organisms viruses specialize in attacking particular cell specialize in attacking particular cell typestypes
Cold virusesCold viruses attack membranes of attack membranes of respiratory tractrespiratory tract
Measles virusesMeasles viruses infect the skin infect the skinRabies virusesRabies viruses attack nerve cells attack nerve cells
Chapter 19 28 Viruses Are Host-SpecificViruses Are Host-Specific
Some viruses linked to cancer (e.g. T-cell Some viruses linked to cancer (e.g. T-cell leukemia, liver cancer, cervical cancer)leukemia, liver cancer, cervical cancer)
Herpes virusHerpes virus attacks mucous membranes attacks mucous membranes of mouth and lips (causing cold sores)of mouth and lips (causing cold sores)•Other herpes virus type causes Other herpes virus type causes
genital soresgenital soresHIV virusHIV virus attacks specific white blood attacks specific white blood cell type, causing AIDScell type, causing AIDS
Chapter 19 29
Some Viruses Infect BacteriaSome Viruses Infect Bacteria
BacteriumBacterium
Newly formingNewly formingbacteriophagesbacteriophages
Chapter 19 30
How Viruses Replicate:How Viruses Replicate:HIV (a)HIV (a)
cytoplasmcytoplasm
nucleusnucleus
DNADNAvRNAvRNA
mRNAmRNA
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
Chapter 19 31
How Viruses Replicate:How Viruses Replicate:HIV (b)HIV (b)
4.Viral proteins madeusing mRNA
5.Viral proteins & RNAassembled
6.Viruses bud fromplasma membrane
Chapter 19 32
How Viruses Replicate:How Viruses Replicate:Herpes (a)Herpes (a)
(cytoplasm)
envelopecoat
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
Chapter 19 33
How Viruses Replicate:How Viruses Replicate:Herpes (b)Herpes (b)
nucleus
mRNA
(cytoplasm)
envelopecoat
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
Chapter 19 34
Viral Infections Are Difficult to TreatViral Infections Are Difficult to Treat
Antibiotics against bacteria are infective Antibiotics against bacteria are infective against virusesagainst viruses
Antiviral drugs may also kill host cellsAntiviral drugs may also kill host cellsViruses “hide” within cells, are hard to Viruses “hide” within cells, are hard to detectdetect
Viruses have high mutation ratesViruses have high mutation rates•Mutations can confer resistance to Mutations can confer resistance to
antiviral drugantiviral drug• Resistant viruses spread and multiply, Resistant viruses spread and multiply,
rendering drug ineffectiverendering drug ineffective
Chapter 19 35 ViroidsViroids
ViroidsViroids are infectious particles with only are infectious particles with only short RNA strands (no protein coat)short RNA strands (no protein coat)
Able to enter host cell nucleus and direct Able to enter host cell nucleus and direct new viroid synthesisnew viroid synthesis
A number of crop diseases are caused by A number of crop diseases are caused by viroidsviroids• e.g. cucumber pale fruit disease, avocado e.g. cucumber pale fruit disease, avocado
sunblotch, potato spindle tuber diseasesunblotch, potato spindle tuber disease
Chapter 19 36 PrionsPrions
A mutated protein that acts as an A mutated protein that acts as an infectious agentinfectious agent
Fatal degenerative disease discovered Fatal degenerative disease discovered in New Guinea tribe (Fore) in 1950in New Guinea tribe (Fore) in 1950
Kuru Kuru causes loss of coordination, causes loss of coordination, dementia, deathdementia, death
Kuru in the Fore tribe was transmitted Kuru in the Fore tribe was transmitted by ritual cannibalism of the deadby ritual cannibalism of the dead
Chapter 19 37 PrionsPrions
Other diseases like kuru include:Other diseases like kuru include:• Creutzfeldt-JacobCreutzfeldt-Jacob (CJD) disease in (CJD) disease in
humanshumans• ScrapieScrapie in sheep in sheep• Bovine spongiform encephalopathyBovine spongiform encephalopathy (BSE or (BSE or
“Mad Cow Disease”) in cattle“Mad Cow Disease”) in cattle
These diseases create holes in brain These diseases create holes in brain tissuetissue
Chapter 19 38
Prions: Puzzling ProteinsPrions: Puzzling Proteins
Chapter 19Chapter 19
The EndThe End