Viruses & Viruses & BacteriaBacteria

Chapter 2.3 and 7

VocabularyVocabulary10.10. obligate obligate

aerobesaerobes11.11. obligate obligate

anaerobesanaerobes12.12. facultative facultative

anaerobesanaerobes13.13. binary fissionbinary fission14.14. conjugationconjugation15.15. plasmidplasmid16.16. pathogenpathogen17.17. antibioticantibiotic

1.1. virusvirus

2.2. capsidcapsid3.3. lytic infectionlytic infection4.4. lysogenic lysogenic

infectioninfection5.5. retrovirusretrovirus6.6. vaccinevaccine7.7. coccuscoccus8.8. bacillusbacillus9.9. spiriliumspirilium

II. Viruses. VirusesA. General CharacteristicsGeneral Characteristics

1. dondon’’t belong in any kingdom, not t belong in any kingdom, not considered considered ““alivealive””

2. dondon’’t use energy or carry on metabolismt use energy or carry on metabolism3. considered acellular or nonlivingconsidered acellular or nonliving4. nono cytoplasm or organelles cytoplasm or organelles5. only 1 type of nucleic acid (DNA or RNA), only 1 type of nucleic acid (DNA or RNA),

cells have bothcells have both6. does not come directly from another virusdoes not come directly from another virus7. can survive without watercan survive without water

B. Viral CharacteristicsViral Characteristics1. All viruses are small, only visible All viruses are small, only visible

through through electronelectron microscope microscope2. Consist of two parts:Consist of two parts:

a. Nucleic acid - DNA or RNA, but never both Nucleic acid - DNA or RNA, but never both b. Outer protein coat called a Outer protein coat called a ““capsidcapsid””

1) Protein coat determines the shape of the Protein coat determines the shape of the virusvirus

3. Three basic shapes:Three basic shapes:a. Geometric shape, ex: Influenza or HIVGeometric shape, ex: Influenza or HIVb. Spiral (helical) shaped, ex: tobacco Spiral (helical) shaped, ex: tobacco

mosaic virusmosaic virusc. Bacteriophage - virus that infects Bacteriophage - virus that infects

bacteriabacteria

T4 Bacteriophage Tobacco MosaicVirus

Influenza Virus

Head

Tail sheath

DNA

Tail fiber

RNA

Capsidproteins

C. Viral InfectionViral Infection1. Lytic CycleLytic Cycle

a. AttachmentAttachment -virus attaches itself to the host cell -virus attaches itself to the host cell1) Viruses are very specific for certain cellsViruses are very specific for certain cells

b. InjectionInjection - a virus use enzymes to enter the cell wall of - a virus use enzymes to enter the cell wall of host cell and its nucleic acid is injected into the host cellhost cell and its nucleic acid is injected into the host cell

c. ReplicationReplication - viral DNA or RNA takes over the host cell - viral DNA or RNA takes over the host cell1) Host cell copies viral nucleic acids, proteins coat Host cell copies viral nucleic acids, proteins coat

(capsid), and viral enzymes(capsid), and viral enzymes2) RNA viruses (retroviruses) have special enzyme to RNA viruses (retroviruses) have special enzyme to

change its RNA into DNAchange its RNA into DNAd. AssemblyAssembly - viral parts are put together to form new - viral parts are put together to form new

complete virusescomplete virusese. Release or lysisRelease or lysis - new viruses break down host’s cell - new viruses break down host’s cell

wall (killing the host cell) and they are released to wall (killing the host cell) and they are released to invade other host cellsinvade other host cells

Lytic InfectionAttachment - virus attaches itself to the

receptor site of host cell. Viruses are very specific

Lytic InfectionAttachment - virus attaches itself to the

receptor site of host cell. Viruses are very specific

Injection -virus use enzymes to enter the cell wall of host and its nucleic acid is injected into the host cell

Injection -virus use enzymes to enter the cell wall of host and its nucleic acid is injected into the host cell

Replication - The viral nucleic acid is replicated and produces proteins that form the viral enzymes and capsids

- Host cell replicates viral nucleic acids, coat proteins, and viral enzymes

- RNA viruses (retroviruses) have special reverse transcriptase enzyme to change its RNA into DNA

Replication - The viral nucleic acid is replicated and produces proteins that form the viral enzymes and capsids

- Host cell replicates viral nucleic acids, coat proteins, and viral enzymes

- RNA viruses (retroviruses) have special reverse transcriptase enzyme to change its RNA into DNA

Assembly - viral parts are put together to form new complete viral units

Assembly - viral parts are put together to form new complete viral units

Lysis or release - new viruses release enzymes to break down host’s cell wall (killing the host cell) and they are released to invade other host cells

Lysis or release - new viruses release enzymes to break down host’s cell wall (killing the host cell) and they are released to invade other host cells

Attachment

Injection of genetic information

Replication

Assembly

Lysis or Release of new virus

What is the definition of Lytic Infection?

2. Lysogenic Cycle a. Attachment - same as lytic cycleb. Injection- same as lytic cyclec. Splicing - the viral DNA is spliced

(inserted) into the DNA of the hostd. Cellular Duplication - During normal cell

division the viral DNA is also copied and passed on with the cell’s own DNA.

e. Activation - An environmental stress stimulates the viral DNA and it goes into the lytic cycle.

2. Lysogenic Cycle a. Attachment - same as lytic cycleb. Injection- same as lytic cyclec. Splicing - the viral DNA is spliced

(inserted) into the DNA of the hostd. Cellular Duplication - During normal cell

division the viral DNA is also copied and passed on with the cell’s own DNA.

e. Activation - An environmental stress stimulates the viral DNA and it goes into the lytic cycle.

•How many of you have had cold sores?

•How many of you have had cold sores?

Herpes Simplex 1 Virus

Lysogenic InfectionAttachment - virus attaches itself to the receptor

site of host cell. Viruses are very specific – this is the same as the Lytic Infection.

Lysogenic InfectionAttachment - virus attaches itself to the receptor

site of host cell. Viruses are very specific – this is the same as the Lytic Infection.

Injection - virus use enzymes to enter the cell wall of host and its nucleic acid is injected into the host cell. Again this is the same as the Lytic Infection.

Injection - virus use enzymes to enter the cell wall of host and its nucleic acid is injected into the host cell. Again this is the same as the Lytic Infection.

Splicing - the viral DNA is spliced into the DNA of the host

Splicing - the viral DNA is spliced into the DNA of the host

Cellular Duplication - During normal cell division the viral DNA is also duplicated and passed on with the cell’s own DNA

Cellular Duplication - During normal cell division the viral DNA is also duplicated and passed on with the cell’s own DNA

Activation - An environmental stress stimulates the activation of the viral DNA and stages 3-5 of the lytic cycle begin

- Replication - The viral nucleic acid is replicated and produces proteins that form the viral enzymes and capsids

Activation - An environmental stress stimulates the activation of the viral DNA and stages 3-5 of the lytic cycle begin

- Replication - The viral nucleic acid is replicated and produces proteins that form the viral enzymes and capsids

Assembly - viral parts are put together to form new complete viral units

Assembly - viral parts are put together to form new complete viral units

Lysis or release - new viruses release enzymes to break down host’s cell wall (killing the host cell) and they are released to invade other host cells

Lysis or release - new viruses release enzymes to break down host’s cell wall (killing the host cell) and they are released to invade other host cells

Lytic cycle Lysogenic Cycle

D. Retroviruses (RNA viruses)Retroviruses (RNA viruses)1. retrovirus = virus that contains RNA which is retrovirus = virus that contains RNA which is

copied to DNA (backwards) when it infects a copied to DNA (backwards) when it infects a host cellhost cell

2. RNA viruses do not have an enzyme to fix RNA viruses do not have an enzyme to fix copying mistakescopying mistakes

a. mutations build up in RNA viruses much more mutations build up in RNA viruses much more rapidly creating new versions of the virusrapidly creating new versions of the virus

1) Ex: new flu strains each yearEx: new flu strains each year

3. AIDS and some cancers are caused by AIDS and some cancers are caused by retrovirusesretroviruses

a. ex: HIVex: HIV

RetrovirusesRetroviruses

E. Viruses vs. CellsViruses vs. Cells

DRAW Table 19-11, pg 483DRAW Table 19-11, pg 483

F. Beneficial Effects of virusesBeneficial Effects of viruses1. Can be used to insert desirable genetic information into Can be used to insert desirable genetic information into

cellscells

a. Genetically engineered organisms like tulip Genetically engineered organisms like tulip colorationcoloration

b. Deliver correct genes into human cellsDeliver correct genes into human cells

2. Used to kill bacteriaUsed to kill bacteria

G. Viral DiseasesViral Diseases1. Ex: rabies, mumps, measles, AIDS,warts, shingles, Ex: rabies, mumps, measles, AIDS,warts, shingles,

chicken pox, influenza, polio, hepatitis A, B, & C, chicken pox, influenza, polio, hepatitis A, B, & C, common cold & many morecommon cold & many more

MumpsMumps

MeaslesMeasles

ShinglesShingles

PolioPolio

I. Combating Viral InfectionsCombating Viral Infections1. our immune systemour immune system2. prevention by vaccinesprevention by vaccines3. antiviral drugs - antiviral drugs - treat the immediate treat the immediate

symptoms, but these are not symptoms, but these are not curescures

a. Ex: Tamiflu, RelenzaEx: Tamiflu, Relenza

Needle Tip

A. General characteristics1. Unicellular and lack a nucleus

2. Earliest known life forms

3. Size: 1-5 micrometers

II. Bacteria

B. Bacterial StructureDRAW Bacterial Anatomy1. All bacteria have an outer cell wall.2. Some have a sticky slime layer

around cell wall called a capsule.3. Very simple internal organization

a. Cytoplasm with very few organellesb. DNA

Bacterial Structure

Peptidoglycan Cell WallCell

Membrane

Ribosome

Flagellum DNA (nucleoid)

Pili

C. Classifying Bacteria1. Two Domains

a. Bacteria = (eubacteria) largest group, cell walls contain peptidoglycan (a carbohydrate)

b. Archaebacteria = lack peptidoglycan, live in extreme environments, & their DNA sequences are more like eukaryotes

2. Identifying Prokaryotesa. Shape & Arrangement

1) Coccus = spherical shapeda) single coccus

a) diplococci (pairs)

a) streptococci (chains)

a) staphylococci (clusters)

Staphylococci (clusters)

2) Bacillus = rod shaped cells

a) single bacillus

b) diplobacilli

c) streptobacilli

streptobacistreptobacillilli

3) spirillium = spiral shaped

Test Your Bacterial Shape and Arrangement Knowledge

b. How they obtain nutrients1) decomposer - live on dead things2) symbiotes - two organisms living

togethera) parasiticb) commensalisticc) mutualistic

D. Best Growth Conditions1. Warmth; 25-37 °C

2. Dark

3. Moisture

4. Food

Where can we normally find these conditions?

E. Movement1. Many forms have flagella (whip-like structures) for movement.

2. Some bacteria have pili which allow them to attach to other things.

F. Feeding & Digestion1. Autotrophic

a. photosynthetic, ex: cyanobacteria

b. chemosynthetic, ex: in deep sea hydrothermal vents

2. Heterotrophica. extracellular digestion

1) secrete enzymes

2) digest their food

3) absorb food back into their cells by diffusion

Why does food get mushy when it rots?

G. Circulation, Excretion and Respiration

1. by diffusion 2. aerobes = require a constant

supply of oxygen in order to livea. ex: Mycobacterium

tuberculosis

3. 2 types of anaerobesa. Some must live without oxygen

1) ex: C. botulinum spores found in honey

b. Some survive with or without oxygen

1) ex: Escherichia coli

H. Reproduction1. Asexual

a. binary fission - cell division splitting into two equal cells

b. spore formation – for harsh conditions

1) form spore (thick internal wall to enclose DNA)2) allows spore to wait until conditions are better

for growth

2. Sexuala. conjugation - exchange genetic information

1) plasmids are independent circular pieces of DNA in bacteria

I. Beneficial Effects - 99% of bacteria

1. decomposition of organic material

2. nitrogen fixation in bean plants

3. Symbiotic relationships, ex: E.coli in our intestines

4. used to make antibiotics

5. food production: e.g. yogurt, cheese, vinegar

6. used as a tool in genetic engineering

J. Harmful Effects - 1% of bacteria

1. Pathogenic (causes disease)

a. directly damaging cells as they digest cells for food

b. indirectly damaging cells by releasing toxins which damage hosts

c. trigger body's immune response, ex: fever or inflammation

d. ex: botulism, tuberculosis, gonorrhea, typhoid fever, bubonic plague, diphtheria, cholera, tetanus, etc.

TB X-rayDiphtheria

Bubonic Plague

Tetanus

2. Other problems caused by bacteriaa. food spoilage (many species)

b. food poisoning, ex: Salmonella

c. disorders like boils, pimples, pneumonia, and some forms of arthritis

Tooth decay

Lyme disease

Tetanus

Tuberculosis

Salmonella food

poisoning

Pneumonia

Cholera

Streptococcus mutans

Borrelia burgdorferi

Clostridium tetani

Mycobacterium tuberculosis

Salmonella enteritidis

Streptococcus pneumoniae

Vibrio cholerae

Regular dental hygiene

Protection from tick bites

Current tetanus vaccination

Vaccination

Proper food-handling

practices

Maintaining good health

Clean water supplies

Disease Pathogen Prevention

Diseases Caused By Bacteria

3. Controlling Bacteria

a. Antibiotics

1) compounds that block the growth and reproduction of bacteria, made from fungi and other bacteria

a) ex: penicillin, streptomycin, tetracycline, etc.

2) problems with antibiotics

a) bacteria develops resistance

b) kills off good bacteria as well as bad

c) inhibits body's natural immunity

b. sterilization = process of destroying ALL microorganisms

c. disinfectants = chemical solutions that kill most pathogens (ex: alcohol in hand sanitizer)

d. Food Storage & Processing1) pasteurization = applying heat to kill

pathogens (ex: milk)

2) lowering temperature slows growth of bacteria, ex: refrigerator

3) chemical treatments such as salt or vinegar

4) properly canned food

Sterilizing an inoculating loop

Typical disinfectant

Pasteurization of milk