BacteriaUNIT 3 - Chapter 19

Prokaryotes• Definition: single-celled organisms that

lacks a NUCLEUS

• OLD Classification – MONERA• Prokaryotes called BACTERIA• All BACTERIA were in the Kingdom –

MONERA

• CURRENT Classification• Prokaryotes (BACTERIA) are divided into 2

very different KINGDOMS• EUBACTERIA• ARCHAEBACTERIA

Eubacteria vs. Archaebacteria• BOTH: Prokaryotes, unicellular, autotrophic

or heterotrophic• EUBACTERIA:

• Larger kingdom• Cell Wall contains PEPTIDOGLYCAN• EX: E. coli and Streptococcus

• ARCHAEBACTERIA:• Some similar DNA sequences to Eukaryotes

(thought to be ancestors)• No PEPTIDOGLYCAN in cell wall• Live in EXTREME conditions (3 types):

• Methanogens—poisoned by O2

• Thermaphiles—live in extreme temps.• Halophiles—live in high saline

are classified into the kingdoms of

live in harsh environments such as

include a variety of lifestyles such as

Bacteria

Eubacteria Archaebacteria

Infecting large organisms

Thick mudLiving in soilAnimal

digestive tracts

Salty lakes Hot springs

E. coli Methanogens

Shapes of Bacteria

Obtain and Use ENERGY• AUTOTROPHS (make their food)

• Photoautotrophs: use photosynthesis to make chemical energy out of sunlight

• Found near lots of light

• Chemoautrophs: get energy from inorganic chemical reactions

• HETEROTROPHS (take in ORGANIC materials)• MOST PROKARYOTES • If food is not handled correctly, bacteria

may eat it and in the process leave poisonous chemicals behind

Bacteria in Nature• DECOMPOSERS “Natures

Recyclers”• Help the ecosystem “Recycle” and break

down dead matter into simpler substances• Works as sewage treatment; produces

purified water; releases nitrogen and CO2

• EXAMPLE: Nitrogen Fixation• Process by which nitrogen is converted

into a form plants can use• Nitrogen gas (N2) must be change into

ammonia (NH3)

Nitrogen-FIxers• Rhizobium (bacteria)

• Attached to the roots of soybeans and legumes

• Convert nitrogen gas to ammonia• Ammonia helps plant (soybean)

Bacteria and DiseasePATHOGENS (disease causing)• Cause disease by 2 methods• Damage TISSUES of organism

• Mycobacerium tuberculosis• Cause Tuberculosis by breaking down lung tissue

• Release TOXIN (poisons)• Salmonella and E. coli• Common types of food poison release toxins• Streptococcus • Causes strep throat releases toxin into the blood

stream

Prevention and Treatment•Vaccines: dead or weakened pathogens (bacteria or viruses) used to induce formation of antibodies or immunity against the pathogen (must be given before)•Antibiotic: block growth and reproduction of bacteria (cure bacterial diseases)

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

Human Uses of Bacteria• FOOD PRODUCTION: cheese, yogurt,

pickles, • INDUSTRIAL: digest oil, remove waste

and poisons, synthesize drugs, genetic engineering

• CONTROLLING BACTERIA• STERILIZTION: means of destroying

• Heat (boiling water)• Chemicals (disinfectants)

• INHIBITING or SLOWING growth• Refrigeration (low temps just slow)• Salt, Vinegar and sugar

VIRUSESUNIT 3 chapter 19

Viruses• STRUCTURE:

• Particles of Nucleic Acid (DNA, RNA), proteins, and lipids

• CORE – contains DNA or RNA• CAPSID – outer protein coat

• CHARACTERISTICS:• Many different sizes and shapes• Only REPRODUCE when infecting living

cell (virus is not a cell)• Viruses are very specific

Review of Living and NON-living8 Characteristics

1. Made of Cells

2. Reproduce

3. Based on Genetic Code

4. Grow and Develop

5. Obtain and use energy

6. Respond to environment

7. Homeostasis

8. Evolve

Viruses are considered NON-living. Why?

Viruses are NON-LivingNON-life like (contrasting)

• Not made of cells

• Do not reproduce independently

• Do not Grow/Develop/Respond to environment

• Do not Obtain and use energy

Life-like (comparing)

• Evolve

• Contain DNA or RNA

Viral Infections are Specific• Highly specific to type of cells they

infect.• Plant viruses do not infect animal cells• Animal viruses only infect certain species

of animals

• BACTERIOPHAGES:• Virus that infects bacteria• EX: T4 and Lambda

Types of Viral Infections: LYTICVirus Enters cell and causes it to

BURST Quickly!!!1. Virus attaches to cell wall2. Virus injects DNA into cell3. Virus takes over cell metabolism and

produces its own proteins & nucleic acids

4. Proteins and Nucleic acids combine to form NEW viruses

5. Enzyme breaks down cell wall & NEW viruses leave to infect other cells

Bacteriophage (virus) attaching Bacteria

Bacteriophage enzyme lyses thebacterium’s cell wall, releasingnew bacteriophage particles thatcan attack other cells.

Bacteriophage proteins and nucleic acids assemble into complete bacteriophage particles Bacteriophage takes over

bacterium’s metabolism, causing synthesis of new bacteriophage proteins and nucleic acids

Bacteriophage injects DNA into bacterium

Bacteriophage attaches to bacterium’s cell wall

Bacteriophage

Bacteriophage DNA

Bacteriophage protein

Bacteriophage protein coat

Bacteriophage DNA

Bacterialchromosome

Lytic Cycle

Types of Viral Infections: LYSOGENIC

• TWO Cycles• LYSOGENIC• LYTIC

• DIFFERS from Lytic because…• DNA is embeded into host DNA• Virus does NOT KILL cell right away

Steps of LYSOGENIC Infection1. Virus injects DNA

2. DNA forms a circle (Prophage)

3. DNA circle (prophage) combines with the bacteria DNA

4. Virus DNA (prophage) replicates with bacterial DNA

5. Virus DNA (prophage) exits bacterial DNA (forms own circle)

6. Begin Lytic cycle… New viruses Burst cell and leave

Bacteriophage proteins and nucleic acids assemble into complete bacteriophage particles

Bacteriophage enzyme lyses the bacterium’s cell wall, releasing new bacteriophage particles that can attack other cells

Bacteriophage DNA inserts itself into bacterial chromosome

Bacteriophage DNA (prophage) may replicate with bacterium for many generations

Bacteriophage DNA (prophage) can exit the bacterial chromosome

Bacteriophage DNA forms a circle

Bacteriophage DNA

Bacterialchromosome

START: Bacteriophage injects DNA into bacterium

Prophage

Lytic Cycle

Lysogenic Cycle

Section 19-3

Lysogenic Infection

Go to Section:

LYSOGENIC Cyle to LYTIC Cycle• Lysogenic cycle (latent or dormant) • The virus will switch to LYTIC cycle under

ADVERSE conditions (Stress, radiation, chemical change)

Diseases:• Polio, Measles, Mumps, AIDS, Flu, Rabies, Yellow Fever,

ColdsLytic Infections• (colds-adenoviruses)Lysogenic Infections (Herpes, EBV, HPV)• (Epstein-Barr EBV) Lytic-Mononucleosis / Lysogenic-

predisposed to lymphoma• (HPV) lytic-genital warts / lysogenic cervical cancerRetroviruses (RSV, HIV, HTLV, FLU)• Genetic material is RNA and makes copy into DNA• Retro- means “backwards”; develops mutations quickly• RSV (Rous sarcoma virus) can lead to sarcoma; HTLV can

lead to leukemia… virus can transform/mutate host DNA

Human Viruses

Oncogenic viruses

Retroviruses

Adenoviruses

Herpesviruses

Poxviruses

DNA

RNA

DNA

DNA

DNA

cancer

cancer, AIDS

respiratory infections

Chickenpox, Mono

smallpox

Type of Virus Nucleic Acid Diseases

WARNING• Following slides contain graphic

pictures.

• Herpes sores…

Herpes Simplex 1

Herpes Simplex II

Symptoms and Prevention• PREVENTION:

• Best way to protect against a viral infection is PREVENTION

• Vaccines (for some)• Only good before virus• Stimulates immune response

• SYMPTOMS:• Caused when virus attacks and destroys

body cells• Lytic cycle (see symptoms)• Lysogenic cycle (virus is dormant, no

symptoms….but still contagious)

AIDS (Acquired Immune Deficiency)CAUSED BY:

• HIV (Human Immunodeficiency Virus)• Virus destroys helper T cellsEFFECTS:• Depresses cell-mediated immunity, Deficit in

antibodies• Immune system turned upside down• Increasing frequency of infections, often rare

types, Lesions on skin, DementiaTRANSMITTED:• In body secretions (blood, semen, vaginal

secretions)• Sexual Intercourse, use of IV needles, some

documented cases by oral sex

HIV•