Download Bacteria

Chapter 20
Viruses –section 1
Bacteria –section 2
VIRUSES
Viruses
Is a Virus Alive?
• A Viruse is considered NON-Living
–
–
–
–
–
Viruses are NOT cells (the basic unit of life)
Do NOT grow
Do NOT have homeostasis
Influenza virus
Do NOT metabolize
Can NOT reproduce
without a host cell
– No scientific name,
instead family names
Virus Size
• The smallest organism that have the properties
of life (themes of biology) are prokaryotes.
• Viruses are smaller than prokaryotes and
prokaryotes are typically smaller than
eukaryotes.
• You would NOT be able to view a virus under a
light microscope.
http://www.cellsalive.com/howbig.htm
Viral Structure
• Virus contains a nucleic acid (DNA or RNA
but not both) within a protein coat.
• Outer protein coat is called a capsid
• Most viruses have an envelope
surrounding the capsid which consist of
proteins, lipids and glycoproteins.
• Glycoproteins are proteins with attached
carbohydrate molecules.
• Shape varies – helix, bullet, round
• Some features for protection
– Envelope, spikes, slime layers
DNA or RNA
Protein coat
aka: capsid
Bacteriophages -
Viruses that infect
bacteria
Tail
Tail fibers
Attaching to Cells
• Prior to replication,
virus must enter cell
• Protein on virus
interlock with surface
markers on cells
• Each virus has specific
cell to “dock” with
• EX: polio virus
attaches to nerve cells
Viral Replication Cycles
• Lytic
– Virus attaches to
cell
– Inserts DNA
– Replication of
viral parts
– Assembly of new
viruses
– Cellular lysis
• Lysogenic
– Virus attaches to cell
– Inserts DNA
– DNA integrates into
host DNA
– Cell replicates
normally with viral
DNA altering protein
synthesis
– Proteins can create
new viruses or not
(latency)
Lytic Cycle
Lytic Cycle
Lytic Cycle Continued
Lysogenic Cycle
Lysogenic Cycle
How Viruses Damage Cells
• Inhibit protein synthesis of host
• Open lysosomes
• Bind membranes together
• Create a toxic level of proteins
The human body protects itself from
viruses using antibodies and fever.
Viruses prefer body temperature.
Which of these diseases is likely to be
caused by a lytic virus?
Characteristics of some Viral Diseases
Disease
Symptoms
Incubation
Measles
Rash, Fever
9-11 days
Shingles
Pain, itching on skin
Years
Warts
Bumpy area on skin
Months
Influenza
Body aches, fever, runny nose
1-4 days
HIV
fatigue, weight loss, fever
2-5 years
Viral Disease
• Chicken Pox
–
–
–
–
Fluid filled blisters
Itching and burning
Common in kids
Vaccine to
prevent
• Herpes zoster –
shingles
– Reactivated chicken
pox
– Highly contagious
– Viral DNA remains in
neurons, dormant
– Pain, fever, skin lesions,
pus filled spots
– Can be due to sun,
stress, fever, trauma, but
main cause unknown
• Cold Sores
– Herpes simplex
– Virus lives in a nerve in
face
– Reactivated similar to
shingles
– Fever, sore throat,
mouth pain, edema
• Herpes simplex 2
– Genital herpes
– Virus lives in
bottom of the spine
– Same reactivation
– Congenital herpes in
newborns
– Tingling, pain during
urination, thick
discharge, fluid filled
vesicles
– Found in 25 mil
Americans
Human Immunodeficiency Virus
HIV
• Composed of 2 molecules of single-stranded
RNA
• Approximately 9,000 nucleotides
• Make up 9 genes
• 3 of these genes are
common to many
different viruses
HIV
– Transmitted through sexual
contact (STD), contaminated
blood, or contaminated
needles
– Retrovirus RNA  DNA
– Reverse transcriptase
– Enters immune system by
endocytosis into WBC
– Prevents WBC from making a
receptor (CD4) that normally
detects pathogens
– Symptoms treated with drug
cocktail
HIV
Description of illness:
– Exposure symptoms – headache,
sore throat, occasional rash
– Upon reactivation – rapid weight
loss, dry cough, night sweats,
unexplained fatigue, white spots
in mouth, memory loss
– Death usually from secondary
infection – Kaposi’s sarcoma,
candidas, Burkitt’s lymphoma
• Rabies
– Virus lives in salivary glands
of animal
– Virus destroys the nerves
– Produces Negri bodies in
brain
– Initial symptoms – tingling
and cold around bite,
nervous
– Phase II – anxiety,
photophobia, arrhythmia,
pupil dilation, difficulty
swallowing
– Gamma globulin treatment
• Smallpox
– Last seen in 1977
– Eradicated by WHO due to obvious
symptoms and short life cycle
– CDC and Moscow
– Self-replicating
• Mononucleosis
–
–
–
–
Fluid transmission
“kissing disease”
Infects WBC’s
Enlarged lymph
nodes, swollen
spleen, sore throat,
nausea, weakness,
fatigue
– Can last up to 6 wks
– Remains latent in
nerves
– Steroid treatment to
boost immune
function
• Measles
– Highly contagious
– Respiratory droplet
spread
– Nasal discharge, dry
cough, fever,
headache, pink eye,
pink lesions, ear
infection
– Targeted for
eradication
– MMR vaccine
• Viral Hepatitis B
– Initially
asymptomatic
– 1-3 month
incubation
– Fever, loss of
appetite, pain,
nausea, fatigue,
jaundice, swollen
liver
– 3 step vaccine
• Hanta Virus
– Deermice and
ticks
– No human to
human
– 2-3 day incubation
– Cough, pulmonary
edema,
hemorrhaging,
renal failure, achy
muscles
– 60% death rate
• Ebola
– Sudan and Zaire
– 93% death rate
– Hemorrhagic fever
• High temperature
• Blood from orifices
– Reston VA, non-human
form
BACTERIA
BACTERIA
• Prokaryotes
– Small, circular DNA, ribosomes
• Kingdom Archeabacteria
– Live in extreme environments (deep ocean,
swamps)
– Mostly live in environments without oxygen
– Some are motile
• Kingdom Eubacteria
– About 5,000 species
– Live in most environments
– Some are motile
How are bacteria different from
eukaryotes?
Prokaryotes
Eukaryotes
Bacteria
Protist - Fungi - Plants – Animals
Lack a cell nucleus & membrane-bound
organelles
Have a nucleus and membranebound organlles
Smaller in size
Typically larger in size
Single cells: Unicellular
Unicellular and Multicelluar
Singel circular piece of DNA
Cell activities are not specialized
Asexually Reproduction:
through binary fission
Metabolic diversity – both anaerobic and
aerobic processes
Linear pieces of DNA
Asexual Reproduction:
chromosomes are pulled to opposite
poles of the cell during mitosis
forming two cells
Sexual Reproduction
Mostly aerobic organisms
Bacterial Structure
• Chromosome -Single circular piece of
DNA
• Cell wall – rigid outer structure
• Capsule and spores – increases
• Pili – helps to stick to surfaces,
aids in reproduction
• Flagellum – movement
Virulence – of a microorganism
like a bacterium or virus, is a measure
of severity of the disease it is capable
of causing
Like ALL cells bacteria have:
• Ribosomes
• Cell Membrane
• Cytoskeleton
• Cytoplasm
• Genetic material
Bacterial Reproduction
• Bacteria divide by binary
fission. One bacterium can
become ½ a million in about 6
hours.
• No mitosis or meiosis because
no nucleus
• Chromosome doubles and cells
splits in half
• Writing scientific names:
Genus:
Arrangement (prefix):
Strepto – chains or filaments
Staphylo – clusters
Diplo – pairs
Shapes
Bacillus – rod
Coccus – round / spherical /circular shape
Sprillum – spiral shape
Example: Streptococcus thermophilus
Famous Microbiologists
•Hooke – named the cell
•Leewenhoek – saw first
organism
•Erlich – Magic Bullet Theory
•Fleming – discovered
penicillin
•Gram – staining and
classification
Discovery of Penicillin: First Antibiotic
From: Time, March 31, 2003
•Fleming happened to observe that Petri dishes with
molds had killed bacteria in rings around the mold
•He postulated that the “mold juice” had killed the
bacteria
•The mold was Penicillium notatum and the “juice” was
named Penicillin
Normal Flora
• Skin
– Staphylococcus
• Throat
– Streptococcus
• Mouth
– Lactobacillus
• Large intestines
– E. coli
Flora – population of microbes
inhabiting the outside or inside
surface of people or other animals.
Beneficial Bacteria
• Clean Environment - help clean up environmental disasters
such as petroleum and chemical spills (oil spills)
• Mining companies
• Make minerals
• Sulfur conversion – technique can be used to harvest copper
or uranium
• Nitrogen Cycle – bacteria covert the atmospheric nitrogen
into a usable form, ammonia (nitrogen-fixing bacteria)
• Make antibiotics
• Chemicals – acetone or butanol
• Genetic Engineering – used to produce many products such
as drugs for medicine and complex chemicals for research
– Can be used as a vector
• Food Production
– Pickles, sauerkraut, cheese, yougurt, sourdough bread,
buttermilk, olives, vinegar, some kinds of sausages
BACTERIAL DISEASES
Bacterial Infections
• Flesh Eating Disease
–
–
–
–
Quick progression
Staphylococcus
Destroys muscles
Strong toxins
produced that
dehydrates
– Tissue death
– Requires
debridement
• Tetanus
– Clostridium
– Rust entry
– Muscle spasms, fast
heart rate, heavy
sweating, low fever,
lockjaw
– Prevent with
vaccine
• Syphilis
– Treponema
– Primary symptoms:
chancre
– Secondary: lesions, swollen
lymph glands, rash on palms
of hands and soles of feet,
anorexia, alopecia
– Tertiary: bone lesions, gastric
pain, palate destruction,
personality change
– Treat in 1 or 2 stage
• Gonorrhea
– Neisseria
– Enters macrophages
– Male symptoms:
swollen urethra, thick
brown discharge,
redness, itchy, scaling
– Female symptoms:
usually asymptomatic
– Causes blindness in
babies – silver nitrate
– Some species
showing antibiotic
resistance
• Lymes Disease
– Borrelia, tick bite
– Stage 1 – bulls eye
rash, hives, neck
stiffness,
– Stage 2 – facial palsy,
swollen heart,
neurological
abnormalities
– Stage 3 – dementia,
arthritis
– Antibiotics must be
able to cross the BBB
• Staph Infections
– Staphylococcus
– Redness, warm to
touch, red streaks
from infection site
– Spreads quickly
• Anthrax
– Bacillus
– Direct contact with
infected animals
– 1-15 day incubation
– Ulcers called eschars,
headache, fever,
nausea
– Endospores viable for
decades
– UV inactivates spores
– Cutaneous and
respiratory
• Cholera
– Vibrio
– Food or water
contamination from
shellfish feces
– Gulf coast of US
– Bacteria attach to
walls of small
intestines causing
hypersecretion of
water
– Cramps, vomiting, 3-4
gallons of diarrhea a
day