yeast (single celled)

mold (multicellular)

mushrooms

most are facultative anaerobes

produce alcohol as a byproduct of fermentation

YEAST

2 types of reproduction

-budding

-fission

YEAST

budding

-cell produces a protuberance

-the nucleus divides

-a cell wall fills in producing two cells

YEAST

pseudohyphae

chains of buds that do not detatch

made by Candida albicans (causes thrush)

YEAST

fission

can grow as either mold or yeast depending on environment

yeast at 37 degrees C

mold at 25 degrees C

Histoplasma capsulatum

Coccidioides immitus

MULTICELLULAR FUNGI 

basic info

-reproduce by making spores

-like pH of ~5

-aerobic

-tolerate very low moisture

-can grow in high sugar and salt environments

MULTICELLULAR FUNGI

2 types

zygomycota

ascomycota

-hypahe are coenocytic

-coenocytic - they have no crosswalls (septa)

-spores are in groups called sporangia

Rhizopus

Mucor

-hyphae are septate (have cross walls)

-spores are in chains and called conidia

Pennicillum (antibiotics, blue & Roquefort cheese)

Aspergillis (opportunistic infection)

-systemic - can spread within body

-subcutaneous - under the skin
(ex. Sporothrix schenckii - causes sporotrichosis in punture wounds, common in farmers)

-superficial - fungi that infect hair, nail, and skin are called dermatomycoses

-caused by Phytophthora infestans

-destroyed potato crop in Ireland in the 1800s

-was thought to be a mold, but G+C ratio typing determined it to be a nonphotosynthetic algae

-caused by Phytophthora ramorum

-killed California oak trees in the 1990s

-unicellular

-some can form a cyst and survive outside a host

-most reproduce asexually

malaria life cycle

The life cycle of malaria parasites in the human body. A mosquito infects a person by taking a blood meal. First, sporozoites enter the bloodstream, and migrate to the liver. They infect liver cells (hepatocytes), where they multiply into merozoites, rupture the liver cells, and escape back into the bloodstream. Then, the merozoites infect red blood cells, where they develop into ring forms, trophozoites and schizonts which in turn produce further merozoites. Sexual forms (gametocytes) are also produced, which, if taken up by a mosquito, will infect the insect and continue the life cycle. 

-transmitted from cats to humans by fecal-oral contact

-can cause birth defects if mom has her first exposure in the 1st trimester

-causes toxoplasmosis

-multicellular, eukaryotes, worms

(gravid worms - pregnant worms)

-most have an egg stage, larval stage, adult stage

-platyhelminths - flatworms

- nematodes - roundworms

trematodes - flukes

cestodes - tapeworms

-flat, leaf-shaped bodies

-oral sucker

-can infect:

lungs - Paragonimus westermani (worldwide)

liver - Clonorchis sinensis (immigrant populations)

blood - Schistosoma spp. (worldwide)

-intestinal parasites

-the head is called the scolex that attaches to the intestines

-they do not digest the host tissue but absorb undigested food

-the body made of proglottids

-proglottids contain the male and female structures that produce eggs

makes up the body of a tapeworm

contains male and female structures that produce eggs

-obligate intracellular parasites

-have DNA or RNA, not both

-may be single or double stranded

-nucleic acid are covered with a coat made of protein called the capsid

-capsid made of sub-units called capsomeres

-some have an outer envelope

-virus = nucleic acid

-virion = nucleic acid + capsid + envelope

-envelopes may have spikes that help them attach to host cells

-spikes may cause hemagglutination (lysis of red blood cells) (ex: influenza)

-covers the nucleic acid in a virus

-made of protein

virus = nucelic acid

virion = nucleic acid + capsid + envelope

some viruses have envelopes with spikes

helps them attach to host cells

spikes may cause hemagglutination

-the specific hosts a virus can infect

-most viruses can only infect one type of cell in one species

-rarely a virus will "cross-species"

-exceptions: human influenza can infect pigs, avian flu can infect humans

-viruses that infect bacteria are called bacteriophages

-viruses that infect bacteria

-have complex structure

-must use living cells

-animals (mice)

-cell cultures from animal cells

-embryonated (fertile) eggs

-animal cells grown in a nutrient solution adhere to walls of container

-a virus is introduced

-it causes the cells to deteriorate and is called the cytopathic effect (CPE)

-two types of cell cultures

-primary: includes diploid cell lines from embryo, live for ~100 generations

-continuous cell lines: from cancer cells, "immortal" (HeLa)

-viruses have an order, family, and genus but no species

-instead we use common names

-subspecies have numbers

viruses - taxonomy

viruses are classifed based on:

-morphology

-nucleic acids (DNA or RNA)

-number of capsomeres (subunits of the capsid)

viral multiplication - bacteriophages

2 types are:

-lytic cycle

-lysogenic cycle

viral multiplication - bacteriophages

LYTIC CYCLE

1. attachment - virus attaches to cell wall or cell membrane proteins
2. penetration - viral DNA or RNA is injected
3. biosynthesis - replicate in cytoplasm ribosomes
   -virus stops host protein synthesis by: destruction of host DNA or interfering with transcription or translation
   -uses host ribosomes and nucleotides to replicate
   -capsid proteins are made, but all the parts are separate
   -this is called the eclipse period
4. maturation - virions are assembled
5. host cell lyses and many viruses are released

viral multiplication - bacteriophages

LYSOGENIC CYCLE

1. DNA or RNA penetrates the cell
2. the viral DNA inserts itself into the host DNA and does not replicate (latency)
3. viral DNA is incorporated into cell progeny
4. when conditions are right, the lytic cycle occurs

1. attachment to proteins or glycoproteins on cell membrane
2. entry into the cells is by endocytosis or fusion (viral envelope fuses with plasma membrane and the capsid)
3. uncoating - enzymes separate the nucleic acids from the protein coat
4. biosynthesis - A: DNA viruses replicate their DNA in the nucleus and their capsid proteins in the cytoplasm
   B: RNA viruses multiply in the host cells cytoplasm
5. maturation - assembly of capsid and virion
6. release - A: budding - viral capsid with enclosed nucleic acids pushed through the plasma membrane. The plasma membrane is now the virus's envelope. May not kill host cell
   B: Non-enveloped viruses exit through ruptures in the host's cell. Usually kills the cell

oncogene - a gene that causes cancer when "turned on"

oncogenic viruses - activate oncogenes

ex: human papilloma virus - cervical cancer

ex: Epstein-Barr virus - Burkitt's lymphoma (also infectious mononucleosis)

ex: Hepatitis B - liver cancer

ex: Kaposi sarcoma - associated herpes virus, found in AIDS patients

cytomegalovirus (CMV)

can damage fetus

Rabies

there is a vaccine

-virus inhabits a nerve without damaging until it is activated

-latent infection that reactivate cause a spike in the amount of detectable virus

-reactivation often caused by fever, sun

-herpes (fever blisters, from fever or sun)

-varicella (chickenpox becomes shingles in 10-20% of those who had chickenpox)

-occur gradually over a long period of time

-ex. HIV

-will evenutally kill you

-infectious particle made of protein

-misfolded protein

-can survive autoclaving (steam under pressue of 120 degrees C for 20 minutes)

-must be killed by incineration

-short pieces of naked RNA with no protein coat

-infect plants and cause crop damage 

-they have a great enough velocity

-they have enough energy

-they are oriented correctly (large molecules)

bonds between atoms are broken or formed

AB<==>A+B

(reversible reaction - can go in either direction)

-temperature (up to a point)

-pressure (increases)

-increased concentration

-enzymes speed the rate

-pH must be "optimal"

-proteins that speed chemical reactions by lowering the activation energy without being changed

-allow reactions to occur at a temperature that is compatible with life

-most enzymes end in "ase"

-only catalyze one reaction

-they are large, three dimensional proteins with a primary, secondary, tertiary, quarternary structure

(primary-sequence amino acids, secondary-alpha helix and b pleated sheets, tertiary-unique 3D structure caused by folding by interaction of side chains, quarternary-two or more proteins)

-only one area with its specific substrate (lock and key)

-the end product of an enzymatic reaction binds to an allosteric site on the first enzyme in the reaction

-this changes the shape of the active site so the first enzyme can no longer function

an area of an enzyme that is NOT where the enzyme binds to the substrate

(changes shape of enzyme, substrate unable to bind)

-reactions with enzymes occur 1 billion times faster than reactions without them!

-one enzyme can catalyze up to 500,000 reactions per second

-some enzymes act alone

-some need a helper

binds to the active site of the enzyme and blocks the substrate from binding.

It competes for the active site of the enzyme, so the rate of reaction is dependent on the concentration of substrate and the concentration of inhibitor

-the protein part is called an apoenzyme

-the other part is called a cofactor

-many cofactors are minerals like iron, zinc, magnesium, and calcium

-"feed a cold, starve a fever"

-colds caused by viruses

-fevers often caused by bacteria

-fever makes environment unfavorable to bacteria that are infecting you

-liver sequesters iron and zinc (cofactors for bacteria) when we have a fever

-a cofactor is called a coenzyme if it is an organic molecule

-conenzymes are usually a vitamin

-ex: niacin - vitamin B3 is part of the coenzymes NAD+ (in catabolic reactions) and part of NADP+ (in anabolic reactions)

-they are electron carriers

-ex: riboflavin - vitamin B2 is part of the coenzymes FMN + FAD which are also electron carriers in cellular respiration

ex: pantothenic acid - another B vitamin is part of CoA in the Krebs cycle in cellular respiration. It is ubiquitous (everywhere)

They are all involved in obtaining energy from food

glucose (6 carbons)

|

glycolysis - 2 pyruvate (3 carbons each) + 2 ATP

|

Aerobic   |  Anaerobic -->   Anaerobic

|

Kreb's cycle, ETC |  Fermentation.........................

|

36 ATP, 38 ATP total|  ~2 ATP |ATP varies 

|

Final electron acceptor:

oxygen |organic molecule|inorganic (not O2)

-final electron acceptors in anaerobic respiration are involved in many environmental cycles

electron acceptor ---> converted into

nitrate  ---> nitrite, nitrous oxide, nitrogen gas (air is usually 79% nitrogen, 21% oxygen)

sulfate ---> hydrogen sufide

carbonate ---> methane

Streptococcus

Lactobacillus

Bacillus

Escherichia

Salmonella

Enterobacter

Saccharomyces

Escherichia

Salmonella

Enterobacter

Propionbacterium

Escherichia

Salmonella

psychrophyles - like cold - 20 - 30 degrees C is optimum

mesophiles - modrate temps - 25 - 40 degrees C

thermophiles - heat-loving - 50-60 degrees C

hyperthermophiles - like hot temps >80 degrees C

pH 6.5 - 7.5 best for most bacteria

humans - 7.35 - 7.45

some (Clostridium botulinum) grow pH < 4 and is found in improperly canned veggies

molds & yeast like pH 5 - 6

-hypertonic solutions (high osmotic pressure - solute concentration outside the cells is greater than inside the cell), usually high salt or sugar, will shrink bacteria and stop growth

ex. honey, saurkraut, jam, cheese

*halophiles - tolerate or require a higher salt environment (Staph. aureus)

-hypotonic (low osmotic pressure) - may cause lysis

growth requirements for microbes - chemical - basic info

-water - solvent

-carbon - the backbone of life; found in all living (organic) matter

-oxygen

-obligate aerobes - require O2

-microaerophiles - require O2 but in concentrations lower than air

-faculative anaerobes - use O2 but can survive without it

-capnophiles - aerobes that require O2 and a high CO2 atmosphere

-obligate anaerobes - do NOT require O2, and many are harmed by it

-aerotolerant anaerobes - do not use O2 but tolerate it

some obligate anaerobes use O2 and produce hydrogen peroxide (H2O2) which kills them because they don't make catalase which breaks down H2O2

-some bacteria cannot make all their needed vitamins, enzymes or amino acids, so they must be acquired from their environment

biofilms - communities of multiple species that work together to maintain their environment

-form on teeth and mucous membranes

-held together with polysaccharides and proteins

-found on almost all indwelling medical devices! (ex catheters, contact lenses, and heart valves)

-resistant to antimicrobial substances

-nutrient material used to grow microorganisms

-broth - liquid

-agar - semi-solid

contain an energy source and needed organic growth factors

ex. - E. coli requires glucose

ex. Haemophilus needs hemolyzed blood agar. It contains "heme" or "X" factor and NAD+ called "V" factor to survive

made from extracts of yeast or meat

composition varies slightly between batches

-broths contain an ingredient to bind any oxygen so it doesn't kill the bacteria

-agar plates are incubated in an airtight vessel. O2 is removed by a chemical reaction

example:

palladium

2H2 + O2 ------------------------> H2O

 catalyst

-Mycobacterium leprae is grown in armadillos!

-Rickettsia & Chlamydia - require cell culture - they are obligate intracellular parasites

Capnophiles - need a high CO2 environment. Used for most bugs that live in the respiratory and GI tract

-stop the growth of some bacteria to isolate others

ex - Sabouraard's Dextrose agar pH=5.6

-this inibits most bacteria and allows fungi to grow

ex - mannitol salt

-inhibits most bacteria except Staphylococcus

help to distinguish pathogenic bacteria by looking for special colony characteristics

ex-mannitol salts-differentiates Staph. aureus from other Staph. organisms - S. aureus ferments the mannitol turning the medium yellow

ex-Beta hemolytic Strep. Group A-O make a clear ring around their colon on blood agar

ex-Salmonella are black on peptone ion agar 

*most samples of infectious material (sputum, throat swab) contain many bacteria

*isolate with a streak plate

-refrigeration - good for a day or two

-deep freezing - in liquid are quick-frozen. they can be grown many years later

-lyophilization - freeze drying (freeze and remove water) - forms a powder that can be stored at room temp - bugs will grow years later when water and nutrients become available

-lag phase - little or no cell growth

-log phase - cells enter a period of exponential increase

-stationary phase - the growth rate slows

-death phase - cell death exceeds cell division

plate counts are reported as CFUs or 

___________________________

-turbidity

-metabolic activity

-dry weight