Description
Unit 1 1/28/17 7:29 PM
Microbiology: study of organisms too small to be seen without magnification
Microorganisms include:
• Bacteria
o Prokaryotic
o Cells made of polysaccharide (peptidoglycan)
o Reproduce asexually
o Most much smaller than eukaryotic cells
o Live alone, in pairs, clusters, chains
o Live anywhere w/enough moisture
• Viruses
o Smaller than the smallest prokaryote
o Acellular (not made of cells)
o Has little genetic material
• Fungi
o Eukaryotic
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o Get food from other organisms
o Have cell walls
o Microscopic Fungi: Molds & Yeasts
▪ Molds
???? Multicellular
???? Long filaments, intertwine
???? Reproduce w/sexual and asexual spores (make
new individual w/out fusing to another cell)
▪ Yeasts
???? Unicellular
???? Oval – round
???? Reproduce by asexual budding (the daughter cell
grows off the mother), some by sexual spores
• Protozoa
o Single cell eukaryotes
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o Similar to animals in nutritional needs & cell structure
o Capable of locomotion
▪ Cilia: Many short protrusions that propel the
microorganism
▪ Flagella: few extensions, whip-like motion
o Live in water, & inside animal hosts
o Most reproduce asexually, some sexual
• Helminths (worms)
o A parasite that can be seen by the naked eye, studied by microbiologists because eggs are microscopic
• Algae
o Unicellular & Multicellular
o Photosynthetic eukaryotes = make their own food from CO2 + water + energy from sunlight
o Large Algae: kelp and seaweeds, found in oceans, Agar used in lab media comes from these
o Small Algae: found in freshwater and oceans
• Archaea
o Prokaryotic
o Cell walls lack peptidoglycan
o Reproduce asexually
o Live alone/in pairs/chains/clusters
o Live in extreme conditions
▪ Highly saline and arsenic rich Mono Lake CA
▪ Acidic Hot Springs of Yellowstone National Park
▪ In oxygen depleted mud at bottom of swamps
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• Immunology: Study of bodies defense against pathogens • Public Health Microbiology
• Epidemiology: study of the occurrence, distribution, spread of disease in humans
o John Snow studied Cholera spread
• Food, Dairy, Aquatic Microbiology (Food Spoilage)
• Agricultural Microbiology: water pollution caused by microbes • Biotechnology
• Genetic Engineering & Recombinant DNA Technology: Microbes in cheese making, alcohol, microbes interaction with immune system • Environmental Microbiology: Study of Microbes in soil, water, other habitats
• Bioremediation: Use living bacteria, fungi, & algae to detox. Polluted environmentsWe also discuss several other topics like What is a sample statistic?
• Industrial Microbiology: Microbes used to make products o Pasteurization: Heat something to kill contaminating bacteria Microbes are also involved in flow of Energy and Nutrients • Photosynthesis: convert CO2 to organic material
• Decomposition: Breakdown dead matter & wastes into simple compounds
Microbes involved in infectious diseases
• Pathogens: microorganisms that harm (this is the minority of microorganisms)
o 2,000 dif. Microbes cause harm
o 10 billion new infections worldwide per yr.
o 12 million deaths by infections per yr.
Science according to the organism studied
• Bacteriology: The study of Bacteria
• Phycology: The study of Algae
• Mycology: The study of Fungi
• Protozoology: The study of Protozoa
• Parasitology: The study of Parasites
• Virology: The study of Viruses
History Of Microbiology
• Prominent Discoveries
o Microscopy If you want to learn more check out Where were cattles first domesticated?
o Scientific Method
▪ Make observation
▪ Generate question
▪ Generate hypothesis
▪ Experiment (w/control groups)
▪ Accept, reject, or modify the Hypothesis
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o Developed Medical Microbiology
o Microbiology Techniques
• Lifestyle of Microorganisms
o Exist freely in soil, water, surface
o Relatively harmless or even beneficial (decomposition)
o If associated with other organisms considered parasites and live in a host
• Early Microscopy
o Robert Hooke - 1660
▪ First compound microscope (microscope w/2 lenses) ▪ Saw cells of cork first and reminded him of a monk’s quarters which were called a “cell” – how we got the
name “cell”
▪ He examined living and non-living things
o Anton van Leeuwenhoek – 1632-1723
▪ Traded in linen & wanted to see the quality so made his own magnifying glasses and achieved the level of
microscopes
▪ Saw things that moved called them Animalcules
▪ When he died never passed on the secret to making the lenses and lost ability to see microscopic things
o Edward Jenner – 1796
▪ Developed first vaccine
???? Knew about variolation (when take puss from
someone w/smallpox & give it to someone else
they either die or are protected)
???? Decided when saw milkmaids hands w/something
that looked like smallpox but they never
contracted it, to take puss from their hands and
give it to a boy
???? The boy survived & was given smallpox, he was
protected, this was considered FIRST
VACCINATION (“vaca,” from “cow”)
o Joseph Lister – 1867
▪ Founder of antiseptic surgery
▪ Opened field of research in antisepsis & disinfection o Ignaz Semmelweis
▪ Introduced hand washing
▪ People not ready for it, didn’t take on even when
proved it worked
▪ Took on when Lister introduced it further
o Spontaneous Generation (Abiogenesis): Commonly held theory that things just started growing randomly, until it was disproved by the following people (proved Biogenesis: creation via biology)
o Louis Pasteur – 1822-1895
▪ Created flasks with bent necks that prevented microbes from falling into sterile solution
???? If broke neck microbes got in and grew
▪ Proved that grapes + yeast = alcohol & grapes + bacteria = acid
▪ Proved Yeast can grow with & w/out oxygen & from other cells
o Robert Koch – 1843-1910
▪ Germ Theory: disease is caused by germs
▪ Pioneer of Etiology: How diseases is caused
▪ Worked w/anthrax in animals & discovered endospores (the resting stage of bacteria) – this was the 1st time bacteria proven to cause disease
▪ Man who worked in lab developed Petri Dishes
▪ Walter Hess developed the media from algae – Agar ▪ Created framework to identify Pathogens: Koch’s Postulates
???? 1. Find evidence of microbe in every case of the disease
???? 2. Isolate microbe from infected subject & grow in lab
???? 3. Inoculate healthy subject & cause same
disease
???? 4. Re-isolate agent from subject
o Alexander Flemming – 1881-1955
▪ Discovered Penicillin 1929 (1st modern antibiotic) ???? Saw that fungi penicillian was killing staph he was growing
???? Penicillin enters widespread US – 1941
▪ Discovered Lysozyme from snot dripping & breaking down bacteria
???? In snot, tears, egg whites
o Selman Waksman – 1944
▪ Discovered Streptomycin – first drug for tuberculosis
▪ Discovered first way to isolate soil bacteria & test
antibiotics
▪ Reference to soil bacteria on grave: “The Earth will
open and bring forth salvation.”
5 I’s of Culturing Microbes
• Inoculation: Introduction of sample into container of media to produce culture of observable growth
• Isolation: Separate one species from another
• Incubation: placed in a temperature controlled chamber and microbe multiples for observable growth
• Inspection: Microscopic and Macroscopic Observation, what you can see upon inspection:
o Pure Culture: growth of 1 single known species
o Mixed Culture: growth of 2 or more identified species
o Contaminated Culture: the mixture was once pure & was mixed w/unwanted microbes growing in it.
• Identification:
o Use micro/macroscopic appearance to identify
o Perform biochemical tests to identify
o Use genetic characteristics to identify
o Use immunological tests to identify
Media to Isolate Microorganisms
• Physical Form of the Media
o Nutrient Agar (made from red algae)
▪ Solid Agar: Solid at room temp and body temp
▪ Holds moisture & nutrients (beef extract, peptone,
agar)
▪ Not digestible for most microbes
▪ Semisolid Agars: help determine if the organism is
motile or not, if it is then it will move in this media
???? Used in clinical tests
o Nutrient Broth: Liquid medium w/beef extract & peptone
• Different Chemical Compositions of Media
o Complex or Non-synthetic: Media has nutrients released by partial chemical breakdown by beef, soy, proteins, has at least 1 ingredient that is not exact (chemically defined)
o Defined: Media in which the exact chemical composition is known
o Synthetic: Contains pure organic and inorganic compounds in an exact amount (chemical formula)
o General Purpose Media: Grows many microbes, considered non-synthetic
o Enriched Media: complex organic substances (blood, serum, hemoglobin, and special growth factors that picky microbe require)
▪ Used to grow less abundant microbes
• Different Functions of Media
o Selective Media: media that contains nutrients that promote the growth of one microorganism and inhibit the growth of others
o Differential Media: media made so there is a change in appearance of media or the organisms that helps the
microbiologists tell the difference between different bacteria ▪ Agar has dye that changes color based on pH
o Blood Agar considered a differential and complex medium
Isolation Techniques
• Streak Plate: Serial dilution on a solid surface, use loop to spread on one quadrant then go on to quadrant 2 and go back into quadrant 1 slightly to dilute the bacteria, repeat 2 more times • Pour Plate Technique:
o Serial dilution of liquids
o Allows growth of different types of microbes because of different environment
o Used for fewer colonies
Colonies: Culture visible on the surface
CFU: Colony Forming Unit which pure culture comes from (comes from a single progenitor)
How to Dispose of Cultures
• Steam Sterilization
• Incineration
Key Characteristics of a Microscope
• Magnification: ability to enlarge objects
• Resolving Power: ability to show detail (Resolution)
o If particle size is smaller it has a better resolution
Compound Microscope
• Hooke used
• Binocular – 2 lenses
o Objective Lens: the lens right above the object, can have a series of lenses (4x, 10x, 40x, and 100x)
▪ Low Power: 10x10=100
▪ High Power: 10x40=400
▪ Oil Immersion: 10x100=1000 used to reduce light
refraction
o Ocular Lens: lens closest to the eye (can be monocular or binocular) – is 10 or 12.5 power (this is the 10 being
multiplied by the objective lens powers above)
• Light needs to be focused on specimen for best resolution Types of Microscopy
• Bright Field Microscopy
o Used in medical labs
o Image made w/light through the object
o Image absorbs light, darker than the background
o Used for live & fixed material
▪ Stain to improve contrast but kills microorganisms
• Dark Field Microscopy
o Illuminates objects from side
o Object white against dark background
o No stain used
o Living objects can be seen
• Fluorescence Microscopy
o UV light used w/filters to protect eyes
o Use dyes that fluoresce when exposed to UV light
▪ Have specificity to certain cell structures
▪ Can be coupled to antibodies to specifically target an
object
▪ Used to target specific bacteria or look for specific viral antigens
• Transmission Electron Microscopy (TEM)
o Uses a wavelength of an electron beam of ~0.5nm and creates a resolution of ~0.3nm = greatest magnifying
resolution
o Use very thin sections (20-100nm) for the beam to go
through specimen
o Use heavy metal salts to stain image & make contrast
o Nuclei diffract electrons
o Max magnification is 120,000x = can see what is inside things • Scanning Electron Microscope (SEM)
o Makes 3D image
o Sample is plated w/thin layer of a metal w/large nuclei (ex. gold)
o Electrons scanned across surface of sample & detector detects reflected electrons
o Image shown on TV screen
o Magnification not as good as TEM, ~10nm
Contrast: difference in intensity between two objects or between the object & the background
• Enhance Contrast by Staining
o Thick cell walls retain blue/purple stain (The Principle stain) o Thin cell walls lose principle/1st stain and allow to see the Secondary Stain = cells are pink
o Staining also deals with charges
▪ Positive Staining: Stains the organism
▪ Negative Staining: Stains the background, acidic dyes
used are repulsed by the negative charges on the cells
and don’t stain them (the capsules of bacteria are
negatively charged) –AKA Capsule Stain
o Simple Staining: made of single basic dye, soak the smear in dye for 30-60 seconds and rinse
o Differential Staining: Use more than one dye to see different cells & structures
Taxonomy
Taxonomy: organizing, classifying, and naming living things, was created by Carl Von Linne (Linneaus)
Classification: The orderly arrangement of organisms into Groups Nomenclature: Assigning names
Identification: determining and recording traits of organisms for placement into taxonomic schemes
Old Whittaker System
• Set up with Binomial (Scientific) Nomenclature, everything had two names – 1st name = Genus & 2nd name = Species
o Ex: Homo Sapiens
• Thought originally only 2 Kingdoms: Plantae and Animalia o Noticed certain organisms didn’t fit and created kingdoms Protista, Bacteria (Monera), and Myceteae for fungi
7 Main Taxa
• Species: the most specific, organisms that can successfully interbreed
• Genera: Similar species
• Families: Similar genera
• Orders: Similar families
• Classes: Similar orders
• Phyla: Similar classes
• Kingdoms: similar phylas
• The classification is determined by genetic/cellular level, use rRNA to compare things, Woes and Fox were the first to do this
There are 3 Domains which cover all organisms and then they are categorized by the 7 main taxa starting with kingdoms and getting more specific from there
• Archaea: Odd bacteria that live in extreme conditions
• Bacteria: True bacteria (*Prokaryotes fall under Bacteria and Archaea)
• Eukarya: have nucleus and organelles
How to Assign Names
• Binomial (Specific) Nomenclature
o 2 Names
▪ Genus – capitalized
▪ species – lowercase
o Both italicized or underlined
o Sometimes shorten first name with first letter and period. o Inspiration for names varied & imaginative
o Names usually mean something
▪ Ex: Staphylococcus aureus (S. aureus)
???? Staphyl = bunch of grapes (tells plane of division)
???? Coccus = “berry,” spherical shaped cell
???? Aureus = “golden,” yellow color
Evolution of Microorganisms
• Phylogeny: the natural relatedness between groups
• Evolution
o All new species come from an existing
o Close relatives have similar features, evolved from a common ancestor
o Usually progress towards a greater complexity
Characteristics of Cells
• Eukaryotic Cells: (Animals, Plants, Fungi, & Protists)
o Membrane-bound organelles (perform specific functions and compartmentalize cytoplasm)
o Has double-membrane bound nucleus with DNA in
chromosomes
• Prokaryotic Cells: (Bacteria & Archaea)
o No nucleus or other membrane bound organelles
o How to classify Prokaryotes:
▪ Microscopic Morphology: individual cocci or bacilli
appearance
▪ Macroscopic Morphology: Colony appearance
▪ Bacterial Physiology
▪ Serological Analysis: use liquid portion of blood after
clotting factors removed to determine the
microorganisms
▪ Genetic and Molecular Analysis
▪ If something causes a similar disease they are
often named something similar
Bacterial Taxonomy based on Bergey’s Manual of Systematic Bacteriology • Classification based on genetic information = phylogenic • Not all organisms have the same amount of G+C content (chemical content), affects DNA H-bonding
• (Remember that bacteria are Prokaryotic) There are 2 main Domains
o Archaea
o Bacteria
• 5 Major Subgroups w/25 different phyla in each one
*Within the 3 Domains (Eukarya, Archaea, and Bacteria) there are Organelles in the Bacteria Category because of Endosymbiosis (The idea that eukaryotic life evolved from prokaryotic life, will have some of the same characteristics)
Species and Subspecies
• Species: bacterial cells w/overall similar pattern of traits • Strain/Variety: A culture from one parent that differs from the others of that species (different structure or metabolism)
o Ex: Biovars and morphovars
• Type: subspecies w/differences in antigenic
makeup/immunoresponse (serotype or serovar), susceptibility to viruses (phage type) & pathogenicity (pathotype)
Diagnostic Scheme for Medical Use
• Phenotypic qualities to identify
• Limited to bacterial disease agents
• Categorizes bacteria based on shape, arrangement, physiological traits, cell wall structure
Dimensions of Bacteria (Prokaryotic)
Morphology: shape of organism
• Cocci: roughly spherical
o Staphylo: clusters of cocci, form when planes of cell divide randomly
o Strepto: Long chains of cocci, form when cocci cell divides down the center plane & the resulting cells stay connected ▪ Diplococcus: cocci that divide down the center plane &
stay connected in pairs
o Tetrad: the cocci divide in two planes and the four resulting cells stay connected
o Sarcina: Cocci that divide in 3 planes, stay connected to make a 3D tetrad
• Bacillus: non-spore forming rods
o Gram Positive (Thick peptidoglycan = retains purple dye) o Obligate Intracellular Parasite are Bacilli
▪ Can’t grow outside the host
▪ Very small
▪ Pleomorphic (shape varies) or Coccobacilli
▪ Ex: Rickettsia and Chlamydia
• Endospore Producing Bacilli
o Soil organisms
o Gram Positive (Thick peptidoglycan = retains purple dye) o Ex: Bacillus & Clostridium
• Helical Bacteria
o Spirochetes: Flexible twisting bacteria, rod-shaped, have flagella at both ends that tightly spiral around cell
▪ Move by creeping motion
▪ Has 70 turns (wound less tight)
o Spirilla: rigid twisting rod shaped structure
▪ Flagella helps move with swimming motion (like
corkscrew)
▪ Have 20 turns (wound tightly)
Size of microorganism: measured in micrometers
• Largest bacteria 0.75mm, could see w/naked eye
• Smallest bacteria 140 nm
Prokaryotic Structures: cell membrane, cytoplasm, ribosomes, one or a few chromosomes
• External Structures: Appendages and Glycocalyx
o Appendages (2 groups)
▪ Motility
???? Flagella: long structures, extend beyond the surface of the cell and glycocalyx, used to propel through the environment,
• 3 parts
o Filament: long, thin, hollow, helical
structure made of protein called
Flagellin
o Hook: curved structure that connects
the filament to the basal body, made
of different proteins
o Basal Body: Stack of 2 and 4 rings of
protein firmly anchored into cell wall,
varies between gram (-) and gram
(+) cells, it doesn’t extend into the
cytoplasm
• Rotates 360 degrees to move prokaryotic cells like a boat propeller
• Number and arrangement of flagella varies o Monotrichous: one flagella at one end
of the cell
o Lophotrichous: group of flagella at
one end of the cell
o Amphitrichous: one flagella at both
ends of the cell
o Peritrichous: Flagella all around the
perimeter of the cell
• Flagellar Responses: Guide bacteria in
certain direction in response to outside
stimulus
o Chemotaxis: guided by chemical
stimuli (either positive or negative)
o Phototaxis: guided by light stimuli
o Signal sets flagella in rotary motion in
either clockwise or counterclockwise
direction, moving towards nutrients
▪ Counterclockwise: smooth,
linear direction = Run, if
bacteria in high concentration
will run more
▪ Clockwise: Tumbles, if bacteria
in low concentration will tumble
more
▪ Attachments or Channels
???? Fimbriae: fine proteinaceous, hair-like bristles on
cell surface
• Function: Adhesion to other cells and
surfaces
???? Pili: Rigid tubular structure
• Function: join bacterial cell for partial DNA
transfer = Conjugation (an exchange of
genetic material in mating types)
• 1-3 present per cell
• Found only in Gram Negative (-) cells (thin
peptidoglycan layer and outer membrane,
doesn’t hold purple stain = pink cell)
o Glycocalyx: surface coating of cell wall
▪ Capsule: tight grouping
???? Chemicals in these are similar to the host so the
white blood cells don’t recognize them and cant
perform phagocytosis on them
▪ Slime Layer: loose grouping
▪ Functions of both are similar (both made of glycoprotein and polysaccharide)
???? Keep cell from drying out (desiccation)
???? Help bacteria stick together to form Biofilms
(aggregates of cells stuck together in a film)
???? Prevent WBC from phagocytosis
• The Cell Envelope: External covering outside of the cytoplasm, 2 layers, helps maintain cell integrity
o Cell Wall: provides structure, protects from osmotic forces, helps attach to other cells, resists antimicrobial drugs
o Cell Membrane: Selectively permeable, nutrients flow in and wastes flow out
o 2 Groups of Cell Envelopes
▪ Gram Positive (+) Bacteria: Thick cell wall made of peptidoglycan around the cell membrane.
???? Contains Teichoic Acid: in part of peptidoglycan layer, does not extend all the way through
???? Contains Lipoteichoic Acid: extend through the whole peptidoglycan layer & attached to cell
membrane
???? 1 Periplasmic Space
???? Peptidoglycan layer 20-80nm thick
???? Ex: Staphylococcus aureus
▪ Gram Negative (-) Bacteria: Outer cell membrane, thin peptidoglycan layer and then the cell membrane inside ???? Has Porins on the outside
???? 2 Periplasmic spaces
???? Peptidoglycan layer 8-10nm thick
???? Ex: Escherichia coli (E. coli)
o Peptidoglycan Structure:
▪ Polymer of NAM/NAG chains
???? NAM: N-acetylmuramic acid
???? NAG: N-acetylglucosamine
▪ Cross links between adjacent NAMs give strength, these differ between Gram(+) and Gram(-)
???? Gram(+) Cross Linkage
• There is an Interbridge of repeating Glycine
units between the Lysine of one NAM & the
Alanine of the NAM next to it
???? Gram(-) Cross Linkage
• There is a direct bond between the DAP of
one NAM & the Alanine of the NAM next to it
▪ Penicillin affects the direct bonds between adjacent chains, but the outer membrane of Gram(-) make it hard for penicillin to penetrate
▪ Lysozyme also breaks down NAM-NAG chains
o Non-typical Cell Walls
▪ Bacteria that don’t have typical cell wall structure
(Mycobacterium & Nocardia)
???? Gram(+) cell wall with Mycolic Acid give cell wall
waxy nature because it’s a lipid = this wall called
an Acid-Fast Cell Wall
• Gives it pathogenicity & high resistance to
chemicals & dyes
• Must use Acid-Fast Stain to diagnose
infections caused by these microorg.
▪ Bacteria w/No Cell Wall (Mycoplasma)
???? Cell membrane stabilized w/sterols (ex:
cholesterol)
???? Pleomorphic (less structured, more flexible)
• Internal Structures of Bacteria (Reminder: Prokaryotic) o Cytoplasm: gelatinous solution of sugars, amino acids & salts, 70-80% water (solvent used in all cell functions)
o Chromosomes: Single, circular, double-stranded DNA, has all the genetic material, in prokaryotes. not packaged around histones but packaged into Nucleoid
o Plasmids: small circular, double-stranded DNA, not essential for bacteria to growth or metabolism
▪ There are variations in Segregation of these, some linear some circle
▪ Sometimes harbor in antimicrobial resistance genes o Ribosomes: Made of 2 subunits of protein & rRNA
▪ 60% made of rRNA (the biggest portion and most
important component, makes peptide bonds, can be
enzymatic making enzymes included the one that
translates)
▪ Function: synthesis of proteins
▪ Different than Eukaryotic Ribosomes because smaller & sediment faster when centrifuged
▪ Two Types:
???? 30S + 50S = 70S Bacterial Ribosomes, found
inside organelles
???? 40S + 60S = 80S Eukaryotic Ribosomes, found outside organelles
• Prokaryotes have BOTH types of
ribosomes
o Inclusions & Granules
▪ Intracellular storage bodies
▪ Size, number & their content varies
▪ When environmental sources are depleted the bacterial cell can use these
▪ Ex: glycogen, poly-β-hydroxybutyrate, gas vesicles for floating, sulfur & phosphate granules (metachromatic granules), particles of iron oxide
o Cytoskeleton: Internal network of proteins associated w/cell wall
o Endospores: formed by microbes, toughest & longest living form of life
▪ High resistance due to high levels of Calcium & Dipicolinic Acid
▪ Longevity = ~250 million yrs.
▪ Resistant to ordinary cleaning & boiling
▪ Destroyed by pressurized steam @ 120°C for 20-30 min.
▪ When dehydrated = metabolically inactive – is how they live for so long
▪ Sporulation: Formation of an Endospore, depends on the species vegetative cell can form endospore
centrally, subterminally, or terminally
???? Step 1) In a Vegetative Cell (single cell develops into an endospore when one or more nutrients are limited, this endospore reactivates to transform
into a vegetative cell) DNA is replicated
???? Step 2) DNA aligns along cell’s long axis
???? Step 3) The cytoplasmic membrane invaginates to form the Forespore
???? Step 4) the cytoplasmic membrane grows and
engulfs the forespore in a 2nd membrane,
vegetative cell’s DNA disintegrates
???? Step 5) A Cortex of Calcium and dipicolinic acid is
deposited between the two membranes
• the cell holding the Endospore at this point
is called the Sporangium
???? Step 6) Spore coat forms around the endospore
???? Step 7) Endospore matures, spore coat
completed, resistance increases
???? Step 8) Endospore released, divides again under
right conditions
Eukaryotic Structures (Major difference from Prokaryotic is contains a membrane-bound nucleus & has membrane-bound organelles, can also be unicellular or multicellular)
• Organisms Studied
o Protozoa: Always Unicellular
o Fungi & Algae: Unicellular or Multicellular
o Helminths: animals w/unicellular egg or larval forms, animals themselves are multicellular
• External Structures
o Glycocalyx: outermost layer of cell, comes in direct contact w/environment
▪ Made of polysaccharides, is a network of fibers
▪ Can be Slime Layer or Capsule
▪ Eukaryotes not as structurally organized as prokaryotes ▪ Function: adhere cells to one another, strengthen cell
surface, protect against dehydration, cell to cell
recognition & communication
o Under Glycocalyx, some Eukaryotes have Cell Wall some don’t ▪ Fungi & Algae – thick rigid cell wall
???? Cell Wall: Provide support & shape
???? Fungi: thick layer of polysaccharide fibers made of
chitin or cellulose + thin layer of mixed glycans
???? Algae: Variation of chemical composition, some
common ones: cellulose, pectin, mannans, silicon
dioxide, calcium carbonate
???? Some cells that have cell walls can also have
things like Sterols
▪ Protozoa, some algae, all animal cells – no cell wall, only Cell Membrane
o Cytoplasmic/Cell Membrane:
▪ Bilayer of phospholipids & proteins
▪ Function: selectively permeable barrier for transporting material into & out of the cell, proteins are like
recognition molecules, receptors, carriers, enzymes, or channels.
???? Endocytosis: Active Transport, membrane
distends to form pseudopods around a substance
and bring it into the cell
• Phagocytosis: Bringing in a solid substance
• Pinocytosis: Bringing in a liquid substance
• Stuff brought in contained in a Food Vesicle
• Amoeboid Action: some use this for
locomotion by extending pseudopod &
streaming into it
???? Exocytosis: how things exported from the cell,
vesicles w/stuff inside fuse to cytoplasmic
membrane & dump it out
▪ Sterols help with stability
▪ Eukaryotic Cells contain membrane-bound organelles, these are 60-80% of cell volume
• In Cytoplasm/Internal Structures
o In TEM microscopic image, the varying darkness in the cytoplasm is varying density
▪ Euchromatin = light, less dense
▪ Heterochromatin = dark, more dense
▪ The more tightly packed DNA (more dense) is being silenced
???? DNA is packaged around Histones ???? beads on a string (Nucleosomes) ???? chromatin fiber ???? form
loops ???? compress to form Chromatid
o Rough Endoplasmic Reticulum:
▪ Ribosomes adhere to it
▪ assemble proteins into their secondary, tertiary, and quaternary structure
▪ transport proteins throughout the cell
▪ modifies protein w/glycoprotein (sugar wrapped around the protein)
o Smooth Endoplasmic Reticulum:
▪ Make Lipids
▪ Release Calcium ions
▪ Detoxify organic chemicals
▪ Produce steroid hormones
o Golgi Complex:
▪ Structure: flattened hollow sacs in a phospholipid bilayer
???? Cisternae: Flattened membrane disk, Golgi
contain 3-20 most contain 6
???? Transitional Vesicles: a sac with molecules that comes from the ER
???? Condensing Vesicles (Secretory Vesicles):
packages secretions into these sacs that fuse to
the cytoplasmic membrane & dump contents
outside cell w/exocytosis
▪ Function: modifies proteins to be sent other places, receives & packages large molecules to export from the cell
o Lysosomes: vesicles with enzymes that come from the Golgi ▪ Involved w/intracellular digestion & protects against microbes
o Vacuoles: membrane bound sacs with particles to be digested, excreted, stored
o Phagosome: A food vesicle (vacuole) that is taken into the cell by endocytosis, when it fuses with a lysosome from the Golgi called a phagolysosome
o Mitochondrion:
▪ Shape: Spherical to elongated, has 2 membranes ▪ Structure:
???? Cristae: Inner bilayer that has many folds to
increase the surface area, where most of ATP
produced in eukaryotic cells produced
???? Matrix: contains (prokaryotic) 70S ribosomes & circular DNA (has genes for some RNA & few
mitochondrial polypeptides made by mitochondrial ribosomes)
▪ Function: Makes ATP, part of the Krebs Cycle (Citric acid cycle), works w/electron transport
o Chloroplast: light harvesting organelle, found in photosynthetic eukaryotes
▪ Structure: two phospholipid bilayer membranes & DNA, make a few polypeptides w/own 70S ribosomes.
???? Thylakoids: membranous sacs that provide a lot of surface area for chloroplasts to
photosynthesize. Chlorophyll found here.
???? Grana: Stacks of Thylakoids
???? Stroma: Space enclosed by the inner membrane, contains mix of metabolic products, enzymes &
ions
o Cytoskeleton
▪ Function: Anchor organelles, help cytoplasmic streaming, move organelles within the cytosol, move cytoplasmic membrane for endocytosis & amoeboid action
▪ Structures:
???? Microtubules made of tubulin, are spindle fibers and are also part of the Eukaryotic Flagella, also
transport things
???? Microfilaments made of actin, used for amoeboid
movement, cytokinesis, cell movement
???? Intermediate filaments made of various proteins
Kingdom Fungi:
• Majority unicellular/colonial, few have cellular specialization • Been around for 650 million yrs.
• Species number difficult because mating forms look different than non-mating forms, could look different & be the same thing • 100,000 species divided into 2 groups
o Macroscopic Fungi (Mushrooms, puffballs, gill fungi)
o Microscopic Fungi (molds, yeast)
▪ Two Morphologies = Dimorphic (Transitions between
two forms to become pathogenic)
???? Yeast: round ovoid shape, reproduce asexually,
the form that is pathogenic
???? Hyphae: long filamentous fungi or molds, the
form that is benign
• When in individuals called “hyphae,” when
make a mat of them called, “Mycelium”
(filamentous fungal growth)
• Fungal Organization
o Grow in loose colonies
o Yeast: soft, uniform in texture & appearance
o Filamentous Fungi: mass of hyphae = Mycelium (cottony, hairy, velvety texture)
▪ Septate: when hyphae is divided with cross walls, each separate part has its own nucleus
???? Aseptate Hyphae: no cross walls dividing
???? Septate Hyphae: cross walls dividing
▪ Vegetative Hyphae: digests & absorbs nutrients
▪ Reproductive Hyphae: makes spores for reproduction