Micro Module 1

microbiology

the study of microbes/microorganisms

prokaryotes

• unicellular

• no nucleus or membrane bound organelles

• archaea, bacteria

eukaryotes

• membrane bound nucleus and organelles

• unicellular or multicellular

• fungi, protozoa, helminths

acellular microorganisms

depend on host cells to multiply

viruses and prions

true pathogens

always cause disease in humans

opportunistic pathogens

cause disease only in weakened host

scientific method

observation, question, hypothesis, experiment, analysis, conclusion

scientific theory

explanation of aspect of natural world that can be repeatedly verified using scientific method

explains why or how

withstands rigorous scientific scrutiny

spontaneous generation

theory that a living thing could develop from a non-living thing

biogenesis

theory that living things arise from another living thing of the same type

• proved by Louis Pasteur using S-necked flask

germ theory of disease

• microbes cause infectious diseases

• koch developed techniques to determine etiological agent of infectious disease

koch’s postulates of disease

help to identify causative agent of infectious disease

1. same organism must be present in every case of the disease

2. organism must be isolated from diseased host and grown as pure culture

3. isolated organism should cause disease into susceptible host

4. organism must be re-isolated from diseased animal

aseptic techniques

treatment/cleaning protocols

goal - decrease contamination and prevent infection

morphology

• phenotype

• shape, size, arrangement

species

basic unit and most taxonomic rank

strain

used to recognize genetic variants of the same species

• mutations and gene transfer often lead to new strains

• typically include numbers or letters after species name

pathogen

microbe with the potential to cause disease

infection

invasion and multiplication of pathogenic microbes in an individual or population

disease

occurs when an infection causes damage to infected host

microbiota

entire community of microorganism that reside in and on us

“normal” microbiota often depends on the location of microbe

microbiome

microbiota and associated genetic material/gene products in an environment

biofilms

communities of single or diverse microbial species that work cooperatively to secrete sticky, protective matrix where bacteria grow

• can develop on nearly any surface

• 80% infectious diseases in human biofilm based

pure culture

separating a single type of microbe from a diverse sample

simple stain

use one dye to determine size, shape, or arrangement

structural stain

used to visualize features such as flagella, capsule, or endospores

differential stain

used to discriminate between differences in bacterial cell walls

• gram stain and acid-fast stain

binary fission

• prokaryote reproduction

• offspring arise from one organism and only receives DNA from that cell

• wide range in time frame for doubling depending on changes in environement

common prokaryote shapes

1. cocci (spheres)

2. bacilli (rods)

3. spirilli (spirals)

monomorphic bacteria

have one shape in all environments

pleomorphic bacteria

can take on different forms/shapes

• this enhances survival, infectivity, and transmission

methanogens

type of archaea

• critical for termites and ruminats to digest cellulose

• aid in human digestion

nucleoid

localized region of bacterial genome

• typically single circular DNA chromosome

inclusion bodies

dense particles of aggregates in prokaryotes

• surplus storage site

• site of viral reproduction

• insoluable

functions of membrane proteins

• transporters

• anchors

• receptors

• enzymes

facilitated diffusion

type of passive transport that uses a transport protein

peptidioglycan

protein and sugar mesh

• makes up cell wall of bacteria

gram negative bacteria

• thin layer of peptidoglycan between cytoplasmic and outer membrane

• have 2nd membrane (outer membrane) rich in lipids

gram positive bacteria

• thick layer of peptidoglycan

• single cell membrane

• retain moisture longer

• presence of teichoic acids (TAs)

periplasmic space

area between peptidoglycan and cell membrane and gram negative bacteria

outer membrane

protective barrier

harder to kill

made up of lipopolysaccharide

contains proteins

porins

pore forming channels

allow substances to pass through outer membrane

teichoic acids

• glycopolymers

• attached to either peptidoglycan or membrane

• stabilize wall, maintain flexibility and shape, help cell division

mycoplasma

• lack cell wall

• contain sterol-enriched plasma membrane

• pleomorphic

• lack of PG = resistant to common antibotics

mycobacteria

• thick, waxy, mycolic acid rich cell wall

• grow slowly because things do not cross easily

• detected through acid-fast stain

slime layer

irregular, diffusable, loose layer of polysaccharides, glycoproteins, glycolipids found on some bacteria

capsule

organized, dense, well defined attached layer of polysaccharides or proteins

• primary virulence factor

pili

aka fimbria

• short, hair-like surface structures

• can be evenly around surface or localized

• typically gram negative

• adherence key virulence characteristic

• exchange genetic material by conjugation

• uses twitching motility

flagella

helical, long, main motility structure

spin like propeller

3 parts: basal body, hook, filament

can be extracellular or intracellular

endoflagella

flagella located in periplasmic space of spirochetes

allow for corkscrew movement

locomotion

• function of flagella

• penetrate viscous environments (mud, mucous, cell membranes)

• infect and invade

taxis

motile response of flagella to environmental stimulus

towards or away

vegetative

term to describe actively growing cells

bacterial spores

metabolically inactive structures used by bacilli to survive harsh conditions

• cells can enter dormant state and germinate when conditions improve

prokaryote significance

• atmospheric oxygen

• decomposition

• food and chemical production

• microbiome

• infection and disease

endosymbotic theory

1. proposes how eukaryotes evolved from archaea

2. mitchondria and chloroplasts are similar size, have 70s ribosomes, small circular DNA genome, phospholipid bilayer surrounded membranes, binary fission (all characteristics shared with bacteria)

fungi

• unicellular and multicellular

• chitin and glucan cell wall

• sexually and asexually reproduce

• can be pathogenic

• ergosterols cell membrane

• typically grow slower than bacteria and lower temp and pH

protists

• largest group

• most are unicellular and microscopic

• sexually and asexually reproduce

• photosynthetic = algae

• non-photosynthetic = protozoans

• can be pathogenic

plants

• most multicellular

• cellulose cell wall

• produce oxygen and seeds

• sexually and asexually reproduce

• no known pathogens

animals

• multicellular

• lack cell wall

• move

• sexual and asexual reproduction

• can be pathogenic

centrosomes

tubules extend from nucleus to cell membrane

cytoskeleton

dynamic and responsive intracellular network of protein fibers to help maintain shape, hold organelles, and facilitate movement

composed of microtubules, microfilaments, and intermediate fibers

nucleolus

dense region of rRNA biosynthesis (ribosome assembly begins)

chromatin

complex of DNA + proteins

endomembrane system

eukaryotic cellular transport system

constists of RER, SER, golgi apparatus, vessicles

rough ER

cisternae

studded with ribosomes

bud off in vesicles

smooth ER

tubules

no associated ribosomes

• involved in biosynthesis of lipids, carbohydrate metabolism, detoxification of toxic compounds

golgi apparatus

• array of cisternae

• enzymes modify lipids and proteins transported from ER - add carbohydrates to produce glycolipids, glycoproteins, proteoglycans

• sort and distribute final products

• help distingush cell types

• serve as cell surface receptors

vesicles

required for survival

transport, secrete, digest, sequester materials

small, fluid filled lipid bilayer enclosed

spherical sacs that can pinch off or fuse with any cell membrane

vacuoles

typically larger than vesicles

often used for storage - osmotic reg in fungi and protists

lysosomes

• degradative vesicles

• digestive enzymes and low pH allows for breakdown of particles

• compartmentalized

peroxisomes

oxidative degradation

enzymatically degrade fats, amino acids, toxins

metabolize oxygen containing waste

protect cells from toxic oxygen intermediates

pinocytosis

“cell-drinking”

small particle endocytosis

phagocytosis

“cell-eating”

large particle endocytosis

receptor mediated endocytosis

targeted uptake where ligands bind to specific membrane receptors on cell surface

glycocalyx

sticky, polysaccharide gel coating extracellular surface of plasma membrane

communicates with extracellular world

roles in cell protection, interactions, adhesion

extracellular matrix

maintain shape, structural stability, transmit signals

produced by animal and some protist cells

mass of carbs and proteins - collagen, fibronectin

often site of bacterial attatchment

fungi cell wall

primarily composed of chitin

also cellulose glucans and proteins

protist cell wall

primarily composed of cellulose and glycproteins

cilia

numerous in eukaryotic cell

shorter, coordinated movement

• protozoans use for locomotion and feeding

• respiratory cells use to move mucus up resp tract

parasites

organism that lives in or on host organism and obtains food from or at expense of host

3 main classes: protozoa, helminths, ectoparasites

parasitic protozoans

may have 2 phase life cycle

portions of life cycle occurs within host and has potential to cause illness

categorized into amoeboid, flagellated, ciliated, sporozoans/apicomplexans

helminths

worms - animal

microscopic aspect of life cycle

2 main categories: flatworms (tapeworms, flukes) and round worms (nematodes)

ectoparasite

require arthropod vectors for part of life cycle

biting insects important vectors that transmit pathogens

often feed on blood

mold

multicellular form of fungi with tubular filaments (hyphae)

septate hyphae

walls between the cells

nonseptate hyphae

lack of separation between the walls

mycelia

macroscopically visible intertwined mass of hyphae (fuzzy)

multicellular fungal characteristcs

1. mold

2. reproduce by using large number of spores

3. microscopic evaluation of hyphae and spores

unicellular fungal characteristics

1. yeast - reproduce asexually, daughter cells that remain attached to parent called psedohyphae

2. dimorphic - change between yeast and mold forms in response to environment

mycoses

diseases caused by fungal infection - many occur on skin surface = cooler

invasive mycises

widespread, involve internal organs, lethal

DNA denaturation

exposure to high heat or certain chemicals causes bonds to break between bases

strands of double helix separate into 2 single strands

mRNA

messenger between DNA and ribosomes

temporary transcript of genetic instructions used as template to make proteins

rRNA

major structural part of ribosome

interacts with mRNA and tRNA

site of protein synthesis

tRNA

delivers amino acids to ribosome, matches mRNA code, transfers onto growing protein

central dogma

describes process or DNA to RNA to protein using replication, transcription, and translation

each includes initiation, elongation, and termination

eukaryotic genomes

chromosomes in nucleus, multiple, linear, diploid

extrachromosomal DNA outside nucleus

prokaryotic genomes

single, cellular chromosome

localized to nucleoid in cytoplasm

several supercoiled domains packaged with histone-like proteins

plasmids

plasmids

extrachromosomal DNA

small, circular, independently replicate

dispersed in cytoplasm

contain non-essential survival advantage genes

general features of DNA replication

1. semiconservative

2. bidirectional process

3. proceeds in 5-3 direction

4. starts at origin

5. multiple enzyme process

6. high degree of fidelity