Mircobiology Chapters 1 + 3

Intro to microbes + Bacteria & Archaea

What is a microorganism?

Organism too small to be seen without magnification

What are the 3 domains to the Tree of Life?

Bacteria, archaea, and eukarya

What are prokaryotes?

bacteria + archaea, contain no nucleus

What are eukaryotes?

everything besides bacteria + archaea, contain nucleus

What are the various microbes that can colonize humans?

bacteria, archaea, protozoa, fungi, helminths, viruses, and prions

How are eukaryotes different from bacteria + archaea? (besides nucleus)

many are single-celled (almost all b&a single-celled), they develop into high complex multicellular organisms, larger in size, small minority compared to b&a

What is the cellular organization of eukaryotes?

contain organelles, some are macroscopic

What is the cellular organization of prokaryotes?

ten times smaller than eukaryotes, lack organelles, all are microorganisms

What are viruses?

not independently living cellular organisms, exist at a complexity between large molecules and cells, composed of small amount of hereditary material (either RNA or DNA) surrounded by a protein coat and sometimes a membrane

What are prions?

simpler than viruses, have no nucleic acid, only protein, act like infectious microorganisms

Order the 5 microorganisms from largest to smallest.

helminth, protozoan, bacteria, viruses, prions

How do microbes drive soil, water, and atmospheric structure & content?

microbes assist with carbon-nitrogen cycle production that insulate the atmosphere, bacteria are the most abundant cellular organisms in the ocean, viruses are the most abundant inhabitants of the ocean, bacteria and fungi live in close association with plants and assist them in obtaining nutrients and water, bacteria and fungi also protect plants against diseases

What are the historical uses of microbes by humans?

• bread production

• alcohol production

• cheese production

• mining metals (bioleaching)

• cleaning up human contamination (bioremediation) (bacteria eat oil)

• biological pesticide (pests consume bacteria on crops)

What is genetic engineeing?

manipulates the genetics of mircobes, plants, and animals for the purpose of creating new products and genetically modified organisms

What is recombinant DNA technology?

makes it possible to transfer genetic material from one organism to another and deliberately alter DNA

What is bioremediation?

uses microbes already present to restore stability or clean up toxic pollutants

Are microbed harmful or harmless?

Vast majority of mircobes are harmless or beneficial to humans

What are pathogens?

Microbes that cause diseases

What is the association between noninfectious diseases and mircobes?

lifestyle diseases (obesity, gastric ulcers, etc.) may have microbial causes linked to them

What is the trend with infectious diseases in humans?

increasing number of patients with weakened defenses - subject to infections by common microbes that are not pathogenic to healthy people + increase in microbes that are resistant to drugs

What is spontaneous generation?

belief that invisible vital forces present in matter led to the creation of life

What is abiogensis?

embraces spontaneous generation, idea that living things can be created from nonliving things

What is biogenesis?

says living things arise only from others of their same kind (other living things)

What did Louis Pasteur do?

studied the roles of microorganisms in the fermentation of beer and wine, he also used swan-neck flasks to disprove spontaneous generation

How did Louis Pasteur disprove spontaneous generation?

Used sterilized swan-neck flasks and exposed one to only air, and one to dust and air. Only the one exposed to dust and air showed microbial growth.

What did Robert Hooke do?

the 1st person to observe cells, not yet microbial cells through

What did Antonie van Leeuwenhoek do?

designed the microscope and 1st observed bacteria

What did Oliver Holmes and Ignaz Semmelweis do?

described the importance of hand-washing in preventing disease in the hospital setting

What did Joseph Lister do?

used aseptic (no microbes) techniques in surgery

What is the Germ Theory of Disease?

the fact that germs cause illness and disease. Louis Pasteur conducted the first studies linking human disease to infection

What did Robert Koch do?

postulated a series of logical steps that establish whether or not an organism is pathogenic and which disease it caused

What impact did the discovery of restriction enzymes have?

allows scientists to use enzymes to cut DNA in tailor-made ways - genetic engineering

What impact did the invention of the PCR technique have?

the PCR detects tiny amounts of DNA and then amplifies them - powerful tool for discovering new organisms, diagnosing infectious diseases, and forensic work

What impact did the importance of small RNAs have?

revealed that only 2% of DNA actually codes for proteins, led to new approaches in how disease is treated because if the small RNAs are important in bacteria that infect humans they can be new targets for antimicrobial therapy

What impact did the human microbe identification have?

set the stage for new knowledge of our microbial guests and their role in our overall health and disease

What is the nomenclature for organisms?

genus + species name, always italicized (underlined when hand-written), when abbreviated = genus name is abbreviated to first initial then a period and full species name is always written

How are prokaryotes different from eukaryotes?

their DNA lacks a true nucleus and histones (freely moving), their cell wall is made up of peptidoglycan, they lack membrane-bound organelles

What structures do all bacterial cells possess?

cytoplasmic membrane, cytoplasm, cytoskeleton, ribosomes, genetic material (one or a few chromosomes)

What structures do most bacterial cells possess?

cell wall and glycocalyx

What structures do some bacterial cells possess?

flagella, pili, fimbriae, outer membrane, nanotubes, plasmids, inclusions, endospores, microcompartments

What is the arrangement of bacteria?

most function as independent single-celled, unicellular organisms, but some act as a group in colonies or biofilms

What are the bacterial shapes?

cocci, bacilli, vibrio, (spirillium and spirochete)

What is the average size of bacteria?

1um (1/1000 mm)

What is pleomorphism?

variations in cell wall structure caused by slight genetic or nutritional differences

What is the Cocci shape?

spherical, can be perfect spheres or oval/bean-shaped

What is the Bacilli shape?

rods, short and plump rod = coccobacillus

What is the Vibrio shape?

rods that are gently curved

What is the Spirillum shape?

rigid helix twisted twice, corkscrew

What is the Spirochete shape?

spring shape

What are filaments regarding bacteria shape?

branching structure

What are the levels of cocci arrangement

• single

• diplococci = pairs

• tetrads = groups of 4

• sarcina = cubical packs of 8, 16, or more

• streptococci = chains

• staphylococci = irregular clusters

What are the levels of bacilli arrangements?

• single

• diplobacilli = pair with ends attached

• streptobacilli = chain

• palisades = cells of chain remain partially attached by small hinge region at the ends

What is spirilla arrangement?

only sometimes in short chains

What is spirochetes arrangement?

rarely remain attached after cell division

What is the structure and function of flagella?

flagella help with motility and they are composed of 3 parts: filament, hook, and basal body

What is the arrangement of flagella?

• monotrichous = single flagellum at one end

• lophotrichous = small bunches emerging from one side

• amphitrichous = flagella at both ends of the cell

• peritrichous = flagella dispersed randomly all over cell surface

How do flagellum provide motility?

chemotaxis, movement in response to chemical signals (run = flagellum rotate counter-clockwise resulting in smooth linear direction, tumble = reversal of direction of flagellum causing cell to stop and change course)

What is the structure and function of fimbriae?

they are small fibers sprouting off bacterial surface, they allow for tight adhesion between fimbriae and epithelial cells

What is the structure and function of pili?

used in DNA transfer between bacterial cells (bridge structure), also assist in attachment and make bacterium motile

What is the structure and function of nanotubes?

very thin, long, tubular extensions of cytoplasmic membrane, used as channels to transfer amino acids or to harvest energy by shuttling electrons to iron-rich substances

What is the S-layer?

single layer of thousands of copies of a single protein linked together like tiny chain link fences, only produced when bacteria are in hostile environment

What is the glycocalyx?

coating of repeating polysaccharide or glycoprotein units (either slime layer - lose, protects against water and nutrient loss, or capsule - tight and sticky, can be used for attachment

What is the role of capsules?

they are formed by many pathogenic bacteria, have greater disease-causing abilities, make antimicrobials not work as well, biofilm production (safety in numbers) (plaque, IUD & pacemaker infections)

What makes up the cell envelope?

cell wall + cytoplasmic membrane + outer membrane (layers outside the cytoplasm)

What is the function of the cell wall?

determines the shape, provides structural support, gains its relative rigidity from peptidoglycan

What is a gram-positive cell wall?

showed purple after staining, thick peptidoglycan sheet, more susceptible to peptidoglycan-targeting medicine, contains teichoic acid and lipoteichoic acid embedded within

What is a gram-negative cell wall?

showed red after staining, thin peptidoglycan sheet, more susceptibility to lysis, contains outer membrane, outer membrane contains lipopolysaccharides (endotoxins) and porin proteins (membrane channels affecting entry of antibiotics)

What is the outer membrane?

only in gram-negative, resistant to antimicrobial chemicals, more difficult to kill than gram-positive, alcohol-based compounds dissolve lipids in the outer membrane and therefore damage the cell

What are acid-fast bacteria cell walls?

contain peptidoglycan and stain gram-positive but bulk of cell wall is composed of unique lipids, mycolic acid (makes bacteria highly resistant to certain chemicals), acid-fast bacteria are even more difficult to kill than gram-negative

What are archaea cell walls like?

not made up of peptidoglycan, some composed entirely of polysaccharides, others made up of pure protein, some lack cell wall entirely

What are mycoplasmas?

natural lack of a cell wall, sterols in the cell membrane stabilize the cell against lysis

What are L forms?

naturally have a cell wall but lose it during part of their life cycle, resistant to antibiotics

What is the cytoplasmic membrane (plasma membrane)?

a lipid bilayer with protein embedded, functions include - energy reactions, nutrient processing, synthesis, regulates transport, selectively permeable

What does selectively permeable mean?

special carrier mechanisms for passage of most molecules

What is the nucleoid?

spot for DNA

What are plasmids?

nonessential DNA which confers protective traits

What are ribosomes?

site for protein synthesis, composed of rRNA + protein, small subunit (30S) + larger subunit (50S) = bacteria unit (70S) or eukaryotic unit (80S)

What is the cytoskeleton?

unique to prokaryotes, contribute to cell shape

What are bacterial endospores?

either dormant or vegetative, sporulation releases the highly resistant cells when induced by environmental conditions, they resist heat, drying, freezing, radiation, and chemicals, they are not meant for reproduction

What is Archaea ribosome type?

70S, but more similar to the eukaryotic 80S

What is archaea protein synthesis like?

archaea do eukaryote-like protein synthesis