microbiology lecture exam 1

Basic shape of all living things

Spherical, cubical & cylindrical

Characteristics of all living things

Internal content - cytoplasm, surrounded by a membrane

DNA (chromosome(s)), ribosomes, metabolic capabilities

Types of cells

Eukaryotic and prokaryotic

Types of eukaryotic cells

Animals, plants, fungi and protist

Types of prokaryotic cells

Bacteria and archaea

Characteristics of eukaryotes

• Contain membrane bound organelles

• double membrane bound nucleus with DNA

• Organized

Characteristics of prokaryotic cells

No nucleus or membrane bound organelles

Unorganized

what are characteristics of life?

• reproduction

• growth and development

• metabolism

• movement and irritability

• cell support, protection, and storage mechanisms

• transport of nutrients and waste

what is a genome?

composed of DNA in chromosomes

what are the different flagellar arrangements?

• monotrichous

• lophotrichous

• amphitrichous

• perittrichous

Monotrichous

Single flagellum at one end opl

lophotrichous

small bunches emerging from the same site

amphitrichous

flagella at both ends of cell

peritrichous

flagella dispersed over surface of cell

flagellar responses

• chemotaxis

• photo taxis

chemotaxis

chemical stimuli ; positive and negative

phototaxis

light stimuli

movement of flagella clockwise results in…

tumbles

movement of flagella counterclockwise results in..

Run

what does fimbriae look like?

fine, proteinaceous, hairlike bristles emerging from the cell surface

function of fimbriae

Adhesion which can lead to infection

what does pili look like?

rigid hollow tubular structure made of pilin protein

what is the function of Pili?

conjugation- joining of DNA for partial transfer of DNA

Is pili found in gram negative or gram positive bacteria?

Gram negative

what is glycocalyx?

coating of molecules external to the cell wall made of sugars and proteins

types of glycocalyx

• slime layer - loosely organized and attached

• capsule- highly organized, tightly attached

functions of glycocalyx

• protect from dehydration and nutrient loss

• contributes to pathogenicity by preventing white blood cells from destroying them via phagocytosis

• attachment - which allows formation of biofilms

what is the cell envelope?

external covering outside of the cytoplasm

what is the cell envelope composed of?

cell wall and cell membrane

function of cell envelope

maintains cell integrity

Cell envelope in gram positive bacteria

thick cell wall composed of peptidoglycll eean and cell membrane

cell envelope in gram negative bacteria

outer cell membrane, thin peptidoglycan layer and cell membrane

what does the structure of the cell wall determine?

cell shape and prevents lysis due to the changing osmotic pressure

alternate word for cell wall?

peptidoglycan

what is a peptidoglycan?

unique macromolecule found only in bacteria and is composed of long chains of sugar (glycan) cross linked with peptide fragments

gram positive cell wall include which two acids?

Teichoic acid and lipoteichoic acid

what is the function of Teichoic acid and lipoteichoic acid?

• cell wall maintaince

• enlargement during cell division

• move cations across the cell envelope

• stimulate specific immune response

periplasmic space in gram positive

thin w

what is per plasmic space?

space between the cell and membrane and cell wall

periplasmic space in gram negative

there’s 2 and in between them is a peptidoglycan

what does a gram negative cell wall look like?

outer membrane, periplasmic space, peptidoglycan, periplasmic space, cell membrane

what does the outer membrane of a gram negative bacteria contain?

lipopolysaccharides (LPS) (ONLY IN GRAM NEGATIVE)

function of lipopolysaccharides

may act as receptors and block immune response

Porin

found in lipopolysaccharides in the upper layer

regulate molecules entering and leaving cell

lipid portion in lipopolysaccharides

act as an endotoxin that may become toxin when released during infection

gram postive characteristics

• one major layer

• overall thicker

• NO outer membrane

• periplasmic space is narrow

• more penetrable to molecules

chemical composition of gram positive bacteria

• peptidoglycan

• teiichoic acid

• lipoteichoic acid

• mycotic acids and polysaccharides

characteristics of gram negative bacteria

• 2 major layers

• thin membrane

• has an outer membrane

• extensive periplasmic space

• less penetrable to molecules

chemical composition of gram negative bacteria

• lipopolysaccharide

• lipoprotein

• peptidoglycan

• porin proteins

what is the purpose of a gram stain

• help us distinguish between gram negative and gram positive bacteria

• helps us classify bacteria

• aids in diagnosing infection and treatment

what does gram positive retain or lose and how does it stain?

retains crystal violet and stains purple

what does gram negative retain or lose and how does it stain?

loses crystal violet and stains red from safranin

why does the crystal violet wash out in gram negative bacteria?

because peptidoglycan is thin therefore it washes out and gram positive stains purple

what stain is used to classify non typical cell walls?

acid- fast stain

examples of nontypical cell walls

mycobacterium and nocardia

examples of bacteria with no cell walls

mycoplasma

what are bacterias with no cell wall stabilized by?

sterols

bacteria with no cell wall are…

pleomorphic

what is a fluid mosaic model?

phospholipid bilayer with embedded proteins

what are the functions of the cell membrane?

• interaction with the environment

• providing site for energy reactions, nutrient processing and synthesis

• passage of nutrients into the cell and discharge of wastes

• cell membrane is selectively permeable

what is a chromosome?

single, circular, double stranded DNA molecule that contains all the genetic information required by a cell

what are plasmids?

• free small circular, double stranded DNA

• not essential to bacterial to bacterial growth and metabolism

what are plasmids used for?

genetic engineering - readilyy manipulated and transferred from cell to cell hew

where are plasmids found?

found in some bacteria but not all and can be in the nuceloid region or free floating

what are ribosomes made of?

60% ribosomal RNA and 40% protein

where are ribosomes found?

in all cells

what is the function of a ribosome?

protein synthesis

how do ribosomes differ in prokaryotic vs eukaryotic?

size and number od proteins

what are inclusion and granules

• intracellular storage bodies

• can vary in size, number and content

• they are used when environmental sources are depleted

cytoskeleton

made up of actin filament

posses internal network of protein polymers that are closely associated with the cell wall

how are endospores produced?

produced by G+ genera

what are its two phase life cycle?

• vegetative (metabolically actively and growing) and endospore (capable of high resistance and very long term survival

what is sporulation?

formation of endospores

• withstands extremes in heat, drying, freezing, radiation and chemicals

• cannot reproduce

what is germination?

return to vegetative growth

vegetative to spore (conditions are bad)

sporulation

spore to vegetative (conditions are good)

germination

what are endospores?

dehydrated cells that are metabolically inactive with thick coat/cuticle

how old are the oldest spores?

250 million

endospores condition (what kill them and what doesn’t)

are resistant to cleaning methods and boiling but pressurized steam at 120 degrees celsius for 20-30mins will destroy them.

what are the different shapes of bacteria?

Coccus, Bacillus and Spirillum

other types of bacillus

coccobacillus and vibrio

other types of spirillum

spirochete - spring like

what is pleomorphism?

variation in cell shape and size within one species ex. mycoplasma

arrangement of cocci

• singles

• diplococci - in pairs

• tetrads - groups of 4

• irregular clusters

• chains

• cubical packets

arrangement of bacilli

diplobacilli

chains

palisades - raw shaped bacteria that line like a picket fence

domain Archaea

adapted to extreme habitats and modes of nutrition

domain bacteria

phylum proteobacteria - gram negative cell walls

phylum firmicutes - mainly gram positive

phylum actinobacteria - gram positive

what are the three types of species

bacteria, archaea and eukaraya

what is the endosymbiotic theory?

eukaryotes come from prokaryotes that engulfed each other eventually evolving together until they are no longer separated

1. nucleus development and membrane folding

2. engulfment

3. symbiosis - temporary

4. coevolution - permanent

5. modern eukaryotes with organelles that have function

when did eukaryotes first appear?

2 billion years ago

different types of eukaryotes

Fungi, algae, protozoa and parasitic worms

what is fungi

harmless heterotrophic saprobes (living organisms) that live off dead plants and animals

• some are parasites living on tissues of other organisms but are not obligate ( made to bind)

• very widespread in many habitats

define mycoses

fungal infections

common fungal infections

athletes foot & ring worm

candidiasis

aspergillosis

blastomycosis

valley fever/ Coccidioidomycosis

histoplasmosis

Athletes foot and ring worm

caused by trichophyton mentagrophytes

candidiasis

caused by Candida albicans

• vaginal yeast infection

• oral thrush

Aspergillosis

cause by Aspergillus

• respiratory infection & allergy to spores

blastomycosis

caused by blastomyces

respiratory infection from Ohio or Mississippi River resulting in flue like symptoms and fungal spores

Valley fever/ Coccidioidomycosis

caused by coccidioides

• respiratory infection with flu like symptoms& rash in southern western US

Histoplasmosis

caused by histoplasma

• respiratory infection from soil that contains large amount of bird or bat droppings