Microbiology Exam 1 GCU

Microbes are

Organisms invisible to the naked eye; germs, microorganisms, pathogens, agents, bugs

Groups of microbes

viruses, bacteria, fungi, protozoans, parasitic worms

Antony van Leeuwenhoek

-First microbiologist, (1632-1723)

-Observed animalcules, later identified microorganisms such as bacteria, protozoa, some fungi and algae

Theory of Spontaneous Generation

"organisms can arise spontaneously from non-living material" also known as Abiogenesis

Detractors of abiogenesis

Francesco Redi, Louis Pasteur, John Tyndall

Francesco Redi

disproved spontaneous generation by placing rotting meat in jars

Supports hypothesis that living organisms give rise to life. Biogenesis!!!!

Louis Pasteur

Father of Modern Microbiology

-Developed swan necked flasks containing sterile growth and would indefinitely remain sterile if broth did not touch bend in neck.

Supports that living organisms give rise to life

John Tyndall

Found that hay infusions contained heat resistant microbes

Ferdinand Cohn

Discovered endospores, heat resistant form of bacteria

important to repeat all conditions as closely as possible when conducting research to further knowledge.

Benefits of microorganisms

nitrogen fixation, oxygen production, degradation of materials

Turbid vs clear

turbid= indication of infection (cloudy)

clear= sterile, no microorganisms

Biodegradation

Degradation (break down) of PCBs, DDT, trichloroethylene. Also helps clean oil spills!

Bioremediation

The use of living organisms to hasten decay of pollutants

Biotechnology

use of microbiological and biochemical techniques to solve practical problems

Genetic engineering

-Introduction of genes into another organism

-Disease resistant plants

-Production of medications (ex: insulin for diabetes)

Research tools

-Metabolisms, genetic same as higher life forms

-All cells composed of same elements

-Synthesize structures in similar ways

-Replicate DNA

-Similar metabolic pathways

Bionomial system of nomenclature

-Genus (capitalized) and species name (not capitalized)

-always italicized (print) or underlined (handwritten)

- Escherichia coli 0157 :H7 or

Escherichia coli 0157 :H7

-May be abbreviated (E. coli)

-Genus: Escherichia

-Species: coli

-Strain- 0157 :H7

Most Microorganisms are not harmful

Some are pathogens

Golden Age of Microbiology

The principle that microorganisms cause diseases is known as Germ Theory of Disease

As spontaneous generation was disproved, golden age of microbiology was born

Macromolecules

most macromolecules are polymers

form chainlike molecules called polymers - consist of many similar/identical building blocks linked by covalent bonds

The repeated units are small molecules called monomers

Monomers are connected by?...

covalent bonds via a condensation reaction or dehydration reaction.

One monomer provides a hydroxyl group (-OH) and the other provides a hydrogen (-H) and together these form water

This process requires energy and is aided by enzymes

The covalent bonds connecting monomers in a polymer are disassembled by?

Hydrolysis

Polymer splits in the presence of water!

functional groups of organic molecules

hydroxyl group

carbonyl group

carboxyl group

amino group

phosphate group

methyl group

sulfhydryl group

aldehyde - makes hydrocarbons hydrophilic, afferent reactivity

Carbohydrates function and monomer

energy source, structural component of cell wall, monosaccharides

Lipids function and monomer

Important component of cell membranes, energy storage

varies for monomers

Proteins function and monomer

Enzyme catalysts, & many cell components

Amino acids

Nucleic Acids function and monomer

store and transmit genetic information & nucleotides

DNA function and monomer

Carrier of genetic information & Deoxyribonucleotides

RNA function and monomer

Protein synthesis; catalysis & Ribonucleotides

Carbohydrates

monomers: monosaccharides, examples; glucose, fructose

polymers: polysaccharides

many monosaccharides join by glycosidic linkages (BOND)

-sugars, starches, cellulose

Two monosaccharides can join with a glycosidic linkage to form a ___________ via _________

Disaccharide via dehydration

Polysaccharides are

2 possible ring structure of glucose

1.) Alpha glucose: digestible

2.) Beta glucose: Indigestible

Starch is

a storage polysaccharide that is composed entirely of alpha glucose monomers.

humans have enzymes that can hydrolyze the a-glycosidic linkages of starch!!!!

Cellulose is

a major component of the tough wall of plant cells!

it is also a polymer of beta-glucose monomers

humans DO NOT have enzymes that can hydrolyze the B-glycosidic linkages of cellulose

Chitin

-Used in the exoskeletons of arthropods

-forms the structural support for the cell walls for many fungi

Dextran

storage product in some bacterial cells

Lipids

Lipids are NOT polymers

Lipids are composed of long hydrocarbon chains

Examples: fats, phospholipids, steroids

Fats

A fat is constructed from two kinds of smaller molecules glycerol and fatty acids

glycerol- 3 carbon skeleton with a hydroxyl group attached to each

fatty acid- a carboxyl group attached to a long carbon skeleton. 16-18 carbons long!

in a fat molecule, three fatty acids are joined to glycerol by an ester linkage. Bond between an OH and a -COOH creating a triaclyglycerol

Phospholipids

structure: glycerol + 2 fatty acids + PO4

PO4= negatively charged

Fatty acid tails= hydrophobic

PO4 head= hydrophilic

*Can self assemble into "bubbles"*

Bubble= micelle

can also form phospholipid bilayer

Phospholipids are important because?...

They make cell membranes!

and create a barrier in water. they define outside vs inside

Steroids include

-cholesterol and certain hormones

-cholesterol and ergosterol are sterols that provide rigidity to animal and fungal cell membranes.

the difference helps with the anti fungal drugs mode of action, exclusively binds and damages the fungal cell membrane without causing any harm to the human host cells.

Proteins

function: Involved in almost everything

-enzymes

-structure

-carriers&transport

-cell communication

-signals

-receptors

-defence

-movement

-storage

Proteins structure

Monomer= amino acids

polymer= polypeptide

-peptide bonds

Primary (1 degree) structure

The primary structure of proteins is the sequence of amino acids in a protein

Primary structure is determined by inherited genetic information

Secondary degree structure, tertiary structure, quaternary structure

Protein denaturation

-unfolding of a protein

-Conditions that alter protein structure

-temperature

-pH

-salinity

-alter shape

-destroys function, bacterial cells die

enzymes are proteins, structure determines function

Nucleic Acids Function

-genetic material

*stores information

-genes

-blueprint for building proteins

DNA->RNA-> proteins

transfers information

-blueprint for new cells, and blueprint for new generation

Nucleic Acids Examples

-RNA

(ribonucleic acid) -single helix AUGC

-DNA (deoxyribonucleic acid) -double helix ATGC

structure: monomers= nucleotides

Nucleotides

-3 parts

Nitrogen base (C-N ring)

Pentose sugar (5C)

Phosphate (PO4) group

*Phosphodiester bond*

-Purines

-Double ring N base

-Adenine (A)

-Guanine (G)

-Pyrimidines

-single ring N base

-cytosine (C)

-thymine (T)

-uracil (U)

Morphology of Prokaryotic Cell includes?....

Shape and Arrangement is the morphology!

Size is measured in micrometers

-An advantage of the smaller size of prokaryotes, compared to eukaryotes, is the high surface area relative to low cell volume and more rapid growth rates

Different morphology of prokaryotic cells

Coccus: round

Bacillus: rod

Vibrio: Comma

Spirillum

Pleomorphic (many shapes)

Bacillus

Prokaryotes divide by?....

binary fission

form characteristic groupings

-Diplococcus (Pairs)

-Streptococcus (chain)

-Sarcina (cubical packets)

-Staphylococcus (Grapelike clusters)

Capsules and Slime Layers-optional

Gel-like layer outside cell that protects and may be used to help the bacteria adhere to surfaces

Capsule: distinct, gelatinous

Slime layer: diffuse, irregular

Most composed of glycocalyx (sugar-carbohydrate shell) although some are polypeptides (proteins)

-Once attached, cells can grow as biofilm, polysaccharide encased community

example: dental plaque, mildewed showerhead, slimy boulder, mold on shower curtain

Bacterial Cell Wall

-the major criteria used in placing bacteria into different groups is based on differences in cell wall structure

made from peptidoglycan, and prevents the bacteria from bursting

Differences in cell wall

1.) Gram positive bacteria: thick peptidoglycan

2.) Gram negative bacteria: Thin peptidoglycan

3.) Acid fast bacteria: Mycolic Acid (waxy fatty acid)

4.) Pleomorphic bacteria: no cell wall (hence, variable shapes)

Grams Stain

First test that is done for identification of bacteria in clinical specimen.

identifies two major groups of bacteria according to cell wall structure. Gram-positive and Gram-negative

Gram Positive Cell Wall

Gram-positive cell wall has thick peptidogylcan layer and stain blue

Gram Negative Cell Wall

Gram Negative cell wall has thin peptidoglycan layer and stain red

Outside is unique outer membrane

The Gram Negative Outer Membrane

Outer membrane blocks passage of many molecules including certain antibiotics

Outer membrane is a bilayer made from lipopolysaccharide (LPS)

LPS= Endotoxin

LPS Includes Lipid A (Immune system recognizes) and O antigen (can be used to identify species or stains

Antibacterial Substances that Target Peptidoglycan

Penicillin interferes with peptidoglycan synthesis

-usually more effective against gram-positive bacteria and growing bacteria

Lysozome breaks bonds linking glycan chain and digests peptidoglycan molecule

Acid Fast Bacteria

detects Mycobacterium

-includes causative agents of tuberculosis and Hansens disease (leprosy)

-cell wall contains high concentrations of mycolic acid

Waxy fatty acid that prevents uptake of dyes

Bacteria That Lack A Cell Wall

Mycoplasma lacks a cell wall!

Mycoplasma: Atypical/walking pneumonia

mycoplasma species have extremely variable shape- pleomorphic

penicillin, lysozome do not affect

Flagella

Involved in motility

nutrients attract, toxins repel. movement is a series of runs and tumbles

Pili

are shorter than flagella

types that allow surface attachment are called fimbriae

twitching motility, gliding motility involve pili

sex plus used to join bacteria for DNA transfer

The Cytoplasmic Membrane

defines the boundary of a cell

-phospholipid bilayer= embedded with proteins

amphipathic nature: hydrophobic tails face in, hydrophilic heads face out= selectively permeable

proteins serve as selective gates and sensors of environmental conditions

fluid mosaic model: proteins are not fixed and static but drift about in lipid bilayer

electron transport chain- embedded in membrane

-critical role in converting energy into ATP

differential staining

endospore stain

resists gram stain, endospore stain uses heat to facilitate uptake of the primary dye malachite green by endospore

counterstain (usually safranin) used to visualize other cells

Endospores are

members of genera including bacillus, clostridium form resistant, dormant endospore

UNIQUE TYPE DORMANT CELL

extremely resistant to heat, desiccation, chemicals, ultraviolet light, boiling water

-endospores that survive can germinate to become vegetative cell

Prokaryotic cell components

chromosome forms gel like region: the nucleoid

-single circular double stranded DNA

-packed tightly and supercoiled

-the chromosome encodes information essential for life

-plasmids are extrachromosomal, circular, supercoiled, dsDNA

-usually much smaller; few to several hundred genes, codes for addition traits

-may share with other bacteria; antibiotic resistance can spread this way

Ribosomes are involved in...

....protein synthesis

prokaryotic ribosomes are 70S

-made from 30S and 50S

Eukaryotic ribosomes are 80S

*ANTIBOTICS IMPACTING 70S RIBOSOME DO NOT AFFECT 80S RIBOSOME*

The Eukaryotic Cell

-Eukaryotic cells are larger than prokaryotic cells

-have membrane-bound nucleus

-have membrane-enclosed compartments called organelles

example: animal and plant cells

Nucleus

contains DNA

-surrounded by two lipid bilayer membranes

-nuclear pores allow large molecules to pass

-nucleolus is region where ribosomal RNA's synthesized

Mitochondria

generate ATP

-Bounded by two lipid bilayers

-mitochondrial matrix contains DNA, 70s ribosomes

Chloroplasts

are site of photosynthesis

-found only in plants, algae

-harvest light energy to generate ATP

-ATP used to convert CO2 to sugar and starch

-contain DNA and 70s ribosomes, two lipid bilayers

Eukaryotic ribosomes

function: protein synthesis

-prokaryotic ribosomes are 70s

-eukaryotic cytoplasmic ribosome is 80S made from 60S plus 40S

-Mitochondria and chloroplasts have 70S ribosomes

-Hence, antibiotics that target bacterial protein synthesis may partially account for some side effects

Endoplasmic reticulum (ER)

-system of flattened sheets, sacs, tubes

-rough ER dotted with ribosomes

-synthesize proteins not destined for cytoplasm

-smooth ER: lipid synthesis and degradation, calcium storage

The Golgi apparatus

-membrane bounded flattened compartments

-macromolecules synthesized in ER are modified

Lysosomes

-contain degradative enzymes

-could destroy cell if not contained.

-old organelles, vesicles fuse with lysosomes: autophagy

-peroxisomes use O2 to degrade lipids, detoxify chemicals

Eukaryotic cytoplasmic membrane

similar to prokaryotic cell membrane

-phospholipid bilayer embedded with proteins

but differs in:

-membranes of many eukaryotes contain sterols

-provide strength to otherwise fluid structure

-cholesterol in mammals, ergosterol in fungi

Eukaryotic cell transport

-Endocytosis: take up materials

-phagocytosis: is the ingestion of particles and is used by protozoa for the intake of food materials

-pseudopods surround, and bring material into the phagosome

-Phagosome fuses with lysosome --> phagolysosome

-exocytosis is the reverse of endocytosis

principles of bacterial growth

microbial growth= increase in number of cells, not cell size

prokaryotic cells divide

binary fission

generation time

time it takes for the population double

varies among species, environmental conditions

Nt= N0 x 2n

Nt is the number of cells at a given time

N0 is the initial number of cells

N is the number of generations

Most microbes live in polysaccharide encased communities called?...

biofilms

-may enhance bioremediation efforts and protect organisms against harmful chemicals

examples: slipperiness of rocks in stream bed, slimy "gunk" in sink drains, scum in toilet bowls, mildewed showerhead, dental plaque

Microbial culture in labratory

-cells grown on culture medium

-contains nutrients dissolved in water

(can be broth (liquid), or solid gel)

cells grown on culture medium can be...

Grown in agar plates, broth tubes

stored on agar slant in the refrigerator, frozen in glycerol solution freeze dried

Pure culture

All the bacterial cells that result from the replication of a single original bacterial species/organism

-allows study of single species

ideal for solidifying media- due to chemical and physical properties that make it neutral and remains solid at room temperature

Robert Koch

Developed methods for pure culture technique

Agar

seaweed

Streak plate method

simplest, most commonly used method for isolating bacteria

spreads out cells to operate

-obtain single cells so that individual colonies can form

Purpose of the growth curve ?

Medical significance

characterized by five stages

1st phase: Lag phase

Microbial cells introduced into sterile medium

adapting to new environment

cells are maturing but not yet dividing

begin synthesizing enzymes required for growth

metabolically active cells

number of cells does not increase

2nd phase: Exponential (log) phase

Cells divide at constant rate

the bacteria are rapidly increasing in number

MOST SUSCEPTIBLE TO ANTIOBIOTICS

Production of primary metabolites (amino acids and ethanol)

-important commercially

Secondary metabolite. example: antibiotics

formation of endospores, capsules

Stationary phase

nutrient levels are too low to sustain growth

total numbers remain constant.

some die, release contents; others grow and become much more resistant to drugs

Death Phase

total number of viable cells decline

Phase of prolonged decline

Some fraction may survive.

Adapted to tolerate worsened conditions

Environmental Factors that Influence Microbial Growth

Prokaryotes inhabit nearly all environments

some live in comfortable habitats favored by humans, some live in harsh environments

extremophiles

Archaea, that live in extreme environments.

Major Conditions that influence growth

-temperature

-atmosphere

-pH

-water availability

Temperature requirements

each species has well defined temperature range

optimum growth usually close to upper end range

Psychrophiles

Found in arctic and antarctic regions

-5 to 15 degrees celsius

Psychrotrophs

20 degrees to 30 degrees celsius

important in food spoilage