SHSU Clark BIOL 2420 Exam 1

Leuwenhoek

Microscopes, animalcules

2 fundamental cell types

Prokaryotic

Eukaryotic

Prokaryotic cells

BACTERIA & ARCHAEA

smaller size gives high surface to low volume, facilitates rapid uptake of nutrients

cons: vulnerability to predators, parasites, and competitors

Eukaryotic

Larger, more complex, many cellular processes take place in membrane bound components

precense of nucleus

bacteria and archea

lack nucleus

found in sufficient moisture, some in extreme environments

asexual

peptidoglycan

Archaeal cell walls are composed of polymers other than peptido

Fungi

Eukaryotic

food from other organisms

cell walls

Mold and Yeasts

Protozoa

single cell

similar to animals

live freely inwater

most are asexual

locomotion - pseudopods, cilia, flagella

Golden age of Microbiology

spontaneous generation id disproved

germ theory - most pathogens identified (1875-1918), work on viruses began, antibiotics, vaccines

Normal Microbiota of the Skin

Termed "normal microbiota" or "normal flora"

prevent disease, immune system, aid in digestion, recycling of nutrients

oxygen production

Nitrogen Fixation

Decomposers

Commercial Benefits

Food production - bread and yeast

fermentation - beer

fermentation of milk - yogurt, cheese, buttermilk

Biodegredation

PCB's, DDT, TRICHLOROETHYLENE

Biotechnology

Use if microbial and biochemical techniques to solve practical problems

Genetic Eengineering

Introduction of genes into another organism, disease resistant plants, production of medication

microbes and disease

most microorganisms are not harmful, viral disease smallpox once a leading killer (10M deaths over 4,000 years, eradicated, no reported cases since 1977)

Plague

1/3 population of Europe dies btwn 1346-50, today fewer than 100 die worldwide, control rodent population, antibiotics available

In US how many infections

750M infections, 200,000 deaths, costs tens of billions of dollars

Emerging Diseases

most newly recognized, swine flu, SARS, MR TB, Lyme, Hep C, AIDS, E. coli, Ebola

Pathogens can become resistant to antimicrobial medications, increases travel and immigration, many diseases eliminated, changes in population - weakened immune system, chronic diseases may be caused by bacteria - crohn's, indigestion, peptic ulcers

Koch's Postulates

suspected causative agent must be found in every case of the disease and be absent from healthy hosts, agent must be isolated and grown outside the host, when agent is introduced into a healthy, susceptible host, the host get the disease, same agent must be found in the diseased experimental host

Scientific Method

make observation

developed a testable explanation called a hypothesis

design experiment to test hypothesis

do experiment and collect and analyze data

draw a conclusion

communicate methods, results and conclusions

a scientific theory is an explanation supported by a large amount of evidence

Biochemistry

study of metabolism: chemical reactions that occur in living organisms

Molecular Biology

explanation of cell function, Pauling proposed that gene sequence could

1, provide understanding of evolutionary relationships and processes

2. establish taxonomic categories to reflect these relationships

3. Identify existence of microbes that have never been cultured

Disease defense - serology

study of blood serum, Von Behring and Kitasato (presence in the blood of chemicals and cells that fight infection)

Disease Defense - Immuniology

study of body's defenses against specific pathogens

Disease Defense - Chemotherapy

Fleming - penicillin

Domagk - Sulfa Drugs

Light Microscope

can magnify 1000x, common, important tool in micro

Electron Microscope

1931 can magnify more than 100,000x

similar to light microscopy

atomic force microscope

1980

General Principles of Microscopy

Wavelength of Radiation, Magnification, Resolution - resolving power or ability to distinguish two objects that are very close together

Resolutin

resolving power or ability to distinguish two objects that are very close together

minimum distnace between two points at which those points can be observed as seperate

depends on quality

maximum resolving power

Contrast

difference in intensity between two objects or an object and its back ground

determines how well cells can be seen

transparent bacteria lack contrast, difficult to see against

stains increase contrast but kill microbes

Bright Field Microscopy

series of lenses for magnification

light passes thru specimen into the objective lens

oil immersion lens increases resolution

Dark Field Microsccopy

best for observing pal objects

only light rays scattered by specimen enter objective lens

specimen appears light against dark background

Phase Microscopy

Used to examine living organisms living or specimens that would be damaged/altered by attaching the, to slides for staining

Fluorescence Microscopy

cells or materials either naturally florescent or tagged with dyes

Molecules absorb light at one wavelength (usually ultraviolet light) and emit light at longer wavelength

most today are epiflorescent: UV light projected onto not throught specimen

Staining

Most microorganisms are difficult to view by bright-field microscopy

Coloring specimen with stain increases

contrast and resolution

Specimens must be prepared for staining

Hans Christian Gram

Danish physician and bacteriologist who developed a method of staining bacteria to distinguish among them (1853-1938)

Revealed two different kinds

Two types of stain

Methylene Blue and Crystal Violet

Differential Staining

Dfferential Stains used to distinguish different types of bacteria, gram stain for most common for bacteria, two groups (Gram + and -) which reflects to fundamental difference in cell wall structure

Acid Fast staing

used to detect mycobacterium

includes causative agents of TB an leprosy

Cell wall contain concentrations of mycolic acid

Waxy fatty acid that prevents uptake of dyes

Harsher methods needed

used presumptive identify agents in clinical specimens

Special Stains

Capsule (negative) stain

some microbes surronded by gel-link layer

stains poorly so negative stain often used

India Ink added to wet mount is common method

Acid Dyes repulsed by negative surface

Flagella Stain

flagella used for motility

too think to be seen with light microscope

stain coats flagella to thicken and make visable

presence and distribution can help in identification

Coccus

Circle Shaped

Bacillus

Rod Shaped

Coccobacillus

Ovular Shaped

Vibrio

comma shaped

Spirillum

spiral shaped bacteria

Spirochete

spiral shaped bacteria

How prokaryotes reproduce

binary fission

Cells often stick together following division

form grouping

populations double each regeneration

Generation time depends on species and growth conditionw

Types of Transport

Facilities Diffusion

Active Transport

Group Translation

Glycocalx

Pericellular matrix

Glycoprotein

Ecosystems

Protects from phagocytes

Flagellum

Peritrichous

Single Polar Flagellum

Tuft of Polar Flagella

Pilus

Special type of Fimbriae

Conjugation

Cell Wall

o Distinguishing characterizes for bacteria

o Provide structure and shape and protects

o Assist some cells in attachment

o Antibiotics can target cell wall

o Give characteristic shapes

o Composed of peptidoglycan

o Two basic types

Gram stain - positive (purple) and negative (pink) gram stains

Endospores

Unique structures produced by some bacteria

Defensive strategy against unfavorable conditions

Vegetative cells transform into endospores when multiple nutrients are limited

Resistant to extreme conditions such as heat radiation, chemicals

Spores are resistant to

Heat, Dryness, Radiation, Alcohol, Bleach, Survive hour boiling, survive 5x lethal dose of radiation, Barely metabolically active

Archeaal Cell Structure

Gycocalyces

Flagella

Fimbriae and Hami

• Lipopolysaccharide

• Teichoic acid

• Outer plasma membrane

• Cytoplasmic membrane

- Pariplasmic space

-Peptidoglycan

Quorum Sensing

regulation of gene expression in response to fluctuations in cell-population density. Quorum sensing bacteria produce and release chemical signal molecules called autoinducers that increase in concentration as a function of cell density.

Growth requirement:

organisms live in association with different species

antagonistic

synergistic

Symbiotic - rely on each other but only one will benefit

Enviromental Factors that influence microbial Growth

Temperature affects 3D structure of proteins

lipid containing membranes of cells and organelles are temp sensitive

-if too low membranes = fragile and rigid, if too high membranes - too fluid

Psychrophiles

(-5 to 20 C)

Mesophiles

(15 to 45 C)

Thermophiles

(44 to 80 C)

Hyperthermophiles

(65 to 105 C)

Obligate Aerobes

need oxygen because they cannot ferment or respire anaerobically.

Obligate Anaerobes

poisoned by oxygen

toxic forms of oxygen are highly reactive and excellent oxidizing agents

resulting oxidation causes irreparable damage to cells

Facultative anaerobes

Can survive in oxygen but prefer not to

Aerotolerant anaerobes

hey do not utilize oxygen, but they can protect themselves from reactive oxygen molecules.

Microaerophiles

Low oxygen

Forms of Toxic Oxygen

Singlet Oxygen

Superoxide

Peroxide anion

Hydrocyl Radical - MOST REACTIVE

pH

Organisms sensitive to changes in acidity

H+ and OH- interfere with H Bonding

Neutophiles

grow best in a narrow range around neutral pH

Acidohiles

grow best in acidic habitats

Alkaliohiles

live in alkaline soils and water

Halotolerant

withstand up to 10% salt

Halophiles

require high salt

marine bacteria ~ 3%

Extreme Halophiles>/= 9% (Dead Sea, utah's Salt Flats)

Nitrogen Requirements

anabolism often ceases due to insufficient nitrogen

acquired from organic and inorganic nutrients

All cells recycle nitrogen fixation by certain bacteria is essential to life

All needs

Carbon, Oxygen, Hydrogen, Nitrogen, Phosphorus, Sulfur

Two groups of organsims based on source of carbon

Autotroph and heterotroph

two groups based on source on energy

Chemotherapy and Phototrophs

Complex Media

exact composition highly variable and often digest proteins

Chemically Defined Media

-

Special Types of Culture Media

useful for isolating and identifying a specific species

Selective medias inhibit growth of certain species

differential media contain substance that microbes change in identifiable way

19th century surgery

minor surgeries were at minor risk of fatal infections

physicians didnt know hands could pass disease

didnt understand microbes could infect open wounds

approach to disease control

microbial control methods depends upon situtin and level of control required

Sterlization

removal of all microorganisms

sterile item is free of microbes including endospores and viruses

Disenfection

elimination of most or all pathogens

some viable microbes may remain

called biocides, germicides, bactericides

antiseptic used on living tissue

Pastuerization

brief heating to reduce number of spoilage organisms, destroy pathogens

Decominization

reduces pathogens to level considered safe to handle

Sanitized

substantially reduces microbial population that meets health standards

Preservation

process of delaying spoilage of foods and other perishables

adjust conditions

add bacteriostatic preservatives

Washing hands

Soap Aids

Hospitals minimizing infections

HAI's, patients more susceptible to infection

may undergo invasive procedures

instruments must be sterilized

Microbiology Labs reducing germs

Routinely work with microbial cultures, rigorous methods of control, must eliminate microbial contamination to both experimental samples and environment

careful treatment both before and afteraseptic

CDC guidlines

BSL 1-4

Food and Production risk reduction

Perishables retain quality longer when contaiminating microbes destoryed, removed, inhibited

Heat treatment most common and reliable

Pharmaceuticals, cosmetics, deodorants

must not have microbial contamination

Selection of Antimicrobial Procedure

selection of effective procedure is complicated, choice depends on numerous factors, type and number of microbes, environmental conditions, risk of infection

Number of Microorganisms

time for heat, chemicals to kill affected population size

Decimal reduction time - D value gauges commercial effectiveness

Risk for infection

critical items must be sterile, semi-critical instruments must be free of viruses and vegetative

Some sterilization and disinfection methods inappropriate for certain items

Heat inappropriate for plastics

Irradiation provides alternative, but damages some types of plastic

Moist heat, liquid chemical