Den 111 (chpt 1-2)

microbiology

1. the study of small life forms including bacteria, special fungi (mold and yeast), certain algae, protozoa, and viruses

bacteriology

study of bacteria

mycology

study of fungi

protozoology

study of protozoa

virology

study of viruses

infection control

preventing microbial contamination and infection

who first discovered microorganisms?

Antoni van Leeuwenhoek first observed microorganisms

pasteurization

destroying pathogens in milk or other fluids by heating it to 63 degrees Celsius for 30 minutes or to 72 degrees Celsius for 15 seconds

bacteriophages

viruses that lives within bacteria

phages = to devour

“bacteria eaters”

only attack bacteria

where can bacteriophages be found

found in soil, sewage, waste and other places where bacteria live to keep bacteria at a minimum.

who recognized the use of heat to destroy vegetative bacteria and resistant bacterial spores

Louis Pasteur and John Tyndall

who first recognized the importance of handwashing to prevent the spread of disease agent?

ignaz semmelweis and Oliver Holmes

who is known as the father of oral microbiology

willoughby d miller and lord joseph lister

prion

proteins that able to induce abnormal folding of normal cellular prion proteins in the brain

beneficial activities of microbes

composting

probiotics for intestinal health

yeasts in baking

beer production

cheese, pickles, yogurt, sour cream

bacteria that appear blue or purple are called

gram-positive

bacteria that appear pink or red are called

gram-negative

spherical bacteria cells

cocci

rod shaped bacteria cell

bacilli

curved or spiral bacteria cell

spirilla

metabolism

the physical and chemical changes that occur during bacterial growth (multiplication or increase number of cells)

enzymes

catalyst that chemically change a substance, such as breaking down proteins into amino acids

speeds up metabolic reactions

function/activity of cytoplasmic membrane

transport of nutrients

energy metabolism

secretion of waste

DNA synthesis

cell wall synthesis

surrounds the cytoplasm

function/activity of cell

gives the cell its characteristic shape

protection from mechanical damage

function/activity of outer membrane (of gram-negative bacteria)

covers the cell wall

contains endotoxins

transport of nutrients

function/activity of capsule

protection from drying

antiphagocytic

attachment to surfaces

covers entire outer surface of the wall

function/activity of flagella

locomotion

used for transportation

function/activity of fimbriae (pili)

attachment to surfaces

transport of DNA between cells

function/activity of nucleoid

DNA control of cell activities

consists of DNA that contains most of genes controlling cell activities

function/activity of endospore

protection against adverse conditions

makes a dense thick-walled structure.

most resistant forms of life against heat, drying, and chemicals

Binary fission

cell divides into two daughter cells, in the next generation each of these daughter cells divides into two similar cells and this continues until the environmental conditions no longer support growth because of lack of nutrients, buildup toxic products, changes in pH, temperature and availability of oxygen.

what do bacteria need for growth

temperature

acidity

nutrients

oxygen metabolism

water

thermophiles

grow best at 56 degrees celsius

mesophiles

grow at a temp ranging from 22 degrees Celsius to 45 degrees celsisus

bacteria that grow and survive in the human body including those that cause infectious diseases (dental caries, periodontal disease, tuberculosis, bacterial pneumonia, tetanus)

psychrophiles

grow at temps from 1 degree Celsius to 22 degrees Celsius

bacteria that are present in the ocean and that spoil food stored in a refrigerator

acidogenic

bacteria that produce acids during growth

aciduric

bacteria that live in highly acidic environments

trace elements

iron - transports oxygen

iodine - formation of thyroid hormones

copper - responsible for function of RBC and bone and connective tissue

zinc - formation of enzymes, helps blood clot. important in immune function

chromium - function of insulin

selenium - antioxidant

water

all life forms require water. it dissolves nutrients and facilitates entrance or transport of nutrients into the cell.

proteases

enzymes released into the environment that break down proteins into amino acids that can enter the cell

obligate aerobes

require the presence of oxygen

microaerophiles

can tolerate conditions at low oxygen concentrations

obligate anaerobes

cannot tolerate oxygen and only grow in its absence

facultative anaerobes

can grow either in the presence of absence or oxygen.

culturing bacteria

culturing = growing

can be liquid (broth) or semi-solid (agar)

agar

seaweed derivative with added nutrients

catabolism

breakdown of nutrients into smaller molecules

anabolism

simple molecules that combine to generate complex molecules

fermentation

an anaerobic process that usually involves the breakdown of sugars with end products of organic acids or alcohols

bacterial metabolism (fermentation)

enzyme breaks down sugar molecule into pyruvic acid

pyruvic acid is converted into lactic acid

lactic acid is then released from the bacterial cell as waste product

that lactic acid waste is what causes the teeth to decay

preventing growth

changing or eliminating a physical or nutritional requirement for growth or by using a chemical agent that interferes with cell division

bacteriostatic

agents or conditions that prevent bacterial growth without killing them

killing bacteria

accomplished by physical or chemical means and is an important aspect of disease prevention and infection control

bactericidal

killing bacteria

virucidal

killing viruses

fungicidal

kills fungi

structure of viruses

smaller than bacteria

structure consists of nucleic acid spore, capsid (surrounded by a protein coat), some also have an envelope (outer structure of lipids, proteins and polysaccharides), and host cell attachment sites (portion of the virus that binds to human cells)

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virus life cycle

not free living

need host to survive

Viral lytic cycle

1. virus attaches to a cell
2. virus penetrates cell membrane and inject nucleic acid into cell
3. viral nucleic acid replicates using host cellular machinery
4. new viral nucliec acids are packaged into viral particles and released from the cell. host cell may be destroyed in the process

persistant viral infections

latent (dormant/hidden), chronic, or slow

examples: herpes simplex, hepatitis B

host cell transformation

some viruses infect host cells and affect the properties of cells without causing lysis

new properties may result in uncontrolled cell growth (tumors, cancer)

apotosis

programmed cell death

fungi

include mushrooms, mold, yeasts

most important fungus in dentistry

oral candidiasis (thrush or denture stomatitis)