Characteristics Of Microorganisms Flashcards
Bacteria
Makes up a large group of one celled MO’s; vary in size shape, and arrangement of cells; grows best at 98.6 F in moist, Dark environment.
Viruses
Small in size and cause fatal diseases; this MO can live and multiply only inside an appropriate host cell.
Protozoa
Large group of one celled organisms; do not have a rigid cell wall; found in freshwater, marine habitat, and moist soil; small number, are responsible for intestinal infections of humans and other invade, the blood, lungs, liver, or brain.
Fungi
Mushrooms, yeast, and mold; oral candidiasis is a common form of this group, and mos found in the dental office.
Prokaryotic cells
Primitive cells
No internal membrane
No nucleus
Example: bacteria
Eukaryote cells
Complex cells
With internal membranes
Have a nucleus
Example: Protozoa, algae, fungi, plants, and animals.
Flagella
Long, thin extension that provides mobility. (propeller).
Frimbiae, pili
Hair-like projections with fine short appendages that allow bacteria to adhere.
Cytoplasmic membrane
Regulates amount of molecules entering or leaving a cell.
Surrounds the cytoplasm; transport nutrients; energy metabolism.
Composed of lipids and proteins.
Anti-microbial agents, handwashing agents at the mouth rinses kill or inhibit the growth of bacteria by acting on the cytoplasmic membrane.
Mesosomes
Present mostly in gram-positive bacteria
At inward folding of the cytoplasmic membrane.
Cytoplasm
Contained within cytoplasmic membrane.
Cell wall
Gives cell its shape; rigid; protection from Mechanical damage.
Outer membrane of Gram-negative bacteria
Contains endotoxin; transporting nutrients.
When endotoxin is released from bacteria present in the body, it can cause damage to nearby body cells.
Capsule
Gelatinous covering produced by the cytoplasmic membrane.
Protection from drying, antiphagocytic; attachment to surfaces.
The presence of capsules reduces the ability of WBC to surround in golf and destroy the bacterium through phagocytosis.
Granules
Function as an energy reserve.
Ribosomes
Contain RNA and proteins (proteins synthesis).
Nucleoid
Contains DNA
Is embedded in the cytoplasm.
Endospores
Thick wall-like structure
One of the most resistant forms of life against heat, drying and chemicals.
Defence mechanism /protection against adverse conditions.
Plasmids
Extra chromosomal, DNA
Give ability of bacteria to grow by being resistant to physical and chemical agents and antibiotics.
Cilia
Provides movement and permits, faster mobility than flagella.
Plasma (cytoplasmic) membrane
Permits movement of molecules across the membrane by active and passive transport; endocytosis and exocytosis occurs at the site.
Endocytosis
Taking in of matter
Exocytosis
Contant released to exterior
Endoplasmic reticulum
Fluid filled channels that synthesize lipids (smooth) and proteins (rough)
Smooth ER
Lacks ribosomal attachment, and appears smooth
Rough ER
Contains ribosomes and appears rough
Vacuoles
Function to gather food
Vesicles
Surrounds proteins; that occur in endocytosis and exocytosis.
Ribosomes
Produce protein
larger in eucaryotic cells than prokaryotic cells.
Mitochondria
Function as the powerhouse
Chloroplasts
Function in photosynthesis
Golgi complex
Function to package protein; especially important for proteins destined for secretion.
Lysosomes
Membraneous sacs that contain digestive enzymes.
Nucleus
Contains genetic DNA material
Cell morphology (size and shape)
Spears or cocci (singular coccus) spherical shape.
Rods or bacilli (singular bacillus) rod shaped.
Spirilla or spirochetes (singular spirillum) spiral shaped.
Binary fission
Cells divide
Each cell divides into two daughter cells
Five major chemical or physical conditions, influence growth of bacteria
1) Temperature
2) acidity
3) nutrients
4) oxygen metabolism
5) water
Three groups based on temperature
Thermophiles; grow best at 56°C with the range from 45 to 70°C
Mesophiles; grows best at body temperature 37°C with the range from 20 to 45°C
Psychrophiles; optimal growth refrigerator, temperature 7°C with the range from 1 to 22°C.
Acidogenic
Bacteria that produce acids during growth
Aciduric
Bacteria that survive and grow in an acidic environment (usually below pH 5.5)
Proteases
Enzymes released into the environment that break down proteins into amino acids that can enter the cell.
Obligate aerobes
Require oxygen at 20% concentration
Microaerophiles
Tolerate low, 4% oxygen concentration
Obligate anaerobes
Cannot tolerate oxygen
Facultative anaerobes
Can grow with or without oxygen
Bactericidal agents
Kill bacteria (chemical, or physical means)
Bacteriostatic agents
Prevent growth without killing them
Classification of viruses
1) Their type of nucleic acid: DNA or RNA
2) the symmetry of the virus: helical, polyhedral, spherical, complex.
3) whether or not, there is an envelope surrounding itself (envelope or non enveloped).
Transmission of viruses
1) droplets (sneezing)
2) direct transfer (touching)
3) contaminated, food, or water
4) insects
Fungi include
1) Mushrooms
2) molds
3) yeasts
Common protozoa diseases
Malaria
