Week 2 Charachteristics Of Micro Organisms Flashcards
Major Groups Of Microorganisms
(MOs)
Bacteria, viruses, Algae. Protozoa,fungi
Protozoa & Fungi
Micro organisms
- Protozoa - large group of one-cell organisms; do not have a rigid cell wall; found in freshwater, marine habitat & moist soil; small number are responsible for intestinal infections of humans and others invade the blood, lungs, liver, or brain
- Fungi - mushrooms, yeast, & mold; oral candidiasis is a common form of this group of mo’s found in the dental office.
Prokaryotes vs. Eukaryotes
1.Prokaryotes cells: Primitive cells
NO internal membrane
NO NUCLEUS
Eg.Bacteria
2.Eukaryote cells: Complex cells
With internal membranes.
HAVE A NUCLEUS
e.g. protozoa, algae, fungi, plants and animals.
Viruses are not in these 2
Prokaryotic Cell
Eukaryotic cell
Prokaryotic Cell
Flagella - long, thin extension that provides mobility. (propeller)
• Fimbriae, Pili - hair-like projections with fine short appendages that allow bacteria to adhere
• Cytoplasmic Membrane - regulates amount of molecules entering or leaving the cell.
• surrounds the cytoplasm; transport of nutrients; energy metabolism
- composed of lipids & proteins
- antimicrobial agents, hand washing agents, and mouth-rinses kill or inhibit the growth of bacteria by acting on the cytoplasmic membrane
• Mesosomes:
• Present mostly in gram-positive bacteria
• - are inward foldings of the cytoplasmic membrane
Prokaryotic contd
• Cytoplasm -contained within cytoplasmic
• membrane
• - aqueous solution which contains water, proteins, carbohydrates and inorganic salts.
Cell wall:
• - gives cell its shape; rigid; protection from mechanical damage
• Outer membrane of gram - negative bacteria:
• Contains endotoxin; transport of 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, engulf, and destroy the bacterium through phagocytosis
Prokaryotic Cell, continued
Granules - function as an energy reserve
• Ribosomes - contain RNA and proteins (protein synthesis)
• Nucleoid - contains the DNA
- is embedded in the cytoplasm
• Endospores:
• Thick wall-walled 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 & chemical agents, and antibiotics
Eukaryotic Cell
•Cell Wall-maintains rigidity of the cell
• Flagella-provides mobility; each flagella contains hollow filaments called microtubules
Cilia-provides movement and permits faster mobility than flagella
Plasma (Cytoplasmic) Membrane-permits movement of molecules acros membrane by active and passive transport; endocytosis and exocytosis occurs at this site
• Endocytosis - taking in of matter
• Exocytosis - content released to exterior
Endoplasmic Reticulum
• 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.
Granules
• Granules-contain polysaccharides (starch) and lipids
Vacuoles
• Vacuoles- function to gather food.
Vesicles
Vesicles - surrounds proteins; that occur in endocytosis and exocytosis
Ribosomes
Ribosomes - produce protein, also is
- larger in eukaryotic cells than prokaryotic cell
Mitochondria
Mitochondria - function as the powerhouse
Chloroplasts
Function in photosynthesis
Golgi Complex
Golgi Complex - function to package protein; especially important for proteins destined for secretion
Lysosomes
Lysosomes - membranous sacs that contain digestive enzymes
Nucleus
Contains genetic DNA material
Characteristics Of Bacteria Cell
Size:
~ Smallest of the unicellular organisms (single celled)
~ Approx. 1-1.5 micrometers wide and 2-6 micrometers long.
~ Bacteria have a very rapid metabolic rate due to large surface
area to volume.
A staining procedure developed by Dr. Christian Gram differentiates bacteria into:
1. Gram -positive (blue /purple) have cell walls composed of a thick layer
- Gram -negative(pink / red) bacteria have cell walls with a thin layer
Cell Morphology (size and shape)
3 basic shapes:
- Spheres or cocci(singular coccus) - spherical shape.
- Rods or bacilli (singular bacillus) - rod shaped.
- Spirilla or spirochetes (singular spirillum) - spiral shape.
Bacterial growth is defined as an increase in cell numbers.
When these cells divide what’s that process called ?
Binary Fission
Each cell divides into 2 daughter cells
Common morphologies of Prokaryotic cells are :
:(A) Staphylococcus aureus (cocci)
(B) Bacillus subtilis (rods), and
(C) Treponema denticola (spirals) compared to
(D) human red blood cells. B subtilis has been mixed with the red blood cells in D for size comparison.
Five major chemical or physical conditions influence
growth of bacteria:
- Temperature
- Acidity: *pH of 5.5 - 8.5, optimal growth @ pH 7.0
- Nutrients
- Oxygen metabolism
- Water
Temperature
Growth of Bacteria
3 groups
• Thermophiles: grow best at 56 degree Celsius, with a range from 45 - 70 degrees Celsius
• Mesophiles: grow best at body temperature (37 degree
Celsius), with range from 22-45 degrees Celsius
• Psychrophiles: optimal growth at refrigerator temperature (7 degrees Celsius), with range from 1- 22 degrees Celsius
Acidity
• Most bacteria that survive in the human body grow over a pH range from 5.5 to 8.5, with optimal growth at pH 7.0.
• Acidogenic: bacteria that produce acids during growth
• Aciduric: bacteria that survive and grow in an acidic environment usually below pH 5.5)
Dental caries:
Nutrients
• Bacteria must synthesize all of the macromolecules of protein, polysacharides, lipids, and nucleic acids ( DNA and RNA) needed to grow.
• These macromolecules are synthesized from the building blocks of amino acids, monosaccharides, fatty acids, etc.
• Bacteria also must use a variety of smaller molecules, such as vitamins and inorganic substances.
• Many bacteria make extracellular proteases, which are enzymes released into the environment that break down proteins into amino acids that can enter the cell.
Oxygen metabolism
• Obligate Aerobes-
• Obligate Aerobes- require oxygen at 20%
concentration
Oxygen metabolism
Microaerophiles
• Microaerophiles: tolerate low (4%) oxygen concentration
Oxygen metabolism
Obligate Anaerobes
Can NOT tolerate OXYGEN
Oxygen metabolism
Facultative Anaerobes
• Facultative anaerobes- can grow with or without oxygen
Bacteriostatic Agents
Prevent Growth
Characteristics of Viruses
Size:
~ extremely small; about one-tenth the size of bacteria ~ composed of a nucleic acid core (DNA or RNA), surrounded by a protein coat, called a capsid.
Some viruses also have an outer structure of lipids. proteins, and polysaccharides, called the envelope.
• * Viruses depend on a host cell for growth and replication
“obligate intercellular parasites
Life cycle of a virus
6 steps
- Attachment or adsorption: virus binds to host cell surface (in order to replicate & infect a host)
- Penetration: virus enters host cell
- Uncoating: Capsid is degraded to release nucleic acid
- Replication or syntheses of virus: virus uses host mechanisms to replicate, synthesize new viral nucleic acid & capsid
- Assembly: capsid surrounds nucleic acid
- Release from Host Cell: after invading host cell it must be able to release from host cell and replicate elsewhere
Classification of Viruses
- Their type of nucleic acid: DNA or RNA
- The symmetry of the virus: helical, polyhedral, spherical, complex
- Whether or not there is an envelope surrounding itself (enveloped or non-enveloped)
Transmission of Viruses
Human viruses may be transmitted by:
1. Droplets (e.g. sneezing)
2. Direct Transfer (e.g. Touching)
3. Contaminated food or water
4. Insects
** Most common route of transmission is through droplets. Many viruses will invade the respiratory tract by entering the nasal cavity. ***
Characteristics of Protozoa
Size:
• They are the largest microorganism encountered in microbiology
Characteristics:
• Composed of a single cell, free living and thrive in water
• Contain no chlorophyll in their cytoplasm so cannot produce carbohydrates by photosynthesis
• Important as decomposers and recycle organic material and important in our food chain
• Protozoa can be found in the stomach and break down cellulose and produce nutrients for their host
Common Protozoa Diseases?
Malaria
Fungi
Fungi include:
1. Mushrooms
2. Molds
3. Yeasts
Characteristics of Fungi
• Are eukaryotic cells
• Contain a nucleus and nuclear membrane but lack chlorophyll
• Most are Aerobic (requires O, for growth)
• exception to some yeasts that can grow anaerobically and ferment to alcohol (Brewers yeast)
1. A yeast form: unicellular form
2. A mold: elongated cells and produce spores that can be airborne and transmitted
Characteristics of Algae
• Consist of unicellular or multi-cellular organisms.
• Contain chlorophyll.
• Have one or more flagella.
• Are found in abundance in both freshwater or marine habitants.
• Has a typical membrane-bound nuclei and cytoplasmic organelles.
• Most do not produce human disease.
