Learning Objectives Key Terms (Midterm 1)

microbiology

the study of living organisms that individually are too small to be seen with the naked eye.

Bacteriology

study of bacteria

mycology

study of fungi

normal microbiota

1.  The microbes that live stably on or in the human body without causing disease under normal conditions 

bioremediation

1. using microbes to clean up toxic pollutants (oil, solvents, pesticides, heavy metals, etc.).

biocontrol

1. using microbes to control disease-causing plant pests.

pathogen

microbe that causes disease

opportunistic pathogen

Pathogens that cause disease when an opportunity presents itself

Healthcare associated infection or nosocomial infection

infection acquired while receiving treatment for other conditions at a healthcare facility.

mycoses

diseases caused by fungi

microcscopy

1. the use of light or electrons to magnify small objects.

light microscopy

1.  the use of a microscope that employs visible light to view a specimen.

electron microscopy

1.  uses a beam of electrons instead of light for visualizing microbes.

resolution

1. the ability of the lenses to distinguish two points as distinct and separate.

magnification

1. the process of enlarging an object in appearance only.

brightfield microscopy

1. the most common type of light microscopy that uses white light to visualize a specimen.

phase-contrast microscope

1. a type of light microscopy that utilizes a compound light microscope with a special condenser.

fluorescence microscopy

1.  microscopy that uses ultra-violet (UV) light to illuminate the specimen.

scanning electron microscope

1. the specimen is coated with a metal stain, and a primary electron beam is passed over the surface of the specimen. The secondary electrons are collected, amplified, and used to generate an image of the specimen.

transmission electron microscopy

1. an electron beam is passed through an ultrathin section of a specimen

fluorescence-antibody technique

1.  Fluorescence microscopy is used in a diagnostic technique that enables the rapid detection of pathogens in clinical specimens.

smear

1.  spreading a thin film of material containing the microbes on the surface of the glass slide

fixation

1. are made to attach to the microscope slide so that they do not get washed off during the staining process.

simple stain

1. use a single basic dye (eg crystal violet, methylene blue, safranin) to stain microbial cells.

differential stain

1. use two different coloured dyes that react differently with different types of bacteria, and thus are used to distinguish them.

acidic stain

1.  stain where the chromophore is the (-) ion. Commonly used to stain the background surrounding bacterial cells.

basic stain

 stain where  the chromophore is the (+) ion. Commonly used by bacterial cells

gram stain

1. This is one of the most useful staining procedures as it classifies bacteria into two main groups:

gram-positive

1.  Bacteria that retain the purple colour at the end of the procedure

gram-negative

1.  Bacteria that lose the purple colour after the decolourizations step

acid-fast stain

1. classifies bacteria as acid fast or non acid fast.

negative stain

1. staining procedure to visualize capsules

glycocalyx

1.  a viscous, gelatinous polymer that consists of polysaccharides and/or polypeptides

capsule

If the glycocalyx is organized and firmly attached to the cell surface

Extracellular polymeric substance (EPS):

1. glycocalyx is unorganized and loosely attached to the surface

flagella (flagellum)

1. long, filamentous structures that some bacteria use for motility.

fiambriae

1. can be found at the poles of a cell or can be evenly distributed over the entire surface. function in the attachment of cells to various surfaces, including epithelial surfaces in the body, and they contribute to the formation of biofilms and other aggregates.

pili (pilus)

l onger than fimbriae, and there are only 1-2 per cell. Involved in cel; motility

axial filaments

1. used by spirochetes for motility. consist of bundles of fibrils that attach to one end of the cell and spiral around the cell beneath an outer sheath

peptidoglycan

1. The main structural component of the cell wall. 

porin protein

1. proteins that form channels in the outer membrane. They enable essential nutrients such as nucleotides, disaccharides, peptides, amino acids and iron to cross the outer membrane.

teichoic acids

1. polymers made of an alcohol (e.g. glycerol) and phosphate. In Gram positive cell wall. Two types

wall teichoic acids

1. which are bound to the peptidoglycan layer.

lipoteichoic acids

1. span the peptidoglycan layer and are anchored in the plasma membrane.

Lipopolysaccharide

1. is a molecule composed of: Lipid A, Core polysaccharide, O polysaccharide

Lipid A

1. is embedded in the top layer of the outer membrane. It is released when Gram-negative cells multiply and when they die.

endotoxin

1.  is responsible for the signs and symptoms associated with Gram-negative bacterial infections

core polysaccharide

1.   attached to lipid A and is composed of unusual sugars. It functions to provide stability to the LPS.

O-antigen

 antigen from O polysaccharide is made of sgar molecules. Ca be used to distinguish different serovars of gram-negative bacteria

lysozyme

 is present in perspiration, tears, mucus and saliva. It hydrolyzes the bonds between the NAG and NAM residues in peptidoglycan backbone, destroying the peptidoglycan and cell wa

sterol

1. lipids in plasma membranes among bacteria that help protect cells from lysis.

phospholipids

1.   in membranes are arranged as a bilayer. 

selective permeability

1.  regulate what moves in and out of the cell.

fluid mosaic model

1. dynamic arrangement of phospholipids and proteins

passive process

1.  involve the movement of substances with the concentration gradient (ie from an area of high concentration to an area of low concentration) without using energy (ATP).

active process

1.  involve the movement of substances against their concentration gradient (i.e. from an area of low concentration to an area of high concentration).

simple diffusion

1.  the movement of molecules across a membrane without the need for integral membrane proteins 

Facilitated diffusion

1. when integral membrane proteins (called transporter proteins) “facilitate” movement of molecules across the membrane.

osmosis

1.  the net movement of water molecules across a membrane from an area of high concentration to an area of low concentration via aquaporins or simple diffusion

Isotonic solution:

1.  a solution that has the same solute concentration as that found inside a cell;

hypertonic solution

1.  a solution that has a higher solute concentration compared to that inside a cell;

hypotonic solution

1. a solution that has a lower solute concentration compared to that inside a cell

osmotic lysis

1.  swelling and the cell will burst

plasmolysis

1. cytoplasm of the cell to shrink

active transport

1.  transport requires energy and transporter protein

ribosomes

1. structures that function in protein synthesis.

cytoplasm

1. refers to the cell substance inside the plasma membrane.

nucleoid

1.  the area of the cytoplasm containing the bacterial chromosome, which is usually a single, circular DNA molecule.

plasmid

1. small, circular, DNA molecule in the cytoplasm of sme bacteria

endospores

1. specialized resting cells made by certain Gram-positive bacteria. Formed internal to the plasmic membrane, can remain dormant for thousands of years. Enables survival under harsh conditions, not reproduction.

organelle

1. membrane-enclosed structures with characteristic shapes and functions.

nucleus

spherical or oval-shaped organelle that contains the DNA of the cell

histone

1. basic proteins that are not found in prokaryotes.

rough endoplasmic reticulum

1.   Looks rough because the outer surface is studded with ribosomes.Makes secreted proteins and membrane proteins (e.g. glycoproteins).

smooth endoplasmic reticulum

1. :No associated ribosomes.Functions in synthesis of phospholipids, fats and steroids

Golgi complex

1.  organelle made of 3-20 stacked, flattened membranous sacs (cisterns).It functions as a transport organelle (is often referred to as the “Post Office” of the cell).

mitochondria

elongated organelles that produce ATP. Surrounded by a double membrane.

lysosome

1.  only found in animal cells. Contains digestive enzymes that can break down bacteria.

chloroplast

1. : present in algae and green plants, serves as the site of photosynthesis.

endosymbiotic theory

1.  Ancestral prokaryotic cells lost their cell walls. Infoldings of plasma membrane around DNA led to formation of the nucleus. Smaller photosynthetic bacteria were engulfed and became chloroplasts. Smaller aerobic bacteria were engulfed and became mitochondria.

bacterial growth

1.  an increase in the number of microbial cells, resulting in an increase in the population of microbes.

psychrophile

1. grow from -10°C to 20°C, with an optimum temperature of 15°C; live deep in oceans and in polar regions.

psychotroph

1. grow from 0°C to 30°C, with an optimum temperature of 20°C to 30°C; microbes in this group grow well at refrigeration temperatures and are common food spoilage organisms.

mesophile

1.  are the most common type of microbe; grow from 10°C to 50°C, with an optimum temperature of 25°C to 40°C; most pathogens are in this group and grow best growth at 37°C (human body temperature

thermophile

1.  grow from 40°C to 60°C, with an optimum temperature of 50°C to 60°C; some produce endospores that survive heat treatments given to canned foods, and thus can contribute to spoilage if such foods are not stored properly.

acidophile

1.  Bacteria that can tolerate and grow at low pH 

obligate halophile

1. require high [salt] (up to 30%) for growth. 

facultative halophile

1.  (salt tolerant) do not require high [salt] but can grow in the presence of high [salt] (e.g. 2-10%). 

autotroph

1.  acquire their carbon from atmospheric CO_2.

chemoheterotrph

1. use organic molecules (e.g. sugars) as both their carbon and energy source.

obligate aerobe

1. require O₂ for growth

obligate anaerobe

1. cannot use O₂, and most are killed by it

aerotolerant anaerobe

1.   cannot use O₂, but can tolerate it

microaerophile

1.  need O₂ at levels lower than in air

catalase

1.  destroys H₂O₂:

peroxidase

1. destroys H₂O₂ without producing oxygen:

biofilm

1. microbes are rarely living as isolated individual species; instead, they commonly live as communities

Quorum sensing

1.  The cells within a biofilm communicate with each other and coordinate their activities using chemical signals,