Microbiology Exam 1

Cellular

Archaea, bacteria, fungi, protozoans

Acellular

Viruses, Prions

Prokaryotes

No membrane bound organelles, contains nucleoid region

Eukaryotes

Membrane-bound organelles, has nucleus

Ubiquitous

Microbes are found everywhere

Prions

No nucleic acid, only protein, acts as infectious organism

Virus

Small amount of DNA or RNA, protein coat and sometimes a membrane

Louis Pasteur

Disproved abiogenesis

Louis Pasteur

Invented pasteurization

Louis Pasteur

Created Germ Theory of Disease

Robert Hooke

Studied objects, plants, and trees. Drew sketches of cell-like structures

Antonie von Leeuwenhock

Invented simple microscope to study fabric. Observed “animals in a drop of water”

Oliver Wendell Holmes & Ignaz Semmelweis

Pushed for handwashing in hospitalsJo

Joseph Lister

Used aseptic techniques & phenol during surgery

Robert Koch

Created Koch’s postulates

Koch’s Postulates

Steps to determine if an organism is pathogenic, and what disease it causes

Koch's Postulates

Showed that bacillus anthracis caused Anthrax

Carbohydrate

Made of monosaccharides

Protein

Made of amino acids

Nucleic acid

Made of nucleotides

Lipid

Made of fatty acids

Pentose Sugar, Nitrogenous Base, Phosphate

3 parts of a nucleotide

Pentose Sugar

Ribose in RNA, Deoxyribose in DNA

Adenosine Triphosphate

Stores energy for later inside cell

Adenosine Diphosphate + Energy

Created when ATP is broken down

CHO(N)(P)

What are organic macromolecules composed of?

Inoculation

introduction of a sample into a container of media to produce a culture of observable growth

Incubation

inoculated media are placed in a temperature and atmosphere controlled environment (incubator) to promote growth

(****during the hours or days of this process, a culture develops as visible growth of microbes in the container of the medium

Isolation

if an individual bactria cell is separate from other cells and has space on a nutrient surface, it will grow into a mound of cells (= a colony ---> consists of ONE species)

Inspection

cultures are observed for the macroscopic appearance of growth characteristics

*cultures are examined under the microscope for basic details such as cell TYPE AND SHAPE

pure culture

grows only single known species of microorganisms

mixed culture

two or more identified species/microbes growing

contaminated culture

pure or mixed culture that has unwanted microbes growing

*this is important because it BAD and can induce FALSE DIAGNOSIS

ex) fungi.

information gathering

testing of cultures with procedures that analyze biochemical and enzyme characteristics, immunologic reactions, drug sensitivity, and genetic makeup

**IMPORTANT to gather the most information about your identification in order to rule out other microorganisms.

Identification

the goal of these procedures is to attach a name to the microbe, usually to the level of species.

-appearance

-biochemical tests

-genetic characteristics

-immunological testing

Magnification

the ability to make things look larger than they are

Resolving Power

ability to show detail

Refraction

the bending of light passing through convex surface of glass

total magnification

objective lens x ocular lens

Resolution (resolving power )

the capacity to distinguish or separate 2 adjacent objects

What is the purpose of oil?

to prevent light scattering for an overall clearer image

*used only 100X objective

Purpose of Staining

-increase contrast

- distinguish between gram-positive and gram-negative bacteria.

Positive staining

surfaces of microbes are negatively/positively charged and attract basic/acidic dyes

Negative Staining

microbe repels dye, the dye stains the background

Simple Stains

one dye is used; reveals shape, size, and arrangement

Differential Staining

use a primary stain and a counter stain to distinguish cell types

Example: gram-staim, acid-fast stain, endospore

Gram stain

-its a differential stain used to classify bacteria as gram-negative or gram-positive

-most significant technique in Microbiology

Physical states of media

1. liquid: nutrient broth; does not solidify

2. solid (agar): a firm surface for colony formation

3. semi-solid: clot-like consistency, contains agar solidifying agent

Types of Media

general, enrichment, selective, and differential media

General Media

used to grow a variety of bacteria, no special growth factors

Enriched Media

contains complex organic substances such as blood, serum, hemoglobin, or special growth factors required by microbes

examples:

- blood agar (microbes lice through)

- chocolate agar (already liced)

Selective Media

contains one or more agents that inhibit growth of some microbes and encourage growth of the desired microbes

Differential media

allows growth of several types of microbes and displays visible differences among desired and undesired microbes

Endospore Stain

Used on clostridium and bacillus species

Green/Pink

What colors are endospores and vegetative cells after an endospore stain?

Flagellar stain

Binds to flagella, thickening & changing color

Pink/Blue

What colors are acid fast cells and non acid fast cells after an Acid fast stain?

Transmission electron microscope

Beam of electrons passes through specimen, excellent resolution of cellular details

Scanning electron microscope

Electrons pass over surface, produces 3-D images with great surface detail

2000x

Max magnification of light microscope

Magnification

Results from light or electron beam refracting as it passes through lens or magnetic field

Resolution

Ability to distinguish objects that are close together clearly

Contrast

Differences in intensity between 2 objects or an object and its background

1 um to 4+ mm

Protozoan size

3 to 10 um

Yeast size

200 nm to 750 um

Bacteria Size

20 to 400nm

Viruses

Synthetic/Defined Media

Same formula every time, every ingredient is known

Non-Synthetic/Complex Media

Contains extracts of animal, plant, or yeast products. Composition varies from batch-to-batch

Agar

Polysaccharide derived from Gelidium

Monotrichous

Describing a microorganism that bears a single flagellum.

Lophotrichous

Having a tuft of flagella at one or both poles

Peritrichous

having flagella distributed over the entire cell.

Fimbria

A short, numerous surface appendage on some bacteria that provides adhesion but not locomotion.

Conjugation

In bacteria, the contact between donor and recipient cells associated with the transfer of genetic material such as plasmids. Can involve special (sex) pili.

Nanotubes

Extensions of bacterial membranes that are channels for nutrient or energy exchange.

Capsule

In bacteria, the loose, gel-like covering or slime made chiefly of polysaccharides. This layer is protective and can be associated with virulence.

L form

A stage in the lives of some bacteria in which they have no peptidoglycan.

Bacterial chromosome

A circular body in bacteria that contains the primary genetic material. Also called nucleoid.

Endospore

A small, dormant, resistant derivative of a bacterial cell that germinates under favorable growth conditions into a vegetative cell.

Glycocalyx

A coating or layer of molecules external to the cell wall. It serves protective, adhesive, and receptor functions. It may fit tightly (capsule) or be very loose and diffuse (slime layer).

Nanotubes

Membrane extensions that allow bacteria to transmit electrons or nutrients to other bacteria or onto environmental surfaces

Plasmid

Double-stranded DNA circle containing extra genes

Lophotrichous

With small bunches or tufts of flagella emerging from the same site.

Amphitrichous

With flagella at both poles of the cell.

Peritrichous

Flagella are dispersed randomly over the surface of the cell.

Bacillus

Bacterial cell shape that is cylindrical (longer than it is wide).

Spirillum

A type of bacterial cell with a rigid spiral shape and external flagella.

Flagellum

A structure that is used to propel the organism through a fluid environment.

Palisades

The characteristic arrangement of Corynebacterium cells resembling a row of fence posts and created by snapping.

Appendages

Accessory structures that sprout from the surface of bacteria. They can be divided into two major groups: those that provide motility and those that enable adhesion.

Motility

Self-propulsion.

Pili

Long, tubular structures made of pilin protein produced by gram-negative bacteria and used for conjugation.

S layer

Single layer of thousands of copies of a single type of protein linked together on the surface of a bacterial cell that is produced when the cell is in a hostile environment.

Glycocalyx

A filamentous network of carbohydrate-rich molecules that coats cells.

Slime layer

A diffuse, unorganized layer of polysaccharides and/or proteins on the outside of some bacteria.

Biofilm

A complex association that arises from a mixture of microorganisms growing together on the surface of a habitat.

Cell wall

In bacteria, a rigid structure made of peptidoglycan that lies just outside the cytoplasmic membrane.

Peptidoglycan

A network of polysaccharide chains cross-linked by short peptides that forms the rigid part of bacterial cell walls. Gram-negative bacteria have a smaller amount of this rigid structure than do gram-positive bacteria.

Gram stain

A differential stain for bacterial useful in identification and taxonomy. Gram-positive organisms appear purple from crystal violet mordant retention, whereas gram-negative organisms appear red after loss of crystal violet and absorbance of the safranin counterstain.