Microbiology exam 1-FAU

List the possible definitions for microorganisms - in terms of size, cellular structure, culturability and their ability to cause diseases.

Bacteria, Algae, Protozoa, Helminths, Fungi, Viruses

List the different eukaryotic groups.

a. Algae, protozoa, and fungi

Which group of microorganisms may be described as being cellular and acellular?

Fungi

Medical Microbiology:

deals with microbes that cause diseases in humans and animals

Public health/ epidemiology:

monitor/control the spread of diseases in communities

immunology studies

complex web of protective substances and cells produced in response to infection (vaccinations)

Industrial microbiology:

safeguard our food and water

Agricultural microbiology:

relationships between microbes and domesticated plants/animals

Environmental microbiology:

study the effects of microbes on the earth's diverse habitats

5. List the benefits of microorganisms in helping to shape planet earth.

-the production of oxygen by microbes allowed species diversification

-account for more than 70% of Earth's photosynthesis

-breakdown dead matter and waste

-microbes are the main forces that drive the structure and content of soil, water, and atmosphere

-Microbes can restore stability or to clean up toxic pollutants

6. How did the earth's atmosphere get majority of its oxygen?

a. Anoxygenic photosynthesis-70% of the earth's oxygen comes from photosynthetic microorganisms (mostly bacteria & algae)

7. How did Bacteria, Archaea and Eukarya evolve and when did representative cells from each group appeared on planet earth?

Bacteria, archaea, and eukarya arose from the last universal common ancestor LUCA, single celled organisms arose 3.5 billion years ago and were only living inhabitants until 2.9 billion years ago.

8. Compare and contrast the characteristics of Bacteria and Archaea?

a. Both are 10x smaller than eukaryotes, both lack organelles, both prokaryotes, archaea cell walls lack peptidoglycan, archaea have a more complex RNA polymerase similar to eukaryotes

9. What critical genetic component of microorganisms helped to categorize them into Bacteria, Archaea and Eukarya.

a. Woese-Fox system of taxonomy, pre-nucleus (Archaea and bacteria) and true nucleus (Eukaryotes)

10. What is an anexic medium?

a. A medium free of other living things except for the one being studied

11. Describe the different media types based on their physical, chemical and functional properties.

a. Physical: liquid, semisolid, solid

b. Chemical: synthetic (chemically defined), complex (not chemically defined)

c. Functional type: general purpose, enriched, selective, differential, anaerobic, specimen transport, assay, enumeration

Water based solutions

Water-based solutions that do not solidify at temps above freezing and flow freely in a tilted

Semi solid media

medium used to determine motility of a bacterium

Solid media

-Provides a firm surface upon which cells can form discrete colonies

-Used to isolate bacteria and fungi

Agar

a gel-like polysaccharide compound used for culturing microbes; extracted from certain red algae

Defined (synthetic) media

all components and their concentrations are known

Complex media

extracts and digests of yeasts, meat, or plants

-may contain ground-up cells, tissues, or secretions

General purpose media

grows a broad range of microbes as possible

Enriched media

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

Selective media

designed for special microbial groups, permit preliminary identification of a genus or even species of a bacteria

e.g - MSA

Differential media

Allow multiple types of microorganisms to grow, but display visible differences between colonies; (differences in colony size or color, media color changes, or formation of gas bubbles or precipitates)

12. What are the five I's of studying microorganisms?

a. Inoculation, incubation, isolation, inspection, identification

13. What processes are involved in the microbial Identification process.

a. The process of discovering/recording the traits of organisms so they can be organized / named and placed in a taxonomic group.

14. What are the properties of a solid medium.

-Provides a firm surface upon which cells can form discrete colonies

- used to isolate bacteria and fungi.

15. What are the characteristics of selective and differential media?

a. Selective: Contains one or more agents that inhibit the growth of certain microbes

b. Differential: Allow multiple types of microorganisms to grow, but display visible differences between colonies

ocular lens (eyepiece)

remagnifies the image formed by the objective lens

body tube

Connects the eyepiece to the objective lenses

Objective lenses

primary lenses that magnify the specimen

mechanical stage

holds the microscope slide in place

Condenser

focuses light through the specimen

Diaphragm

controls the amount of light entering the condenser

illuminator

light source

fine focusing knob

Focusing the image to fine detail.

light intensity

adjusts current to lamp

17. What is the sequence of magnification in a typical compound light microscope - with regards to the order of lenses participating in the magnification process?

a. 4x, 10x, 40x, 100x

Contrast

The degree of contrast between a magnified image and its surroundings is measured by a quality called the refractive index, The higher the refractive index, the greater the contrast

Magnification

A clear, glass sphere can magnify most objects, Results from a complex interaction between visible light waves and the curvature of a lens

Refraction

Defined as bending or change in the angle of the light ray as it passes through a medium, such as a lens, The greater the difference between the two substances, the greater the refraction

Resolution

The capacity of an optical system to distinguish or separate two adjacent objects or points from one another

How can a clearer image be achieved with a compound light microscope?

a. Fine adjustment knob or by oil immersion lens

Bright field microscopy

specimen will produce an image darker than the surrounding brightly illuminated field

dark field microscopy

brightly illuminated species surrounded by a dark(black) field

phase contrast microscope

light microscope that enhances contrast; useful in examining living, unstained cells

-contains devices that transform subtle changes in light waves passing through the specimen into differences in light intensity

Differential Interference Contrast microscopy

provides 3D images. no staining required

21. What is the purpose of staining in microscopy?

Provides contrast, makes inconspicuous features stand out, Dyes impart colors to cells by becoming affixed to them through a chemical reaction

Dyes used in microbial staining:

Basic: have a positive charge, attracted to acidic, negatively charged components on bacterial cell walls.

Acidic: have a negative charge, repelled by acidic, negatively charged components on bacterial cell walls

22. What are the differences between simple and differential staining?

a. Simple: Require a single dye, Uncomplicated procedure

b. Differential: Use two different colored stains to clearly contrast cell types or cell parts

List specific examples of certain types of differential staining techniques?

a. Gram stain, Acid-fast stain, Endospore stain, Capsule stain

Cytoplasmic membrane

controls the flow of materials in and out of the cell pool; a thin sheet of lipid and protein; transports food

Nucleoid (chromosome)

composed of condensed DNA molecules, DNA directs all genetics and heredity of the cell and codes for all proteins

Ribosomes

Makes proteins

Cytoplasm

A jellylike fluid inside the cell in which the organelles are suspended

Fimbriae

adhesive factor; virulence factor

outer membrane

gram-negative; controls flow of materials and portions are toxic to mammals

pilus

sex structure; transfer plasmid genes to help other bacteria survive; conjugation (asexual)

Capsule

forms biofilms (protect, adhesive, receptive); virulence factor

Plasmid

holds extra genes

Flagellum

specialized appendage attached to cell body; provides motility

S layer

used for protection and/or attachment

Which parts of a typical pathogenic Bacteria may interact with the host in the establishment of a disease.

-Pilus: transfers bacterial DNA

-Fimbriae: sticks onto the host cell

26. How can sterility be achieved?

-Autoclaving, Dry heat, radiation, chemicals, high pressure, and filtration

27. What are the major differences between a Gram positive and a Gram negative Bacteria?

-Gram positive bacteria have a thick layer of peptidoglycans causing them to stain purple

-Gram negative bacteria have a thin layer of peptidoglycans causing them to stain pink

28. What are the differences between a hypertonic and a hypotonic solution?

Hypotonic: a solution that contains more solute than solvent

Hypertonic: a solution that contains more solvent than solute

29. What happens to a cell when it is placed in a hypertonic, hypotonic or an isotonic environment?

Cells in a hypotonic state swell, hypertonic shrink , and isotonic is a balance between both.

30. How did the chloroplast and mitochondria develop in eukaryotic cells?

-most likely evolved from engulfed bacteria from the theory of endosymbiosis

31. Compare and contrast the characteristics of Bacteria and eukaryotic cells.

Eukaryotic cells contain membrane bound organelles, plants, fungi, and animals Bacteria: prokaryotic single celled archaea that has no membrane bound organelles

32. Describe the different cell wall types in microorganisms.

-Bacteria: cell wall made up of peptidoglycans

-Archaea: cell wall distinct from bacteria/eukaryotes; mostly made up of Hydrocarbons

33. Contrast the nature of eukaryotic cell membranes to that of prokaryotes.

Eukaryote: Protect cell from its surrounding and controls movement of substances in and out of the cell and organelles, selectively permeable

Prokaryote: plasma membrane and cytoplasm

Describe the morphological characteristics of the Fungal group.

Lack flagella,walls of hyphae made of chitin, and heterotrophic

35. Differentiate between a septate and a non-septate hypae.

Septate: contain dividers between cells allow for the flow of cytoplasm and nutrients through the mycelium.

Non-septate: form one long cell with many nuclei.

36. What is the mode of nutrition in most Fungi?

Decompose organic dead matter

37. Differentiate between Fungal spores and Bacterial endospores.

Fungi spores are used for reproductive means and bacterial endospores are nonreproductive.

38. List and describe the major asexual Fungal spores and their differences.

Sporangiospores: formed by successive cleavages within a sporangium

Conidiophores: free spores not enclosed by a spore bearing sac

39. List some examples of specific culture media for Fungal isolates.

Isolation on special media, hyphal type, colony texture, pigmentation, genetic makeup

40. List one example each of superficial and systemic diseases that can be caused by Fungal agents in human tissues.

-Superficial diseases: candida albicans and yeast infections

-Systemic diseases: cryptococcus neoformans and cryptococci

List other economic and industrial impacts of the Fungal group.

Negative impact: many are pathogenic to corn and grain

positive: essential in decomposing organic matter and returning it in the soil, production of antibiotic, food flavoring