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Exam 1
review questions
112
Microbiology
Not Applicable
02/08/2010

Additional Microbiology Flashcards

 


 

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Term
What is microbiology?
Definition

the study of very small living things

 

a set of techniques for studying very small organisms

Term
What types of organisms are studied by microbiologists?
Definition
Microbiologists study microorganisms including, but not limited to bacteria, viruses, protozoa, fungi and helminthes; basically, the very small members of the Three Domainds of living things.
Term
What are the three domains of living things?
Definition
Bacteria + Archaea + Eukarya
Term
What is the basis for placing organisms in one of the three domains?
Definition
They are classified into one of the three domains by their cell structure and function.
Term
The cells of organisms of which two domains are prokaryotic?
Definition
Bacteria + Archaea
Term
Which domain includes the organisms composed of eukaryotic cells?
Definition
Eukarya
Term
Describe three fundamental characteristics that distinguish prokaryotic cells from eukaryotic cells.
Definition

prokaryotic cells:

  1. relatively simple cell structure
  2. their DNA is located in a poorly defined region inside the cell
  3. they are usually very small

 

eukaryotic cells:

  1. more complex
  2. their DNA is set apart from the rest of the cytoplasm enclosed in a double-layered membrane of the nucleus
  3. their cells contain other membranous structures like mitochondria, endoplasmic reticulum, Golgi bodies, and lysosomes which are not found in prokaryotic cells
Term
The organisms in one of the domains will not be discussed much in this course. Why not?
Definition
The Archaea won't be studied in detail in this course because they have little medical importance.
Term
What are pathogens?
Definition
Pathogens are microorganisms (i.e. bacteria, viruses or parasites) that can cause disease in humans, animals and plants.
Term
Why is it important to understand the fundamental cellular differences in different types of pathogens?
Definition
It is important to understand the fundamental cellular differences in different types of pathogens because it is key to understanding how microorganisms affect us.
Term
In addition to the living things that can be pathogenic to humans, what other type of pathogen is studied by microbiologists?
Definition
Viruses.
Term
Why are they not considered living things?
Definition
They are not considered living things because they are not composed of cells.
Term
Leaving aside the small number of bacterial species that are pathogens, what are someo f the major roles that bacteria play int he biosphere of Earth?
Definition
The bacteria play a vital role in capturing energy and raw materials and cycling them through the biosphere.
Term
What are the four eukaryotic kingdoms?
Definition
fungi + plants + animals + protists
Term
Which of these include pathogens that affect humans?
Definition
fungi + protozoans + protists + helminths
Term
Which group of organisms in the animal kingdom are human pathogens?
Definition
helminths (parasitic worms)
Term
Viruses attack and parasitize what types of living things?
Definition
Every type of living thing.
Term
What is taxonomy?
Definition
Taxonomy is the science of classification - of grouping similar organisms together and showing how they are related to each other.
Term
What is the proper way to write the scientific name of an organism?
Definition

A scientific name consists of its genus (very similar organisms) and species (the exact type of organism in that group.)

When writing a scientific name, the genus is capitalized and the species name is not. It should be italicized - or if that's not possible, underlined.

 

i.e. Acomys carhirinus

Term
Why are bacterial species difficult to classify?
Definition
Bacteria are especially difficult to classify, since there are millions of different types on Earth, but most of them look pretty much the same.
Term
What modern techniques are helping bacterial taxonomistst classify bacteria?
Definition
Metabolic differences and DNA sequencing are useful tools bacterial taxonomists use to classify bacteria.
Term
How are viruses classified?
Definition
Viruses are classified using the Baltimore classification system (devised by Nobel Prize winner David Baltimore) and assigns viruses to one of seven different groups based primarily on their nucleic acid component.
Term
What is a compound microscope?
Definition
A microscope using 2+ lenses
Term
What is a simple microscope?
Definition
A simple microscope uses a single tiny lens.
Term
Which kind do you use in lab?
Definition
compound
Term
Give examples of how samples of microorganisms are collected.
Definition
A swab can be made of the mouth or a wound, sputum can be examined, blood or fluid from body cavities may be withdrawn, a urine or fecal sample collected, and so on.
Term
Which of these samples will normally include harmless microorganisms, as well as a pathogen if one is present?
Definition
Samples from the skin, respiratory or digestive tracts may contain harmless microorganisms, as well as a pathogen.
Term
Which should not contain any microorganisms in the absense of infection?
Definition
Samples of blood, urine, cerebrospinal or serous fluid should not contain any microorganisms.
Term
How might a sample be contaminated with additional microorganisms that makes it more difficult to identify which microorganisms is causing an infection?
Definition
A sample may be contaminated during collection or handling.
Term
What procedures are used to avoid contamination or a sample?
Definition
The "clean catch" instructions for a urine sample, using sterile collection supplies and containers and healthcare workers using standard sterile techniques are essential to prevent contamination of a sample.
Term
What is meant by "microbial growth"?
Definition
It means that the microorganisms/bacteria are multiplying.
Term
What is inoculation?
Definition
Inoculation is introducing a cell/microorganism into a culture medium.
Term
In general terms, different types of media are used for three purposes. They are?
Definition

various kinds of media are used to:

  1. provide the microorganism with what it needs to multiply
  2. to encourage growth of the one we want to study and discourage the growth of those we do not
  3. to reveal the characteristics of the microorganism that will allow us to identify it, such as motility or differences in metabolism
Term

Give an example of when each of the following would be a good choice

an agar slant, agar deep, agar plate, broth tube

Definition

agar slant - when a larger surface area is needed to inoculate

agar deep - usually used for "stabs", which is useful in determining if the organism will grow - or grows best - int he presence/absence of oxygen, and also for seeing if the microorganism is motile

agar plate - allow the bacteria to spread out more, so that that isolated colonies can be studied

broth tube - often used just to keep a culture growing, or with the addition of particular substances, to reveal differences in metabolism

Term
What is the purpose of nutrient media?
Definition
It provides everything the organism needs to grow.
Term
What is the difference between a simple (or defined) medium and a complex medium?
Definition
Simple media are made of mixing up specific chemicals like salts, sugars and amino acids. It is often called defined medium becaise it is clear exactly what is in the medium. Complex media usually include something more complicated like blood or meat extract. It is difficult to kow what all is in a complex medium and it is known that some types of microorganisms won't grow well without it.
Term
What is incubation?
Definition
Incubation is simply giving the microorganism the necessary time and environmental conditions to grow.
Term
Why are medical microbiological specimens usually incubated at 37°?
Definition
In medical microbiology, since the organisms studied most often are those that are human pathogens, incubation is oftten in a warm incubator set to 37° C, which is human temperature.
Term
What is a bacterial colony?
Definition
A pile up of bacteria descended from a single bacterium.
Term
A single bacterium is too small to see with the naked eye, but noting the characteristics of an isolated bacterial colony provides information that can help identify what might be causing a disease. Why is that?
Definition
All of the members of a bacterial colony are identical (barring a random mutation as they grew), so studying the colony gives us information about the single bacterium that gave rise to it. Once an isolated colony is visible, it is easy to remove a little of the colony for further study or closer examination.
Term
What is a selective medium?
Definition
Selective media allow certain organisms to grow while discouraging the growth of others.
Term
How are selective media useful?
Definition
It would be useful if you are trying to separate a pathogen making someone sick (so that you can identify it) from all of the other microorganisms that are normally found on human body surfaces.
Term
Besides examining the characteristics of a bacterial colony, in what other way is having isolated colonies of bacteria useful to the microbiologist?
Definition
It can help the diagnose the disease that is causing a person's illness.
Term
Viewing microorganisms using a microscope can give us more information to help identify a microorganism. Give examples of when simply seeing a certain type of microorganism through the microscope might give a microbiologist the answer to the question, "What kind of microorganism is making this patient sick?"
Definition
Simply viewing a sample may not be enough. A fecal sample will contain many microorganisms, but parasitic worms or their eggs, or pathogenic protozooans, should not be present. If they are seen, you have your answer.
Term
We (and most medical labs) routinely used standard compound light microscopes. Explain what is meant by a)standard b)compound, and c)light when describing a microscope.
Definition

standard - because our microscopes haven't been fitted with specialized lenses that allow flourescent, phase contrast, or DIC (differential interference contrast or Nomarski) microscopy

compound - 2+ lenses

light - because light is used to form the image that you see when you look through the lens

Term
What is meant by magnification?
Definition
The apparant size of the object that you are viewing.
Term
What is meant by resolution?
Definition
How clear the image is.
Term
What factor limits the amount of magnification and resolution possible with a light microscope?
Definition
The size and quality of the lens, the medium through which the light passes (oil causes more scattering of light than air), and the wavelength of visible light itself.
Term
Using good quality lenses improves resolution, as does oil immersion. Why is it possible to see smaller objects using an electron microscope?
Definition
The shorter the wavelength is, the better the resolution. Since the wavelengt is shorter in an electron microscope than a light microscope, we are able to see smaller objects more clearly.
Term
What is the difference between simple stains and differential stains?
Definition
A simple stain uses 1 dye to color the sample and make it visible with the microscope and a differential stain uses 2+ dyes.
Term
Be able to describe the four bacterial cell shapes and the common cell arrangements.
cocci
Definition
round
Term
rods
Definition
elongated
Term
spirilla
Definition
spiral shaped/corkscrew
Term
vibrio
Definition
curved/comma shaped
Term
other
Definition
square + star shaped
Term
single
Definition
1
Term
pair
Definition
2 linked together
Term
tetrad
Definition
groups of 4
Term
strepto
Definition
chain
Term
staphylo
Definition
cluster
Term
What is a differential medium?
Definition
Differential media are media to which dyes, pH indicators, or other substances have been added that result in a visible difference of certain species growing in or on it compared to other species.
Term
Give examples of the types of information that differential media can reveal to help identify a microorganism.
Definition
Differential media often reveal something about the metabolism of a microorganism - for example, whether or not it produces a particular enzyme. It can also reveal things like whether or not the microorganism is motile (can move), produces gases, or can digest lactose.
Term
What is an atom?
Definition
smallest unit of matter of a specific element
Term
What are the three basic components of an atom, and what are the characteristics of each?
Definition
They are composed of protons, neutrons and electrons in the center/nucleus of the atom and the electrons are moving rapidly aorund the nucleus.
Term
Characteristics of protons
Definition
have a + charge
are found in the nucleus
determine the identity of an atom
atomic number = protons in an atom
Term
Characteristics of neutrons
Definition
found in the nucleus
have no electrical charge (may vary or change)
atoms of the same element with different numbers of neutrons are called isotopes of that element (some isotopes of some elements are radioactive)
Term
Characteristics of Electrons
Definition
are very small
found somewhere in the cloud outside the nucleus
each electron has one negative electrical charge
the number of electrons are equal to the protons so that the + and - charges "cancel each other out", meaning there is no NET electrical charge
electrons come and go (chemical reactions)
Term
What is an ion?
Definition
An ion is an atom that has gained or lost an electron or two. It is charged because the number of electrons do not equal the number of protons in the atom or molecule.
Term
How is an ion formed?
Definition
This generally happens when an electron is transferred from one atom to another.
Term
What determines whether it is a positive or negative ion?
Definition
Gaining an electron results in an ion with a net charge of -1 (negative ion) and losing an electron results in an ion with a net charge of +1 (positive ion).
Term
Valence electron
Definition
electron(s) in the outermost shell
Term
What is a molecule?
Definition
2+ atoms joined together
Term
How are the atoms in a molecule held together?
Definition
Sharing electrons holds atoms in a molecule together (covalent bond)
Term

What are "the four most important things" you need to know about ions and molecules?


Explain why each is important to understanding the basic chemistry of living things...

Definition
  1. molecules and ions are different sizes
  2. molecules have a shape
  3. molecules and ions are always moving
  4. electrical charge is very important
Term

Explain why each is important to understanding the basic chemistry of living things.

  1. molecules and ions are different sizes
  2. molecules have a shape
  3. molecules and ions are always moving
  4. electrical charge is very important
Definition
  1. Whether or not a molecule can move in or out of a cell depends, in part, on how large it is. (i.e. large molecules like triglycerides, starches and proteins are too big to pass through openings in the cell's plasma membrane and must be broken down into their components [monomers], or digested, before they can cross the membrane.)
  2. Each different protein has its own unique shape and it can do what it does because of the shape that it has (form = function)
  3. The energy of movement can be used to work in a cell. This movement allows diffusion to happen, powers the movement of substances into and out of the cell, and brings molecules together so that they can react with each other - releasing energy and/or creating new substances needed by the cell. (Diffusion + chemical reactions cannot happen if the molecules/ions are not moving.) The warmer the molecules/ions are, the faster they move.
  4. Anything with a charge will interact with anything with a charge.
Term
What types of basic chemical particles will interact with electrically charged particles?
Definition
ions, ionized molecules, polar molecules
Term
What will interact with water? Why?
Definition
Anything with a charge. Since water has a charge, it will react with anything with a charge.
Term
Explain the difference between hydrophobic and hydrophilic substances.
Definition
Hydrophobic substances cannot mix, dissolve in or interact with water; hydrophilic substances are the complete opposite.
Term
What basic chemical property makes a particle (ion, molecule) hydrophobic or hydrophilic?
Definition
Whether or not it has a charge.
Term
Give some examples of hydrophobic and hydrophilic particles.
Definition
Hydrophobic particles are mainly lipids. Hydrophilic particles are anything with a charge, including ions, polar molecules and ionized molecules.
Term
What is a polar molecule?
Definition
When an atom in a molecule has a stronger attraction for electrons than the other atoms in the molecule, the electrons spend more time around the atom with the stronger attraction.
Term

What is the most important polar molecule to living things?


What is the interaction between polar molecules called?

Definition

H2O

Hydrogen bonds

Term
What is an acid?
Definition
An acidic solution is a solution with more H+1's than OH-1's.
Term
What is a base?
Definition
A base causes the water solution to have more OH-1's than H+1's.
Term
What is the scale by which we describe how acidic or how basic a solution is?
Definition
pH scale - a measurement of just how acidic an acid is, or just how basic a base is.
Term

Be able to interpret pH numbers.

Which pH's are acidic and which are basic?

Definition

acidic: 0-6

basic: 8-14

Term
Each time the pH number changed by one, how much has the acidity or basicity changed?
Definition
Every time you change the acidity by 1, you change the concentration of H+ times ten.
Term
Which pH is neutral (neither acidic or basic)?
Definition
7
Term
What is a biomolecule?
Definition
Biomolecules are carbon-containing molecules made by living things.
Term
What ar ethe four groups of biomolecules?
Definition

carbohydrates

proteins

lipids

nucleic acids

Term
What is a monomer?
Definition
Small molecules that may be joined together to make larger molecules (e.g. glucoses, amino acids or nucleotides)
Term
What is a polymer?
Definition
Large moleculse made by many monomers joined together (e.g. starch, protein, DNA)
Term
Which of the three groups of biomolecules are made up of monomers and the polymers they come from?
Definition
carbohydrates + nucleotides + proteins
Term
Name the common monomers and polymers of carbohydrates.
Definition

monomers - monosaccharides, or simple sugars.

3 important ones: glucose (easily available energy for cells, formed by photosynthesis)

fructose (the same atoms arranged differently. plants convert some glucose to fructose)

galactose (found in milk)

 

2 monosaccharide monomers can be joined to form a disaccaride (polymer)

disaccharides include sucrose and lactose

polysaccharides include starch, glucogen and cellulose

Term
The common polymers are made by cells by joining which monomer?
Definition
glucose
Term
What are the main functions of carbohydrates in cells?
Definition
The main function of the carbohydrates is to provide energy to cells, although carbohydrates are also a part of some cell structures.
Term

What are two nucleic acid polymers?

 

What are the monomers from which they are made?

Definition

DNA + RNA

 

Nucleotides

Term
What is the function of nucleic acids in cells?
Definition
DNA + RNA provide instructions that tell the cell how to ake proteins that every cell needs in order to survive and function.
Term

Which famous RNA nucleotide has another important role in cells besides being used as a building block of RNA?

 

What is its other role in cells?

Definition

ATP (the RNA nucleotide with an adenine base)

 

A small molecule can transfer energy from one chemical reaction to another. ATP is sometimes called the "energy currency of the cell".

Term
What are the monomers and polymers of the protein group of biomolecules?
Definition

monomer - amino acids

polymer - polypeptide

Term
What are some examples of the functions of proteins in cells?
Definition
Allows the cell to control what enters and leaves it, to do work in the cell, control chemical reactions within a cell, etc.
Term
What is the "original code" for how to make the proteins a cell needs?
Definition
DNA
Term
What cell organelle actually makes the proteins?
Definition
amino acids
Term
What nucleic acid takes the instructions for how to make one particular protein to these organelles?
Definition
RNA
Term
What is a "gene"?
Definition
instructions to make a protein + sequence of DNA
Term

What are two basic groups of lipids, based on their structure?

 

Since they are so different, what characteristic leads themm to be put in the same group?

Definition

fatty-acid based lipids and sterols

 

They include small molecules that can be joined together to make larger ones (not string shaped) and all of hem are hydrophobic, or significant part of the lipid molecule is hydrophobic.

Term
What is the difference between saturated and unsaturated fatty acids?
Definition
The straight ones are saturated, the bent ones are unsaturated.
Term
What is the basic structure of a triglyceride and what is the main function of triglycerides in cells?
Definition
3 fatty acids + 1 glycerol; used by the body primarily to store energy
Term
What is the basic structure of a phospholipid and what is the main function of phospholipids in cells?
Definition
2 fatty acids + 1 phosphorus-containing group + 1 glycerol; used by cells to form the "lipid bilayers" of their membranes
Term
What is a sterol, and what are the functions of sterols?
Definition

Sterols are made by eukaryotes, most sterol molecules are found in membranes - scattered throughout the lipid bilayer between the phospholipid "tails" - where they keep the membrane from being either too fluid or too stiff.

 

The sterol found in animal cells is cholesterol. Plants make phytosterols, and fungi make ergosterol. In humans, a small amount of cholesterol is modified to form the steroid hormones: estrogen, progestone, testosterone, cortisol, and aldosterone.

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