Exam 1 – Microbiology Test Questions – Flashcards

Unlock all answers in this set

Unlock answers
question
What is microbiology?
answer

the study of very small living things

 

a set of techniques for studying very small organisms

question
What types of organisms are studied by microbiologists?
answer
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.
question
What are the three domains of living things?
answer
Bacteria + Archaea + Eukarya
question
What is the basis for placing organisms in one of the three domains?
answer
They are classified into one of the three domains by their cell structure and function.
question
The cells of organisms of which two domains are prokaryotic?
answer
Bacteria + Archaea
question
Which domain includes the organisms composed of eukaryotic cells?
answer
Eukarya
question
Describe three fundamental characteristics that distinguish prokaryotic cells from eukaryotic cells.
answer

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
question
The organisms in one of the domains will not be discussed much in this course. Why not?
answer
The Archaea won't be studied in detail in this course because they have little medical importance.
question
What are pathogens?
answer
Pathogens are microorganisms (i.e. bacteria, viruses or parasites) that can cause disease in humans, animals and plants.
question
Why is it important to understand the fundamental cellular differences in different types of pathogens?
answer
It is important to understand the fundamental cellular differences in different types of pathogens because it is key to understanding how microorganisms affect us.
question
In addition to the living things that can be pathogenic to humans, what other type of pathogen is studied by microbiologists?
answer
Viruses.
question
Why are they not considered living things?
answer
They are not considered living things because they are not composed of cells.
question
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?
answer
The bacteria play a vital role in capturing energy and raw materials and cycling them through the biosphere.
question
What are the four eukaryotic kingdoms?
answer
fungi + plants + animals + protists
question
Which of these include pathogens that affect humans?
answer
fungi + protozoans + protists + helminths
question
Which group of organisms in the animal kingdom are human pathogens?
answer
helminths (parasitic worms)
question
Viruses attack and parasitize what types of living things?
answer
Every type of living thing.
question
What is taxonomy?
answer
Taxonomy is the science of classification - of grouping similar organisms together and showing how they are related to each other.
question
What is the proper way to write the scientific name of an organism?
answer

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

question
Why are bacterial species difficult to classify?
answer
Bacteria are especially difficult to classify, since there are millions of different types on Earth, but most of them look pretty much the same.
question
What modern techniques are helping bacterial taxonomistst classify bacteria?
answer
Metabolic differences and DNA sequencing are useful tools bacterial taxonomists use to classify bacteria.
question
How are viruses classified?
answer
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.
question
What is a compound microscope?
answer
A microscope using 2+ lenses
question
What is a simple microscope?
answer
A simple microscope uses a single tiny lens.
question
Which kind do you use in lab?
answer
compound
question
Give examples of how samples of microorganisms are collected.
answer
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.
question
Which of these samples will normally include harmless microorganisms, as well as a pathogen if one is present?
answer
Samples from the skin, respiratory or digestive tracts may contain harmless microorganisms, as well as a pathogen.
question
Which should not contain any microorganisms in the absense of infection?
answer
Samples of blood, urine, cerebrospinal or serous fluid should not contain any microorganisms.
question
How might a sample be contaminated with additional microorganisms that makes it more difficult to identify which microorganisms is causing an infection?
answer
A sample may be contaminated during collection or handling.
question
What procedures are used to avoid contamination or a sample?
answer
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.
question
What is meant by "microbial growth"?
answer
It means that the microorganisms/bacteria are multiplying.
question
What is inoculation?
answer
Inoculation is introducing a cell/microorganism into a culture medium.
question
In general terms, different types of media are used for three purposes. They are?
answer

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
question

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

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

answer

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

question
What is the purpose of nutrient media?
answer
It provides everything the organism needs to grow.
question
What is the difference between a simple (or defined) medium and a complex medium?
answer
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.
question
What is incubation?
answer
Incubation is simply giving the microorganism the necessary time and environmental conditions to grow.
question
Why are medical microbiological specimens usually incubated at 37°?
answer
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.
question
What is a bacterial colony?
answer
A pile up of bacteria descended from a single bacterium.
question
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?
answer
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.
question
What is a selective medium?
answer
Selective media allow certain organisms to grow while discouraging the growth of others.
question
How are selective media useful?
answer
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.
question
Besides examining the characteristics of a bacterial colony, in what other way is having isolated colonies of bacteria useful to the microbiologist?
answer
It can help the diagnose the disease that is causing a person's illness.
question
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?"
answer
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.
question
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.
answer

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

question
What is meant by magnification?
answer
The apparant size of the object that you are viewing.
question
What is meant by resolution?
answer
How clear the image is.
question
What factor limits the amount of magnification and resolution possible with a light microscope?
answer
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.
question
Using good quality lenses improves resolution, as does oil immersion. Why is it possible to see smaller objects using an electron microscope?
answer
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.
question
What is the difference between simple stains and differential stains?
answer
A simple stain uses 1 dye to color the sample and make it visible with the microscope and a differential stain uses 2+ dyes.
question
Be able to describe the four bacterial cell shapes and the common cell arrangements.
cocci
answer
round
question
rods
answer
elongated
question
spirilla
answer
spiral shaped/corkscrew
question
vibrio
answer
curved/comma shaped
question
other
answer
square + star shaped
question
single
answer
1
question
pair
answer
2 linked together
question
tetrad
answer
groups of 4
question
strepto
answer
chain
question
staphylo
answer
cluster
question
What is a differential medium?
answer
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.
question
Give examples of the types of information that differential media can reveal to help identify a microorganism.
answer
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.
question
What is an atom?
answer
smallest unit of matter of a specific element
question
What are the three basic components of an atom, and what are the characteristics of each?
answer
They are composed of protons, neutrons and electrons in the center/nucleus of the atom and the electrons are moving rapidly aorund the nucleus.
question
Characteristics of protons
answer
have a + charge
are found in the nucleus
determine the identity of an atom
atomic number = protons in an atom
question
Characteristics of neutrons
answer
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)
question
Characteristics of Electrons
answer
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)
question
What is an ion?
answer
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.
question
How is an ion formed?
answer
This generally happens when an electron is transferred from one atom to another.
question
What determines whether it is a positive or negative ion?
answer
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).
question
Valence electron
answer
electron(s) in the outermost shell
question
What is a molecule?
answer
2+ atoms joined together
question
How are the atoms in a molecule held together?
answer
Sharing electrons holds atoms in a molecule together (covalent bond)
question

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...

answer
  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
question

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
answer
  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.
question
What types of basic chemical particles will interact with electrically charged particles?
answer
ions, ionized molecules, polar molecules
question
What will interact with water? Why?
answer
Anything with a charge. Since water has a charge, it will react with anything with a charge.
question
Explain the difference between hydrophobic and hydrophilic substances.
answer
Hydrophobic substances cannot mix, dissolve in or interact with water; hydrophilic substances are the complete opposite.
question
What basic chemical property makes a particle (ion, molecule) hydrophobic or hydrophilic?
answer
Whether or not it has a charge.
question
Give some examples of hydrophobic and hydrophilic particles.
answer
Hydrophobic particles are mainly lipids. Hydrophilic particles are anything with a charge, including ions, polar molecules and ionized molecules.
question
What is a polar molecule?
answer
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.
question

What is the most important polar molecule to living things?


What is the interaction between polar molecules called?

answer

H2O

Hydrogen bonds

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

Be able to interpret pH numbers.

Which pH's are acidic and which are basic?

answer

acidic: 0-6

basic: 8-14

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

carbohydrates

proteins

lipids

nucleic acids

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

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

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

What are two nucleic acid polymers?

;

What are the monomers from which they are made?

answer

DNA + RNA

;

Nucleotides

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

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?

answer

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".

question
What are the monomers and polymers of the protein group of biomolecules?
answer

monomer - amino acids

polymer - polypeptide

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

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?

answer

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.

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

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.

Get an explanation on any task
Get unstuck with the help of our AI assistant in seconds
New