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327 Cards in this Set

  • Front
  • Back
What is Microbiology?
The study of organisms too small to be seen with the naked eye.
5 reasons it's important to study microbiology?
Agriculture, Medicine, Food Industry, Genetic Engineering, Keep us alive, Cause Disease
6 groups microbiologists study?
Prokaryotes: Bacteria, Archaea
Eukaryotes: Fungi, Protozoa, Algae
Also: Viruses
Difference between prokaryotes and eukaryotes:
Proks have no membrane bound organelles or nucleus, Euks do have membrane bound organelles and nucleus
How do microbes affect food availability?
Pests and fungi may destroy crops, but other microbes act as preservatives. Also genetically engineered crops.
4 ways microbial diseases have affected history:
Black plague in Europe, smallpox in Americas, Soldiers dying more from infections than in battle, TB and AIDS
When was the light microscope discovered?
in the 1600s
Who first observed small eukaryotes that turned out to be fungi growing on leather?
Robert Hooke
Who was the first person to use the term "cells?"
Robert Hooke
Who built simple microscopes to view "wee animalcules" and "beasties?"
Antoni Van Leeuwenhoek
Who published the first drawings of bacteria (prokaryotes?)
Antoni Van Leeuwenhoek
Define Spontaneous Generation
the idea that living organisms arise from non-living matter.
Who disproved the idea of spontaneous generation and how did he do it?
Louis Pasteur--sterilized broth, put it into flasks, bent the necks so that air could enter but microbes would be caught in swan neck. This led to development of methods for controlling microorganism growth.
Define pasteurization
use of moderate heat to reduce number of microorganisms in food
Define Germ theory of Disease. Who came up with this?
The idea that germs are what got people sick, not evil spirits, past sins, etc. Louis Pasteur came up with this.
List the observations, hypothesis, and whether or not the hypothesis is testable in the germ theory of disease
Observations: germs can infect and grow on food.
Hypothesis: Can germs infect/grow on people? Do germs cause disease?
Testable because: are germs found in infected tissue? Can transmission of germs cause disease?
what is the purpose of Koch's postulates?
Provides means of testing germ theory hypothesis. Provides answers to "Does this germ cause that disease?" Organism must meet all 4 criteria.
List Koch's 4 postulates:
1. The microbe is found in all cases of disease but is absent in healthy individuals
2. The microbe is isolated from the disease host and grown in pure culture
3. When the microbe is introduced to a healthy host, the same disease occurs.
4. The same strain of microbe is obtained from the newly diseased host.
Contribution of Joseph Lister
British surgeon who determined that survival rates increased if surgeons washed hands, used disinfectants, and sterilized instruments.
Who was Ignas Semmelweiss?
Noticed that women giving birth in the hospital with med students had a higher rate of purperal/childbed fever and death than those women who gave birth outside the hospital. Determined the med students were bringing "cadaver particles" in from autopsy room to delivery room. Had med students wash hands in chlorinated lime water, which significantly reduced mortality rate. Ridiculed by his peers, admitted to insane asylum, died of Streptococcus infection.
Contributions of Edward Jenner
Discovered that milkmaids who had been exposed to cowpox were immune to small pox, vaccinated people (including his son) with pustule material from cowpox, achieved immunity
Lady Montagu's story
She had horrible scars from smallpox. She traveled to Turkey where there was very little smallpox and discovered they were using smallpox pustule material to inoculate people. Brought this idea back to Europe, inoculated her kids.
Who had the idea of a "magic bullet" that would kill pathogens but not harm humans?
Paul Ehrlich
3 contributions of Paul Ehrlich:
1. found arsenic compounds to treat trypsanomes
2. Discovered Salversan to treat syphilis
3. Used term "chemotherapy"--using chemicals to kill pathogens without harming the patient
Who won the Nobel Prize in Medicine for the discovery of Penicillin?
Alexander Fleming
What did Alexander Fleming discover about Penicillin?
That it had antimicrobial effects on Staphylococcus
What did Florey and Chain receive the Nobel Prize in medicine for?
determining the mode of action for penicillin and developing a method of mass producing the drug.
What percentage of deaths were caused by TB in 1881?
1/7 (15%)
What bacterium do we now know causes TB?
Mycobacterium tuberculosis
Why was it hard to determine whether TB was contagious?
It was hard to see in lab--slow growing and difficult to stain due to high lipid content
What contribution did Koch make to the study of TB?
He thought it was contagious, developed acid-fast staining procedure, and was patient enough to get a pure culture in lab. Was awarded Nobel Prize for his work on TB.
What were the first two examples of solid media that Koch tried?
Potato Slices and beef broth solidified with gelatin
Why did the potato slices and beef broth gelatin not work for Koch?
Potato Slices: too much moisture, fungi growth, too many contaminants
Gelatin Beef Broth: gelatin liquifies above 28 degrees C, many microbes produce gelatinase.
What is agar? Why was it superior to previous solid culture medium?
It's a polysaccharide derived from red algae. It was suggested by Fannie Hesse, a wife of Koch's coworker. It's superior b/c it remains solid until 100 degrees C and most microbes cannot digest it.
Who invented the Petri Dish?
Richard Petri, Koch's assistant, in 1887
About how many microbes in our biosphere can be cultured in the lab? Why?
about .1%...because most microbes just don't grow on typical medium...many live in harsh conditions that are difficult to recreate in the lab.
List 4 types of harsh environments microbes grow in and give examples.
Anaerobic--bottom of swamps, high pressure--bottom of ocean, hot or cold temps--below 0 degrees C or up to 113 degrees C, no organic carbon--use light for energy, CO2 for carbon
What would you use to culture microbes in a natural mud environment?
A Winogradsky column--different species grow in different layers, reflecting different conditions.
Four prevalent elements that microbes cycle on earth.
Nitrogen (N2 to NH4)
Carbon cycle--photosynthetic microbes take CO2 and convert it to useful Carbon
Sulfur Cycle
Phosphorus cycle
Three Reasons that microbial species are difficult to classify:
1. Difficult to distinguish by shape
2. Often reproduce asexually
3. Pass DNA to each other without reproduction
Two general ways to classify bacteria:
Via biochemical properties (gram stain, ability to metabolize different substrates) or DNA sequences (accepted method--because bacterial genomes are small)
Outline the phylogenetic tree of life:
3 domains determined by rRNA sequencing, all from common ancestor:
1. Bacteria (prokaryotes)
2. Archaea (prokaryotes)
3. Eukarya (eukaryotes)
- algae and plants
- fungi and animals
- protists
Most prokaryotes that we encounter are ______________.
Bacteria
Most prokaryotes that live in extreme environments are ___________.
Archaea. (ex: Methanococcus and Halobacterium--THEY ARE NOT BACTERIA!)
3 differences between Bacteria and Archaea:
1. Different membranes
2. Archaeal ribosomes similar to eukaryotic ribosomes
3. many archaea live in harsh environments
____________: Eukaryotic microorganism, non-photosynthetic, decomposers.
Fungi
Most fungi have cell walls made of __________.
Chitin
Yeasts are ______cellular and molds are ______cellular.
Uni, multi
2 examples of fungi in everyday life:
Saccharomyces yeast is used to make beer and bread, penicillium mold produces antibiotic penicillin.
_______________: Eukaryotic microorganism, photosynthetic, contain chlorophyll.
Algae.
Algae have cell walls usually made of ____________.
Cellulose
______________: Eukaryotic microorganism, unicellular, motile, no cell walls.
Protozoa
List 3 examples of Protozoa:
Amoeba, Paramecium, and Giardia
Why does the small size of prokaryotes provide an advantage?
Their small size allows nutrients to reach all parts of the cell quickly.
How small are the smallest prokaryotic cells?
.2 micrometers
How small are the smallest eukaryotic cells?
2 micrometers
Which type of bacteria generally has a diameter of 2 micrometers?
Cocci
Controversially described ____________________ are bacteria less than .2 micrometers.
nanobacteria
Prokaryotes have a wide variety of _____________________ that help in identification.
Cellular Morphologies
Simplest bacteria shape is a sphere, called __________.
coccus (singular), cocci (plural)
Describe 5 arrangements of sphere shaped bacterial cells
Cocci (single cells)
Diplococcus (2 cells)
Streptococcus (chains of more than 2 cells)
Staphylococcus (grapelike cluster of cells)
Tetrads (packets of 4 cells)
Most common bacterial shape is _________.
Rods (bacillus-singular, bacilli- plural)
Describe the arrangements of baccillus:
Can occur singly or in chains, don't grow in clusters.
Rigid, spiral-shaped bacteria are called ___________. (Singular: _______)
Spirilla, spirillum
Flexible, spiral-shaped bacteria are called _________. These are corkscrew shapes with multiple curves.
Spirochetes
__________: curved rods
Vibrio
Describe the differences between simple and compound microscopes:
Simple microscopes have one lens, can magnify 50-300X. Compound microscopes have multiple lenses with much higher magnification (1000X)
The _____________ lens is located between the light source and specimen, focuses light rays up through the specimen, but provides NO magnification.
Condenser
The ____________ lens system is closest to the specimen.
Objective
Typical scope has ___, ___, and ____ objective lenses.
10, 40, 100
In each objective is/are (a single lens/multiple lenses)
Multiple
The ____________ lens system is closest to your eye.
Ocular
Each ocular has (one/multiple) lens
Multiple
The ocular lens systems typically magnifies _____X.
10X.
How do you determine the total magnification ability of a microscope?
Multiply the magnification factor of the objective and the ocular. (An 100X objective and 10X ocular will provide 1000X total magnification>)
Can you see any internal structures at 1000X magnification? What about viruses?
No, no.
What is resolution?
The ability to distinguish between 2 objects that are close together.
What is the highest resolution of a typical light microscope? What does this mean?
.2 micrometers. Objects closer together than .2 micrometers can't be distinguished.
What two things determine resolution:
Wavelength of light and numerical aperture.
5 ways to increase resolution:
1. Use shorter wavelengths of light
2. Wider lens closer to specimen has higher numerical aperture
3. Use immersion oil
4. Increase contrast (by staining)
5. Multiple lenses (correct each others aberrations.
The shorter the wavelength, the __________ the resolution.
Higher.
Which wavelength produces the lowest resolution? Highest resolution
Red is lowest, blue gives highest
What is the numerical aperture?
the measure of light-gathering ability of an objective lens
How does immersion oil work?
If you fill space between specimen and objective with oil, resolution increases because the oil keeps light from scattering as much as in air since the oil has the same refraction as glass.
List two ways to increase contrast.
Staining cells or using a specific kind of microscop.
What is the pigmented portion of the dye called?
chromophore.
Which has positive charge (chromophore or cell surface), which has negative charge?
Chromophore-positive charge, cell surface-negative charge.
List three examples of basic stains:
crystal violet, methylene blue, safranin
What are the main differences between simple stains and differential stains?
Simple stains: use one dye, don't differentiate between types of cells or structures. Diff stains use more than one dye, and distinguishes between different types of bacteria or different structures.
Describe 2 types of differential stains:
1. Gram stain: distinguishes gram + and gram - bacteria.
2. acid fast stain: distinguishes mycobacterium species from other species.
What is the name of the microscope we typically use?
A bright field light microscope--we see stained cells on a bright background.
List 7 types of microscopy.
1. dark field microscopy
2. differential interference contrast microscopy
3. fluorescence microscopy
4. electron microscopy
5. tranmission electron microscope
6. scanning electron microscope
7. phase contrast microscopy
In phase-contrast microscopy, cells slow the speed of light passing through them so cells differ in _____________ from their surroundings.
refractive index
What amplifies the difference in phase/refractive index in the lens of a phase contrast microscope?
a special ring called an annular ring.
In which two types of microscopes can you observe living cells in a wet mount?
Phase-contrast and dark-field
Phase-contrast microscopy is primarily used to show _______________.
internal organelles of eukaryotes.
In _______________, cells appear bright against a dark background.
dark-field microscopy
What does the dark field stop in condenser do?
It prevents light from passing directly through the specimen.
How does light reach the specimen in a dark-field microscope?
from the sides only
How does light reach the objective in a dark field microscope?
Only light scattered by sample reaches objective.
Describe how a differential interference contrast microscope works.
- polarized light passes through specimen
- sample boundaries bend light
- second polarized lens blocks light
- bent light results in 3D appearance
In fluorescense microscopy, some compounds absorb energy from _____________, then radiate energy back as _______________.
invisible radiation (short wavelength), longer visible wavelength.
______________________: absorb high energy light (short wavelength) then emit low energy light (long wavelength)
fluorophores.
What are fluorescense microscopes used for?
to view cells that make fluorescent compounds such as chlorophyll, or cells that have been stained with fluor. dyes.
What type of light source is used in a fluoresence microscope?
UV light
How do you label molecules of interest in a cell?
You can fluorecently label molecules by attaching fluor directly to some molecules (DAPI binds DNA) or by attaching a labeled antibody to molecules.
How to labeled anitbodies work in identifying cells?
Antibody binds specific molecules, and fluor is covalently bound to the antibody.
What limits the resolving power of light microscopes?
the wavelength of light used.
Electron microscopes use ___________________ instead of visible light and ___________ instead of lenses.
beams of electrons, electromagnets.
What's the magnification power of an electron microscope?
Over 100,000x
List three types of things that can be viewed with an electron microscope?
viruses, proteins, nucleic acids.
The sample in an electron microscope must be coated with ______ to reflect electrons back.
heavy metal.
In an electron microscope, the electron beam and the sample are in a ________.
vaccuum
_____________________: a microscopic knife that cuts samples into small slices.
microtome
In transmission electron microscope, the sample is stained with __________________.
a heavy metal like uranium, osmium.
The transmission electron microscope is a high resolution microscope used to view ___________, __________, and __________.
cell structures, DNA, and some protein molecules.
In which type of microscopy does the sample have to be sliced very thin?
transmission electron microscope
In scanning electron microscope, the sample is coated with ____________.
heavy metal.
Which type of microscopy retains and gives a 3D image?
scanning electron
How is the image in an SEM formed?
formed from electrons reflected from the specimen
What is an SEM used to visualize?
Surface cell structures
List 5 basic cellular structures:
1. cytoplasm
2. cytoplasmic membrane
3. nucleus or nucleoid
4. ribosomes
5. cell wall
Identify 3 main differences between proks and euks:
1. prok have simpler internal structure, euks are larger and more complex
2. proks lack membrane enclosed organelles, euks have membrane bound organelles
3. proks split into two domain: bacteria and archaea, euks make up just one domain.
List 5 groups in the eukaryotic domain:
algae, fungi, protozoa, plants, animals.
Do viruses belong to any category or domain?
No, they are non-living and non-cellular
How do viruses reproduce?
Only inside a host cell.
_____________: a cell's complete set of genes
genome
DNA is arranged to form ____________.
chromosomes.
Prokaryotes have a ______, ______ chromosome and sometimes extrachromosomal DNA called ______.
single, circular, plasmids.
Eukaryotes have several ___________ chromosomes.
linear
_____________: membrane enclosed structure that contains the chromosomes, found in eukaryotes.
nucleus.
__________: mass of DNA not bound by membrane, found in prokaryotes.
Nucleoid.
In the bacterial cell, the cytoplasm contains DNA in the _________ and is surrounded by the ____________.
nucleoid, envelope.
The envelope has a ____________ boundary plus a structural ___________.
lipid membrane, cell wall.
________________: "fluid" selective permeability barrier made of phospholipids and proteins that form a bilayer.
cytoplasmic membrane
In CM phospholipid bilayer, the interior is ___________ and the exterior is _____________.
hydrophobic, hydrophilic.
The attraction of nonpolar fatty acid portions of one phospholipid layer for other layer result in ______________ of cell membrane.
selective permeability
__________________ membrane proteins span the membrane.
integral
_________ membrane proteins are bound to surface of membrane.
peripheral
three functions of cytoplasmic membrane:
1. permeability barrier
2. protein anchor
3. energy conservation
Two functions of the permeability barrier factor of the CM:
1. prevents leakage of cytoplasmic metabolites into environment
2. transports nutrients and wastes into and out of cell
What can diffuse freely through cytoplasmic membrane?
Water, small polar molecules
How do non polar compounds get transported into and out of cells?
by integral and peripheral membrane proteins.
____________: site of many proteins involved in transport, bioenergetics, and chemotaxis.
protein anchor (cytoplasmic membrane)
Eukaryotes have _______________ to generate energy by respiration.
mitochondria
In prokaryotes, respiration occurs at the ________________.
cytoplasmic membrane
Photosynthetic eukaryotes have ___________ to carry out photosynthesis in the _____________.
chloroplasts, cytoplasmic membrane
The bacterial cell wall is also known as the ____________ and is made of ______________.
sacculus, peptidoglycan
Peptidoglycan is made of ___________ linked to each other by short polymers of _______________.
sugar chains, amino acids.
Which two sugars make up the backbone of peptidoglycan?
N-acetyleglucosamine, and N-acetylmuramic acid.
Describe the structure of peptidoglycan.
Chains of sugars arranged M-G-M-G-M-G, held together by peptide crosslinks between N-acetylemuramic acids.
Gram-negative bacteria have unusual amino acid __________________ in the crosslink.
meso-diaminopimelate.
What are two functions of peptidoglycan?
Provides rigidity and shape to cell, prevents it from exploding due to high pressure.
What are archaea cell walls made of?
polysaccharides or other proteins (lack peptidoglycan).
Some archaea cell walls contain ______________, others have a paracrystalline surface layer (___________) made of protein.
pseudopeptidoglycan, S-layer
Gram-negative bacteria have (few/many) layers of peptidoglycan
Few (only 10% of cell)
Gram-positive bacteria have (few/many) layers of peptidoglycan.
many (as much as 90%)
In gram-positive bacteria, the crosslinks within peptidoglycan are different in that they often have ________.
L-lysine
___________________: negatively charged polymers that are only found in gram + cell walls.
teichoic acids
__________: enzyme that destroys peptidoglycan, leading to cell lysis.
lysozyme
Where is lysozyme found and why is it important to cells?
found in many animal secretions, thought to be a major line of defense against infection by bacteria.
Gram-negative bacteria has a _______________ that's made of a lipid bilayer.
outer membrane
the outer membrane of gram-negative bacteria consists of an outer ____________ layer and an inner ____________ layer.
outer lipopolysaccharide (LPS), inner phospholipid
The outer membrane of gram-negative bacteria contains ________ which are proteins involved in transport.
porins
__________________ is a toxic portion of the LPS which causes fever, vomiting, etc. if ingested.
Endotoxin Lipid A
______________: transmembrane proteins that allow for permeability through the outer membrane by creating channels that cross the membrane.
porins
_____________: water-filled channels through which small substances can pass.
non-specific porins
________________: channels with binding gates for certain molecules that only allow those molecules to pass through.
specific porins
_____________: the space between the outer and cytoplasmic membranes
Periplasm
The periplasm is mostly seen in gram (+/-) bacteria, through gram (+/-) do have a small one.
mostly in gram neg, a small one in gram pos
The periplasm contains proteins such as:
hydrolytic enzymes and binding proteins
5 layers of gram-positive envelope from outer to inner:
capsule, s-layer, thick cell wall, thin periplasm, plasma membrane
What is a capsule? Where is it found? Do all species have it?
It's basically a polysaccharide slime layer that protects cell, found in gram + and gram - bacteria, but not all species have it.
5 layers of gram-negative envelop from outer to inner:
capsule, outer membrane, thin cell wall, thick periplasm, plasma membrane
The bacterial ___________ is a single loop of double stranded DNA, compacted by supercoiling.
nucleoid
How many base pairs are found in bacterial DNA?
4x10^6 (4,000,000)
The bacterial nucleoid is attached to the ________________, no membrane separates the DNA from the cytoplasm.
cell envelope
The bacterial nucleoid replicates __________ for each cell division and an exact copy of the chromosome is made.
once
The growth of most microorganisms occurs by ______.
binary fission
In bacterial cell division, the cell _______ as it grows, and a new cell wall is added at the __________ of the cell
elongates, equator
Bacterial DNA replicates ______________ to make 2 chromosomes.
bidirectionally?
Can bacterial DNA begin next replication before fully dividing for the first time?
Yes
The bacterial cell undergoes __________ at the equator, resulting in two daughter cells with the same shape.
septation
________________: division apparatus in the cell formed by Fts proteins, allows cell to divide correctly.
divisome
The group of proteins required for cell division and chromosome replication in bacteria are known as ______ proteins.
Fts
______ protein defines the division plane in prokaryotes and polymerizes to form a ring where cell division will occur (marks the spot)
FtsZ
_______ protein is the ATP-hydrolyzing enzyme that provides energy for assembly of other proteins to the ring.
FtsA
_______ protein is involved in peptidoglycan synthesis for the new cell wall, it's activity is blocked by penicillin.
FtsI
_______ helps define cell shape by forming filamentous spiral shaped bands around the inside of the cell and exerting pressure against the cytoplasmic membrane
MreB
_______ shaped bacteria lack the MreB gene.
coccus
The default bacterial shape is the _______.
sphere
How is the new cell wall synthesized during bacterial growth?
new glycan units are inserted into preexisting wall material.
_____________ create openings in existing cell wall to make space for new call wall glycans to be inserted without letting the cell lyse (critical step)
autolysins
_______________ may occur if there is an error in inserting new cell wall material (spontaneous cell lysis).
autolysis
________________ is a hydrophobic lipid alcohol that binds the N-acetyleglucosamine/N-acetylemuramic acid/pentapeptide peptidoglycan precursors.
bactoprenol
_______________ helps transport new glycan units through the cytoplasmic membrane to become part of growing cell wall.
bactoprenol
___________ is the formation of peptide cross links between NAMs in which peptidoglycan precursors are bonded into expanding peptidoglycan layer.
transpeptidation
The transpeptidation reaction is inhibited by _________.
Penicillin
Prokaryotic cells often contain ____________ that function as storage materials or to orient the cell.
inclusion granules
__________ are densely compacted material in cytoplasm, give 5 examples:
inclusion granules, 1. magnetosomes 2. glycogen, 3. polyphosphate, 4. poly-B-hydroxybutyrate, 5. sulfur
______________: intracellular particles of magnetite (Fe3O4); allow organisms to respond to a magnetic field.
magnetosome
_____________: carbon and energy source
glycogen
_______________: stores inorganic phosphate, can be used in making different cellular molcules.
polyphosphate
______________: carbon and energy source that is being used in some plastics now to make them biodegradable.
poly-B-hydroxybutyrate
Some gram-negative prokaryotes can store elemental ____________ in globules in the periplasm and use it as an energy source.
sulfur
_________: are non-motile extensions that help bacteria attach to surfaces and other bacteria. examples:
fimbriae, neisseria, biofilms
Fimbriae are (shorter/longer) than flagella, may have _____ per cell.
shorter, 100's
______________: hollow, non-motile tubes made of a special protein that connects certain cells together so that they can exchange DNA
Pili
Order of pili, fimbriae, and flagella based on size from longest to shortest:
Flagella>Pili>Fimbriae
________ may be used to move DNA from one cell to another by conjugation.
Pili
A cell may have ______ pili (#) per cell.
1-10
The stick polysaccharide or polypeptide layer surrounding the cell is also known as the ____/______/______.
capsule, slime layer, glycocalyx
The capsule/slime layer/glycocalyx protects the cell from ________ and _________.
phagocytosis (eating by other cells) and dessication (drying out)
The capsules/slime layer/glycocalyx also helps cells:
attach to objects such as teeth
___________ are long, helical protein filaments that can be attached at ends or over entire cell, used for cell motility.
flagella
How do bacterial flagella propel cells?
they rotate, proton passage drives rotation CW or CCW
Describe motion of eukaryotic flagella
whip-like
Describe 4 different types flagella may be arranged:
1. monotrichous (single flagellum at one end)
2. lophotrichous (several flagella at one or both ends)
3. peritrichous (several flagella all around the cell)
4. amphitrichous (one at each end)
What parts make up the flagella?
It's made of 3 parts: basal body, hook, filament.
the _______ is the part of the flagella that is embedded within the cell envelope.
basal body
The basal body is made of ______________ connected by a central rod.
2 or 4 protein rings
Which protein rings do gram positive bacteria have in the basal body?
MS ring, C ring (outer to inner)
Which protein rings do gram negative bacteria have in the basal body?
L ring, P ring, MS ring, and C ring (outer to inner)
The _____ ring is in the cytoplasm, attached to inner surface of cytoplasmic membrane)
C
The ________ ring is in the cytoplasmic membrane. The end of the central rod is attached to this ring.
MS ring
The _____ ring is the the peptidoglycan layer.
P
The _____ ring is the the LPS layer.
L
The _____ in the curved structure made of protein that connects the filament to the basal body.
Hook
The ____ is the long, rigid, helical structure made of protein called flagellin.
filament
Some prokaryotes such as filamentous cyanobacteria, myxoccoccus, ctyophaga, and flayobacterium move by ______________ instead of flagella.
gliding motility
Gliding can occur from ___________ that moves cell along solid surface.
slime secretion.
Motile bacteria can respond to ___________ and _________ in environment by moving toward or away from the signal molecule.
chemical and physical gradients
Directed movements toward or away from a chemical or physical signal are known as __________.
taxes
___________: directed movement of organisms in response to chemical signals.
chemotaxis
__________________: directed movement of organisms in response to light
phototaxis
_________________: directed movement of organisms in response to oxygen.
aerotaxis
___________: directed movement of organisms in response to ionic strength (e.g. salt concentration)
osmotaxis
Attractants cause __________ rotation, in which flagella bundle together and push cell forward in what's called a ________________.
counter clockwise, run
Repellents cause ___________ rotation, in which flagella fly apart which causes a change of direction called a ____________.
clockwise rotation, tumble
Runs + tumbles cause ___________ in which the cells don't go in one straight direction.
random walks
_________________ detect attractant concentrations including sugars, amino acids, other nutrients.
receptors.
When attractant concentration increases, the run is _____ and the net movement of bacteria is toward the attractants.
prolonged
What 3 things does all life require?
electron flow, energy, and materials
Which nutrients are needed in the largest amounts?
CHONPS (Carbon, Hydrogen, Oxygen, Nitrogen, Phosphorus, Sulfur)
Electron flow is necessary to drive all life processes, and requires a __________ and a ________.
source of electrons and ultimate electron acceptor
_______________: inorganic molecules that are electron donors
lithotrophs
________________: organic molcules that are electron donors
organotrophs
When the ultimate electron acceptor is an inorganic molecule such as nitrate or oxygen, the process is known as ___________.
respiration
When the ultimate electron acceptor is an organic molecule such as pyruvate, the process is called ______________
fermentation
A source of energy is necessary for life in order to ________.
move electrons.
In ________, light energy excites electrons, and the excited molecules are electron donors.
phototrophs
In __________, chemicals are electron donors and the oxidation of the chemical results in the donation of electrons.
chemotrophs
___________ are the major elements in the cell such as CHONPS as well as ions necessary for protein function.
Macronutrients
Which ions are necessary for protein function?
Mg 2+, Ca 2+, Fe 2+, K+
_____________ are the trace elements and organic growth factor compounds necessary for enzyme function.
micronutrients
What are the trace elements?
Cobalt, Copper, Zinc, etc.
A large amount of ____________ is needed by the cells to form organic compounds such as amino acids, fatty acids, sugars and nitrogenase bases to carry out cellular functions.
Carbon
__________________: are prokaryotes that obtain carbon (and make all celullar structures) from CO2.
autotrophs.
________________ must obtain carbon from other organic compounds.
Heterotrophs.
Why is nitrogen needed by cells?
to make amino acids, nitrogen bases, and other cell constituents.
__________________: are capable of using atmospheric nitrogen gas.
nitrogen-fixing prokaryotes
Most prokaryotes obtain nitrogen from compounds such as _________ and ________
ammonia and nitrate
__________________ get their energy from oxidation of (removing electrons) organic compounds.
chemoorganotrophs
____________________ get their energy from oxidation of inorganic compounds (Only in proks)
Chemolithotrophs
___________ contain pigments that allow them to use light as an energy source.
Phototrophs
____________: carbon source is organic compounds.
heterotrophs
____________: carbon source is carbon dioxide
autotrophs
______________ contains all materials necessary for growth, and varies for different bacterial species.
Culture media
Culture media must contain 4 types of sources:
electron, energy (if not phototrophic), carbon (if not autotrophic), nitrogen (if not N2 fixer)
How do you obtain a pure culture?
by dilution streaking
In a pure culture, all the cells in the colony derive from one single cell and are _____________.
genetically identical.
Dilution in liquid culture reduces the number of cells _________.
In each tube.
When diluting in liquid culture, you can spead the liquid on the plate to see _________.
single colonies
A __________________ can be used to directly count bacterial cells by viewing them under a microscope and counting the cells in the grids.
Petroff-Hauser counting Chamber
What is used to electronically directly count bacteria?
the Coulter Counter
What's a drawback of total/direct counts? How can this be remedied
Can't tell if cells are alive or dead...use special stains to distinguish living cells.
A _________ measures optical density.
Spectrophotometer
Spectrophotometer/turbidity measures are _________ but rapid.
Indirect
A suspension of cells looks ____________, cells scatter the light that passes through the suspension.
Turbid
The more turbid a suspension is, the (more/less) cells you have, the (more/less) light is scattered.
more, more
Can you tell if cells are dead or alive in turbidity/spectrophotometer reading?
No, you can't tell.
For turbidity measurements to be substituted for direct counting methods, a _____________ must be made.
standard curve
Once a standard curve is made for a specific organism growing in a specific culture medium, when can it be used in the future?
for future cultures of the same organism in the same medium to estimate cell numbers.
Which type of counting methods allow to count only living cells?
viable
Viable counts only count cells able to _________.
reproduce (form colonies)
Viable counts require _____ to form the colonies.
Time (overnight)
Usually, the ____________ of bacteria in a sample is unknown, so _________ of sample is necessary before spread or pour plates are done.
concentration, dilution
Why do we study microbial growth?
To understand the science behind it, apply it to practical situations such as food industry, health care industry, etc.
When 1 cell divides to form 2 cells, one _____________ has occured.
generation
______________________: the time for number of cells in a culture to double.
Generation time.
Bacteria can have a generation time from ______ to __________.
10 minutes to days.
Under ideal conditions, one generation of Escherichia coli takes ________.
20 minutes
Generation time is also called ___________ because with each generation the cell population double.
doubling time
Why is generation time in the lab usually shorter than in nature?
Because the lab provides constant ideal conditions, and natural populations rarely have ideal conditions.
__________________: characteristic type of growth pattern of microbial populations where the number of cells double over a regular time interval.
exponential growth
Exonential growth can be represented on a ________________ graph.
semilogarithmic
Semilogarithmic graphs are useful for estimating _______________.
generation time.
On semi log paper, what's the scale on the X axis? Y axis?
X- linear
Y- logarithmic
What goes on the X axis? Y axis? How do you find generation time?
X-Time
Y- # cells/ml or absorbance.
Look to see how long it takes for the # of cells to double.
What are the 4 phases of bacterial growth?
Lag phase, exponential (log) phase, stationary phase, death phase.
The graph of # of cells vs. time is also known as the ______________.
growth curve
During the ______ phase, there is a delay before the cells divide and there is no increase in cell number.
Lag phase
The reason for no increase in cell number during the lag phase is likely due to the _____________, in which cells are making everything they need to grow in the new medium.
adjustment period
During the exponential or log phase, the increase in number of cells is _______________.
geometric. 1, 2, 4, 8, 16
During the _______________, a key nutrient will run out or toxic waste product will build up.
stationary phase
What happens to most cells in the stationary phase?
They survive but stop dividing.
What happens in the death phase?
nutrients run out and waste builds up, cells can no longer survive and may lyse.
Describe a batch culture.
It has a constant volume of culture medium, closed system, nothing added or removed, commonly used in lab.
What happens to a batch culture over time?
It's constantly being altered by metabolic activities of the organisms growing in it; nutrients get depleted, wastes build up. Medium continually changes, not same as in beginning.
Describe a continuous culture.
Fresh medium is constantly added from the top, used medium is constantly removed from the bottom. Nutrient concentration should remain constant the whole time.
____________: is a continuous culture device that allows cell populations to remain in exponential growth for long periods of time.
Chemostat
______________ are dormant survival structures formed by some species of Gram + rod bacteria during harsh condtions.
endospores
Where do endospores form?
"endo" = inside mother cell
What types of bacteria form endospores and what types of things are these spores resistant to?
Bacillus and Clostridium, resistant to heat, radiation, drying, acids, etc.
How long do endospores survive?
indefinitely
_____________: is the formations of an endospore when environmental conditions are not favorable. (Takes about 8 hours)
Sporulation
_______________: formation of a vegetative cell from an endospore when conditions are favorable.
germination
List the 4 layers of the endospore from inner to outer.
core, cortex, spore coat, exosporium
_________ is the center of the endospore, which contains the mostly dried out cell wall, CM, cytoplasm, and nucleoid.
core
______ surrounds the core of the endospore, and is made of loosely cross-linked peptidoglycan.
cortex
___________ is the protein which covers the cortex of an endospore
spore coat
__________ is the thin layer of protein which covers the spore coat of the endospore
exosporium
__________ and ___________ help dehydrate endospore, stabilizes DNA and protects it from heat denaturation.
calcium diplicolonic acid
Small _________________ protect DNA from UV radiation, desiccation, dry heat and also serve as carbon and energy sources during germination.
Acid-soluble proteins
_________ fix N2 from atmosphere
heterocysts
_______ form inside fruiting body, multicellular structure.
myxospores
__________ form spores when food runs out, produce aerial hyphae, disseminates cells. (Ex.)
actinomycetes, streptomyces