Micro Exam 1 (Ch. 1, 2, 3, & 4)
Terms in this set (305)
microorganisms that cause disease
What is microbiology?
the study of microorganisms (microbes)
*study of entities too small to be seen by the unaided human eye
What does "micron" mean?
What does "biologia" mean?
study of living things
How small is "small" in micro?
<0.2mm = 200 ()m = 200,000 nm
What are the major groups of microorganisms?
Multicellular animal parasites
Bacteria and Archaea
prokaryotes (uni cellular ONLY)
*don't have a nucleus
*NO ORGANELLES present
*smaller in size
*cell wall made of peptidoglycan
What is peptidoglycan?
a network of sugar polymers cross-linked by polypeptides
Fungi, algae, protozoa, helminths
*Have a nucleus
*ORGANELLES ARE present
*larger in size
*cell wall is variable
Viruses & bacteriophages
Acellular (without cell)
Prokaryote- unicellular ONLY
Peptidoglycan cell walls
BINARY FISSION: 1 bacteria divides into two
For energy: organic chemicals, inorganic chemicals, or photosynthesis
Prokaryote- unicellular ONLY
Live in extreme environments
1. methanogens- reduces carbon dioxide to methane
2. extreme halophiles- organisms that thrive in high salt concentrations
3. extreme thermophiles- microorganisms whose optimal growth temperature is between 65 and 85°C (extreme hot and cold)
Eukaryotes: can be uni or multicellular
Chitin cell walls (a large, structural polysaccharide made from chains of modified glucose)
For energy: organic chemicals
Multicellular: molds and mushrooms, consisting of masses of mycelia, which are composed of filaments called hyphae
What is a mycelium and hyphae?
Mycelium is an extension of the hyphae of fungi .
A hyphae is a thread-like, branching structure formed by fungi.
The mycelium is the most important and permanent part of a fungus. The mycelia network that emanates from a fungal spore can extend over and into the soil in search of nutrients.
Eukaryotes: can be uni or multicellular
Absorb or ingest organic materials
May be MOTILE via pseudopods, cilia, flagella
Eukaryotes: can be uni or multicellular
Cellulose cell walls (a structural carbohydrate and is considered a complex sugar because it is used in both protection and structure)
For energy: photosynthesis
Produce molecular oxygen and organic compounds
Acellular: w/o cell
Consists of DNA and RNA core
Core is surrounded by a protein coat that may be enclosed by a lipid envelope
Are replicated only when they are living in a host cell (A.K.A. only comes to life, or multiplies, after hijacking a living cell)
A virus that infects bacteria
Multicellular Animal Parasites
Eukaryotes: can be uni or multicellular
Parasitic flatworms and roundworms are called helminths
Microscopic stages in life cycles
*A group of eukaryotic organisms consisting of the flatworms and roundworms, which are collectively referred to as the helminths.
*Inspired Rod of Asclepius
Sub-Disciplines of Micro
study of prokaryotes
study of fungi
study of algae
study of protozoa
study of viruses
study of the immune system
What are the impacts of microbes on Earth?
Microbes are the EARLIEST organisms found in the fossil record.
They perform essential reactions in the environment.
Microbes can be harnessed to work for us.
They sometimes cause infectious diseases.
Ubiquity of microorganisms
(the fact of appearing everywhere)
Found nearly everywhere
Occur in large numbers
Live in places many other organisms cannot
Microbes in the environment
Study of Environmental Microbiology
Microbial photosynthesis account for most of the atmospheric oxygen on Earth
Microbes are essential for decomposition of dead organisms
Many biologically important elements (S, N, P) are cycled by microbes
human use of microorganisms
Humans have been using microorganisms for thousands of years
-Baker's and brewer's yeast
-Moldy bread on wounds
Biotechnology, genetic engineering, biomediation
*medical micro- study factors of microbes and what makes them viral for inhibiting them
*Public Health Micro and Epidemiology- monitor and control the spread of diseases in communities
*immunology- studies web of protective substances and cells produced in response of protection
*Environmental micro- study effect of microbes on earth's habitats
Harnessing the Power of Microbes
Studies of Industrial Microbiology and Food Microbiology
-Microbes can be used to make or preserve food products (e.g. yogurt, salami, cheeses)
-Microbes can produce important compounds (e.g. antibiotics, MSG, ethanol)
Biotechnology and Bioremediation
1. Biotechnology- when humans manipulate microorganisms to make products in an industrial setting
-Genetic engineering- create new products and genetically modified organisms (GMOs)
-Recombinant DNA technology- allows microbes to be engineered to synthesize desirable proteins (i.e. drugs, hormones, and enzymes)
2. Bioremediation- introducing microbes in to the environment to restore stability or clean up toxic pollutants
-Water and sewage treatment
e.coli bacteria produces indigo from __________.
Infectious diseases and the human condition
Only a few percent of all microbes are associated with diseases such as:
Influenza and pneumonia
If you study HIV, what sort of microbiologist would you be considered?
Historical Foundations of Microbiology
Thousands of microbiologists over 300 years, prominent discoveries include, microscopy, scientific method, development of medical microbiology , and microbiology techniques
The fall of superstition and rise of micro
Used to think disease was a punishment and not from microbes
abiogenesis (spontaneous generation)
Life comes from non-living things
*theory was disproved by Redi's, Jablot's, Schwann's, and Pasteur's Experiment that proved biogenesis
the production of living organisms from other living organisms
proved that maggots do not spontaneously generate from deteriorating meat.
- Boiled infusions in a dish
- Covered dish prevented dust falling in infusion
- Covered infusion remained sterile
vs. growing microbes
Shultze and Schwann's Test
Sterilized tube to kill microbes
- Verified principle that cells can only come from pre-existing cells
1. Placed samples of broth in flasks with long swan necks and melted the glass of the necks to bend them into different shapes
2. Boiled the broth in some of the flasks to kill any organisms present, and left others unboiled (controls)
3. Fungi and other organisms appeared in the unboiled flasks but not the boiled ones (even after a long time)
4. The broth in the flasks was in contact with air (which had been suggested was needed for spontaneous generation), but that didn't occur, so disproved it
5. Snapped necks of some of the flasks to leave a shorter vertical neck, and organisms were soon apparent and decomposed the broth
6. Concluded that the swan necks prevented organisms from the air getting into the flasks and that no organisms appeared spontaneously
What did Robert Hooke do?
He coined the word "cells" after looking at cork slice by viewing them under a microscope
*may have been the first to see microorganisms
What did Zacharias Janssen invent?
What did Antonie van Leeuwenhoek do?
Father of microscopy
First person to accurately describe living microbes (used a simple microscope)
Made and reported many detailed observations-used a single lens microscope to observe pond water and other things
Discovery of Microscope ----> "Cell Theory"
In the 18th century
idea that all living things are composed of cells, cells are the basic units of structure and function in living things, and new cells are produced from existing cells
coined by Schwann and Schleiden, and Virchow
Golden Age of Microbiology
Beginning with Pasteur's work, discoveries included the relationship between microbes and disease, immunity, and antimicrobial drugs
-many microbial metabolism studies undertaken
-microbiological techniques refined
-many disease producing organisms discovered; grow best at body temp (98.6 F); mesophiles (an organism that grows best in moderate temperature)
-A better understanding of the role of immunity and ways to control and prevent infection by microbes
What did Louis Pasteur do?
disproved spontaneous generation by creating pasteurization
*Pasteurization or pasteurisation is a process in which certain packaged and non-packaged foods are treated with mild heat, usually less than 100 °C, to eliminate pathogens and extend shelf life
*short time to eliminate the denaturation of proteins
Koch's Postulates (1876)
Cause (microorganism)/effect (symptoms of disease) relationship
1. The organism should be present in all animals suffering from the disease and absent from all healthy animals.
2. The organisms must be grown in pure culture outside the diseased animal.
3. When the culture is inoculated into a healthy susceptible animal, the animal must develop the symptoms of the disease.
4. The organism must be reisolated from the experimentally infected animal and shown to be the same as the original isolate.
*Isolate organism from unhealthy organism, inject into healthy organism, then reisolate from now unhealthy organism and study.
Koch's work led to the discovery of
nutrient broth and nutrient agar
methods for isolating microorganisms
What did Joseph Lister do?
he was the first to use phenolic acid as a disinfectant during surgery to kill microbes in the air
Small amounts of dead or weakened pathogens used for protection (immunity) against virus
Derived from "vacca" for cow
Discovery of antibiotics
- microbes themselves produce antimicrobial compounds
- Alexander Fleming (1929): Penicillin from mold Penicillium notatum
In 40's streptomycin was isolated from actinomycetes (Streptomyces griseus)
all of the microorganisms that live in a particular environment, such as a human body
What are biofilms?
a thin, slimy film of bacteria that adheres to a surface.
Ebola hemorrhagic fever
An infectious disease with high death rates, caused by the Ebola virus.
Causes fever, hemorrhaging, and blood clotting
Outbreaks every few years
*Mutates and causes new strand of viruses
Three domains of microorganisms
Bacteria (prokaryote), Archaea (prokaryote), Eukarya (eukaryote)
Types of Eukarya
Multicellular: Kingdom Plantae, Kingdom Fungi, Kingdom Animalia
Why should you study chemistry in Biology?
Chemicals are in everything: you, food, etc.
What is matter?
Anything that has mass and takes up space
Can exist in 3 states:
What is an atom?
Smallest particle of an element that retains properties of the element
What are the subatomic particles of an atom?
protons (p+), neutrons (n0), electrons (e-)
What makes up the nucleus?
Protons and neutrons
What surrounds the nucleus?
electrons (exist in an electron cloud)
What holds atoms together in a molecule?
The attraction of positive protons to negative electrons
2 electrons on outer shell forming a cloud of negative charge, neutron and proton in center to make nucleus, nuclei.
What determines isotope?
Number of neutrons
What is the mass number?
protons + neutrons
*can change with number of neutrons
ex: Carbon- (x)
What is the atomic number?
number of protons
*stays the same
What are isotopes?
Atoms of the same element with different numbers of neutrons
*can be extremely unstable
What are isotopes used for?
Radioactive isotopes are used in research and medical applications and in dating fossils and ancient materials
Different numbers of protons, neutrons, and electrons create _______________.
Different types of elements
*each element has a characteristic atomic structure and predictable chemical behaviour
*each assigned a distinctive name with an abbreviated shorthand symbol
States that atoms lose, gain or share electrons in order to acquire a full set of eight valence electrons to become stable
*A complete outer shell with eight electrons increases chemical stability
What are chemically inert elements?
Inactive elements that don't react with other elements because of full outer shell
What are chemically active elements?
Elements with incomplete valence shell
*electronegative = electron hungry
If a neutron were added to a carbon atom, what would be the result?
Do most elements exist naturally in pure form?
What is the combination of two or more atoms called?
A molecule (like N2)
What are molecules formed from two or more different elements called?
A compounds (like C6H12O6)
What are molecules and compounds held together by?
What are the types of chemical bonds?
Bonds created by sharing electrons with other atoms
*STRONGEST bond- most common bond in living cells
Form between C, H, O, N, S, and P
Covalent bond: polar and nonpolar molecules
Polar molecules: unequal distribution of electrons (O2 binds tightly, H2 weakly)
*True of most biological molecules (ex water)
Non-polar molecules: electrically neutral molecule where electrons are shared equally
*Weak bonds, but important for structure of biological molecules
Formed when one or more electrons are transferred from one atom to another
Gives away an electron and can separate into charged particles called ions
Cations (+) Na
Anions (-) Cl
Electrolytes are charged molecules that dissolve to form ions
No transfer or sharing of electrons, JUST FATAL FORCE OF ATTRACTION
Very weak bonds; occurs when a hydrogen atom in one molecule is attracted to the electrostatic atom in another molecule
WHat is the most important molecule?
Carbon: living organisms are carbon based
What is the difference between molecular and structural formulas?
Structural: Shows bonds
What do chemical equations illustrate?
-reactants: molecules ENTERING the reaction
-products: substances LEFT by a reaction
What is a synthesis reaction?
Reactants bond together to form an entirely new molecule
What is a decomposition reaction?
When something is broken down into smaller molecules
What is an exchange reaction?
Where parts of the reacting molecules are shuffled around to produce new products
(AB + XY → AX + BY)
What is a catalyst?
substance that speeds up the rate of a chemical reaction
Solutions vs solutes vs solvent
A solution is a mixture of solutes that are dispersed in a solvent
-cannot be separated by filtration or settling
-"like dissolves like"
-water is most common solvent because of its polar nature
water loving (lipophobic- not fat soluble) = POLAR
-attracts water to surface
water hating (lipophilic- fat soluble) = NONPOLAR
having both hydrophilic and hydrophobic properties (lipophobic and lipophilic) POLAR & NONPOLAR
ex: phospholipid bilayer
Acidic solutions have a pH that is
less than 7 (1-7)
-Inc. from 7 to zero
+10 H+ ions
When a component dissolved in water (acid) releases excess _______ ions
Basic solutions have a pH that is
more than 7 (7-14)
-Inc. from 7 to 14
+10 OH- ions
When a component releases excess _______ ions, it is basic
What does the pH scale measure?
how acidic or basic a substance is
What is a buffer?
a substance that minimizes changes in pH
What are inorganic chemicals?
NOT carbon based
Usually doesn't contain C and H
ex: NaCl, CaCO3
What are organic chemicals?
carbon compounds with a basic framework of the element carbon bonded to other atoms
*most of the chemical reactions and structures of living things involve organic chemicals
How many electrons does Carbon need to become stable?
4; it has 4 in last shell, needs 8 valence electrons to be stable
always makes 4 COVALENT bonds
can form linear, branched, or ringed structures
can form single, double, or triple bonds
the components of organic molecules that are most commonly involved in chemical reactions
KNOW TABLE 2.3 FOR FUNCTIONAL GROUPS
Hydroxyl, Carboxyl, Amino, Ester, Sulfhydryl, Carbonyl, Phosphate
Difference between monomer and polymer?
Polymers are large compounds formed by combinations of monomers
-A monomer is a small unit that can join together with other small units to form polymers
What are macromolecules?
polymers consisting of many small repeating molecules called monomers
-small organic molecules can combine into large macromolecules
Examples of polymers?
Polymers; repeating subunits
What are the 4 kinds of macromolecules?
*all macromolecules except lipids are formed by polymerizations (monomers linked into polymers)
How are monomers joined to form polymers?
Dehydration synthesis or condensation reactions
*water as a product (possible because of covalent bonds)
R-OH+OH-R' ----> R-R' + H2O
Cell structures and energy source
consist of C, H, and O with the formula (CH2O)n
-monosaccharides are simple sugars with 3-7 carbon atoms
-disaccharides are formed when 2 monosaccharides are joined in a dehydration synthesis (can be broken down by hydrolysis- water as product)
-polysaccharides consist of 10-100's of monosaccharides joined through dehydration synthesis (starch, glycogen, cellulose are polymers of glucose that are covalently bonded differently; Chitin is a polymer of 2 sugars repeating many time- Fungi cell wall)
What is dehydration synthesis?
the process of joining two molecules, or compounds, together following the removal of water
What is a hydrolysis reaction?
A covalent bond is broken by adding a molecule of water
What is an aldehyde group?
What is a ketone group?
OH pointing down on glucose? Up?
1-4 linkage of alpha glucose monomers
all OH's point down so can be broken down by digestion enzymes
1-4 linkage of beta glucose monomers
OH's alternate down & up so the body can't break down with digestion enzymes
Dextran, agar, peptidoglycan, lipopolysaccharide, glycocalyx
slime layer of glucose polymer
seaweed; complex polymer of galactose and sulfur containing carbohydrates; solidifying agent
a protein carbohydrate compound found in bacteria cell walls
polysaccharides are linked to peptides
complex of lipid and polysaccharide, gram negative bacteria
The external surface of a plasma membrane that is important for cell-to-cell communication/attachment and acts as a receptor
primary component of cell membranes (fats, oils, energy storage)
C, H, O; NOT A TRUE POLYMER
Nonpolar and INSOLUBLE in water
-triglycerides: glycerol molecule and 3 fatty acid chains
When you eliminate the H2O molecule in a lipid, what do you create?
What is an ester bond?
A condensation bond that makes a triaglyceride by attaching fatty acids to a glycerol backbone
Carboxyl groups on the fatty acids are attached to the Hydroxyl groups on the Glycerol
What is a saturated fat?
solid at room temperature; closely compacted bonds
balance of C is satiated by H; single bonds
What is unsaturated fat?
liquid at room temp
double bonds between carbons (Cis)
What is the functional group on fatty acids?
What are phospholipids?
a lipid containing a phosphate group in its molecule; remove one fatty acid and replace with phosphate group
Amphipathic- both hydrophilic (phosphate) /phobic (2 fatty acids)
Important for membrane- polar head, nonpolar tails
Steroids are a class of lipids that have a basic structure of four linked carbon rings and include cholesterol (need in cell membrane and acts as buffer), vitamin D, and a variety of hormones (estrogen/progesterone)
What is the main function of a triglyceride?
Mycobacterium tuberculosis (italics)
Contains complex lipids such as waxes and glycolipids
-essential in cell structure and function
-enzymes are PROTEINS that speed chemical reactions
-Transporter proteins move chemicals across membranes
-Flagella are made of proteins called flagelin
-Antibodies are also proteins that the body makes when you get a vaccine
What does an amino acid consist of?
central carbon, amino group (H-N-H) , carboxyl, group (O=C-OH), and R group
*the changing R group gives you all the 20 different amino acids
How do amino acids differ? Stereoisomers
D- right (H2N is on right)
L- left (H2N is on left)
*L forms are most often found in nature
Where do peptide bonds form?
Between the carboxyl group of one amino acid and the amine group of another amino acid
How do peptide bonds form?
dehydration synthesis (H2O as a product)
Primary structure of protein
the amino acid sequence of the polypeptide strand
Secondary structure of protein
alpha helix and beta pleated sheet with 3 polypeptide strands
Tertiary structure of protein
Helix and pleated sheets fold into a 3D shape of protein
Quaternary structure of a protein
results when a protein consists of multiple folded polypeptide chains
Hemoglobin exists in all 4 structures
What are the possible shapes of proteins?
Native state- the functional 3D form of a protein
Denatured- when the protein's native state has been disrupted
*Each different type of protein develops a unique shape, so it can only react with molecules that fit its particular surface features (ex: enzymes and antibodies)
What are conjugated proteins?
"combined" with other things to make different molecules
*amino acids and other organic molecules
-nucleoproteins- nucleic acids
DNA and RNA
DNA is specially coded genetic program that transfers its program to RNA
Both are polymers of repeating units called nucleotides
What are nucleotides?
building blocks of DNA
composed of: nitrogenous base, pentose sugar, and a phosphate
What are the types of nitrogenous bases?
Purines (two rings): adenine (A) and guanine (G)
Pyrimidines (one ring): thymine (T) and cytosine (C), and uracil (U)
*DNA consists of all the nitrogenous bases except uracil
*RNA all but thiamine
How is the nitrogenous base bonded to ribose in RNA and deoxyribose in DNA?
What covalently bonds the pentose sugars in nucleic acids?
Phosphate (PO4 3-)
What are the pairs of nucleotides?
A with T
C with G
What are the functions of DNA?
Genetic material of all cells
encodes info for the cell
dictates protein synthesis
genes get transmitted from 1 generation to another
Four monomers: A, C, G, T
What is RNA?
Organizers of protein synthesis; involved in translation
single-stranded nucleic acid that contains the sugar ribose instead of deoxyribose and uracil instead of thymine
consists of a long chain of nucleotides
-Messenger RNA: mRNA: a copy of a gene that provides the order and type of amino acids in a protein
-Transfer RNA: tRNA: a carrier that delivers the correct amino acids for protein assembly
-Ribosomal RNA: rRNA: a major component of ribosomes
Energy molecule of cells
Adenosine triphosphate; a nucleotide containing adenine, ribose, and three phosphates
gives off energy when the bond is broken between the outermost phosphates (forms ADP) and can store energy for chemical reactions
- ADP can be converted back to ATP when the third phosphate is restored
What is it called when you remove 1 phosphate from ADP?
Cells are the fundamental unit of life. What are their characteristics?
-tend to be spherical, polygonal, cubical, or cylindrical
-have a cytoplasmic membrane
-have ribosomes for protein synthesis
-reproduce to form progeny cells
-obtain energy from their environment
At what level of protein structure are alpha helices and beta sheets formed?
How do bacteria divide (prokaryotic)?
How do eukaryotic cells divide?
Mitosis (body) and meiosis (sex) and budding
-Animals, plants, fungi, and protists
-Contain a nucleus and other organelles that are bound by membranes
-Have DNA associated with histones
-cell wall made of cellulose
-uni and multi cellular
-Bacteria and archaea
-do not have a nucleus or other membrane-bound organelles
- do NOT have DNA bound by histones
-cell wall made of peptidoglycan
What is taxonomy?
the science of naming and classifying organisms (living things)
What are the components of an amino acid?
amine, carboxyl, R group
What are the components of a nucleotide?
nitrogenous base, pentose sugar, phosphate group
What is a nucleotide?
monomer of nucleic acid (many nucleic acids linked together)
What is systematics?
The classification and study of evolutionary relationships among organisms
What is microbial nomenclature?
*Carl von Linnaeus
What is identification?
discovering and recording the traits of organisms so they can be named and classified
What is the two-name (binomial) designation that every organism has in microbial classification?
Genus (italics and always capitalised) and species (italics)
What is the main difference between genus and species?
Genus is a lower classification level that lies below family and above species, whereas species is the fundamental category of closely related organisms that lies below the genus
What are the levels of classification?
3. Phylum or division
What were earlier classification systems?
*Had "phenotypic" traits in early classification, meaning physical characteristics were viewed to classify organisms
1. Two Kingdom: Plants and Animals
2. In the 60's was Five Kingdom: Animals, Plants, Fungi (microbes), Protists (microbes), Monera (microbes)
3. 3 "Domains" by Carl Woese: Archaea (all microbes), Bacteria (all microbes), Eukarya (some microbes)
What is unique about bacteria?
They don't have a sex! Because they divide by binary fission, they look exactly alike and pass down from generation to generation
Don't exhibit a typical mode of sexual reproduction
What are the 3 domains?
Bacteria, Archaea, Eukarya
What are Eukarya categorized into?
Multicellular (Plantae, Fungi, Animalia) and unicellular/multicellular (Protists)
What were some of the original classification systems in Prokaryotes?
Shape (morphology), arrangement (position), growth characteristics, and habitat
What are classification systems considering in present times?
sequence of nitrogenous bases in rRNA and phenotypic information
In what ways do bacteria species show variation?
Subspecies, strain, or type and serotype
What is a serotype?
Representatives of a species that stimulate a distinct pattern of antibody responses
What are subspecies, strain, or type?
Bacteria of the same species that have slightly differing characteristics
Domain of unicellular prokaryotes that have cell walls that do not contain peptidoglycan
Many are found in EXTREME environments
What are non-pathogens?
Nonpathogenic organisms are those that do not cause disease, harm or death to another organism and is usually used to describe bacteria. It describes a property of a bacterium - its ability to cause disease. Most bacteria are nonpathogenic
What is true for prokaryotes?
They lack membrane enclosed organelles
What are the methods for culturing organisms?
What does culturing for an organism mean?
To characterize microorganisms in the lab
What is inoculation?
Adding microbes into medium; spread sample on surface of a solid medium
What is incubation?
The act of promoting growth of a culture on/in a media to provide higher numbers for testing (20-40 C)
What is isolation?
where populations of a species are separated
What is inspection?
The colonies or broth cultures are observed microscopically for growth characteristics and analyzed
What is identification?
Type of microbe is determined
What is a pure culture?
single species or kinds; usually created by subculture
What is a mixed culture?
microbial culture consisting of two or more species
What is a contaminated culture?
includes unwanted microorganisms of uncertain identity or contaminants
What is a colony?
aggregation of cells arising from a single parent cell
What is aseptic technique?
A procedure performed under sterile conditions
*flame inoculating loop and head of test tube
What is the streak plate method?
A small droplet of culture or sample is spread across the surface of a medium with an inoculating loop
The pattern used to inoculate gradually thins out the sample and separates the cells in order to encourage the growth of discrete colonies
*Isolated appear in third, and predominantly fourth, quadrants
How can you classify media?
-semisolid: determines motility
-solid: useful for isolating and culturing bacteria and fungi (Agar is most common)
-Defined or synthetic: precisely chemically defined
-Complex or nonsynthetic: if even one component is not chemically definable
What is reducing media?
absorbs oxygen or slows its penetration and grow anaerobic microbes and determines oxygen requirements
What is carbohydrate fermentation media?
contains sugars and pH indicators to show fermentation; useful for identification of microorganisms
What is assay media?
used to test the effectiveness of antimicrobial drugs
How do you prepare living specimens?
Wet mount & Hanging drop mount
-cells suspended in fluid, 1-2 drops of culture is then placed on slide and overlaid with a cover of glass
-hanging drop uses vaseline and a depression slip and coverslip and sample is suspended from coverslip
What is the smear technique?
Developed by Robert Koch
Spread a thin film made from a liquid suspension of cells on a slide, allow the slide to air dry, and then finish with heat fixing
Why do we stain smears?
Staining allows features of the cell to stand out
Dyes are classified as basic (cationic) or acidic (anionic)
one dye is used
ex: malachite green, crystal violet, basic fuchsin, and safranin
reveals shape, size, and arrangement
Uses 2 types of dyes, the a primary stain and a counterstain to distinguish cell types or parts
ex: Gram, acid-fast, and endospore
The most universal diagnostic staining technique for bacteria
A process by which components of bacterial cell walls are bound to Gram's stain
Depending on the amount of peptidoglycan in their cell walls, bacteria stain differently and are classified as Gram-negative (red) or Gram-positive (purple)
acid fast stain
a differential stain used to identify bacteria that are not decolorized by acid-alcohol
acid-fast (pink) non acid-fast (blue)
Used to distinguish parts of cells that aren't revealed by conventional staining
Dye is forced by heat into resistant bodies called spores or endospores
Distinguished between the stores and the cells they come from (vegetative cells)
What is a prokaryotic cell?
cell that does not have a nucleus or organelles
What is the basic cell structure of a prokaryotic cell?
-Capsule, slime layer
What is the basic cell structure of a eukaryotic cell?
What structures are common to ALL bacterial cells?
one (or a few) chromosomes
What structures are found in MOST bacterial cells?
surface coating or glycocalyx
Structures found in SOME bacterial cells?
What are the parts of a Prokaryotic Cell?
Glycocalyx: a coating or layer of molecules external to the cell wall. It serves protective, adhesive, and receptor functions. It may fit tightly or be very loose and diffuse.
Bacterial chromosome or nucleoid: composed of condensed DNA molecules. DNA directs all genetics and hereditary of the cell and codes for all proteins.
Plasmid: double-stranded DNA circle containing extra genes.
Pilus: an elongate, hollow appendage used in transfers of DNA to other cells.
Ribosomes: Tiny particles composed of protein and RNA that are the sites of protein synthesis.
Actin cytoskeleton: long fibers of protein that encircle the cell just inside the cell membrane and contribute to the shape of the cell.
Flagellum: specialized appendage attached to the cell by a basal body that holds a long rotating filament. The movement pushes the cell forward and provides motility
Fimbriae: fine, hairlike bristles extending from the cell surface the help in adhesion to other cells and surfaces
Inclusion/Granule: stored nutrients such as fat, phosphate or glycogen deposited in dense crystals or particles that can be tapped into when needed
Cell wall: a semigrid casing that provides structural support and shape for the cell
Cell (cytoplasmic) membrane: a thin sheet of lipid and protein that surrounds the cytoplasm and controls the flow of materials into and out of the cell pool
Outer membrane: extra membrane similar to cell membrane but also containing lipopolysaccharide. Controls flow of toxic materials and portions of it are toxic mammals when released
Endospore: Dormant body formed within some bacteria that allows for their survival in adverse conditions
Cytoplasm: water-based solution filling the entire cell
How do you name an organism?
Genus and species
Review shapes and arrangements of organisms!!!
pg. 3 of Ch. 4 and in lab book
-Spiral (spirillum, vibrio, spirochete)
-pairs: diplococci, diplobacilli
-chains: streptococci, streptobacilli
What are the three components of flagella? Structure?
filament, hook (sheath), basal body
electric motor, rotates rapidly, propels the cell through the environment, chemotaxis and phototaxis
What is the arrangement of flagella?
Polar- flagella attached at one or both ends of the cell
What are the types of flagella?
*Monotrichous- single flagellum
*Lophotrichous- small bunches or tuffs of flagella emerging from the same site
*Peritrichous- dispersed randomly over the structure of the cell
What is the proton gradient?
The product of the electron transport chain. A higher concentration of protons outside the inner membrane of the mitochondria than inside the membrane is the driving force behind ATP synthesis
What is chemotaxis?
movement of an organism in response to a chemical stimulus
What is phototaxis?
movement in response to light
What does gram positive mean?
Bacteria containing a lot of peptidoglycan in their cell walls also tend to have less complex cell walls, stain purple
What does gram negative mean?
Bacteria have thin peptidoglycan, but have more complex cell walls (extra outer membrane of lipopolysaccharide), use oxygen and stain pink/red
Where do axial filaments or endoflagella live?
In a fluid environment (can corkscrew and move through viscous media)
What is a spirochete?
group of helical gram negative bacteria with axial filaments that cause an organism to corkscrew, thus burrowing in a hosts tissue
*causes STD's such as syphilis
Where do fimbriae and pili exist? (only certain groups of bacteria have these)
Outside of cell wall
Fimbriae- allows attachment
Pili- facilitate transfer of DNA from one cell to another
What are biofilms?
a thin, slimy film of bacteria that adheres to a surface
What is the glycocalyx?
Portion of glycolipids and glycoproteins form an extensive sugary coat called glycolax. Act like a molecular signal that enables cells to recognize on another and prevents bacteria from drying out/dehydrating
*repeating polysaccharide units, protein, or both
*sometimes helps the cell adhere to the environment
*differ among bacteria in thickness, organization, and chemical composition
-slime layer: a loose shield that protects some bacteria from loss of water and nutrients
-capsule: when the glycocalyx is bound more tightly to the cell and is dense and thicker (pathogenic because they can skip phagocytosis)
^^^can't have both on bacteria
How do capsulated bacteria appear in a plate?
Shiny and slime layers look rough
Do majority of bacteria have a cell envelope?
Where is the cell envelope located?
outside the cytoplasm
What composes the cell envelope?
In some bacteria, the outer membrane
What is the periplasmic space?
The area between the cell membrane and the lipopolysaccharide layer (or outer membrane)
What are the differences in cell envelope structure?
The difference of Gram Positive and Gram Negative bacteria lies in the cell envelope
What is gram positive?
Has two layers and thick peptidoglycan
Cell wall and cytoplasmic membrane
What is gram negative?
Has three layers and thin peptidoglycan
Outer membrane, cell wall, cytoplasmic membrane
Stains red/pink: lost primary stain
What is peptidoglycan?
Polymer of disaccharide (or 2 sugars):
-N-acetylmuramic acid (NAM)
"murin" means wall
*connect with one another to form peptidoglycan
NAG and NAM are interconnected to build peptidoglycan layer
Where they are connected is called the glycosidic layer
What is in a gram positive cell wall?
Teichoic acids- lipoteichoic acid links to plasma membrane & wall teichoic acid links to peptidoglycan
May regulate the movement of cations
Contribute to the antigenicity- important for lab results
*can be killed by Penicillin
What is in a gram negative cell wall?
Outer membrane- protects bacteria so harder to kill
Lipopolysaccharides, lipoproteins, phospholipids
Periplasmic space between outer membrane and the plasma membrane
What links together to form peptidoglycan in gram positive bacteria?
I DON'T UNDERSTAND THIS WHAT SOS?!?!
Polypeptides; many peptides linked together
Peptides: carboxyl group with one amine group in amino acid and lose water--- 2 amino acids reacting together via hydration
What is antigenicity?
Antigenicity is the capacity of a chemical structure to bind specifically with a group of certain products that have adaptive immunity: T cell receptors or antibodies
What is wall teichoic acid?
on cell wall
What is lipoteichoic acid?
lipid linked teichoic acid. Only in Gram +
on membrane with attached lipid
Core polysaccharide- supports
O polysaccharide- determines if Gram (+) or (-)
Lipid A- releases endotoxins when bacteria dies
What are the two types of toxins?
exotoxins- release toxins as bacteria is living
endotoxins- release toxins after bacteria dies
What is the cell wall of a prokaryote (bacteria) composed of?
*NO teichoic acids
What is the Gram Stain mechanism?
1. Crystal violet-iodine crystals form in cell
2. Gram positive: alcohol dehydrates peptidoglycan, CV-I crystals do not leave (purple)
3. Gram negative: alcohol dissolves outer membrane and leaves holes in the peptidoglycan, CV-I washes out (red)
What are the 4 steps in Gram staining?
1. Crystal violet (primary stain)
2. Gram's Iodine (mordant)
*CV-I complex is created here
3. Alcohol (decolorizing agent)
4. Safranin (counterstain)
What have atypical cell walls?
Mycoplasma and archaea
Mycoplasma: lack cell walls and have sterols in plasma membrane
Archaea: wall-less or walls of pseudomurein (lack NAM and D-amino acids)
What is mycoplasma?
bacteria that naturally lack a cell wall
cell membrane is stabilized by sterols and is resistant to lysis
-very small bacteria
-range in shape from filamentous to coccus
-important medical species
Damage to cell wall
Lysozyme digests disaccharide
in peptidoglycan Penicillin inhibits peptide bridges in peptidoglycan
What is a protoplast? Spheroplast?
A Gram-positive wall-less cell
L forms are wall-less cells that swell into irregular shapes
What is monomorphic bacteria? Pleomorphic?
Fixed shape, one form/ change shape, many forms
acid fast bacteria
Retain the primary stain even when treated with acid alcohol
Cell walls contain mycolic acid (a wax)
Includes pathogens such as Mycobacterium and Nocardia species which include human pathogens as M. tuberculosis and M. Leprae
*cannot stain with common Gram staining procedure- has ti use special dye, carbon fuchsin
cell membrane structure
•Also known as the cytoplasmic membrane
•Very thin (5-10 nm)
•Contain primarily phospholipids and proteins
•The exceptions: mycoplasmas and archaea
•Provides a site for functions such as energy reactions, nutrient processing, and synthesis
•Regulates transport (selectively permeable membrane)
What are chromatophores?
Structures responsible for color
"to bare color"
What is the difference in DNA in prokaryotes vs. Eukaryotes?
Eukaryotes have a linear DNA and eukaryotes have a circular DNA
*in prokaryotes it is aggregated in the nucleoid
What are plasmids?
Plasmids are small loops of extra DNA that aren't essential; double stranded circles of DNA
Synthesize toxins and antibiotic resistant
What are inclusion bodies?
In Prokaryotes ONLY
It is used to survive when nutrient is depleted; storage of nutrients
*polyhydroxybutyrate- Carbon storage
*magnetosomes- magnetic iron crystals
--NOT ALL HAVE; mainly aquatic
What are ribosomes?
not an organelle!!
made of RNA and proteins
special type of RNA (ribosomal RNA, rRNA)
Characterized by S units- the prokaryotic ribosome is 70s
What are granules?
a type of inclusion body
Why do bacterial endospores form?
Endospore formation is usually triggered by a lack of nutrients, and usually occurs in gram-positive bacteria. In endospore formation, the bacterium divides within its cell wall, and one side then engulfs the other. Endospores enable bacteria to lie as dormant bodies for extended periods, even centuries
*Hard to kill because of this seed-like nature, vegetative cell is original cell, sporangium just perishes and endospore is still alive
*See phases on pg. 15 of Ch.4 notes
What is endospore germination?
Breaking of dormancy in the presence of water and a specific germination agent (quite rapid- 1 to 2 hours)
The agent stimulates the formation of hydrolytic enzymes, digest the cortex and expose the core to water
What are endospores significance to medicine?
Have several bacterial pathogens, can only be killed by autoclave
Molecules of extrachromosomal DNA are also known as?
Are lysosomes pro or eukaryotes?
Eukaryotes because prokaryotes do not have organelles
What is anthrax?
"acute disease cause by bacillus anthracts spores
not fungal, used in war, can be lethal transported by clothing shoes, dead bodies"
What are histones?
proteins that DNA wraps around
What are eukaryotes?
Eukaryotes are cells that have a nucleus, and organelles that have different functions(like the mitochondria, which produces energy).
Eukaryotes can include simple organisms like protozoa, fungi, helminths
*microscopic, unicellular, and multicellular
may be unicellular or multicellular
fungi and algae
Helminths (have unicellular egg or larval forms)
LOOK AT CELL FIGURES!!!
cell wall of eukaryotes
Composed of polysaccharides:
1. Algae- Cellulose, silicate, and agar
2. Fungi- Chitin
3. Yeast- Glucan and mannan
4. Protozoa- Flexible outer covering called
Do animal cells have a cell wall?
No, only plant cells (fungal cells) have a cell wall- animal cells have a cell membrane
What is a chloroplast?
A structure in the cells of plants and some other organisms that captures energy from sunlight and uses it to produce food
What are external features of a eukaryotic cell?
What structures are exclusive to a plant cell?
Plasmodesmata: gap junction
flagella in eukaryotes
used for cellular locomotion, long and few in relation to size of cell
cilia in eukaryotes
uses cilia to swim in water
What is the boundary of a eukaryotic cell?
The external surface of a plasma membrane that is important for cell-to-cell communication
*usually composed of polysaccharides and appears as a network of fibers, a slime layer, or a capsule
Functions: protection, adhesion, reception of signals
cell wall of eukaryotic cells
Ridgid, provide support and shape, chemically different from prokaryotic cells
-Fungi: thick inner layer of chitin or cellulose/ thin outer layer of mixed glycans
-Algae: varied in chemical composition/ may contain cellulose, pectin
A phospholipid bilayer embedded with proteins that surrounds the cytoplasm and defines the boundary of the cell
*also contains sterols: gives stability, especially important in cells without a cell wall
Which group of microbes usually does not have a cell wall?
Protozoa (animal cell)
*Bacteria, fungi, algae, all have cell walls
What are the internal structures of a eukaryotic cell?
Nucleus- nuclear envelope, nucleolus, chromosomes
Organelles-ER-ribosomes, Golgi apparatus- lysosomes, mitochondria, chloroplasts
Cytoskeleton- microtubules, microfilaments
DNA (genetic material)
Haploid- gamete cells: meiosis (23 chromosomes)
Diploid- somatic cells: mitosis (46 chromosomes)
Multiple linear chromosomes are present
DNA is condensed on proteins (hostones)
What is formed when chromatids condense?
Chromosomes (made up of DNA)
A system of membranes (cisternae) that is found in a cell's cytoplasm and that assists in the production, processing, and transport of proteins and in the production of lipids
-smooth: makes more enzymes, makes steroid hormones, lipid metabolism, detox reactions
-rough: ribosomes docked, protein synthesis (connected to the nucleus)
Characteristics of a eukaryote ribosomes
Two subunits: 40s and 60s
Total size is 80s
Translates mRNA into proteins
different shape from prokaryotes but similar
found in chloroplasts and mitochondria
Protein trafficking center
vesicles bud off
composed of a lipid bilayer
Cell organelle that stores materials such as water, salts, proteins, and carbohydrates
Lipid enclosed space
Storage site for water, food, enzymes, and waste
*central: provide turgor pressure
*contractile: eliminate water
*lysosomes: contain digestive enzymes
Action of lysosomes in phagocytosis
Lysosomes are filled with acidic enzymes and can digest anything
Site of respiration
Double lipid bilayer
OWN GENETIC MATERIAL
An organelle found in plant and algae cells where photosynthesis occurs
Own genetic material
A network of fibers that holds the cell together, helps the cell to keep its shape, and aids in movement
Involved in motility
Actin- polymerized into chains
microtubules- (green) made of tubulin
Some eukaryotic cells don't perform aerobic respiration. Which cellular organelle can these cells do without?
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