Exam 1 Study Guide Flashcards
Chapters 1-5, 7
List the top three cause of death in the US. Describe how the role of microbes has changed in the last 100 years.
- Heart diseases
- Cancer
- stroke
- In the last 100 years, microbes used to be the main cause of death, but now, because of clean water and no sewage contamination, vaccination, discovery of antibiotics by Alexander Flemming
what were the first living creatures on planet earth?
- microbes are the first living creatures on planet earth
- microbes are more diverse than plants and animals
- more abundant than any other living thing
where do microbes grow?
- in every ecological niche on earth that has a source of liquid H2O
what effect do microbes have on the environment?
- they can transform the geosphere
- Can affect the climate by production/use of CO2, N2, O2, and CH4
- Participate in symbiotic relationships with other organisms
what are microbes involvement in diseases?
- only a small fraction of microbes cause diseases
- diseases caused by microbes are called “infectious diseases”
where in the human body can bacteria be found?
- colonization can only occur at body sites that provide nutrients and the right environment for the microbes to flourish
- can live stably in/on the human body
when do microbiota start to collect in the human body and how long do they stay?
- begin to acquire as newborns
- may colonize the body indefinitely
- may colonize the body fleetingly
how does microbiota help the body?
- normal microbiotas prevent growth of pathogens
- normal microbiotas produce growth factors such as vitamins B and K
- may help train the immune system to discriminate threats
swan-neck flask experiments
Louis Pasteur had swan-neck flasks that once the solution was boiled within them, no new growth occurred. But, if they were broken, then microbial growth did occur. He learned that no new growth occurred was because all the dust and germs from the air were trapped in the neck instead of in the solution. This helped to develop a new way to keep solutions sterile.
disproved theory of spontaneous generation
- Spontaneous generation: living organisms could develop from nonliving matter
- Challenged multiple times: Francesco Redi in covering meat; when they were covered, no maggots, when they were open, there were maggots.
- Lazzaro Spallanzani: boiling water in a flask prevented microbial growth, concluded that germs must be in the air
- Swan-neck experiments
- John Tyndall & Ferdinand Cohn: broth was sterile even when exposed to air, proved that dust had germs in it
yeast fermentation to make alcohol
- Louis Pasteur proved that fermentations were carried out by living organisms and not by the degradation of sugars from chemical instability
- Specific yeasts and bacteria have to do with fermentation
- Beet sugars: yeast was replaced with bacteria
- Wine in France: contamination of wines by other microbes
pasteurization
Developed by Louis Pasteur, used to heat liquids to destroy microbes, found out when he consulted the wine industry in France
Louis Pasteur
Trained as a chemist, contributed much to the world of microbiology, Developed pasteurization, discovered fermentation was done by specific yeasts and bacteria, developed a vaccine after discovering attenuated bacteria could not cause disease and developed the anthrax and rabies vaccines, and disproved spontaneous generation through the swan-neck experiments
Antony van Leeuwenhoek
In 1673, he constructed simple microscopes composed of double convex glass lenses held between two silver plates. These microscopes could magnify 50-300 times and illuminated them by shining a light at a 45 degree angle of the specimen plane (dark field illumination).
Edward Jenner
Pasteur named attenuated bacteria a vaccine (vacca meaning cow) after Jenner because he used material from cowpox lesions to protect people against smallpox.
Ignaz Semmelweis
First person to realize that a pathogen could be transmitted from one person to another (1847-1848). Found that doctors and medical students were infecting pregnant women with fluids from other procedures due to a lack of hand washing. Pioneer of antisepsis in obstetrics.
Robert Koch
- Developed the first demonstration that bacteria can cause disease, mycobacterium tuberculosis can cause TB, developed pure culture methods using agar,
- Developed Koch’s postulates
etiology of anthrax
- The first direct demonstration that bacteria could cause disease came from Koch’s study of anthrax, realizing that Bacillus anthracis caused anthrax outbreaks
- Pasteur and Chamberland later developed a vaccine for it
what are Koch’s postulates
- The microorganism must be present in every case of the disease but absent from healthy organisms
- The suspected microorganisms must be isolated and grown in a pure culture
- The same disease must result when the isolated microorganism is inoculated into a healthy host
- The same microorganism must be isolated again from the diseased host
John Snow
- Discovered the cause of cholera was from unwashed hands and shared foods and not by bad air. Also found that the Broad street pump was contaminated, which was causing people to get the disease.
Alexander Flemming
- In 1929, he rediscovered the fungus penicillium that produced penicillin. It was the first antibiotic that could successfully control bacterial infections
- It was mass produced by WW 2
Paul Ehrlich
- father of antibiotics
- developed arsenic based medication for syphilis
define cell
- the smallest structural and functional unit of an organisms, typically microscopic and consisting of cytoplasm and nucleus enclosed in a membrane, can be eukaryotic or prokaryotic
- Made of molecules, those molecules are used to create structure, and that structure performs a function
define microbe
entities that cannot be seen with the naked eye
- need magnification to see them
what are the hallmarks of the cell?
- be able to replicate itself
- source of energy
- control the flow of chemicals (cell membrane)
- DNA as the primary genetic material (not only RNA)
what are prions?
An infectious agent consisting only of proteins; prions cause a variety of spongiform encephalopathies such as scrapie in sheep, acellular
what are virions?
Simple virus particles, composed only of proteins and a nucleic acid and can be extremely small, acellular
what are viruses?
An infectious agent having a simple acellular organization with a protein coat and a nucleic acid genome, lacking independent metabolism, and multiplying only within living host cells
what kingdoms and domain are a part of prokaryotes?
domain: Bacteria
kingdoms: bacteria and archaebacteria
- monera is a kingdom with the other 5
what kingdoms and domain are a part of eukaryotes?
kingdoms: plant, animal, protist, and fungi
domain: eukarya
what are the six major bio-elements?
- carbon
- hydrogen
- oxygen
- nitrogen
- phosphorous
- sulfur
besides the 6 major bio-elements, what other elements are important to life?
magnesium, zinc, iron, sodium, and potassium
which bio-elements form carbohydrates?
sugars are made up of CHO
which bio-elements form lipids?
fatty acids and glycerol are made up of CHO
which bio-elements form nucleic acids?
nucleotides are made up of CHONP
which bio-elements form proteins?
amino acids are made up of CHONS
define magnification
- power of the lens
- calculated by multiplying the objective and eyepiece magnifications together
define refractive index
how the structure in the microscope slide bent the light
define resolution
- how clear the specimen is
- the ability of a microscope to distinguish between small objects that are close together.
- just because there is a higher magnification doesn’t mean that the resolution is clear
what is the purpose of oil immersion?
Used to increase the total magnification power of a microscope because oil has a high refractive index, therefore increasing the aperture of the objective lens
define smear preparation (role of heat fixation)
a smear is a film of cells, in heat fixation, this process is used to observe bacteria and archaea. The process preserves overall morphology and inactivates enzymes, but destroys proteins and subcellular structures
what is the role of microbes in maintaining temperature on earth? (role of microbes in CO2 and CH4 recycling?)
- Cyanobacteria were the first organisms to release oxygen in abundance into the atmosphere
- Only bacteria can fix nitrogen
- Microbes are important in fixing carbon
- It plays a role in producing and removing greenhouse gases like CO2 and CH4
- They could be used to remove pollution
what membrane-bound organelles are present in eukaryotes but not in prokaryotes?
mitochondria/chloroplasts, lysosome, golgi aparatus, and endoplasmic reticulum
compare prokaryotes and eukaryotes on the presence and makeup of cell wall
- Prokaryotes have a rigid cell wall, in eukaryotic organisms, vertebrates don’t have cell walls but plants do
- cell walls in prokaryotes are made of peptidoglycan, some eukaryotic cell walls are made of cellulose or chitin
compare the prokaryotes and eukaryotes on the presence of organelles
- In eukaryotic organisms, organelles are membrane bound while prokaryotic organisms have free organelles.
- Prokaryotes also lack some internal structures that are in eukaryotes like the endoplasmic reticulum and the Golgi apparatus
compare the prokaryotes and eukaryotes on their chromosomes structure and organization
- Eukaryotes have double stranded linear DNA and prokaryotes have double stranded circular DNA. Eukaryotes have mitochondrial DNA with histones and prokaryotes use plasmids
ionic bond
most atoms have less electrons than protons, so they carry either a positive or negative ion. Cations are positive and anion carries a negative charge. When a cation and anion approach each other, they are attracted by their opposite charges. This ionic attraction that holds two groups together is an ionic bond
covalent bond
- are joined together by sharing pairs of electrons.
- If electrons are equally shared between identical atoms, the covalent bond is strong and non-polar
- If there are two different atoms, the covalent bond formed is polar because the electrons are pulled toward the more electronegative atom
- strongest bond
hydrogen bond
- when a hydrogen atom is covalently bonded to a more electronegative atom such as oxygen or nitrogen, the electrons are unequally shared and the hydrogen atom carries a partial positive charge.
- Although hydrogen bonds are weak, there are so many in proteins and nucleic acids that they play a major role in determining protein and nucleic acid structure
hydrophobic interaction
a nonpolar substance lacking affinity for water (or which is not readily soluble in water)
what is the role of water in biological activities?
- H bonds between water molecules contribute to high BP
- H bonds hold and absorb energy making water a temperature buffer
- Water is a polar molecule and capable of forming H bonds with others, this makes water an excellent solvent
define water activity (Aw)
a quantitative measure of water availability in the habitat; the water activity of a solution is one-hundredths its relative humidity
define osmosis
when two solutions are separated by a semipermeable membrane that allows movement of water but not solutes.
define osmolarity
solute concentration
define osmotolerant
organisms that grow over a fairly wide range of water activity or solute concentration
define halophiles and explain why they survive in their environment
- like high concentrations of salt
- They can live in these extreme conditions because they synthesize or obtain from their environment molecules called compatible solutes. Compatible solutes can be kept at high intracellular concentrations without interfering with metabolism or growth
what is the difference between endergonic and exergonic reactions?
- An endergonic reaction is a reaction that does not spontaneously go to completion as written; the standard free energy change is positive and the equilibrium constant is less than one; requires energy
- An exergonic reaction is a reaction that spontaneously goes to completion as written, the standard free energy change is negative, and the equilibrium constant is greater than one; releases energy
what is the difference between hydrolysis and dehydration?
- hydrolysis: bonds are broken and a water molecule is added
- Dehydration: bonds are formed and a water molecule is lost, synthetic reaction
what is the difference between hydrolytic and condensation reactions?
Condensation involves the formation of a new chemical bond while hydrolysis involves the breakdown of a chemical bond
Define folding and denaturation of protein molecules.
if a protein is altered so severely that the protein no longer functions, the protein is said to be denatured
what are the factors that affect protein shape?
- pH
- temperature
- salt concentration
- changing these variables alters the activity/function of a protein
what are the different levels of protein folding? What kind of bonds are associated with each level?
- Primary structure: hydrogen and peptide bonds
- Secondary structure: hydrogen and peptide bonds
- Tertiary structure: hydrogen, peptide, disulfide bridges, hydrophobic interactions
- Quaternary structure; van der Waals forces, hydrogen, peptide, disulfide bridges
define an amphipathic molecule
An amphipathic molecule is a molecule that has both hydrophobic and hydrophilic regions. One example of this could by phospholipids
basic dyes
have positively charged groups, bind to negatively charged molecules such as nucleic acids, many proteins and the surfaces of bacterial and archaeal cells
acidic dyes
have negatively charged groups; bind to positively charged cell structures
negative staining
a staining procedure in which dye is used to make the background dark while the specimen is unstained, uses acidic dye that binds to the background, india ink
positive staining
uses basic dye that binds to the specimen, CV
simple stain
employs a basic dye to impart a color to a cell. Easy way to increase the contrast between otherwise colorless cells and a transparent background; uses one stain to show morphology, size, and arrangement
differential stain
distinguishes one group of organisms from another
gram stain
used to separate bacteria into two major groups, gram-positive and gram-negative. The staining characteristics of these groups reflect a fundamental difference in the chemical structure of their cell walls. This is the most widely used staining technique
acid-fast stain
used to detect members of the genus mycobacterium in a specimen, due to the lipid composition of their cell walls, these organisms do not readily take up stains
special stains
stains specific structures inside or outside of a cell
capsule stain
because the viscous capsule does not readily take up stains, it stands out against a stained background, example of a negative stain
endospore stain
stains endospores, a type of dormant cell that does not readily take up stains. These are produced by the genera Bacillus and Clostridium
flagella stain
the staining agent adheres to and coats the otherwise thin flagella, enabling them to be seen with the light microscope
fluorescent dyes and tags
fluorescent dyes and tags absorb ultraviolet light and then emit light of a longer wavelength. They are used in conjunction with a fluorescence microscope
fluorescent dyes
some fluorescent dyes bind to compounds found in all cells, others bind to compounds specific to only certain types of cells
fluorescent tags
antibodies to which a fluorescent molecule has been attached are used t tag specific molecules
What are the three medical important structures present in bacteria?
capsule, endospore, and flagella
define and describe the importance of wet mount
• Wet mount: bacterium in a drop of water. The refractive indices of bacterial cell structures are greater than that other water, therefore light passes through the cell structure will refract, showing the structure of the cell
explain the steps involved in gram staining procedure
- Step 1: crystal violet (primary stain) for 1 minute, water rinse – cells stain purple
- Step 2: iodine (mordant) for 1 minute, water rinse – cells remain purple
- Step 3: alcohol (decolorizer) for 10-30 seconds, water rinse – gram positive cells remain purple, gram-negative cells become colorless
- Step 4: safranin (counterstain) for 30-60 seconds, water rinse, blot dry – gram positive cells remain purple, gram-negative cells appear red
What is the significance of acid-fast staining procedure?`
- It is used to identify mycobacterium tuberculosis and M. leprae, the pathogens responsible for tuberculosis and leprosy
- These bacteria, as well as other mycobacteria, have cell walls containing lipids constructed from mycolic acids, a group of branched-chain hydroxy fatty acids, which prevent dyes from readily binding to the cells
Which microscope uses the differences in refractive index and cell density to visualize live cells?
phase-contrast microscopes
plasma membrane
selectively permeable barrier, mechanical boundary of the cell, nutrient and waste transport, location of many metabolic processes (respiration and photosynthesis), detection of environmental cues for chemotaxis
gas vacuole
buoyancy for floating in aquatic environments
inclusions
storage of carbon, phosphate, and other substances
periplasmic space
- in typical gram-negative bacteria, contains hydrolytic enzymes and binding proteins for nutrient processing and uptake, in typical gram-positive bacteria, may be smaller or absent
ribosomes
protein synthesis
nucleoid
localization of genetic material (DNA)
cell wall
gives prokaryotes shape and protection from osmotic stress
capsules and slime layers
resistance to phagocytosis, adherence to surfaces
fimbriae and pili
attachment to surfaces, bacterial mating
flagella
movement
endospore
survival under harsh environmental conditions
what is the significance of periplasmic space?
- The space between the plasma membrane and the outer membrane in typical gram-negative bacteria, and between the plasma membrane and the cell wall in typical gram-positive bacteria.
- Contains hydrolytic enzymes and binding proteins for nutrient processing and uptake
- One of the areas used for synthesis of peptidoglycan (also in cytoplasm and plasma membrane)
glycocalyx
network of polysaccharides extending from the surface of the cell. a capsule or slime layer composed of polysaccharides can also be referred to as a glycocalyx
capsule
usually composed of polysaccharides; well organized and not easily removed from cell