MMG 201 Exam 1

how is morphology maintained

by the cell wall in combination with cytoskeletal elements. The cell wall also protects the cell from osmotic pressure

Explain how lenses are used in microscopy to manipulate visible and ultraviolet light

A convex lens can be used to magnify because it can focus at closer ranges than a human eye A concave lenses and mirrors can redirect the light path

Explain the function of chloroplasts

here photosynthesis occurs At least three membrane systems; the outer membrane, the inner membrane, and the thylakoid membrane

describe unique features of gammaproteobacteria

highly mobile bacteria. It often infects wounds and burns, can be chronic UTIs, and can be an important cause of respiratory infections in pts with cystic fibrosis or pts on vents.

Explain how immersion oil is useful in microscopy

At very high magnification, resolution may be compromised when light passes through small amount of air between the specimen and the lens. To solve this problem, a drop of oil can be used to fill the space. Since the oil has a refractive index similar to that of glass, it increases the maximum angle at which light leaving the specimen can strike the lens.

explain how prokaryotes are classified

Bacteria are classified as being gram positive, gram negative, and "atypical" Gram positive bacteria possess a thick peptidoglycan cell wall that retains the primary stain during the decolorizing step Gram negative bacteria possess a thin peptidoglycan cell wall that does not prevent the crystal violet from washing away during the decolorizing step

spirochete

long, loose, helical spiral

compare normal/commensal/resident microbiota to transient microbiota

Commensal: there are thousands living in the mouth, some prefer to inhabit the surface of the tongue, whereas other prefer the internal surface of the cheeks, and yet others prefer the front or back of the gums. Resident: consists of microorganisms that constantly live in or on our bodies. Transient: refers to microorganisms that are only temporarily found in the human body, and these may include pathogenic microorganisms.

Explain the function of a pilus

longer, less numerous protein appendages that aid in attachment to surfaces

Describe what van Leeuwenhoek did

He is known as the "father of microbiology". Is credited for making the first microscope, after becoming interested in lens making and his innovative techniques produced microscopes that allowed him to observe microorganisms.

what are the organelles unique to eukaryotic cells?

Membrane bound nucleus ER Gogli Chloroplasts Mitochondria Lysosomes

Evidence that supports the endosymbiotic theory

More recent genetic sequencing and phylogenetic analysis show that mitochondrial DNA and chloroplast DNA are highly related to their bacterial counterparts, both in DNA sequence and chromosome structure. Mitochondrial DNA and chloroplast DNA are reduced compared with nuclear DNA because many of the genes have moved from the organelles into the host cell's nucleus. Mitochondria and chloroplasts ribosomes are structurally similar to bacterial ribosomes, rather than eukaryotic ribosomes of their hosts. The binary fission of these organelles strongly resembles the binary fission of bacteria, as compared with mitosis performed by eukaryotic cells. Konstantin Mereschkowski suggested in 1905 that chloroplasts may have originated from ancestral photosynthetic bacteria living symbiotically inside a eukaryotic cell. He also proposed a similar origin for the nucleus of plants, thus, was the first articulation of the endosymbiotic theory.

what is an example of betaproteobacteria

N. gonorrhoeae causes the STI gonorrhea

what is an example of gammaproteobacteria

Pasteurella haemolytica causes severe pneumonia in sheeps and goats.

compare and contrast similar structures found in prokaryotic and eukaryotic cells

Prokaryotic cells lack a nucleus surrounded by a complex nuclear membrane and generally have a single, circular chromosome located in a nucleoid. Eukaryotic cells have a nucleus surrounded by a complex nuclear membrane that contains multiple, rod-shaped chromosomes. All plant cells and animal cells are eukaryotic Eukaryotes tend to be larger prokaryotic cells lack membrane-bound organelles: however, they often contain inclusions that compartmentalize their cytoplasm.

What is an example of alphaproteobacteria

Rickettsias- that require part of their life cycle to occur inside other cells called host cells Metabolically inactive outside a host cell

compare the distinguishing characteristics of bacterial and archaea cells

The archaeal cell membrane is composed of ether linkages with branched isoprene chains Bacterial cells have ester linkages with unbranched fatty acids Archaeal cell walls lack peptidoglycan, but some contain a structurally similar substance called pseudopeptidoglycan or pseudomurein The genomes of archaea are larger and more complex than those of bacteria

what is meiosis

The goal is to create four genetically distinct gametes, with each gamete possessing half the number of chromosomes found in the original cell

explain the cell wall

The primary function of the cell wall is to protect the cell from harsh conditions in the outside environment. The major component of the cell wall is called peptidoglycan

Explain Symbiosis

any interaction between different species that are associated with each other in a community. Can be beneficial or harmful or no effect.

what are the features and uses of a differential interference contrast microscope?

are similar to phase-contrast microscopes in that they use interference patterns to enhance contrast between different features of a specimen. results in high contrast images of living organisms with a 3D appearance.

Explain the function of Flagellum

are structures used by cells to move in aqueous solutions

What are the unique features of a positive stain?

a dye that will be absorbed by the cells or organism being observed, adding color to objects of interest to make them stand out against the background.

what is capsule staining?

a negative staining technique. The dye stains the background, and makes a halo appear around the border of the cells.

Give the function of a stage

a platform where the specimen is placed

Explain the function of the endoplasmic reticulum

interconnected array of tubules and cistern with a single lipid bilayer. There are two types; rough and smooth

What is a simple stain?

a single dye used to emphasize particular structures in the specimen. will generally make all of the organisms in a sample appear to be the same color, even if the sample contains more than one type of organism.

what is acid-fast stains?

able to differentiate two types of gram-positive cells: those that have waxy mycelia acids in their cell walls, and those that do not.

what are the unique features of a negative stain?

absorbed by the background but not by the cells or organism in the specimen

Explain what cell theory is

all cells come from other cells, cells are the fundamental units of organisms

Explain the function of the golgi apparatus

composed of a series of membranous discs called dictyosomes, each having a single lipid bilayer, that are stacked together. Enzymes in the golgi modify lipids and proteins transported from the ER to the golgi, often adding carbohydrates components to them, producing glycolipids, glycoproteins, or proteoglycans.

Explain the contribution of Snow to germ theory

conducted studies to track the source of cholera outbreaks in London. Demonstrated that cholera bacteria were transmitted via drinking water. Influential in that it represents the first known epidemiological study, and it resulted in the first known public health response to an epidemic.

explain what a compound microscope is

consist of two or more lens

Explain what a simple microscope is

consists of a single lens- a magnifying glass

vibrio

curved rod

explain the function of the nucleolus

dense region within the nucleus where ribosomal RNA biosynthesis occurs.

what is gram-staining?

differential staining procedure that involved multiple steps. 1. crystal violet, is applied to a heat-fixed smear. 2. Gram's iodine, a mordant, is applied. 3. a decolorizing agent is added. 4. a secondary counterstain is added.

Explain the contributions of Pateur to germ theory

discovered properties of fermentation by microbes. Demonstrated with his swan-neck flask experiments that airborne microbes, not spontaneous generation, were the cause of food spoilage, and he suggested that if microbes were responsible for food spoilage and fermentation, they could also be responsible for causing infection. Foundation for the germ theory of disease

what is a differential stain?

distinguishes organisms based on their interactions with multiple stains. Two organisms in a differentially stained sample may appear to be different colors

explain the plasma membrane

exhibits permeability, allowing some molecules to enter or leave the cell while restricting the passage of others. The plasma membrane of most bacterial and eukaryotic cells is a bilayer composed mainly of phospholipids formed with ester linkages and proteins.

Explain how pasteur disproved spontaneous generation

filtered air through a gun-cotton filter and, upon microscopic examination of the cotton, found it full of microorganisms, suggesting that the exposure of a broth to air was not introducing a "life force" to the broth but rather airborne microorganisms Also made a series of flasks with long, twisted necks, in which he boiled broth to sterilize it. Allowed air inside the flasks to be exchanged with air from outside, but prevented the introduction of any airborne microorganisms, which would get caught in the bends of the flasks. Predicted that sterilized broth in the flasks would remain sterile as long as the swan necks remained intact. Disproved the spontaneous generation theory

Explain how Hooke contributed to cell theory

first used the term "cells" in 1665 to describe the small chambers within cork that he observed under a microscope of his own design.

explain the function of membrane bound ribosomes

found attached to the ER and make proteins for insertion into the cell membrane or proteins destined for export from the cell

Explain the function of free ribosomes

found in the cytoplasm and serve to synthesize water soluble proteins

describe unique features of epsilonproteobacteria

gram-negative bacteria and have small amounts of oxygen in their environments

Describe chalmydia

gram-negative nonproteobacteria , obligate intracellular pathogens that are extremely resistant to the cellular defenses

describe unique features of deltaproteobacteria

gram-negative that includes sulfate-reducing bacteria. Few are pathogenic

what are the features of low G+C gram-positive bacteria

have less than 50% G and C nucleotides in their DNA

what are the features of high G+C gram-posistive bacteria

have more than 50% G and C nucleotides in their DNA

what is the function of an objective lens?

magnifies and ranges from 4x to 100x

explain the function of the lysosomes

membrane-bound organelles of the endomembrane system that contain digestive enzymes. Break down various particles, such as food, damages organelles or cellular debris, microorganisms, or immune complexes.

Explain the function of peroxisomes

membrane-bound organelles that are not part of the endomembrane system Produce hydrogen peroxide and possess the enzyme catalase

Explain what a brightfield microscope is

most common, compound microscope with two or more lenses that produce a dark image on a bright background. can be molecular or binocular

what is an example of deltaproteobacteria

myxobacteria, lives in the soil, scavenging inorganic compounds.

explain neutralism

neither of the symbiotic organisms are affected in any way Ex. the coexistence of metabolically active bacteria and endospores. The bacterium Bacillus anthracis typically forms endospores in soil when conditions are unfavorable. If the soil is warmed and enriched with nutrients, some B. anthracis endospores germinate and ramin in symbiosis with other species of endospores that have not germinated.

describe spirochetes

nonproteobacteria that have long spiral shaped bodies Ex. T. pallidum pallidum causes the sexually transmitted infection known as syphillis

describe plantomycetes

nonproteonbacteria found in aquatic environments, reproduce by budding

Explain what spontaneous generation is

notion that life can arise from nonliving matter. Aristotle noted as evidence that several instances of the appearance of fish in a new puddle of water. Mice seemed to appear among grain stored in barns with thatched roofs.

Describe unique features of Alphaproteobacteria

obligate or facultative intracellular bacteria. Some species are characterized as oligotrophs- capable of living in low nutrient environments such as deep oceanic sediments, glacial ice, or deep undersurface soil.

Explain the contribution of Semmelweis to germ theory

observed that mothers who gave birth in hospitals wards staffed by physicians and medical students were more likely to suffer and die from puerperal fever after childbirth. Suspected that students carried disease from the autopsies to the patients examined. Suggested that the number of puerperal fever cases would be reduced if physicians and medical students simply washed their hands with chlorinated lime water before and after examining every patient.

How do you calculate the total magnification for a compound microscope?

ocular magnification x objective magnification

explain parasitism

one organism benefits while harming the other Ex. the relationship between humans and many pathogenic prokaryotes because these organisms invade the body.

explain commensalism

one organism benefits while the other is unaffected. Ex. when the bacterium Staphylococcus epidermidis uses the dead cells of the human skin as nutrients.

explain amensalism

one population harms the other but remains unaffected itself Ex. Some amensalist species produce bactericidal substances that kill other species of bacteria.

Explain the function of a capsule

organized layer located outside the cell wall that is usually composed of polysaccharides or proteins

Explain how Redi disproved spontaneous generation

performed an experiment in 16668 that was one of the first to refute the idea that maggots spontaneously generate on meat left out in the open air. Predicted that preventing flies from having direct contact with the meat would also prevent the appearance of maggots. Left meat in each six containers- two open to air, two covered in gauze, and two tightly sealed. Maggots developed in the uncovered jars, but no maggots appeared in either the gauze or tightly sealed jars. Concluded that maggots could only form when flies were allows to lay eggs in the meat, and that maggots were the offspring of flies, not the product of spontaneous generation.

what is mitosis

produces two identical idaughter cells. consist of interphase and the mitotic phase

explain the contributions of Koch to germ theory

proposed a series of postulates based on the idea that the cause of a specific disease could be attributed to a specific microbe. His "one microbe, one disease" concept was the culmination of the 19th century's paradigm shift away from miasma theory and toward the germ theory of disease.

explain the function of the cytoskeleton

provides structural support as well as a network over which materials can be transported within the cell and on which organelles can be anchored

explain what fixation is

refers to the process of attaching cells to a slide. Either by heating or chemically treating the specimen

bacillus

rod

describe the CFB group

rod shaped nonproteobacteria adapted to anaerobic environments Ex. Fusobacteria inhibit the human mouth and may cause severe infectious diseases.

coccus

round

what are the features and uses of a fluorescence microscope?

use fluorescent chromosomes called fluorochromes, which are capable of absorbing energy from a light source and then emitting this energy as visible light.

What are the features and uses of confocal microscopes?

uses a laser to scan multiple z-plans successively. Produces numerous high resolution images at various depths.

what are the features and uses of two-photon microscopes?

uses a scanning technique, and long-wavelength to visualize specimens

Explain the function of the endomembrane system

series of membranous tubules, saves, and flattened disks that synthesize many cell components and move materials around the cell.

coccobacillus

short rod

explain the function of fimbriae

short-bristle like proteins projecting from the cell surface by the hundreds. enable the cell to attach to surfaces and to other cells. Important for colonization, infectivity, and virulence.

Describe unique features of betaproteobacteria

some include species that are human pathogens, able to cause severe, sometimes life-threatening disease.

spirillum

spiral

explain the function of inclusions

stores nutrients in a polymerized form. It is advantageous because it reduces the buildup of osmotic pressure that occurs as a cell accumulates solutes.

Explain the function of a nucleus

surrounded by a complex nuclear membrane that houses the DNA genome. Controls all activities within the cell and also serves as an essential role in the reproduction and heredity.

Explain the function of ribosomes

synthesizes proteins, and organisms in all three domains of life possess ribosomes. prokaryotic ribosomes are located in the cytoplasm and are called 70s. bacterial and archaea ribosomes have different protein and rRNA molecules.

Explain magnification

the ability of a lens to enlarge the image of an object when compared to the real object

Explain resolution

the ability to tell that two separate points or objects are separate; low resolution appears fuzzy, high resolution appears sharp.

What are the features and uses of a phase-contrast microscope?

uses refraction and interference caused by structures in a specimen to create high-contrast, high-resolution images without staining. used to observe live specimens

explain what a wavelength is

the distance between one peak of a wave and the next peak

Explain what endosymbiotic theory is

the theory that the mitochondria and chloroplasts arose as a result of prokaryotic cells establishing a symbiotic relationship within a eukaryotic host.

what are the unique characteristics of phototrophic bacteria

they use solar energy to synthesize ATP through photosynthesis

what is flagella staining?

thickens the flagella by first applying mordant which coats the flagella and then the specimen is stained with parasoaniline or basic fuchsin.

What is the function of an ocular lens?

typically magnifies the image 10x

What are the features and uses of a brightfield microscope?

typically shows bright objects on a dark background. Can create high-contrast, high-resolution images of specimens without the use of stains.

what are the features and uses of an electron microscope?

uses short-wavelength electron beams rather than light to increase magnification and resolution. A transmission electron microscope uses an electron beam above the specimen that is focused using a magnetic lens (rather than a glass lens)

what is endospore staining?

uses two stains to differentiate endospores from the rest of the cell

explain the contributions of Lister to germ theory

was trying to determine the causes of postsurgical infections. Many physicians didn't give credence to the idea that microbes on their hands, on their clothes, or in the air could infect patients' surgical wounds. Insisted on handwashing and extreme cleanliness during surgery. Began using carbolic acid spray disinfectant/antiseptic during surgery. Now became standard medical practice

explain mutualism

when two species benefit from each other Ex. Humans have a mutualistic relationship with the bacterium Bacteroides Thetaiotaomicron, which lives in the intestines.

explain the function of a plasmid

where extrachromosomal DNA is found. Small-circular, double-stranded DNA molecules. commonly found in bacteria, but can be found in archaea and eukaryotic organisms. Carry genes that confer advantageous traits such as antibiotic resistance; thus, they are important to the survival of an organisms.

Explain the function of a nucleoid

where prokaryotic DNA and RNA associated proteins are concentrated