Exam 1 Study Guide

Spirillum (Ch 1 & 3)

A bacterium having a slightly curled or spiral shaped cylinder is called a cpirillum, a rigid helix, twisted twice or more along its axis (like a corkscrew).

Bacillus (Ch 1 & 3)

A cell that is cylindrical is termed a rod, or bacillus. There is also a genus named Bacillus. Rods are also quite varied in their actual form. Depending on the species, they can be blocky, spindle-shaped, round-ended, long and threadlike (filamentous), or even club-shaped or drumstick shaped. Note: when a rod is short and plump, it is called a coccobacillus.

Compare and contrast the gram positive and gram negative cell wall structure.

A gram-positive cell wall structure has a thick peptidoglycan membrane with wall teichoic and lipoteichoic acids. By contrast, the gram-negative cell wall has a thin layer of peptidoglycan with periplasmic space on either side of it. The gram-negative cell wall structure also contains an outer membrane layer consisting of phospholipids, porin proteins, LPS, and lipoproteins. By contrast, the gram-negative cell wall has a thin layer of peptidoglycan with periplasmic space on either side of it. Both gram-positive and gram-negative cell walls have a cytoplasmic membrane which includes membrane proteins.

Function of cell membrane in prokaryotes (Ch 1 & 3)

A thin sheet of lipid and protein that surrounds the cytoplasm and controls the flow of materials into and out of the cell pool. (In all bacteria)

Synthesis: Replication and Protein Production.

Almost immediately, the viral nucleic acid begins to synthesize the building blocks for new viruses. First, the + ssRNA, which can serve immediately upon entry as mRNA, starts being translated into viral proteins, especially those useful for further viral replication. The + strand is then replicated into - ssRNA. This RNA becomes the template for the creation of many new + ssRNAs, used as the viral genomes for new viruses. Additional + ssRNAs are synthesized and used for late-stage mRNAs. Some viruses come equipped with the necessary enzymes for synthesis of viral components; other utilize those of the host. Proteins for the capsid, spikes, and viral enzymes are synthesized on the host's ribosomes using its amino acids.

Function of pili in prokaryotes (Ch 1 & 3)

An appendage used for drawing another bacterium close in order to transfer DNA to it. (In some bacteria)

Spirochete (Ch 1 & 3)

Another spiral cell containing periplasmic flagella is the spirochete, a more flexible form that resembles a spring.

Release.

Assembled viruses leave their host in one of two ways. Non-enveloped and complex viruses that reach maturation in the cell nucleus or cytoplasm are released when the cell lyses or ruptures. Enveloped viruses are liberated by budding form the membranes of the cytoplasm, nucleus, endoplasmic reticulum, or vesicles. During this process, the nucleocapsid binds to the membrane, which curves completely around it and forms a small pouch. Pinching off the pouch releases the virus with its envelope.

Discuss the life cycle of a bacteriophage.

Bacteriophages go through adsorption, penetration, replication, and assembly. Once the host is so full with viruses it will split open. This is called the lytic cycle of a bacteriophage. But phages can go through a lysogenic cycle instead. These phages go through adsorption and penetration but do not immediately go through the stages of replication, assembly, and releasing. The inactive phage enters the prophage state. Occasionally, induction occurs following the prophage state. Lysogeny is less deadly than lytic.

Function of chromosome in prokaryotes (Ch 1 & 3)

Composed of condensed DNA molecules. DNA directs all genetics and heredity of the cell and codes for all proteins. (In all bacteria)

Function of periplasmic flagella (spirochetes) in prokaryotes (Ch 1 & 3)

Corkscrew shaped bacteria called spirochetes show an unusual, wriggly mode of locomotion caused by two or more long, coiled threads, the periplasmic flagella or axial filaments. A periplasmic flagellum is a type of internal flagellum that is enclosed in the space between the cell wall and the cytoplasmic membrane.

What are cytopathic effects, a transformed cell and an oncovirus? (Ch 5)

Cytopathic effects (CPEs) are defined as virus-induced damage to the cell that alters its microscopic appearance. Individual cells can undergo gross changes in shape or size, or develop intracellular changes. It is common to find inclusion bodies, or compacted masses of viruses or damaged cell organelles, in the nucleus and cytoplasm. One very common CPE is the fusion of multiple host cells into single large cells containing multiple nuclei. These syncytia (singular, syncytium) are a result of some viruses' ability to fuse membranes. RSV is even named for this effect. Some animal viruses enter a host cell and permanently alter its genetic material, leading to cancer. Experts estimate that up to 20% of human cancers are caused by viruses. These viruses are termed oncogenic, and their effect on the cell is called transformation. Transformed cells have an increased rate of growth; alterations in chromosomes; changes in the cell's surface omlecules; and the capacity to divide for an indefinite period. Mammalian viruses capable of initiating tumors are called oncoviruses. Some of these are DNA viruses such as papillomavirus (cervical cancer), herpesviruses (Burkitt's lymphoma), and hepatitis B virus (liver cancer).

Types of genetic material in viruses (Ch 5)

DNA or RNA

Function of plasmid in prokaryotes (Ch 1 & 3)

Double-stranded DNA circle containing extra genes. (In some bacteria)

Function of endospore in prokaryotes (Ch 1 & 3)

Dormant body formed within some bacteria that allows for their survival in adverse conditions. (In some bacteria)

Compare pro vs. eukaryotic (Ch 4)

Eukaryotes have a nucleus while prokaryotes do not.

How do eukaryotic cells reproduce? (Ch 4)

Eukaryotic cells reproduce sexually and asexually.

Function of fimbriae in prokaryotes (Ch 1 & 3)

Fine, hairlike bristles extending from the cell surface that help in adhesion to other cells and surfaces. (In some bacteria)

Discuss at least 5 important cellular organelles found in eukaryotes.

I am going to discuss five important cellular organelles found internally in an eukaryotic cell. There is the cytoplasm, nucleus, many different organelles, ribosomes, and the cytoskeleton. The cytoplasm is what makes up the liquid interior of the cell. The nucleus is the most prominent structure in the internal of an eukaryotic cell. Many different organelles such as ER, Golgi apparatus, lysosomes, mitochondria, and chloroplasts that all have different jobs within the cell. There are many ribosomes in the cytoplasm, cytoskeleton, rough ER, and other places throughout the cell. The ribosomes are where protein synthesis starts. The cytoskeleton is the framework of an eukaryotic cell.

Coccus (Ch 1 & 3)

If the cell is spherical or ball-shaped, the bacterium is described as a coccus. cocci can be perfect spheres, but they also can exist as oval, bean-shaped, or even pointed variants.

Penetration and uncoating.

In this example, the entire virus is engulfed (endocytosed) by the cell and enclosed in a vacuole or vesicle. When enzymes in the vacuole dissolve the envelope and capsid, the virus is said to be uncoated, a process that releases the viral nucleic acid into the cytoplasm.

Koch's postulates and scientists: van Leeuwenhoek, Lister, Pasteur, Semmelweis (Ch 1 & 3)

Koch's postulates: a series of proofs, or logical steps, that verified the germ theory and could establish whether an organism was pathogenic and which disease it caused van Leeuwenhoek: a Dutch linen merchant and self-made microbiologist; made the first microscope Lister: first to introduce the aspectic techniques Pasteur: swan-neck flask experiment disproves spontaneous generation (abiogenesis); lead to the germ theory of disease Semmelweis: discovered that women who just gave birth were infected by doctors who had come from the autopsy room

Function of slime layer in prokaryotes (Ch 1 & 3)

Monolayer of protein used for protection and/or attachment (In some bacteria)

General characteristics of protozoans (Ch 4)

Most protozoan cells are single cells containing all of the major eukaryotic organelles. Their organelles can be highly specialized for feeding, reproduction, and locomotion. The cytoplasm is usually divided into a clear outer layer called the ectoplasm and a granular inner region called the endoplasm. Ectoplasm is involved in locomotion, feeding, and protection. Endoplasm houses the nucleus, mitochondria, and food and contractile vacuoles. Protozoa can move through fluids by means of pseudopods, flagella, or cilia. Protozoa lacks cell walls.

What are prions, viroids, satellites? (Ch 5).

Not all noncellular infectious agents are viruses. One group of unusual forms, even smaller and simpler than viruses, is implicated in chronic , persistent diseases in humans and animals. A common feature of these conditions is the deposition of distinct protein fibrils in the brain tissue. Researchers have hypothesized that these fibrils are the agents of the disease and have named them prions. Other fascinating virus like agents in human disease are defective forms called satellite viruses that are actually dependent on other viruses for replication. (ex. adeno-associated virus (AAV) and the delta agent). Plants are also parasitized by viruslike agents called viroids that differ from ordinary viruses by being very small (about 1/10 the size of an average virus) and being composed of only naked strands of RNA, lacking a capsid, or another type of coating.

Know which of these belong to each type of cell wall; what has mycolic acid in cell wall? (Ch 1 & 3)

Peptidoglycan is one special class of compounds in which polysaccharides (glycans) are linked to peptide fragments. This molecule provides the main source of structural support to the bacterial cell wall. The cell wall of gram-negative bacteria also contains lipopolysaccharide, a complex of lipid and poly saccharide responsible for symptoms such as fever and shock

In general what are the different kinds of eukaryotic microbes? (Ch 4)

Protozoa, algae, helminth, and fungi

How are viruses cultivated? (Ch 5)

Scientists have developed methods, which include inoculation of laboratory-bred animals and embryonic bird tissues (such methods are termed in vivo) and cell (or tissue) culture methods (called in vitro). The primary purposes of viral cultivation are to: 1. isolate and identify viruses in clinical specimens. 2. prepare viruses for vaccines; and 3. do detailed research on viral structure, multiplication cycles, genetics, and effects on host cells.

Function of flagella in prokaryotes (Ch 1 & 3)

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. (In some bacteria)

Endosymbiotic theory and evidence for the theory. (Ch 4)

Symbiogenesis, or endosymbiotic theory, is an evolutionary theory of the origin of eukaryotic cells from prokaryotic organisms. It holds that the organelles distinguishing eukaryote cells evolved through symbiosis of individual single-celled prokaryotes (bacteria and archaea). The theory holds that mitochondria, plastids such as chloroplasts, and possibly other organelles of eukaryotic cells represent formerly free-living prokaryotes taken one inside the other in endosymbiosis. Among the many lines of evidence supporting symbiogenesis are that new mitochondria and plastids are formed only through binary fission, and that cells cannot create new ones otherwise; that the transport proteins called porins are found in the outer membranes of mitochondria, chloroplasts and bacterial cell membranes; that cardiolipin is found only in the inner mitochondrial membrane and bacterial cell membranes; and that some mitochondria and plastids contain single circular DNA molecules similar to the chromosomes of bacteria.

General characteristics of helminths (Ch 4)

Tapeworms, flukes, and roundworms are collectively called helminths, from the Greek word meaning "worm". Adult specimens are usually large enough to be seen with the naked eye, and they range from the longest tapeworms, measuring up to about 25 m in length, to roundworms less than 1 mm in length. Helminths are included in the study of microbes mainly due to their infective abilities and the production of microscopic eggs and larvae. On the basis of body type, the two major groups of parasitic helminths are the flatworms (phylum Platyhelminthes) and the round worms (phylum Aschelminthes, also called nematodes). Flatworms have a very thin, often segmented body plan, and roundworms have an elongated, cylindrical, unsegmented body. The flatworm group is subdivided into the cestodes, or tapeworms, named for their long, ribbon-like arrangement, and the trematodes, or flukes, characterized by flat, ovoid bodies. Not all flatworms and roundworms are parasites by nature; Many live free in soil and water.

General characteristics of fungi (Ch 4)

The approximately 50,000 species of fungi identified to date can be divided into two groups: the macroscopic fungi (mushrooms, puffballs, gill fungi) and the microscopic fungi (molds, yeasts). Although the majority of fungi are either unicellular or colonial, a few complex forms such as mushrooms and puffballs are considered multicellular. Cells of the microscopic fungi exist in two basic forms: years and hyphae. A yeast cell is distinguished by its round to oval shape and by its mode of asexual reproduction. Hyphae are long, threadlike cells found in the bodies of filamentous fungi or molds.

What is the endosymbiotic theory and give the evidence for the theory.

The endosymbiotic theory is that eukaryotic cells, bacteria, and archaea evolved from older cells called the last common ancestor. The first eukaryote were single-celled and independent but evolved into colonies. As they evolved further some colonies became specialized. From there, complex organisms evolved.

Lysogenic and lytic phases? (Ch 5)

The host cell becomes so packed with viruses that it lyses-splits open-thereby releasing the mature virions. This process is hastened by viral enzymes produced late in the infection cycle that digest the cell envelope, thereby weakening it. Upon release, the virulent phages can spread to other susceptible bacterial cells and begin a new cycle of infection. Alternatively, phages can be less obviously damaging in a cycle called the lysogenic cycle.The condition in which the host chromosome carries bacteriophage DNA is termed lysogeny.

How to write a scientific name; taxonomy categories: kingdom, phylum, class, etc. (Ch 1 & 3)

The method of assigning a scientific name is called the binomial system of nomenclature. The scientific name is always a combination of the generic (genus) name followed by the species name. The generic part of the scientific name is capitalized, and the species part begins with a lowercase letter. Both should be italicized (or underlined if using handwriting). The taxonomic categories from top to bottom are domain, kingdom, phylum or division, class, order, family, genus, and species.

How do viruses multiply? (Ch 5)

The process of viral multiplication is an extraordinary biological phenomenon. Viruses are minute parasites that seize control of the synthetic and genetic machinery of cells. The nature of this cycle dictates the way the virus is transmitted and what it does to its host, the responses of the immune defenses, and human measures to control viral infections. The general phases in the life of animal viruses are adsorption, penetration and uncoating, synthesis, assembly, and release from the host cell. The length of the entire multiplication cycle varies from 8 hours in polioviruses to 36 hours in some herpesviruses.

Adsorption

The virus encounters a susceptible host cell and adsorbs specifically to receptor sites on the cell membrane. The membrane receptors that viruses attach to are usually glycoproteins that the cell requires for its normal function. Glycoprotein spikes on the envelope (or on the capsid of naked viruses) bind to the cell membrane receptors.

Function of 70 S ribosomes in prokaryotes (Ch 1 & 3)

Tiny particles composed of protein and RNA that are the sites of protein synthesis. (In all bacteria)

Assembly

Toward the end of the cycle, mature virus particles are constructed from the growing pool of parts. In most instances, the capsid is first laid down as an empty shell that will serve as a receptacle for the nucleic acid strand. One important event leading to the release of enveloped viruses is the insertion of viral spikes into the host's cell membrane so they can be picked up as the virus buds off with its envelope.

Function of cytoplasm in prokaryotes (Ch 1 & 3)

Water-based solution filling the entire cell. (In all bacteria)

What is a bacteriophage and how do they reproduce? (Ch 5)

When bacterial viruses were first discovered, it appeared that the bacterial host cells were being eaten by some unseen parasite; hence, the name bacteriophage was used (phage coming from the Greek word for "eating"). Most bacteriophages contain double-stranded DNA, although single-stranded DNA and RNA types exist as well. E. coli is the most widely studied bacteriophage. T-even phages such as T2 and T4 are widely studied. They have an icosahedral capsid head containing DNA, a central tube (surrounded by a sheath), collar, base plate, tail pins, and fibers, which in combination make an efficient package for infecting a bacterial cell. T-even bacteriophages go through adsorption, the nucleic acid penetrates, entry of the nucleic acid causes the cessation of host cell DNA replication and protein synthesis; replication and synthesis of viral proteins occurs; the parts spontaneously assemble into bacteriophages.

Bacterial cell shapes and arrangements (Ch 1 & 3)

bacillus, coccus, spirillum, spirochete, etc.

Characteristics of viruses (Ch 5)

capsid, capsomeres, nucleic acid core, envelope v. non-enveloped

Characteristics of organic molecules (Ch 1 & 3)

carbohydrates, lipids, proteins, and nucleic acids

Eukaryotic cell characteristics (Ch 4)

cilia, flagella, cell membrane, cytoplasm, nucleus, 80S ribosomes, endoplasmic reticulum, Golgi, mitochondria, chloroplasts

Prokaryotic cell characteristics ( Ch 1 & 3)

flagella, pili and fimbriae, periplasmic flagella (spirochetes), slime layer, cell wall, cell membrane, cytoplasm, endospore, 70 S ribosomes, plasmid, chromosome