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Microbiology Test 1 Tarleton State University - incomplete
Terms in this set (121)
Microbiology is ____ and can refer to them as ____
the study of microorganisms, including bacteria, archaea, and eukaryal microorganisms, and viruses. Collectively, we can refer to all of them as microbes.
both microorganisms and viruses; they interact with each other and other organisms in many complex ways.
All living organisms share certain features, including
metabolism, growth, reproduction, genetic variation resulting in evolution, response to outside stimuli, and internal homeostasis.
process by which organisms maintain a relatively stable internal environment.
A cell is
the simplest structure capable of carrying out all the processes of life.
All cells contain various macromolecules, including
polypeptides, nucleic acids, lipids, and polysaccharides. Many polypeptides function as enzymes .
Historically, all living organisms were classified as eukaryotes or prokaryotes, depending on whether they did or did not have a nucleus. Today, the taxonomy of living organisms consists of three domains:
Bacteria, Archaea, and Eukarya.
This classification scheme of domains reflects the
phylogeny of all living organisms.
Evolutionary history of a species or group of species.
Our ability to classify microorganisms has been aided greatly by
the polymerase chain reaction (PCR).
subcellular and can be classified as microbes.
Because of their relatively simple structures,
microbes have been useful research models.
This conservation of genetic processes provides compelling evidence that all living organisms are
Life probably evolved on Earth around 3.8 billion years ago. Simple organic molecules, possibly associated with iron-containing surfaces, became enclosed within a
The identification of ____ lends support to the RNA world hypothesis of the origin of life.
RNA molecule that can act as a catalyst within a cell.
The precursors of life, the so-called ____, may have used RNA as the major informational molecule.
Woese's proposed first living organism containing information stored in genes not yet linked together on chromosomes
Eukarya arose through endosymbiosis, in which
free-living bacteria became engulfed within a developing eukaryal cell, providing the host with the ability to harvest sunlight or undergo aerobic respiration.
In all cells, the main informational molecule is double-stranded DNA, a
molecule ideally suited for containing information and for faithful replication. This DNA-based information is converted into functional molecules through the processes of transcription and translation.
Mutation in the DNA allows for
genetic variation, a prerequisite for evolution.
All living organisms must obtain organic molecules. ____ ingest them. ____ produce their own organic molecules.
Heterotrophs and Autotrophs.
Microbial metabolism has affected the ____, and microbes are intimately involved in the ____ of many chemicals, including ____
biosphere; biogeochemical cycling; nitrogen fixation.
regions on Earth that can support life
Biogeochemical cycling is the
transition of chemicals between organic and inorganic forms that results in cycling through and within parts of the ecosystem.
Nitrogen fixation is the
conversion of atmospheric N2 into inorganic compounds, such as ammonia, for cell use.
The work of a number of microbiologists, including ____, led to the development and acceptance of the germ theory of disease.
The germ theory is
the theory that infectious diseases are caused by certain microbes.
Koch's postulates, developed in the 1800s, provide a
means of demonstrating that a particular microorganism causes a particular disease.
Today, we have an assortment of antibiotics, antivirals, and vaccines that treat or prevent many ____. The development of these therapies has depended in large part on our understanding of the structure of these microbes and their replication strategies. Other techniques, like ____, also have led to a decrease in the incidence of certain infectious diseases.
infectious diseases; pasteurization
any technique using mild heating, irradiation, or high pressure to prevent spoilage by destroying pathogenic microorganisms without cooking the food product.
do not make a cell wall and, as a result, do not have a regular shape.
Actinomycete group grow as irregularly branching filaments called ____ that are composed of chains of cells.
Hyphae can form three-dimensional networks called ____ that can rise above the substrate, penetrate down into soil, or both.
A distinctive multicellular arrangement found in cyanobacteria is the formation of smooth, unbranched chains of cells called ____ that may have a polysaccharide sheath coating the entire filament.
The ____ of a bacterial cell, the aqueous environment within the plasma membrane, contains a diverse array of components.
The largest single entity in the cytoplasm is the ____, a convoluted mass of DNA (usually a single, circular chromosome) coated with proteins and RNA molecules still in the process of being synthesized.
Finally, the topology of the DNA molecule is adjusted by ____, enzymes that encourage the chromosome to coil upon itself (supercoiling) in order to collapse it into a more compact mass.
Depending on the environment and growth conditions, bacterial cells sometimes store extra carbon, nitrogen, or phosphorus in ____ ____ large enough to be seen by microscopy as granules within the cytoplasm.
composed of DNA, RNA, protein; genetic information storage and gene expression.
composed of protein; protection and compaction of genomic DNA.
Enzymes involved in synthesis of DNA, RNA:
composed of protein; replication of the genome, transcription.
composed of protein, RNA; control of replication, transcription, and translation
composed of RNA, protein; translation (protein synthesis)
composed of DNA; variable, encode non-chromosomal genes for a variety of functions.
Enzymes involved in breaking down substrates:
composed of protein; energy production, providing anabolic precursors.
composed of various polymers; storage of carbon, phosphate, nitrogen, sulfur.
composed of protein; buoyancy.
composed of protein, lipid, iron; orienting cell during movement.
composed of protein; guiding cell wall synthesis, cell division, and possibly partitioning of chromosomes during replication.
Some aquatic bacteria, for example, produce air-filled ____ ____ that provide buoyancy to the cells. These gas vesicles can regulate the cell's position in a water column in response to light or nutrient levels.
Cyanobacteria also can produce ____ that contain the key enzymes involved in the conversion of inorganic carbon into organic matter.
Just as our skeleton provides a structural framework for organizing our organs and tissues, the ____ is important for the internal organization of cells.
The FtsZ protein forms a ring, the ____, which is needed for bacterial cell division.
FtsZ is evolutionarily related to ____, a protein that serves as the main building block of eukaryal microtubules, a major component of the cytoskeleton of eukaryal cells
FtsZ monomers polymerize into filaments that bundle together to form the ____.
MreB polymerizes into filaments that look strikingly similar to ____ filaments, the heart of cytoskeletal structures called microfilaments in eukaryal cells.
In bacteria, ____ forms long helical bands underlying the plasma membrane.
____ helps guide cell wall formation to produce an elongated cylinder rather than a spherical shape.
Like MreB, the ____ protein forms actin-like filaments. Experiments have shown that ____ filaments aligned with the long axis of the E. coli cell are responsible for moving copies of plasmids, extrachromosomal molecules of DNA, to opposite sides of the cell.
These observations suggest that ____ ____ could actively participate in the positioning and segregation of bacterial chromosomes during cell division.
Most bacterial cells also contain a semi-rigid cell wall made of ____ and some bacteria contain a second membrane, the outer membrane.
The cell envelope is the
structure surrounding the cytoplasm, composed of the plasma membrane, cell wall, and, in Gram-negative cells, an outer membrane.
The ____ ____, also referred to as the cell membrane or the cytoplasmic membrane, is a bilayer composed primarily of phospholipids. The structure of these phospholipids is ____, meaning that they have a polar portion and a non-polar portion.
plasma membrane; amphipathic.
Some bacteria produce sterol-like molecules called ____. Like sterols, ____ are largely planar molecules that are thought to stabilize the plasma membrane.
Many ____ either cross or are integrated into the membrane bilayer.
Key functions of the plasma membrane proteins include:
The control of access of materials to the cytoplasm through differential permeability.
The capture and/or storage of energy through photosystems, oxidative electron transport, and maintenance of chemical and electrical gradients.
Environmental sensing and signal transduction.
A fundamental property of the plasma membrane is its differential or
The cell is in a ____ ____ when the cytoplasm has a higher solute concentration than the external environment, causing water to move into the cell.
The cell is in a ____ ____ when the cytoplasm has a lower solute concentration than the external environment, causing a net loss of water from the cell.
Some transport proteins simply ____ ____, allowing specific molecules to pass through the membrane from higher to lower concentration.
____ ____ systems in the plasma membrane are driven by the expenditure of energy to drive the movement of solutes against a concentration gradient.
a membrane transport process that carries two substances in the same direction across the membrane.
With ____, the energy-requiring uptake of one molecule is driven by the energetically favorable ejection of another.
Both symport and antiport mechanisms are examples of ____, in which two different molecules are being moved.
____ stands for "ATP-binding cassette," reflecting the fact that these proteins include a nucleotide-binding domain by which ATP is hydrolyzed to provide the energy for transport.
In ____ ____, organic molecules are oxidized and the released energy is used to drive the synthesis of ATP.
In ____, light energy is captured and used to reduce inorganic carbon, forming organic molecules.
It can be used to drive the active transport of nutrients across the membrane. The ____ ____ also powers rotation of the flagellum in most bacteria.
As they accumulate outside the plasma membrane, these protons create concentration and charge gradients that combine to create a ____ ____ ____.
proton motive force.
The bacterial cell wall consists of a highly crosslinked polysaccharide-peptide matrix called ____.
peptidoglycan; the organization of peptidoglycan also gives bacterial cells their characteristic shapes.
Peptidoglycan forms a net-like structure composed of a glycan backbone made up of alternating molecules of N-acetylglucosamine (____) and N-acetylmuramic acid (____), connected by β-1,4-glycosidic bonds.
The ____ ____ carries a short peptide chain that is used to crosslink peptidoglycan strands, creating the protective network surrounding the cell.
N-acetylmuramic acid (NAM).
In E. coli and most other Gram-____ bacteria, the fourth amino acid attached to one NAM residue is directly linked to the third amino acid present on another NAM residue.
In most Gram-____ species, the tetrapeptide chains are crosslinked via a short peptide interbridge.
Many potential enemies of bacteria, including bacteriophages and animals, encode or produce the enzyme ____, which degrades peptidoglycan.
____ hydrolyzes the β-1,4-glycosidic bond between NAG and NAM, profoundly weakening the cell wall.
The ____ ____, a technique for staining bacterial cells developed by Hans Christian Gram in 1884, allows us to differentiate two types of bacteria: ____-____ and ____-____. Electron microscopic examinations of bacteria have revealed that these two categories of bacteria differ in the organization of the cell wall and the presence or absence of an additional outer membrane.
Gram stain; Gram-positive; Gram-negative.
____-____ bacteria have a thick cell wall with many overlapping strands of peptidoglycan. Beneath this structure is the ____, a thin space between the cell wall and the plasma membrane. The ____-____ cell wall is exposed to the environment and provides an important protective function for the cell, but it is not impermeable. After all, nutrients must be able to get to the plasma membrane, where they can be taken into the cell. Peptidoglycan is the most abundant polymer in the ____-____ cell wall, but a mixture of other polymers can constitute up to half of the dry weight of the cell wall, depending on the species.
Gram-positive; periplasm; Gram-positive; Gram-positive.
A charged polymer called ____ ____, which is not found in Gram-negative bacteria is intermingled with the peptidoglycan. ____ ____ are polymers of either ribitol phosphate or glycerol phosphate. Many of the ____ ____ molecules are firmly anchored in the cell wall by covalent attachment to peptidoglycan chains. Alternatively, some ____ ____ are connected to the plasma membrane through the covalent addition of a lipid tail.
teichoic acid; teichoic acids; teichoic acid; teichoic acids.
The cells first are stained with ____ ____, the primary stain.
Exposure to this reagent results in the loss of the crystal violet-iodine complex from ____-____ cells.
Crystal violet-iodine complexes remain in ____-____ cells because of their thick cell walls.
purple (retains the crystal violet primary stain).
pink or light red (loses the crystal violet but is stained with safranin).
A relatively thin layer of peptidoglycan surrounds ____-____ bacteria. This slim cell wall may seem like scant protection, but it is supplemented by another structure, the ____ ____. For this reason, the plasma membrane of ____-____ bacteria often is referred to as the ____ ____.
Gram-negative; outer membrane; Gram-negative; inner membrane.
The space between the inner and outer membranes is the ____.
____ have dramatically thickened cell envelopes, with additional layers of protein outside the peptidoglycan.
The outer membrane of Gram-negative bacteria is a bilayer, but it only contains phospholipids in the inner leaf of the bilayer. The outer leaf is composed of a molecule called ____.
In Gram-negative bacteria, ____ ____ typically form trimeric, or three-subunit, pores through the outer membrane. These pores allow diffusion of small polar molecules, including some nutrients, across the outer membrane from the external environment into the periplasm, where they are available to plasma membrane transport systems.
In addition to porins, the outer membrane contains proteins called ____-____ ____ that bind scarce nutrients (such as iron and vitamin B12) with high affinity and deliver them into the periplasm by active transport.
The ____ ____ ____ ____, is appropriate as it literally injects proteins, such as toxins, into host cells and are evolutionarily related to proteins involved in making flagella.
type III secretion system.
peptidoglycan, teichoic acids, and proteins in the case of Gram-positives versus
lipopolysaccharides and proteins for Gram-negative bacteria.
For active movement, bacteria commonly use ____, spiral filaments that extend from the surface of the cell and rotate in order to propel the cell.
This process of using chemical signals from the environment to direct motility is called ____
During ____ ____, some non-flagellated bacteria, such as myxobacteria and cyanobacteria, slide smoothly over surfaces.
Pilus or pili are
proteinaceous fiber that protrudes from the cell surface; often used for attachment.
A thick layer of polysaccharides, called a ____, surrounds these cells.
Some species of bacteria have a less well-defined outer layer, known as the ____ ____. Again, this structure typically consists of polysaccharides and can serve several purposes. The term ____ can refer to both capsules and slime layers.
slime layer; glycocalyx.
In wet habitats, microorganisms can form attached communities called ____
A regular, crystalline-like layer of protein referred to as a ____ ____ or ____-____.
surface array or S-layer.
Antibiotics in the ____-____ family also attack peptidoglycan. ____-____ destroy these antibiotics, providing bacteria with resistance to them.
____ may differ in their ability to adhere.
____ possess a membrane-bound nucleus. Additionally, ____ cells contain other internal organelles and a complex cytoskeleton.
The ____ contains the genetic material. Within this double membrane-bound organelle, DNA replication and transcription occur.
The ____ ____, which includes the endoplasmic reticulum (ER) and the Golgi apparatus, is involved in protein trafficking.
Mitochondria and chloroplasts are responsible for cellular energetics. Cellular respiration occurs within the ____. Conversion of solar energy to chemical energy and carbon fixation occurs within the ____. Both organelles generate ATP via ____. The amitochondriates are eukarya that lack mitochondria.
mitochondria; chloroplast; chemiosmosis.
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