Microbiology Test 1
Which of the following is evidence supporting the theory of endosymbiosis? A.The lipid composition of the endoplasmic reticulum and Golgi apparatus resembles the cytoplasmic membrane of bacterial cells. B.Eukaryal cells are always larger than bacterial cells. C.Mitochondria and choloroplasts have their own DNA and protein synthesizing machinery. D.All of these choices.
C.Mitochondria and choloroplasts have their own DNA and protein synthesizing machinery.
To answer this question, first click to view the associated animation. The _____ is the major site of active transport in a eukaryotic cell. A.ER B.nucleus C.cell membrane D.mitochondrion E.lysosome
C.cell membrane
A bacterium's scientific name is binomial and based on its A.domain and phylum. B.order and class. C.genus and species. D.kingdom and family. E.domain and species.
C.genus and species.
During diffusion, molecules move from an area of ___ concentration to ___ concentration. A.high: high B.low: low C.high: low D.low: high E.none of these choices
C.high: low
Budding occurs in: A.viruses. B.bacteria. C.yeasts. D.algae. E.none of these choices.
C.yeasts.
Vacuole
Cell organelle that stores materials such as water, salts, proteins, and carbohydrates
Capsule is composed of what
Composed of usually loose network of polysaccharides it covers the surface of cell . The function is to protect from phagocytes; contributes to biofilm formation.
compostion and function Ribosomes
Composition RNA, protein function - Translation (protein synthesis)
Flagella
Composition is protein subunits location is extend outward from surface , except in spirochetes , where periplasmic flagela wrap around cell . The function is to provide motility
_______ occurs whenever water move into a cell causing it to swell and burst
Cytolysis
Halophiles
"salt-loving" archaea that live in environments that have very high salt concentrations
So aside from motility, what other stuff is still left on the outside of bacterial cells?
- Adherence molecules to stick to surfaces • Mediated by pili (s. pilus), fibers of pilin protein possess other proteins on their tips for sticking. • A sex pilus is a different structure used for conjugation (sending a DNA plasmid from one cell to another). • Some scientists prefer to use "pili" only for conjugation structures and "fimbriae" (s. fimbria) for adherence. Adherence molecules to stick to surfaces • Some microbes (Caulobacter, Hyphomonas) will use an extension of the cell envelope tipped by a "holdfast" of polysaccharides. • These extensions provide extra surface area for nutrient absorption as well as the adherence capability.
Mitosis is
- Basic cell division: copying of one nucleus into two nuclei - Followed by cytokinesis to produce two identical cells from one original cell
• Phylogeny
- Comparisons of rRNA gene sequences can establish phylogenetic "trees." - Woese and Fox began these studies in the 1970s. - The first portion termed "archaeons" were the methanogens - a poorly characterized group of microbes capable of producing methane as a byproduct
Motility from flagella
- Composed of three basic pieces: • Filament of multiple flagellin proteins, 5‒10 μm long • Hook protein portion that connects filament to basal body • Basal body: disk-like structure that produces torque on filament to turn it like a propeller
How did early organic molecules change into the four macromolecules of cells today?
- Early iron-containing surfaces may have helped provide the right environments by "sticking" the molecules to their surfaces. - But any early life would still need to have genetic information, the ability to catalyze biochemical reactions, and a way of separating the cell interior from the external environment.
How does flagella move?
- Energy to spin flagella derived from proton motive force (PMF) - Complex structures with up to 40 different proteins - Spinning one way produces a "run" (directional movement) while spinning the other way produces a "tumble" (nondirectional movement) By using chemoreceptor proteins to sense changes in concentrations of attractants or repellents, cells can produce more runs to move in a particular direction
How do proteins find their destinations (internal/external)?
- More locations means more protein signal sequences
Archaeal cell structure
- Shapes can vary, as well. • Rods, spheres, spirals • Irregular shapes • Rectangular shapes - All archaeons possess a plasma membrane. - Most archaeons have a cell wall. - Both structures are different from their equivalents in Bacteria and Eukarya.
Life cycles of model organisms
- Yeast and Chlamydomonas may alternate haploid/diploid stages. • Allows for better survival and genetic variation - Saccharomyces can undergo meiosis to form an ascus. • Haploid mating types can fuse to reproduce sexually or be maintained by asexual mitos
What do some RNA molecules have the ability to do ?
-Some RNA molecules have the ability to catalyze reactions (these are known as ribozymes, a combination of ribonucleic acid and enzymes) -This means RNA could serve the dual purpose of genetic information storage AND catalyzing reactions!
What are the effects of lysozyme on cell?
1.Lysozyme cuts peptidoglycan 2. Without an intact cell wall , the rod shape is lost. 3. In hypotonic conditions water rushes in. 4. Internal pressure call cell lysis(the disintegration of a cell by rupture of the cell wall or membrane)
-How does the cell wall actually form?
1.NAM is synthesized in the cytoplasm and linked UDP(Uridine diphosphate glucose (UDP-glucose) is a nucleotide sugar. UDP-glucose consists of the pyrophosphate group, the pentose sugar ribose, glucose, and the nucleobase uracil. It is used as a substrate for enzymes called glucosyltransferases.) 2. NAM is linked to bactoprenol(is a lipid synthesized by three different species of lactobacilli.[)3. NAG added to NAM 4.Bactoprenol flips NAM-NAG to periplasm 5. Disaccharide added to existing chain. Crosslinking of chain also occurs. 6. Bactoprenol flips back to cytoplasm.
What is the difference between a capsule and a slime layer?
A capsule is a coat of mostly proteins that is strongly attached to the cell. A slime layer is mostly sugar, and is loosely attached to the cell
secretory pathway
A role in protein trafficking uses ER/Golgi apparatus- Eukaryal proteins are often extensively modified in these structures prior to reaching their destinations.
Gram-positive cells have
A thick outer layer of peptidoglycan - A very narrow periplasmic space - Teichoic acids in the peptidoglycan (negatively charged)
Gram-negative cells have
A varying width periplasmic space containing a very thin layer of peptidoglycan - An outer membrane composed of lipopolysaccharide (LPS)
What is the function of bactoprenol? A) It is a hydrophobic alcohol that transports peptidoglycan precursors across the cytoplasmic membrane. B) It is responsible for forming the peptide cross-links between muramic acid residues in adjacent glycan chains. C) It triggers the recruitment of FtsZ and the initiation of the divisome. D) It supplies the energy necessary for transpeptidation to occur.
A) It is a hydrophobic alcohol that transports peptidoglycan precursors across the cytoplasmic membrane.
Which of the following is not a characteristic that distinguishes living organisms from nonliving? A. DNA as the genetic material B.Metabolism C.Growth D.Reproduction
A.DNA as the genetic material
What characteristic differentiates eukaryal microbes from bacteria? A.Membrane bound nucleus. B.Phospholipid-based cytoplasmic membrane. C.Presence of small subunit rRNA. D.Presence of cell walls.
A.Membrane bound nucleus.
The study of microbiology include all the following except. A.Plants B.Viruses C.Bacteria D. protist
A.Plants
The most common bacterial shapes include all of the following except? A.helical B.spirilla C.vibrio D.cocci E. bacilli
A.helical
Bacteria have extra chromosomal pieces of DNA in the cytoplasm called A.plasmids. B.inclusion bodies. C.carboxysomes. D.nucleoids.
A.plasmids.
How are archaeons similar and different from bacteria? A. Archaeons are similar to bacteria in morphology only. Like bacteria, the archaeons also lack a membrane-bounded nucleus to contain their genomes. B. Archaeons are similar to bacteria in size only. Like bacteria, the archaeons also lack a membrane-bound nucleolus to contain their genomes. C. Archaeons are similar to bacteria in the size of their genomes only. Like bacteria, the archaeons also lack a cell wall. D. Archaeons are similar to bacteria in morphology, size and in the size of their genomes. Like bacteria, the archaeons lack a membrane-bounded nucleus to contain their genomes.
D. Archaeons are similar to bacteria in morphology, size and in the size of their genomes. Like bacteria, the archaeons lack a membrane-bounded nucleus to contain their genomes.
Select the INCORRECT statement. A. Thermophiles are organisms that prefer to grow at high temperatures. B. Acidophiles are organisms that prefer to grow under highly acidic conditions. C. Hyperthermophiles are organisms that prefer to grow at temperatures greater than 80 degrees Celsius. D. Barophiles are organisms that grow under extreme pH conditions. E. All of these choices are correct. There are no incorrect statements.
D. Barophiles are organisms that grow under extreme pH conditions. ome are also barophiles (thriving in high pressures, e.g., at the bottom of the ocean).
Chemotaxis involves the use of chemoreceptors and flagella. The process involves chemoreceptors A.sensing certain attractants or repellants, becoming activated and communicating with flagella via cytoplasmic proteins to control whether the flagella should continue to propel the bacteria forward or to reverse direction and cause tumbling instead. B.detecting certain concentration gradients, becoming activated and communicating with flagella via cdc2 proteins to control propelling or tumbling. C.becoming stimulated by tubulin proteins and communicating with flagella via unique intracellular chemicals to control propelling or tumbling. D.sensing any kind of attractants or repellants, becoming deactivated and communicating with cilia and then flagella via cytoplasmic proteins to control propelling or tumbling.
A.sensing certain attractants or repellants, becoming activated and communicating with flagella via cytoplasmic proteins to control whether the flagella should continue to propel the bacteria forward or to reverse direction and cause tumbling instead.
What are the critical structural and functional properties of the bacterial cell envelope?
ALL cells have a plasma membrane (PM). • Separates the interior of the cell from the external environment • Usually composed of a phospholipid bilayer with embedded proteins The PM may have sterol molecules called "hopanoids" in it to help with stability across temperature ranges
organic molecule that are broken down microbes to harness chemical energy
ATP
Autotroph
An organism that makes its own food by producing organic molecules.
Water diffuses through the pores called ______ of the cell membrane
Aquaporins
How do we know that Archaea is a distinct domain of life?
Archaeons "look" like bacteria. - However, genetic analyses show them to be different. - They live in some of the most inhospitable places (for humans) on Earth.
The DNA of archaeons is complexed with histones, suggesting A. archaeons are more closely related to bacteria than eukarya. B. archaeons are more closely related to eukarya than bacteria. C. archaeons have a unique method of packaging their genetic material. D. histones are adaptations to life in extreme environments.
B. archaeons are more closely related to eukarya than bacteria.
Which model organism does not possess mitochondria? A.Saccharomyces cerevisiae B.Giardia lamblia C.Dictyostelium discoideum D.Chlamydomonas
B.Giardia lamblia
Sexual reproduction requires gametes that are ____________ A.Diploid B.Haploid C.Aneuploid D.Disjunction
B.Haploid
Select the correct statement regarding autotrophs and/or heterotrophs. A.Autotrophs (or "self feeders") are incapable of producing their own organic carbon from inorganic carbon sources. B.Heterotrophs ("other feeders") cannot make their own organic carbon and therefore must ingest organic carbon produced by autotrophs. C.Heterotrophs (or "self feeders") are capable of producing their own organic carbon from inorganic carbon sources. D.Autotrophs ("other feeders") cannot make their own organic carbon and therefore must ingest organic carbon produced by autotrophs.
B.Heterotrophs ("other feeders") cannot make their own organic carbon and therefore must ingest organic carbon produced by autotrophs.
This part of the cell membrane contains hydrophilic heads and hydrophobic tails. A.Carbohydrates B.Phospholipid bilayer C.Membrane pores D.Hopanoids
B.Phospholipid bilayer
There is wide variability in physiology and morphology both between and within the major groups of Archaea. In light of this variability, on what basis are species assigned to each phylum within the domain? A.Species are assigned to phyla based on temperature optima. B.Species are assigned to phyla based on nucleic acid sequence similarity. C.Species are assigned to phyla based on compounds used as energy sources. D.Species are assigned to phyla based on the structure of the cytoplasmic membrane.
B.Species are assigned to phyla based on nucleic acid sequence similarity.
Pili and fimbriae are both surface appendages but pili are involved in _____ and fimbriae are involved in _____. A.transformation; conjugation B.conjugal transfer of DNA; adhesion C.contraction; conjugation D. None of these choices is correct.
B.conjugal transfer of DNA; adhesion
What is the role of the plasma membrane in eukarya? A.energy metabolism B.homeostasis C.cell shape D.protein sorting
B.homeostasis
Archaea are thought by many to be descended from the first life forms because A.their cell membranes have a primitive construction. B.the first identified Archaea were extremophiles, making them well suited for the conditions on Earth when life arose. C.they are prokaryotic. D.they have a RNA genome.
B.the first identified Archaea were extremophiles, making them well suited for the conditions on Earth when life arose.
What are some characteristics of the three domains?
Bacteria and Archaea both don't have a nuclear membrane.. In bacteria the plasma membrane is similar to Eukarya . In Archaea the plasma membrane is different from Bacteria and Eukarya. There is a cell wall found in nearly all species of Bacteria constructed of peptidogolycan. The cell wall found in Archaea is constructed of various materials . Bacteria and Archaea both have single polymerase (an enzyme that synthesizes long chains or polymers of nucleic acids. DNA polymerase and RNA polymerase are used to assemble DNA and RNA molecules, respectively, by copying a DNA or RNA template strand using base-pairing interactions). Bacteria has Histone-like proteins. Archaea has Histones(histones are highly alkaline proteins found in eukaryotic cell nuclei that package and order the DNA into structural units called nucleosomes. They are the chief protein components of chromatin, acting as spools around which DNA winds, and playing a role in gene regulation.)
What are the three domains of life?
Bacteria,eukarya ,archea
What acts as a proton pump and captures light energy and uses it to move protons?
Bacteriorhodopsin
Endosymbiotic theory— How did organelles develop?
Basic idea is that one primitive microbe ingested another, forming a symbiosis. - Since all eukaryotes have mitochondria, but only some have chloroplasts, two endosymbiotic events must have occurred
Capsules can help bacteria form biofilms.
Biofilms provide protection and enhanced survivability in harsh environments. • Examples of biofilms include dental plaque and mold on bathroom surfaces.
Which of the following is a form of reproduction found in yeast? A.Budding B.Meiosis followed by mitosis C.Meiosis followed by fertilization D.All of the choices
D.All of the choices
The components of a eukaryal cell membrane include A.phospholipids. They have straight (unbranched) acyl chains attached to glycerol via ester linkages. These lipids form a bilayer that establishes permeability barrier between compartments of the cell and between the cell and its environment. B.proteins. The protein content of the membranes in a eukaryote is typically much lower than the plasma or outer membranes of bacteria. The proteins serve various function including transport of specific molecules, adhesion and attachment, and as receptors. C.sterols. The eukaryal membrane also contains sterols that serve, in part, to control membrane fluidity. The fluidity of the membrane is also affected by the degree of saturated versus unsaturated lipids and the amount of protein. D.All of these are correct.
D.All of these are correct.
Which of the following characteristics are used to classify bacteria? A.Cell morphology. B.Gram reaction. C.Metabolism. D.All of these choices.
D.All of these choices.
Which of the following characteristics make microbes excellent model systems for experimentation? A.Fast generation times means numerous offspring in a short period of time. B.Some microbes are easy to culture in the laboratory. C.Microbial genomes are smaller and easier to manipulate. D.All of these choices.
D.All of these choices.
What feature is found in Archaea and Eukaryotic cells, but not bacteria? A.Ribosomes B.Cell membrane C.Nucleoid D.Histones
D.Histones
Which of the following are not correctly matched? A. Algae-photosynthetic B.Fungi- grows as threads C.Bacteria- no nucleus D.Protozoa- Photosynthetic E.Virus-- may contain DNA
D.Protozoa- Photosynthetic
So far, all methanogens identified are A.Aerobic B.Microaerophiles C.Facultative anaerobes D.Strict anaerobes
D.Strict anaerobes
What kinds of substances are found inside bacteria? A.macromolecules B.enzymes C.proteins D.all of these choices
D.all of these choices
Unlike bacteria, the cytoplasmic membrane of archaea A.is not semipermeable. B.contains integral proteins. C.is not composed of lipids. D.can exist as a monolayer.
D.can exist as a monolayer.
Biofilms are A.deep associated communities of only two species of bacteria. B.surface associated communities of only two species of bacteria. C.massive communities of fimbriae from a wide variety of Gram-negative bacteria. D.surface associated communities of one or more species of bacteria. E.deep associated communities of one or more species of fungi.
D.surface associated communities of one or more species of bacteria.
What is the importance of RNA in the basic information flow of modern cells?
DNA is transcribed into a 'working copy' in the form of messenger (m)RNA. mRNA is translated into the proteins needed to make a cell work.
What is the importance of RNA in the basic information flow of modern cells ?
DNA is transcribed into a working copy in the form of messenger (m) RNA .mRNA is translated into the proteins needed to make cell work.
• What do eukaryal cells look like?
Defined by presence of a membrane-bound nucleus - Usually larger than bacterial/archaeal cells - Usually contain intracellular compartments (organelles) - May possess a cell wall structure - Complex internal cytoskeleton in place
Meiosis is
Different from mitosis (four cells from one original cell, but each has half the original cell's quantity of DNA) - Achieved by one round of DNA replication followed by two rounds of cell division - Chances for genetic recombination • Segregation of maternal/paternal chromosomes • "Crossing over" between chromosomes prior to segregation - Events ensure each haploid cell is genetically distinct, increasing chances for genetic variation in sexual reproduction
What harmful and beneficial roles do eukaryal microbes play?
Diseases caused by eukaryal microbes: - Protozoa can cause significant human diseases. Fungi are less likely to cause disease, but can do so in immunocompromised individuals. rotozoa and fungi can cause significant disease in plants (potato blight and the great Irish famine, mid- 1800's)
Fermentation
Doesn't need oxygen but yield much energy for microbes p
The two major phyla of the Archaea are the: A. Korarchaeota and Thaumarchaeota B. Nanoarchaeota and Crenarchaeota C. Euryarchaeota and Crenarchaeota D. Thaumarchaeota and Euryarchaeota E. Euryarchaeota and Nanoarchaeota
C. Euryarchaeota and Crenarchaeota
Halophiles rely on a high intracellular concentration of which ion to maintain osmotic balance? A. Na+ B. Ca+ C. K+ D. Mg+
C. K+
Which of the following measures has been effective in controlling and reducing deaths from infectious diseases? A.improved hygiene in healthcare settings B.discovery and widespread use of vaccines and the development of antibiotics C.improved public health measures including sewage treatment and garbage removal D.improved preparation and handling of food and water. E.All of these choices are correct.
E.All of these choices are correct.
This structure is the powerhouse of the eukaryotic cell. A.Nucleus B.Cell membrane C.Endoplasmic reticulum D.Chloroplast E.Mitochondrion
E.Mitochondrion
The key features of living organisms include all of the following EXCEPT A.metabolism and growth B.reproduction and genetic variation C.ability to respond to external stimuli D.homeostasis E.transmission of nerve impulses
E.transmission of nerve impulses
How did microbial life arose on Earth ?
Early conditions formed RNA and micelles. -These came together into a primitive cell using RNA for storing genetic info and coding. -Primitive cells eventually changed from using RNA to DNA instead for storing their genetic information.
How did early organic molecules change into the four macromolecules of cells today?
Early iron-containing surfaces may have helped provide the right environments by "sticking" the molecules to their surfaces. -But any early life would still need to have genetic information, the ability to catalyze biochemical reactions, and a way of separating the cell interior from the external environment
What changed Earth's early atmosphere over time?
Early oxygen producing autotrophs.
How can the plasma membrane be used for capturing energy?
Embedded electron transport chains can help create proton motive force (PMF). • Can be used for respiration/photosynthesis (more in Chapters 6 and 13) • Can be used to derive energy for motion (flagella)
proton motive force
Emphasizes the capactiy of the gradient to preform work.
What are functions of these Macromolecules?Polypedtides
Enzymes catalyze the vast majority of biochemical reactions in the cell
What is the functions of Polypetides?
Enzymes catalyze the vast majority of biochemical reactions in the cell
Cell wall role in cell support
Eukaryal cells can broadly be separated into those with and those without cell walls. - Cell walls can vary widely between the domains- Cellulose and chitin in eukaryal cells use specific b-1,4-glycosidic bonds between sugars for strength and rigidity. - Some eukaryal cells only create cell walls at specific points in their life cycles (Giardia, Entamoeba).
How do eukaryal microbes replicate?
Eukaryal life cycles are complicated due to haploid/diploid states and the possibilities for sexual reproduction (involving meiosis) or asexual reproduction (involving mitosis)
How do we study the genetics of microbes Today?
Examining effects of single mutations in DNA individually. Study and comparing pieces of genomes to each other (bioinformatics) across domains
How do NUTRIENTS cross the plasma membrane?
Facilitated diffusion: using a protein channel to move particles WITH a concentration gradient (no energy) • Active transport: using energy to move particles AGAINST a concentration gradient - Co-transport mechanisms (symport/antiport) - ATP-binding cassette (ABC) transporters
Cell division is assisted by
spindle fibers.
Tonicity is a measure of
the effective osmotic pressure gradient, as defined by the water potential of two solutions separated by a semipermeable membrane.
How are archaeons different from bacteria?
they are - thinner - usually composed of two or more different versions of flagellin protein - likely growing from BASE rather than from TIP
Capsules
thick layer of polysaccharides surrounding some cells • Can provide adhesion, defense against host immunity, protection against drying out (desiccation)
Surface arrays (S-layers)
• Crystalline array of interlocking proteins • Found in Gram-positive and Gram-negative cells • Can act as armor, protecting a cell against predation or infection with bacteriophages
Mitochondria and chloroplasts are semi-autonomous meaning
• Each has their own DNA, ribosomes, transcription machinery, and can replicate independently of the rest of the cell. • However, most of their proteins originate from the DNA in the nucleus of the cell.
Three major structures comprise the eukaryal cytoskeleton.
• Microtubules • Microfilaments • Intermediate filaments Each differs in structure/function; all contribute to cell shape. - The cytoskeleton can't provide the same protection as a cell wall, however.
Each peptidoglycan disaccharide (also known as murein, is a polymer consisting of sugars and amino acids that forms a mesh-like layer outside the plasma membrane of most bacteria, forming the cell wall.) subunit is
• N-acetylmuramic acid (NAM) with a small peptide chain - The peptide varies by species. • N-acetylglucosamine (NAG) While the amino acids in the peptide on NAM can vary from species to species, the way the peptides are crosslinked in the CW can also vary.
How do items cross the plasma membrane and get into a cell?
• O2 and CO2 are small and can diffuse across readily. • H2O is helped across by aquaporin protein channels. • Osmosis is the flow of water across the PM toward the side with a higher solute (particle) concentration. • Osmosis can cause a cell to swell with water or shrivel as water leaves, but a strong cell wall can help keep a bacterial cell alive during these hardships.
The categories of eukaryal microbes and their characteristics?
Fungi: Saccharomyces cerevisiae • Heterotrophic; cell walls of chitin; used to make bread, beer, wine • Easy, cheap tool to study eukaryotic structures/gene expression Protozoa: Giardia lamblia • As a whole, a BROAD category—some heterotrophic, some photosynthetic; variable cell walls; different motility strategies; different reproduction strategies • Giardia is interesting because it is genetically "old," it lacks mitochondria, and it causes human disease Slime molds: Dictyostelium discoideum • Still protozoan! Model for studying ecology, cell motility, and cell-cell communication - Second slime mold type (Physarum) fuses many cells into a continuous, multinucleate giant cell. Algae: Chlamydomonas • Some algae are single-celled, but many are multicellular. • All are photosynthetic with cellulose cell walls. • Chlamydomonas has a two-flagella form good for studying eukaryal flagella biogenesis/function. • Chlamydomonas is also studied because of its ease of growth and durability
Who created insulin by inserting the gene into E.coli cells
Genentech in San Franciso
Distinctive properties of Archaea: • Evolution
Genetic sequence analyses indicate both Archaea and Eukarya may have branched off from Bacteria. - Development of histones may have been an early "branch point event" in the evolution of Archaea and Eukarya. - The unique plasma membrane is also interesting but is not required to thrive in harsh environments.
what is a model organism for studying protozoa
Giarda
What about nonflagellar motility?
Gliding motility: smooth sliding over a surface, not well understood (myxobacteria, cyanobacteria) - Twitching motility: slow, jerky process using fibers (pili) that can be extended, attached to a surface, and pulled back to pull along a surface (N. meningitidis, P. aeruginosa) - Polymerization of actin in host cells for propulsion of bacteria into adjacent cells (Shigella dysenteriae, Listeria monocytogenes)
what eukaryotic organelle modifies ,sort and transport proteins
Golgi apparatus
What is the stain method developed in 1884 by Hans Christian?
Gram can separate many microbes into one of two classes. 1.Bacteria are stained with crystal violet . all cells are stained purple .2. Iodine stabilizes crystal violet with cellular material. 3. Alcohol may extract the crystal violet from the cell. The stain complex is removed from Gram -negative cells,but remains in the Gram positive cells. 4. Bacteria are stained with safranin. Gram negative cells are stained pink ; Gram positive cells still appear purple.
The archaeal plasma
Has a different bilayer construction - The plasma membrane can even be a monolayer instead of a bilayer. • In this case, each lipid has a phosphoglycerol molecule on both ends. • This is often seen in archaeons living in hightemperature environments due to its stability
Mitochrondria
Import of nuclear encoded proteins into the mitochondria
What is a domain?
In biological taxonomy, a domain (Latin: regio[1]), also superkingdom or empire,[2] is the highest taxonomic rank of organisms in the three-domain system of taxonomy designed by Carl Woese, an American microbiologist and biophysicist. According to the Woese system, introduced in 1990, the tree of life consists of three domains: Archaea, Bacteria, and Eukarya.[1] The first two are all prokaryotic microorganisms, or single-celled organisms whose cells have no nucleus. All life that has a nucleus and membrane-bound organelles, and multicellular organisms, is included in the Eukarya
So how did the first microbial life arise according to Stanley Miller?
In the 1950s, a grad student named Stanley Miller worked with his mentor, Harold Urey, to simulate the "spark" that might have started forming organic molecules from the primordial soup.
How did eukaryal microbes originate?
It is generally thought that life started 4.5 to 4 bya, but eukaryotes appeared around 2.1 to 1.6 bya. ‒ How/why did eukaryotes evolve?
Why can the LPS from Gram-negative cell can be harmful?
Lipid A portion induces a strong inflammatory response. - O (outer) side chain of polysaccharides can vary dramatically (and even be changed by the microbe to evade host immune responses).
Comparison of plasma membranes in Bacteria,Archaeons,and Eukarya
Lipid structure function membrane fluidity Bacteria -Ester linkage straight fatty acid chains Archaeons-Ester linkage Branched isoprenoid chains Eukarya-Ester linkage straight fatty acid chains
Which main two people debunked the theory that microbes don't cause disease?
Louis Pasteur and Robert Koch.
Lysosome
Main function is digestion of macromolecules . contains digestive enzymes.
Mitochondrion
Main function is energy production . an interesting feature is a double membrane contains DNA independent replication . not present in amitochondriate.
Hydrogenosome
Main function is production of h2 and ATP
Vacuole
Main function is storage and structure . an interesting feature is food vacuoles serve as sites of digestion
Crenarchaeota
Many members are thermophiles or hyperthermophiles (growing at temperatures greater than 55°C or 80°C, respectively) - Many are also acidophiles (thriving in low pH). - Some are also barophiles (thriving in high pressures, e.g., at the bottom of the ocean). - To survive in these conditions, these microbes possess multiple adaptations to thrive.
Comparison of plasma membranes in Bacteria,Archaeons,and Eukarya
Membrane structure function: Membrane assembly Hyrophillic surface hydrophobic core Bacteria- Phospholipid bilayer Archaeons- Bilayer or monolayer diverse lipid composition(sulfo,glyco,isoprenoid.) Eukarya- Phospholipid bilayer
Crenarchaeota: Mesophiles/psychrophiles
Mesophiles/psychrophiles - Often detected by rRNA gene sequences but not by cultivation - Mesophiles = 15‒40°C - Psychrophiles < 15°C - Possibly very important to biogeochemical cycling of carbon and nitrogen in the oceans - Possible that some members belong in a new phylum • Cenarchaeum symbiosum resides in a marine sponge. • Its sequence shares some genes with crenarchaeotes but also some with euryarchaeotes. • New phylum? IN FLUX...
How do microbes live?
Microbes live in diverse groups in nature, with many different members forming a microbial community and ecosystem. - Microbes in the intestines - Plaque on teeth - Slime on rocks on beaches - Mold growths on bathroom surfaces
What is microbiology?
Microbiology is the study of microbes. -Microbes are forms of life too small to be seen with the naked eye (bacteria, fungi, algae, protists). -The field examines how microbes interact with humans, with food, and how they can be used BY humans (among other aspects).
How did mitochondria arise in eukaryal cells?
Mitochondria contain a DNA molecule that encodes a primitive ribosome similar to that of bacteria. It is currently believed that mitochondria arose when a bacterial cell was engulfed inside of an archaeal or early eukaryotic cell. The bacterial cell provided ATP to the host cell while the host provided protection as well as a steady food supply resulting in an endosymbiotic relationship. Endosymbiosis also led to the development of chloroplasts.
Archaea are the only cells that coud have a _________ plasma membrane
Monolayer. (the plasma membrane of Archaea can be found as monolayers, where the isoprene chains of one phospholipid connect with the isoprene chains of a phospholipid on the opposite side of the membrane. Bacteria and eukaryotes only havelipid bilayers, where the two sides of the membrane remain separated.)
What are the major groups of archaeons?
Most well-characterized archaeons can be classified in either the Euryarchaeota or Crenarchaeota phylum. - Two other phyla have been proposed. • Korarchaeota (from rRNA sequences obtained from nonculturable microbes) • Nanoarchaeota (with only one current member: the symbiotic archaeon Nanoarchaeum equitans
How do structures on the surface of bacterial cells allow for complex interactions with the environment?
Motility from flagella: spiral, hollow, rigid filaments extending from the cell surface • Locations and number vary from species to species.
In a isotonic solution what is the net movement of water and what happens to the cell
Moves both ways Healthy cell
In a hypotonic solution what is the net movement of water and what happens to the cell
Moves into the cell Swells and may even burst
In a hypertonic solution what is the net movement of water and what happens to the cell
Moves out of the cell Shrinks and becomes weak
About how long ago did microbes dominated the planet?
Multicellular fossils dating to about 0.5 billion ybp (years before present) have been found
What are the subunits of PEPTIGLOYCDAN in both Archaea and Bacteria?
NAG NAT in Archaea and NAG NAM in Bacteria
What are peptidoglycan subunits ?
NAG-NAM
Structure of the cytoskeleton
Nine microtubule doublets form a tube around a core pair of microtubules (the axoneme). • Motion occurs when ATP is burned, helping microtubules in the axoneme slide past each other
Facts about flagella
Not all cells have EXTERNAL flagella! - Some spirochetes have flagella in the periplasm. - As they spin, they rotate the entire cell body like a corkscrew.
What is considered a critical storehouses of genetic information ?
Nucleic acids (DNA/RNA)
___ is the diffusion of ______ across a cell membrane
Osmosis ; water
which of these includes in gram positive cell envelope?
Peptiglycodan
______ occurs whenever water moves out of a cell, and the cell shrinks in size
Plasmolysis
What macromolecules (major units) are needed for life to happen?
Polypedtides- Amino acids. Nucleic acids-Deoxyribonucleotides /Ribonucleotides Lipids-Diverse structures Polysaccharides- Sugars
What can be embedded in a lipid bilayer forming a cell's plasma membrane?
Polysaccharides and polypetides
Why has death tolls been reduced?
Prevention of infection through • Use of antiseptics (Joseph Lister) • Sanitation improvements (sewage treatment) • Food/water safety (pasteurization) • Personal hygiene improvements • Vaccination - Treatment of infections (antibiotics!)
Euryarchaeota: Halophiles - Halobacterium
Produces energy through an odd form of phototrophy • Doesn't use chlorophyll or an electron transport chain • Uses bacteriorhodopsin to harness light energy and produce a proton motive force (then used to make ATP) • Bacteriorhodopsin gives off reddish hue
Histones
Protein molecule around which DNA is tightly coiled in chromatin
What are the critical structural and functional properties of the bacterial cell envelope?
Protein secretion and the PM: making proteins and shipping them outside the cell - Uses ATP energy! - Toxins, siderophores, enzymes, etc. - The bacterial cell wall (CW) is a crucial structure. - It is composed of crosslinked strands of peptidoglycan subunits forming a matrix (similar to a chain-link fence). - It gives the cells their shape and protection from osmotic lysis/mechanical forces.
Comparison of plasma membranes in Bacteria,Archaeons,and Eukarya
Proteins function structural Bacteria - High abundance Archaeons-High abundance Eukarya- Low abundance
How can the plasma membranes hold sensory systems?
Proteins in the PM can be used to detect environment changes. • The cell can use the detected changes to alter gene expression to respond.
The archaeal cell wall...
Provides physical and osmotic protection. - In Archaea, it may be composed of pseudomurein (slightly different from peptidoglycan structure). - Some Archaea lack a cell wall
Nucleus
Purpose of signal: import into nucleus (Nls)internal sequence one or two short series of lysine (k) and arginine(r) sample sequence kkkrk
Basophils
Release histamine
How are bacteria categorized and named?
Remember that most microbes still can't be cultured! - What we CAN grow, we name according to the standard binomial system. • Species: group of strains sharing common features, while differing considerably from other strains • Genus: group of closely related species Above the genus level, we use family, order, class, phylum, and finally domain
Euryarchaeota: Halophiles
Require NaCl concentration greater than 1.5M - High salt environments are fairly rare. • Great Salt Lake in Utah • Dead Sea between Israel and Jordan - These areas vary between 5 to 34% salinity. - The ocean is typically 3.5% salinity (0.6 M)!
This scientist established a set of criteria to determine if a microbe is the cause of a specific disease.
Robert Koch
What does the cell membrane do?
Separates the external environment from the interior of the cell providing protection
Distinctive properties of Archaea: Structure
Similar shapes to Bacteria/Eukarya - Both Archaea and Bacteria usually possess singular, circular chromosomes and lack a membrane-bound nucleus. - Archaeal DNA is complexed with histones (like Eukarya). - Many of the DNA replication enzymes of Archaea "look" like those of Eukarya. - The Archaea plasma membrane structure is unique to this domain
Classification depends on many features:
Size/shape • Gram type • Colony morphology • Presence of structures such as capsules/endospores • Physiologic/metabolic traits (see Ch. 13) • DNA sequence data (in more recent years)
Are there molecules or structures that might satisfy those requirements?
Some RNA molecules have the ability to catalyze reactions (these are known as ribozymes, a combination of ribonucleic acid and enzymes) - This means RNA could serve the dual purpose of genetic information storage AND catalyzing reactions
Many eukaryal microbes are primary producers (providing energy) or biodegraders (recycling nutrients)
Some algae produce great amounts of oxygen through photosynthesis in the oceans. • Some eukaryal microbes can degrade cellulose, recycling plant matter better than animals can (termite gut protozoa).
What happens with antibiotic resistance?
Some bacteria can produce an enzyme to destroy the critical b-lactam ring structure. - BUT we can add a second drug to inhibit that enzyme and restore the first drug's efficiency!
How can molecules get OUT of a Gram-negative cell's periplasmic space then?
Some move from the periplasm to outside directly (these are known as autotransporters and are rare). - Some use single-step (never entering the periplasm) transport systems. C
What are some of the shapes Bacteria can take?
Spherical (s. coccus, pl. cocci) - Rod-shaped (s. bacillus, pl. bacilli) -Comma-shaped (s. vibrio, pl. vibrios) Spiral (s. spirillum, pl. spirilla) - Pleiomorphic (varied shapes
Comparison of plasma membranes in Bacteria,Archaeons,and Eukarya
Sterols function in membrane stability Bacteria -No Archaeons-No Eukarya-Yes
What is the functions of Polysaccharides
Structural(such as cellulose and chitin) and energy storage (such as glycogen and starch.)
Euryarchaeota: Halophiles - How do these cells deal with the osmotic shock and loss of water?
Studies on Halobacterium salinarum show they maintain a very high intracellular K+ concentration to offset the very high extracellular Na+ concentration.
Are Viruses considered to be alive ? Explain why or why not?
Technically, viruses aren't considered to be alive. -They don't replicate outside of a host cell. -They (usually) have little to no biochemical activity outside of a host cell. -They are inert and nonreactive outside of a host cell.
How can nutrients get through the cell walls?
The Gram-positive peptidoglycan layer has large pores throughout its matrix. - The Gram-negative cell has porin and TonB proteins in its outer membrane to transfer molecules into the periplasmic space. • Once there, active transport mechanisms can move the molecule into the cytoplasm.
How can the characteristics of a cell wall explain how Gram stain works?
The alcohol decolorization step shrinks the large pores in the Gram-positive cell, helping to lock the crystal violet stain in. - The alcohol also may strip away some of the outer membrane lipids in the Gram-negative cells, making them more likely to lose the initial crystal violet stain.
What happens when you weaken the cell wall?
The cell can't resist osmotic pressure changes.
Why did the broth in Pasteur's experiment remain sterile?
The curve of the flask prevented bacteria from gaining access
What kinds of internal structures help to organize bacterial cells?
The cytoskeleton is a series of internal proteins that assist in keeping everything in (or moving it to) the right locations in cells. Some cytoskeleton proteins are involved in cell wall synthesis during cell division (FtsZ and MreB).
What is in the cytoplasm of bacterial cells?
The largest area is the nucleoid region, housing the chromosome(s) and DNA replication machineryThe remainder of the cytoplasm is a stew of macromolecules (tRNA, rRNA, mRNA, proteins, etc.). - Inclusion bodies may also be present. • Polyhydroxybutyrate granules: carbon storage • Sulfur globules: sulfur storage • Gas vesicles: buoyancy control • Carboxysomes: location of carbon fixation reactions • Magnetosomes: organelle associated with direction finding
What are the different types of eukaryal microbes?
The phylogeny of eukaryal microbes - Creating phylogenetic trees from rRNA gene sequences is possible (see Chapters 1 and 2
What is the primary function of the proton motive force?
The proton motive force occurs when the cell membrane becomes energized due to electron transport reactions by the electron carriers embedded in it. Basically, this causes the cell to act like a tiny battery. Its energy can either be used right away to do work, like power flagella, or be stored for later in ATP.
Petigloycdan
The two main functions of peptidoglycan in bacteria are to maintain the shape of the cell and to counteract the high osmotic pressure of the bacterial protoplast — without peptidoglycan or when the integrity of peptidoglycan is compromised, the bacteria undergo immediate osmotic lysis
What can studying the genetics of microbes teach us about the evolution of life on Earth?
The very early environment on Earth was drastically different than it is today. -There was little oxygen in the atmosphere, and the surface of the planet was a soup of chemicals in liquid form. -This early atmosphere and environment led to the initial synthesis of the first forms of macromolecules (and their use in primitive single-celled life).
What are the roles of mitochondria and chloroplast in cell metabolism?
These organelles use electron transport chains to produce ATP (chemiosmosis). - Mitochondria participate in later stages of cellular respiration. - Chloroplasts use the ATP they produce to fix carbon into organic compounds (often glucose)
Euryarchaeota: Methanogens
They reduce CO2 with H2 to produce methane (CH4) and water (H2O) in an unusual reaction. - Energy released can be used to fix carbon. - All identified methanogens are strict anaerobes. • Found in human gut and swamp sediments The methane produced in these areas forms gas from humans and combustible air from swamps. - Methanogens possess a great deal of diversity but share a common meta- bolic property.
So why study microbes at all if they're so hard to see?
They're very fast, cheap, and easy to grow. -They can produce enzymes and other molecules for industrial/medical uses. -Most of them have small numbers of genes, making them simpler to study. -Genetic manipulation of single-celled bacteria is usually much easier than multicellular eukarya
What evidence supports endosymbiotic theory?
Three main lines of evidence: • Mitochondria/chloroplasts resemble bacteria in both size and shape. • Arrangement of double membranes around these structures is consistent with ingestion idea. • Each has its own DNA, and that DNA sequence is much more like bacteria than eukaryotic DNA - EXCEPTION: Amitochondriates lack mitochondria. The idea is that these cells evolved out of using them to obtain energy, and instead obtain their energy in other ways (Giardia is an example of these).
True or False Bacterial cells exhibit great differences in composition, size, and shape. However, at their core, all bacteria still depend on the same DNARNAprotein system that is a common underlying theme to all cellular life on Earth.
True
True or False .Bacteria is simple once proteins are done there is no need for modifications
True
What are the varying size of bacteria?
Usually smaller than eukaryal cells (bacteria are often 0.5‒5 μm in length) - SMALL eukaryal cells are usually >5 μm in diameter There are exceptions to the general size of bacterial cells. - Thiomargarita namibiensis: up to 700 μm in diameter! - Epulopiscium fishelsoni: 200‒700 μm x 80 μm! - Some mycoplasma cells are only 0.2 μm in diameter.
What is Vacuole function?
Vacuoles are membrane-bound organelles that are found in cells of plants, animals and fungi.The main function of vacuoles is to contain the waste products of the cells and isolate them from the rest of the organelles and the cytoplasm. Vacuoles maintain an acidic pH internally. This allows them to denature misfolded proteins transferred to the vacuole from the cytoplasm. The vacuoles can also help remove unwanted or toxic materials from the cells by exporting them to the cell membrane, where they are released to the outside surroundings of the cell
What can be done by altering the genomes of microbes?
We can mass produce molecules that humans want.
Can the CW structure be degraded artificially ?
YES! - Artificially by blactam antibiotics - These work by preventing peptidoglycan crosslinking, weakening the cell wall structure.
Can the cell wall structure be degraded naturally?
YES! - Naturally by lysozyme and lysostaphin secretions Lysozyme cleaves backbone of peptidoglycan Lysostaphin acts on the crossbridge of a certain Staphylococcus species only.
What does dsDna provide?
a backup copy of the genetic information in case of a problem
What is the role of plasma membrane in homeostasis.
ability to maintain an internal environment vs. changes outside - Phospholipid bilayer with embedded proteins that allow molecule transport • Facilitated diffusion (no energy required from cell) • Active transport (cell expends energy)
What does FtsZ do?
aids in cell division
- Paramecium ingesting
algae and using them for photosynthesis
Which of the following is not a macromolecule?
amino acids
How did Louis Pasteur disprove spontaneous generation theory in the late 1800s?
broth boiled to sterilize it. Sterilized broth cools. Microbes from outside become trapped in bent neck of flask. Broth remains sterile. When flask is tilted broth contains microbes in neck of flask, after hours or days microbes replicate in broth.
What is the active site of transport in eukaryotic cell
cell membrane
What do bacteria have instead of histones?
compactosomes
Surface array (S-layer)
composed of protein it covers the surface of cell the function is to protect from bacteriophage.
What is pili and what does it allow
composed of protein subunits the location is to extend outward from cell . the function allow attachment ; tip often binds to specific molecules . In some bacteria , pili are retractable and allow "twitching motility."
DNA nucleoid composition and function:
composition is DNA ,RNA,protein function genetic information storage and gene expression
composition and function of Regulatory factors
composition is RNA,protein function-control of replication,transcription,and translation
What is the compostion and function of Chromosome- packaging proteins
composition is protein function - protection and compaction of genomic DNA
What is the composition and function of Enzymes involved in synthesis of DNA ,RNA
composition is protein function- replication of the genome, transcription
These organisms are thought to have contributed to the oxygenating of early Earth's atmosphere.
cyanobacteria
What did Robert Koch do?
determined Bacillus anthracis and Mycobacterium tuberculosis were the causes of anthrax and tuberculosis (respectively). • His work with anthrax helped sheep herders and cattle ranchers avoid costly animal losses.
Pasteur's contributions to microbiology include
disproving the theory of spontaneous generation.
which theory suggest that permanent eukaryotic ingested other eukaryotes forming other cells
endosymobic theory
which of the following describe cells that have membrane bound organelles?
eukaryotes
What is fimbrae and what does it carry?
fimbria (plural fimbriae), also referred to as an "attachment pilus" by some scientists, is an appendage that can be found on many Gram-negative and some Gram-positive bacteria that is thinner and shorter than a flagellum Fimbriae carry adhesins which attach them to the substratum so that the bacteria can withstand shear forces and obtain nutrients. For example, E. coli uses them to attach to mannose receptors
FtsZ
forms a ring at the future site of the septum of bacterial cell division.
Where can you find microbial fossil records?
fossilized mats discovered in Australia.
Dictyostelium
is even more complex. • It exists in a haploid unicellular form until conditions worsen. • Then a multicellular "slug" is formed with a stalk and a fruiting body. • Spores form in the fruiting body, restarting the life cycle as haploid cells. • These haploid cells can fuse into a diploid macrocyst form. • The macrocyst form undergoes meiosis to generate more haploid cells.
Peptide chain
linked to the NAM subunit
which of the following is involved in moving internal organism in bacteria ?
machnestomes
Peroxisome
main function is breakdown of fatty acids. Contains various oxidative enzymes like catalase and oxidase
Chloroplast
main function is photosynthesis an interesting feature is a double membrane contains DNA independent replication Unique to photosynthetic organisms
Nucleus
main function is that it contains most of cells DNA site of transcription an interesting feature is a double membrane containing pores. Outer membrane continuous with endoplasmic reticulum
Rough endoplasmic reticulum
main function site of translation and protein folding an interesting feature is an rough er has protein synthesizing ribosomes attached to it
Golgi apparatus
main function: modifies , sorts,and transports proteins connected to the er through a series of vesicles
Chlamydomonas
maintains a motile haploid state. - When conditions become bad, haploid cells differentiate and fuse into a diploid form, generating a hardier spore form
What is the function of Lipids?
make up cellular membranes that form physical boundary between the insides of cell and surrounding membranes of internal organelles
A single lipid layer known as a ___________ may have been an early form of plasma membrane separating interior contents from the external environment.
micelle
which of the following may have been an early form of the plasma membrane ?
micelle
Three components of cytoskeleton
microfilaments, microtubules, intermediate filaments
which region contains thr chromosome in the bacterial cell?
nucleoid region
What are the building blocks of nucleic acids?
nucleotides
which of the following is not a feature of bacterial cytoplasm?
nucleus
- How do the archaeons move around, stick to surfaces, sense the environment, and acquire nutrients?
ome use an S-layer (single layer of many identical armorlike subunits) to protect against predation/viruses and to mediate adhesion. • Some form cannulae, hollow glycoprotein tubes that link cells together to form a complex network. Some archaeons possess flagella. • Similar to bacteria in that they rotate to move the cell
Heterotroph
organism that obtains energy from the foods it consumes; also called a consumer that ingest organic molecules
which is the flow of water in the plasma membrane
osmosis
Saccharomyces
ot limited to ascus formation - Budding off of smaller cells can occur or fission of identically sized cells
what is the component of plasma membrane of eukaryotic cell
phoslipids. proteins .sterol
which term represents the history of an organism evolution?
phylogeny
which is used for conjugation purpose?
pili
what type of plant pathogen was responsible for Irish potato famine
protozoan
MreB
provides structure
What is the function of Nuclecic Acids?
provides the instructions for assembly and reproduction of the cells. Ribonucleotides-Involved in the production of polypetides
Rough endoplasmic reticulum
purpose of signal: import into rough er blinding signal recognition particle 5-10 hydrophobic sequence lx lx
Aerobic respiration
requires oxygen but yields much more energy.
who establish rules making it possibke for other to determine which microbe caused a certain disease.
robert koch
What is the role of the nucleus?
role in the storage and expression of information - Double membrane structure contains linear chromosomes of cell (DNA) - Nucleolus (non-membrane bound) exists within nucleus (ribosome synthesis) - Spatial separation means transcription occurs in nucleus; translation occurs in cytoplasm.
Plasmids are
small circular DNA molecules that replicate separately from the bacterial chromosome
