Term
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Definition
| A protein coat of a virus |
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Term
| What is the structure of viral envelopes and how are they synthesized? |
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Definition
| The envelope is lipid-rich and is either borrowed from the membrane of the host cell or synthesized in the host cell cytoplasm; envelope typically contains virus-specific proteins |
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Term
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Definition
| A mature virus outside of the host cell |
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Term
| What are the five ways in which viruses differ from living organisms? |
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Definition
1. They cannot reproduce on their own - they require the host cell's reproductive machinery to reproduce
2. Viruses do not metabolize organic nutrients - they use ATP made available by the host cell
3. Viruses are not separated by their external environment by a barrier (i.e. cell wall or membrane)
4. Viruses possess either DNA or RNA, but never both
5. Viruses can be crystallized without losing their ability to infect |
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Term
| What is a chemical receptor? |
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Definition
| A specific glycoprotein on the host cell membrane |
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Term
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Definition
| A virus that infects bacteria |
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Term
| How does a bacteriophage infect a cell? |
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Definition
| It attaches to the the host cell with its specific chemical receptor; then, viral enzymes digest a hole in the host cell's cell wall; finally, the virus' tail injects the virus' nucleic acid into the host cell |
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Term
| How do viruses enter eukaryotic cells? |
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Definition
| Via an endocytotic process (engulfing) |
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Term
| What is a virulent virus? |
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Definition
| A virus that follows the lytic infection cycle |
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Term
| Explain the lytic infection cycle |
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Definition
| The virus commandeers the host cell's reproductive machinery and begins reproducing new viruses. The new viruses are either released one at a time from the cell in a reverse endocytotic process or the cell fills with viruses and eventually bursts (lyses) |
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Term
| What is the eclipse period? |
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Definition
| (Lytic Cycle) - The time between when the virus first infects the cell and when the first fully formed virion appears |
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Term
| What is the latent period? |
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Definition
| The time between infection of the host cell and lyses of the host cell |
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Term
| What is a temperate virus? |
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Definition
| A virus that follows a lysogenic infection cycle |
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Term
| Explain the lysogenic infection cycle |
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Definition
The viral DNA is incorporated into the host cell's genome. If the virus contains RNA and the enzyme reverse transcriptase, then DNA is reverse-transcribed from the RNA and then incorporated into the host cell genome.
When the host cell replicates its DNA it also replicates the viral DNA.
The viral DNA often remains dormant until activated by some form of stress. |
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Term
| What is a provirus? A prophage? |
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Definition
| A dormant virus following the lysogenic infection cycle. Prophage is a dormant virus that infects a bacterial host cell. |
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Term
| What happens when a temperate virus/provirus/prophage become activated? |
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Definition
| They become virulent viruses. |
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Term
| Explain the difference between plus-strand RNA viruses and minus-strand RNA viruses. |
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Definition
Plus-strand RNA viruses can directly translate proteins from their RNA.
Minus-strand RNA viruses only contain the complement to mRNA, so the RNA must be transcribed to plus-strand RNA before being translated. |
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Term
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Definition
| A retrovirus carries the enzyme reverse transcriptase in order to create DNA from its RNA (and then the DNA is incorporated into the host cell genome) |
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Term
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Definition
| Small rings of naked RNA that only infect plants |
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Term
| How do bacteriophages differ structurally from some viruses? |
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Definition
| Some viruses contain a capsid, nucleic acids, and a lipid-rich protein envelope while most bacteriophages also have a tail, base plate, and tail fibers. |
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Term
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Definition
A cell that does not contain a membrane bound nucleus; instead, they contain a nucleoid (AKA chromatin body, nuclear region, or nuclear body) that is not enclosed by a membrane
They also do not possess complex, membrane bound organelles, but do contain organelles (ribosomes, mesosomes, etc) |
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Term
| What are the domains of prokaryotes? Which one also has similarities to eukaryotes? |
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Definition
Archaea and Bacteria;
Archaea |
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Term
| What is the difference between autotrophs and heterotrophs? |
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Definition
| Autotrophs use CO2 as their main source of carbon while hetertrophs use organic matter |
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Term
| What is the difference between phototrophs and chemotrophs? |
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Definition
| Phototrophs are organisms that use light as their energy source; Chemotrophs are organisms that use organic or inorganic matter (chemicals) |
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Term
| Define cocci, bacilli, spirilla, and spirochetes |
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Definition
Cocci - round shaped bacteria
Bacilli - rod-shaped bacteria
Spirilla - Helical shaped bacteria that are rigid
Spirochetes - Helical shaped bacteria that are not rigid |
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Term
| What are prokaryotic ribosomes comprised of? |
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Definition
| A 30S and 50S subunits to give a 70S ribosome |
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Term
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Definition
| The phospholipid bilayer that surrounds the cytosol in most prokaryotes |
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Term
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Definition
| The spherical structure formed when amphipathic molecules (such as phospholipids) are placed in solution. The polar ends face the outside while the nonpolar ends face the inside (in polar solutions) |
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Term
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Definition
| The inner and outer sides of the membrane |
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Term
| What is the difference between an integral (instrinsic) protein and a peripheral (extrinsic) protein? |
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Definition
Integral proteins are amphipathic proteins that traverse the membrane from the inside of the cell to the outside
Peripheral proteins are situated entirely on the surface of the membrane |
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Term
| What is the fluid mosaic model? |
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Definition
| The membrane is fluid because it is held together by intermolecular forces. Therefore, the molecules can move around but cannot separate. Mosaic refers to the asymmetrical distribution of membrane proteins |
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Term
| What affects membrane fluidity in prokaryotes? In eukaryotes? |
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Definition
Prokaryotes - hopanoids reduce membrane fluidity
Eukaryotes - cholesterol moderates membrane fluidity |
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Term
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Definition
| Rapid, random motion of molecules |
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Term
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Definition
| The net movement of a compound from a region of high concentration to low concentration |
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Term
| Define chemical concentration gradient, electrical gradient, and electrochemical gradient |
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Definition
Chemical concentration gradient - the change in the concentration of a compound over a specified distance
Electrical gradient - the direction in which a positively charged particle tends to move
Electrochemical gradient - the sum of the chemical concentration gradient and electrical gradient vectors |
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Term
| What is a semipermeable membrane? |
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Definition
| A membrane that does not completely stop a compound, but simply slows it (i.e. it can still wiggle through the membrane) |
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Term
| Which two aspects of a compound affect its semipermeability and how? |
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Definition
Size and polarity
Small, nonpolar molecules can passively diffuse, while large polar molecules require facilitated diffusion |
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Term
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Definition
| The diffusion of compounds through leakage channels due to random motion |
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Term
| Define facilitated diffusion |
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Definition
| The diffusion of compounds down the electrochemical gradient with the assistance of transport/carrier proteins embedded on the membrane (membrane essentially becomes selectively permeable) |
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Term
| What is active transport? |
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Definition
| The transport of molecules against their electrochemical gradient; requires energy |
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Term
| What is secondary active transport? |
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Definition
| Using ATP indirectly to create an electrochemical gradient and then using the energy from the gradient to acquire or expel a molecule |
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Term
| What is the bacterial cell wall composed of? |
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Definition
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Term
| Define hypertonic, isotonic, and hypotonic |
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Definition
Hypertonic - the cytosol contains more particles than surrounding solution
Isotonic - the cytosol contains the same amount of particles as surrounding solution
Hypotonic - the cytosol contains less particles than surrounding solution |
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Term
| What is the difference between gram-positive bacteria and gram-negative bacteria? |
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Definition
Gram-positive: appear purple when stained because the gram stain does not leak out of the cell (cell wall is very thick)
Gram-negative: appear pink because gram stain leaks out of the cell (cell wall is less thick than gram-positive); also contains a second plasma membrane outside the cell wall (cell wall sandwiched between two plasma membranes) |
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Term
| How do many antibiotics attack bacteria? |
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Definition
| They destroy the disaccharide linkage in peptidoglycan to disrupt the cell wall, causing lyses of the cell, thus killing the bacterium |
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Term
| What is the structure and function of bacterial flagella? |
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Definition
Long, hollow, rigid, helical cylinders composed of protein called flagellin
Rotate counterclockwise (viewing from outside the cell) to help bacteria move; rotating clockwise causes tumbling which allows the bacteria to change direction |
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Term
| Explain bacterial binary fission |
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Definition
| The circular DNA in bacteria is replicated by two DNA polymerases to make complementary single strands. The single strands combine with the template strands to form two identical circular DNA. The cell then divides with each cell receiving one of the circular DNA |
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Term
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Definition
| Small circles of DNA that exist and replicate independently of the bacterial chromosome |
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Term
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Definition
| A conjugative plasmid is required because it contains the gene for the sex pilus; one of the plasmid's strands is nicked and one end of this nicked strand begins to separate from its complement as its replacement is replicated. The loose strand is then replicated and fed through the sex pilus. |
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Term
| What is the difference between an F-plasmid and R-plasmid? |
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Definition
The F-plasmid is the fertility factor. If the pilus is made while the F factor is integrated into the chromosome then some or all of the chromosome may be replicated and transferred through sex pilus.
The R-plasmid donates resistance to certain antiobiotics and is also a conjugative plasmid. |
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Term
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Definition
| The process by which bacteria may incorporate DNA from their external environment into their own DNA (i.e. from lyses of other bacterial cells or by DNA placed in the external environment in the lab) |
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Term
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Definition
| Transduction occurs when the capsid of a bacteriophage mistakenly encapsulates a DNA fragment of the host cell. When they infect new bacterium they transfer the harmless bacterial DNA instead of the virulent viral DNA fragments. |
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Term
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Definition
Eukaryotic hetertrophs that obtain their food by absorption rather than ingestion (they secrete their digestive enzymes into the external environment then absorb the digested compounds)
They also spend most of their life in the haploid state |
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Term
| What is the cell wall of fungi called and composed of? |
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Definition
Septa, and it is composed of chitin which is more resistant to microbial attack than cellulose
Septa are usually perforated to allow cytoplasmic streaming between cells |
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Term
| What are mycelium and hyphae (fungi)? |
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Definition
| Mycelium is the tangled mass that fungi exist in in their growth state, and hyphae are the multiply branched thread like structures that make up the mycelium |
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Term
| When do fungi reproduce asexually and when do they reproduce sexually? |
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Definition
Asexual reproduction usually occurs when the environment is good (if the environment is good for the parent, it will also be good for an identical child)
Sexual reproduction usually occurs when the environment is tough (if the environment is tough for the parent, it may or may not be tough for a child that is different from the parent) |
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