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Bacteria
prokaryotic organisms; prokaryotes lack a true nucleus and membrane-bound organelles
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Viruses
not considered living organisms, since they cannot carry out metabolism outside of a host cell
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Bacteriophages
viruses that infect bacteria
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Fungi
lack chlorohyll but are eukaryotic organisms and therefore have membrane-bound organelles
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Archaea
- ex: methogens (prokaryotes that produce methane)
- extreme halophilies - live at high concentrations of NaCl
- extreme thermophiles - live where super hot
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Prokaryotic plasma membrane is composed of .....
- phospolipids arranged in lipid bilayer
- philic head with phobic tail
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Prokaryotes have a cell wall to maintain cell shape, protection, & rigidity. Bacteria can be divided into two groups:
gram-positive and gram-negative
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Characteristics of Gram-Positive
thick cell wall - peptidoglycan
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Characteristics of Gram-negative
thin layer of peptidoglycan between layers of periplasm and coated with lipopolysaccarde and proteins
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Oligate anaerobes
cannot survive in the presence of oxygen
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Facultative aerobes
can survive with or without oxygen
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Oligate aerobes
require oxygen to survive
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Photoautotrophs
- photosynthetic, using light energy to produce their own nutrient molecules.
- Photosynthetic bacteria use the plasma membrane as the site of photosynthesis
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Chemoautotrophs
use energy derived from inorganic molecules such as ammonia (NH3) or hydrogen sulfide (H2S) to drive nutrient production
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Photoheterotrophs
uses light to generate energy but must obtain their carbon in organic form (glucose)
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Chemoheterotrophs
must consume organic molecules both as an energy source and as a source of carbon
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In prokaryotes, transcription and translation occur both in the cytosol....why?
there is no seperate membrane-bound nucleus
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In eukaryotes, transcription takes place where?
nucleus, where splicing of introns takes place before leaving the nucleus
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Genetic transformation takes place when DNA is incorportated into the recipient. Describe transformation...
DNA taken up from the enviorment and integrated into the bacterial genome
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Genetic transformation takes place when DNA is incorportated into the recipient. Describe transduction
genetic material is passed from one bacterial cell to another via a virus .... recombination of bacterial DNA
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Genetic transformation takes place when DNA is incorportated into the recipient. Describe conjugation
- genetic information is directly transferred from one bacterial cell to another via temportany connection known as a conjugation bridge
- Cells containing F plasmid are called F+, cells lacking F plasmid are called F-
- F+ cells extends sex pilli to recipeient F- cell to form the conjugation bridge
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transduction, genetic material is passed from one bacterial cell to another via a virus. In generalized transduction....
DNA from any part of the host's chromosome becomes a part of the viral genome, replacing the viral genome
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specilized tranduction works when
DNA from a specific part of the host's chromosomes becomes part of the viral genome, usually replacing some viral genes
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Hfr cells
when part of the plasmid intergrates into the chromosome
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Viruses consists of genetic material surrounded by a protein coat. Viruses are oligate intracelluar partsites, which means....
- they can express genes and reproduce only within a living host cell
- Viruses are unable to survive outside of a host cell, since they lack the structures necessary for independent activity and reproduction
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Retroviruses are a special group of RNA viruses. When a viral RNA enters the host cell, it is first copied into double-stranded DNA, integrating into the genome of the host cell. What enzyme does a retrovirus need to copy DNA from RNA?
- Reverse transcriptase
- Since animal cells do not contain this, viruses must carry the enzyme with them
- Since the virus integrates in the genome of the host, it can escape immune detection
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What are bacteriophages? They have a polyhedral head and tail appartaus with tail fibers to attach to the host
virus that infects bacteria
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A Bacteriophage infects host cell by attaching to it, releasing enzymes that create a hole in the bacterial cell wall, then inject its DNA into bacterial cell host - once inside, the bacteriophage can reproduce through lytic or lysogenic cycle...what's the difference?
Lytic- viral DNA is translated and transcribed, weakening the cell wall where it bursts
Lysogenic-viral DNA becomes integrated into bacterial genome in prophage form, where it lies dormant, until its activated and starts the lytic cycle
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Fungi possess cell walls made of ....
chiton
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Glycolipids are similar to phospholipids, except glycolipids have one or more carbohydrates attached to the three-carbon glycerol backbone. Glycolipids are found in abundance..where?
in the membranes of myelinated cells composing the human nervous system
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What do steriods look like? Name an example
- four ringed structure
- hormones, vitamin A, cholestrol which is important for membrane fluidity
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Lipoproteins are classified by their density. The greater the ratio of lipid to protein, the lower the density. The major class of lipoproteins in humans are LDL. no question
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Function of phospholipids?
structural component of membranes
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Function of triacylglycerols?
store metabolic energy, provide thermal insulation, and padding
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Function of steriods?
regulate metabolic activities
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Some fatty acids function to do what
serve as local hormones
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Primary struture of amino acids looks like what?
a single chain
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Secondary structure of amino acids look like what?
- beta-pleated sheet or alpha-helix - a,helix and the beta-pleated sheets are the secondary structure and contribute to the conforllIation of the protein. All proteins have a pri- mary structure and most have a secondary structure.
- Beta-pleated sheets: connecting segments of the two strands of the sheet can lie in the same direction (parallel) or in opposite directions (al/liparallel)
- Alpha-helix: single chain twisted
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What does the tertiary structure look like for the amino acids?
The tertiary structure refers to the three dimensional shape formed when the peptide chain curls and folds
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What forces create the tertiary structure for amino acids?
1.2.3. 4. 5.covalent disulfide bonds between two cysteine an1ino acids on djfferent parts of the chain;electrostatic (ionic) interactions mostly between acidic and basic side chains;hydrogen bonds;van der Waals forces;hydrophobic side chains pushed away from water (toward center of protein)
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