exam 2 Flashcards
prokaryotes
- single cell organisms
- lack a nucleus and membrane bound organelles
eukaryotes
- multi-celled organisms with membrane bound nucleus and other organelles
three domain system
- eukarya
- archaea
- bacteria
bacteria cell structure
- no nucleus
- genetic material in a circular chromosome
- cell wall made of peptidoglycan
- flagellum for movement, pili for attachment
- capsule made from polysaccharides, proteins, or both (surrounds only some bacteria cells)
archaea
- single celled prokaryotic microorganisms
- lack peptidoglycan in cell walls
- thrive in extreme environments
- genetic and metabolic pathways more similar to eukaryotes than bacteria
bacteria shapes
- cocci (spherical)
- bacilli (rod shaped)
- spirilla (spiral shaped)
bacteria reproduction
- mainly binary fission
- some exchange genetic material by transduction, conjugation, transformation
conjugation
- direct transfer of genetic material from one bacteria to another through a pilus (tube-like structure)
- requires donor and recipient cell
transformation
- bacteria takes up naked DNA fragments from the environment
- DNA comes from broken (lysed) cells
thermophiles
bacteria/archaea that thrive in hot temps (41°C - 70°C)
psychrophiles
bacteria/archaea that survive in extremely cold temps
- 15°C or lower
halophiles
bacteria/archaea that thrive in environments of extreme high salt concentration
acidophiles
bacteria/archaea that thrive in environments with a pH or 2.0 or below
infectious diseases spread in 3 ways:
1) person to person
2) bites from insects or animals
3) ingesting contaminated foods or microbes in the surrounding environment
virulence
- ability to cause disease
- heritable and variable
endospores
- tough, thick walled dormant structures formed during times of environmental stress
- contains copy of cells DNA, RNA, ribosomes, and enzymes
- metabolic activity stops and cell breaks down
- resistant to high temps, UV, and antibiotics
- in favorable conditions resumes growth
antibiotics
- discovered in 1928, widespread use by the 40s
- extensive use in the late 20th century led to drug-resistant strains of bacteria
biofilms
bacterial colonies in a polysaccharide rich matrix that shields bacteria from antibiotics
bioremediation
use of bacteria and archaea to clean sites polluted with organic solvents
gut microbiome
100 trillion bacteria and archaea naturally inhabit the gut
gram-positive bacteria
- thick layer of peptidoglycan with teichoic acids providing rigidity and assist in ion transportation
gram-negative bacteria
- thin layer of peptidoglycan surrounded by an outer membrane that contributes to pathogenicity and antibiotic restrictions
- more aggressive and causes more infectious diseases
cell wall composition
- gram stain (dyeing the system to examine the cell walls)
- cyanobacteria (lineage of photosynthetic bacteria first to perform oxygen’s photosynthesis)
- gram-positive (cells look purple)
- gram-negative (cells look pink)
cyanobacteria
- lineage of photosynthetic bacteria
- first to perform oxygenic photosynthesis
- changed earth’s atmosphere to a high oxygen concentration
cyanobacteria bloom when…
- thrive in nitrogen and phosphorous rich environments
- excess nutrients trigger bloom growth
- reduces water clarity and oxygen levels, release toxins harmful to humans/aquatic organisms
- decomposing cyanobacteria release nutrients back into the water
unique properties of viruses
- infectious particles, not organisms
- to make and release new viruses, they must take control of the host cell’s genetic material
properties of a virus
- protein shell surrounding nucleic acid core
- can have DNA or RNA, not both
- lack enzymes for metabolic processes and machinery for synthesizing proteins
capsid
shell surrounding nuclei acid in viruses, made from protein subunits called capsomers
envelope
- not all viruses have one
- modified piece of the host cell membrane
virion
fully formed virus active in the host cell
- able to establish infection
bacteriophage
- parasitize every known bacterial species
- make the bacteria they infect more pathogenic for humans
