C-2 Flashcards
(55 cards)
why is cell size limited using square-cube law
the surface area is supporting the volume by transporting food/raw materials into the cell and excreting waste out of the cell - needs to be large enough to support the chemistry inside but not too big
square-cube law
volume grows faster than surface area
surface area to volume ratio as a cell gets smaller
the ratio increases
surface area to volume ratio as a cell gets larger
the ratio decreases
size range of most microbes
1 micrometer = bacteria
binomial nomenclature rules
- capitalize genus
- don’t capitalize species
- italicize or underline scientific name
- names may be abbreviated but only if written in full prior in work
what is the general way microbes are named and classified
- appearance/morphology
- nucleus or not
- molecular techniques
why is species not as useful to microbiologists as other biologists
may be similar species, but not as specific to the diseases they cause so they are mostly ignored
morphology
shape and arrangement of microbes
how is morphology used to name microbes
usually the first word in the name is the cell shape
prokaryotes vs eukaryotes
prokaryote: no nucleus, nucleoid region instead where DNA is supercoiled
eukaryote: a nucleus, nucleolus that contains genes involved in making ribosomes
how are the 3 domains sorted into prokaryotes and eukaryotes
whether they have a nucleus or not
glycocalyx
capsule or slime layer - protects cells from desiccation (drying out) and environmental stress and phagocytosis
fimbriae and pilli
extend beyond glycocalyx to help bacteria attach to surfaces and other bacteria (similar to flagella but smaller)
flagella
used for motility or movement
cell wall
gives cells structure, shape, and protection from osmotic pressure
endospores
helps cells hibernate when growth conditions aren’t favorable, helps cells resist heat, drying, and other harsh conditions
what types of bacteria make these structures (gram positive or negative)
gram positive- endospores
gram negative- membranes,
biofilm
an aggregation of microbes that stick together and to surfaces; help protect the innermost organisms from antibiotics and immune responses (ex. plaque on tooth)
what bacterial structures are important for biofilm formation
frimbriae have adhesins to stick to surfaces
gram postive vs gram negative bacteria
gram positive- thicker layer of peptidoglycan, single cytoplasmic membrane (dense cell wall)
gram negative- thinner layer of peptidoglycan, inner cytoplasmic membrane and outer LPS membrane (less dense, more layers)
lag phase
- acclimation period
- adjusting to the environment
- making materials for growth/building new cell components
- slow reproduction
- not limited by space or nutrients
log phase
- exponential growth
- constant rate of increase (number of cells over time)
- actively dividing
- not limited by space or nutrients
stationary phase
- space and nutrients are decreasing (limit ability to grow)
- waste is also accumulating
- death rate = birth rate
