Prokaryotic Cell Structure and Function Flashcards
what do all cells have?
cytoplasm, cell membrane, DNA/RNA, proteins, ribosomes
what is the size difference between eukaryotes and prokaryotes?
eukaryotes are 10x larger than prokaryotes
structure of typical bacterial cell
most have a cell wall, cell coating surface
some have fimbriae, inclusion bodies, cytoskeleton, pili, flagella, form endospores
flagellar basal body purpose
used for movement for the cell or sticking onto surfaces
flagella purpose/movement
helps swim through a fluid in a boat propeller like motion
3 parts of the flagella
filament inserted by hook which connects it to the basal body which determines the spin of the cell
flagella is found in…
all spirilla, half bacilli, very few cocci
chemotaxis
bacterial movement based on the presence of a chemical
positive chemotaxis
movement towards a chemical signal (food)
negative chemotaxis
movement away from a chemical signal (toxin)
runs and tumbles
the technique bacteria use to find a food source
- run: movement in a random
run
straight movement in a random direction
tumbles
change in movement when moving away from a chemotaxis positive signal
runs and tumbles when going towards toxin
runs are shorter and tumbles are more frequent
phototaxis
movement in response to light
aerotaxis
movement in response to oxygen (dependent on whether microbe is aerobic or anaerobic)
magnetotaxis
movement in response to magnets
galvanotaxis
movement in response to an electric current
bacterial fimbriae
shorter and in larger quantities, made of various types of proteins, helps cell stick to surfaces
bacterial conjugation
use of pili to exchange a few genes between bacterial cells
S layer
single protein that is coated by the cell to help them stick onto surfaces
Glycocalyx layer
layer that helps adhere the bacteria onto tissues/surfaces
Capsule
thick exterior of the cell that helps adhere to the cell strongly
Biofilms
3D structure formed by a community of microbes clumped together
When do biofilms form?
moist/water rich and food rich environment
How are biofilms removed?
physical disruption/sonication
What structures create the cell envelope?
cell wall and cell membrane
What macromolecule is the cell wall made of?
carbohydrates
Peptidoglycan
makes up the cell wall of bacteria providing it structure and shape
Purpose of the cell membrane
regulates movement of materials into and out of the cell
Mycoplasmas cell exterior
no cell wall; have sterol in membrane for structure
Archaea cell membrane
makeup
membrane is made of hydrocarbons instead of fatty acids
Gram positive (2 components)
cell wall and cell membrane
Gram positive characteristics
thicker cell wall due to the peptidoglycan, teichoic acid, little to no periplasmic space
Teichoic acid
makes the cell wall flexible
Gram negative (3 components)
outer membrane, cell membrane, plasma membrane
Gram negative characteristics
thin cell wall (prone to lysis), endotoxins/LPS outer membrane, porin proteins
Lipopolysaccharides (LPS)
used for cell communication and recognizing another gram negative cell
Endotoxin
LPS in the cell wall of bacteria
Do mycoplasmas have a cell wall?
no