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
What organisms has circular DNA?
bacteria
Where is the DNA located in prokaryotic cells?
floats around in the cytoplasm
Nucloid
where DNA is found in bacterial cells
Plasmid
circular piece of DNA that contains advantageous genes
Where are plasmids found?
nucleoid region
Bacterial ribosomes consist of…
rRNA and ribosomal proteins
Subunits of bacterial ribosomes
ribosome (70S)
large subunit (50S)
small subunit (30S)
Inclusion bodies
membrane bound (used for storage of sugars, gas, nutrients); aid prokaryotic cells when there are shifts in their environment
Granules
metal/salt crystal structure which helps bacteria determine their orientation/direction based on the magnetic poles of the earth
Micro-compartments
store enzymes
Bacterial cytoskeleton
bacterial cells that contain actin filaments
Endospores
spores which form in the interior of the bacterial cell in harsh conditions; it appears at a certain life stage
Example of bacterial endospores (human use/pathogens)
bacillus subtilis (used to make soy sauce and other food), bacillus anthracis
Why are endospores unique?
extremely hearty; able to survive in many variations of their environment
State of endospores
vegetative state: nutrients present
endospore state: no nutrients present; covers itself in a protective coating before
Diplococci
two cells
Streptococci
spheres in chains
Tetrads
groups of 4
Sarcina
cube-like; typical to have pack of 8/64
Staphylococci
form in grape-like clusters
Bacillus
rod-shaped (anything that is not a perfect sphere
Vibro
curved rod/comma shaped
Spirillum
coil shaped
Spirochete
coil shaped
What is the difference between spirillum and spirochetes?
Spirilla have less coils (3-5) ; spirochetes bend and flex while spirillia have a corkscrew like motion
Ribosomal RNA gene
16s rRNA
Why are ribosomes used for taxonomy?
they are a highly conserved
Cyanobacteria
photosynthetic bacteria
Proteobacteria
medically important, mostly gram negative, categorized by alpha, gamma, beta…
Firmicutes
medically important, mostly gram negative
Actinobacteria
medically important (include some antibiotics)
Chlamydae and Ricketssia
obligate intracellular parasite (must be inside of the cell to survive)
Spirochetes
affect human behavior
Bacteriodetes
happy intestinal bacteria
Obligate intracellular parasites
parasites that must be inside of a cell to grow and divide
What is the primary source of energy for cyanobacteria?
sunglight
Characteristics of cyanobacteria
has existed for 3.5 billion years, have thylakoids, no chloroplasts or organelles, create oxygen, fix nitrogen
Fix nitrogen
takes nitrogen gas and converts it to NO3 NO2 or NH4
What is the toxic byproduct cyanobacteria creates?
oxygen
Purple sulfur bacteria
contain bacteriochlorophyll, form granules, use sunlight for energy and use the sulfur to convert to chemical energy
What do mycobacterium use for movement?
cytoplasm and plasma membrane
Halophiles
prokaryotic salt loving archaic cells
Thermofiles
heat loving (180F-212F)
Methanogens
synthesize methane; ruminants contain methanogens and they are also responsible for melting permafrost
Periplasmic flagella
“internal flagella”; flagella found in the periplasmic space (in spirochetes)
Periplasmic
space between cell membrane and cell wall
Porin proteins
channels which transport molecules
True or False: Mycobacteria lack a cell wall
false
True or False: biofilms involve bacteria only
false
What term is not used to describe bacterial cell shapes
Tetrad
Bacterial endospores are not produced by…
staphylococcus
Which cell structure is an important component in modern genetic engineering techniques?
plasmids
A bacterial genus that has waxy mycolic acid in the cell walls is
mycobacterium
If bacteria living in salty seawater were displaced to a freshwater environment, the cell structure that would prevent the cells from rupturing is the
cell wall
Spirochetes have a twisting and flexing locomotion due to appendages called
periplasmic flagella
Which of the three domains includes organisms that would be most likely to survive the environmental conditions that existed on Earth nearly 4 billion years ago?
archaea
The bacterial chromosome is part of the
nucleoid
Bacterial flagella are made primarily of
flagellin
Endospores are…
resistant to destruction by radiation, living structures, resistant to heat and chemical destruction, metabolically inactive
The most immediate result of destruction of a cell’s ribosomes
protein synthesis would stop
True or False: Endospores growing inside the human body can cause disease.
false
True or False: Mycoplasmas require entrance into a host cell in order to replicate
false
