Prokaryotic Cells Flashcards
Each cell (of bacterial organisms) is its own organism? T/F
True
Each bacterial organism has to have enough stuff going on in the cell that it can act as its own organism? T/F
True
Prokaryotes are bacterial and Archaea organisms
True
Characteristics of Prokaryotes:
- ) no membrane bound organelles
- ) no membrane bound nucleus. (The area containing the DNA is called the “Nuclear Region”).
- ) Smaller in size when compared to Eukaryotic cells. A Prokaryote is smaller than the smallest Eukaryota
- ) consists of bacteria and Archaea
Size of Bacterial cells:
Diameter= 0.2-2 µm in diameter Length= 2-8 µm in length
The human eye can see between:
300-500 microns in length
Shapes of bacteria include:
Coccus= round
bacillus= rod
spirillia (spirochete)= spiral
Hierarchy of bacteria talk
Gram reaction (positive/negative), Shape (coccus, bacillus, spirillia), arrangement (cluster, chain, etc.)
Example of how to talk about bacteria:
Staphylococcus epidermidis= “gram positive cocci (pl) that grows in clusters”
Why do you need to discuss the arrangement of bacteria?
it explains how the bacteria divides on its own divisional plane
What is the plural of coccus?
Cocci
Explain coccoid arrangements
Diplococcus, chains, clusters, tetrads
What is Diplococcus?
Diplococcus comes in pairs. It is an arrangement term in bacteria. Cocci remain in pairs after division and it’s often seen in Neisseria spp and is a super short rod
What does “chains” mean?
Chains is an arrangement of bacteria. It is end to end division and is often found in Streptococcus spp
The term “clusters” mean:
Grapelike clusters. It is often found in Staphylococcus spp
Tetrads are:
A bacteria arrangement that comes in groups of 4
Staphylo means
Clusters
Bacilli arrangements:
They mostly appear as single rods.
They are Diplobacilli (pairs),
Chains (Bacillus cereus is found in chains), and
Coccobacilli (oval shaped and look like really short rods in pairs)
Spirilla arrangements include:
Vibrios -
(curved rods that kind of look like boomerangs),
Spirilla -
(helical or corkscrew shaped and rigid), and
Spirochetes -
(Helical and flexible).
Spirilla and Spirochetes look very similar but you can tell them apart by looking to see which one is rigid and which one is flexible.
Structures outside the cell wall (MUST KNOW):
- ) Glycocalyx
- ) Flagella
- ) Axial Filaments
- ) Pili or fimbriae
- ) Peptidoglycan
- ) Plasma Membrane
Glycocalyx
Includes both capsule or slime layer.
It protects pathogens from being taken up by host defenses and is very slippery!
It allows adherence to surfaces and protects from the environment (drying, chemicals, etc.)
Glycocalyx possibly may provide nutrients.
Why is a slippery Glycocalyx beneficial to an organism?
because it can prevent the organism from evading the immune system.
If it’s slippery and hard to grab a hold of, then you’re immune cells aren’t going to be as effective in cleaning out that organism.
Glycocalyx will be sticky to things it wants to be sticky to? T/F
True
The most important thing about a Glycocalyx is:
it allows it to evade the immune system by being slippery
A capsule is less dense than a slime layer? T/F
False, a slime layer is less dense than a capsule
Flagellum (flagella pl.)
long, filamentous appendage. (allows organism to be motile)
It is not present in all bacteria.
It’s primarily used for motility. (flagella rotate about the diameter of the cell, pushing it much like the propeller on a ship),
Additional functions include: binding to cells and substrates.
Most bacteria flagellum have sticky ends to them? T/F
True
Structure of Flagella include:
Hook is the twirly part that allows the filament to move around.
Filament (part that twirls and allows the bacteria to be mobile)
Basal body (the anchor).
Bacteria flagella is really just made of 3 parts.
Flagellar arrangements include
Monotrichous- 1 filament, polar (at one end) (trichous means having hairlike projections)
Lophotrichous- 2 or more filaments, polar
Amphitrichous- multi filaments at each end
Peritrichous- filaments distributed all around the cell (they have what’s called tumbling motility)
Axial filaments:
Axial filaments are unique to the spiral shaped bacteria.
They analogous to a flagella that is built into the membrane (like striping on a candy cane)
The rotation of these filaments causes the bacteria to rotate, resulting motion of the organism.
Motility
is a huge advantage to bacteria. It allows bacteria to migrate to an area where it has the best chance of survival and replication.
Movement towards or away from a stimulus is called taxis
Chemotaxis is movement based on chemicals
Phototaxis is movement based on light (a lot of aquatic organisms do this)
Fimbriae
looks kind of like flagella.
It has short, thin fibrous appendages on the outside of the cell seen with Gram (-) bacteria and some Gram (+).
The thin fibrous appendages each have a sticky bit on them.
If it doesn’t stick to anything, it basically ends up in the toilet which won’t be an organism that causes disease.
Being frimbinated allows the fimbriae to stick to the gut mucosa and start an infection
Adhesion to surfaces & other bacteria
Pilus (pili pl.)
Sex pili (not sexual reproduction) are used for cell conjugation (transfer)
Conjugation is a method of transferring DNA to another bacterial cell.
DNA is usually in the form of a plasmid
The Cell Wall Functions:
Separates the inside from the outside (creates a barrier)
Maintains cell shape
Maintains osmolarity
Contributes to pathogenicity
Divides bacterial cells into two groups based on the Gram stain
A barrier between the inside and outside of the cell. The barrier decides what comes and goes.
Active and Passive transport
The Cell Wall Contains (listen to lecture video 3 for photos of diagrams):
Peptidoglycan -
N-acetylglucosamine (NAG), N-acetylmuramic acid (NAM), and polypeptides.
NAM is cross-linked by polypeptides
The amount of chains present in the cell well, in conjunction with the amount of cross-linking determine if the cell will be gram positive or gram negative. (The test was explained in the laboratory portion)
Active transport:
Requires ATP and it can go against a concentration gradient
Passive transport:
No ATP required and it goes with a gradient (from high to low)
Plasma Membrane:
Encloses the cell
Made of phospholipid bilayer
The head is polar (hydrophilic-likes water)
The tail is non-polar (hydrophobic-doesn’t like water)
Selectively permeable
Contains lots of proteins
Osmotic Pressure:
Is needed to stop the flow of water across the membrane.
Conditions include:
Isotonic, Hypotonic, and Hypertonic
Hypertonic:
the overall concentration of solutes is higher outside of the cell
Isotonic:
the overall concentration of solutes equals that of the cell
Hypotonic:
the overall concentration of solutes is lower outside of the cell
Cytoplasm:
Is the fluid component of the cell.
Is composed mostly of water but also contains:
Inorganic molecules Organic molecules DNA Ribosomes Inclusions
Bacterial Genomic DNA
Chromosomes:
single, circular, double stranded DNA, and accounts for 20% of a cell’s volume.
Plasmids:
very very small, circular, extra chromosomal DNA.
Doesn’t contain any genes required for life on them, however; they have genes that are beneficial to bacteria.
Replicate independently of the chromosome
Plasmids:
Typically carry genes for:
Antibiotic resistance, toxins, and tolerance to toxic metals
Can be transferred from one bacteria to another: conjugation
and
Are highly useful in the fields of molecular biology and biotechnology
Ribosomes:
Common to both prokaryotes and eukaryotes
Sites of where protein synthesis occur
- two subunits which contain protein and rRNA
- bind to mRNA and synthesize proteins
Some differences between prokayotic and eukaryotic ribosomes
Inclusions and Granules
Are storage units (food isn’t always available)
Depending on type can store:
- salts
- gases
- lipids
- fats
Endospores (spores):
Resting structures formed by some bacteria when stressed
Non-reproductive and highly durable. Spores consist of a very thick wall with many additional layers underneath.
Formed internal to the cell membrane.
Most common spore- formers are Bacillus and Clostridium
Fungal spores-
are the reproductive cells of those organisms
Bacterial spores-
Have nothing to do with reproduction. They are basically a protective unit
If a spores environment changes (in a negative way):
It grabs all it’s important “stuff” (genetic information, DNA, ribosomes, etc.), they will form a spore casing around it (called an endospore), the cell will then fall apart and all you’re left with is a “free spore”.
It is then almost impossible to destroy the spore. The spore is a super protective coating.
Process of making endospores:
Process of making a spore is called: Sporulation or Sporogenesis
Germination/Explorulation: Process from going from a spore to a vegetative state.
