Chapter 4 Anatomy Of Prokaryotes Flashcards
Why doesn’t penicillin harm human cells?
Penicillin only attacks the peptidoglycan cell was of bacteria.
What is the Greek word for prokaryote?
What are the two domains that are apart of this category?
Prokaryote comes from the Greek words for prenucleus
- Bacteria
- Anchaea
What are three examples of Archaea?
- methanogens
- Halophiles
- Thermophiles
Eukaryotes comes from the Greek words for?
True nucleus
Prokaryote vs Eukaryotes what are the differences?
P= one circular DNA not in a membrane (nucleus) E= linear chromosomes in a nuclear membrane (nucleus
P=No Histones. E= Histones
P=No organelles. E= organelles- small structure inside the cell
P=Peptidoglycan cell walls in bacteria. E= Polysaccharide cell wall (plants)
P=no cell walls if Archaea
P=Binary fission for cell division. E=Mitotic & Meiotic cell division
What are the structural characteristics of Prokaryotic cells?
Average size: 0.2 - 1.0 um x 2-8 um
Most bacteria are monomorphic (one shape)
Very few are Pleomorphic
What is the basic shape for Bacillus, Coccus?
What is the shape for Spirillum, Vibrio, and Spirochete?
Bacillus = rod shaped
Coccus = spherical. (Two cocci together is called diplococci)
Spiral
Vibrio is slightly bent
What are the arrangements for cocci and bacillus?
Pairs
Tetrads
Sarcina
Pairs- Bacillus is diplobacilli, Coccus = diplococci
Tetrads= groups of 4
Sarcina = group of 8
What are clusters of Coccus called?
What are chains called in both bacillus and Coccus?
Staphylococci
Streptococci for Coccus and Streptobacilli for Bacillus
Most prokaryotes secrete what on their surface?
What is it made of?
What is the characteristics of this in a bacterial cell?
Glycocalyx
It’s the outside cells was and it means its a sugar coat
In bacteria the glycocalyx is viscous (sticky) which is external to the cell wall and is composed of polysaccharide, polypeptide, or both
If the glycocalyx is organized and is firmly attached to the cell wall its called?
How can you determine if this is present
Capsule
Use negative staining
What do capsules prevent, and what does it contribute to?
Prevents phagocytosis
This contributes to bacterial virulence
If the substance is unorganized and only loosely attached to the cell wall the glycocalyx is described as?
Slime Layer
It’s a mucoid
What is the function of Extracellular Polymeric Substance (EPS)?
Is the glycocalyx used in Biofilms to attach to a surface or target environment.
What are a few diverse surfaces that bacteria can attach to?
Rocks in fast moving streams, plant roots, human teeth, medical implants, water pipes, and even other bacteria
Where do you find flagella and what is it used for?
What are the three parts?
Outside the cell wall, used for movement
Filament: made of the protein flagellin
Hook, which is attached to the filament
Basal body, which anchored it to the cell was and plasma membrane
Bacteria that lack flagella are called
Atrichous meaning without projections
What is peritrichous?
What is polar flagella?
Distributed over the entire cell
Polar- at one or both ends
If polar, what is it if a single flagellum at one pole?
Or multiple flagella coming from one pole is called?
Monotrichous
Lophotrichous
What is it called when there is flagella at both poles?
Amphitrichous
How do flagella rotate?
They rotate along its axis. This is motility
What is the term for the type of movement toward or away from a stimulus?
What are the names for the stimuli of chemical and light?
Taxis
Chemotaxis
Phototaxis
If the chemotactic stimulus is positive what is it called?
Also for negative?
Attractant
Repellent
What flagella protein is useful for distinguishing among __________ or variations within a species of gram-negative bacteria?
H antigen are used for identification among SEROVARS (different species.
Ex. E.coli O157:H7
Spirochetes move by what means?
What is the make up of these things?
Axial filaments or endoflagella
Bundles of fibrils that arise at the ends of the cell beneath an outer sheath and spiral around the cell
What is an example of spirochetes and what is it responsible for?
How does it move?
Treponema pallidum its the causative agent of syphilis.
Rotation causes cell to move- like corkscrew through a cork
What gram type of bacteria contain hair like appendages that are shorter, straighter, and thinner than flagella, which consist of the protein pilin?
There are two types?
Fimbriae (singular fimbria) and pili.
Fimbriae allow for attachment on various surfaces, rocks, glass, liquids, and it also helps bacteria adhere to epithelial surfaces. What factor does this increase?
Factor in pathogenicity
Fimbriae is only found in gram-negative, what is an example?
Neisseria gonorrhoeae
How do bacterial cells transfer DNA from one cell to another?
What is this process called?
What is another term for this appendage?
Pilus- facilitate transfer of DNA from one cell to antlers through a process called conjugation
Also called sex pili
The Pilus is also involved in movement? Please describe this movement
Gliding motility- smooth movement ex. Myxobacterium
Twitching motility- short jerky movement seen in Pseudomonas aeruginosa
What is the advantage of gliding motility?
Allows for travels in environments with a low water content, such as biofilms and soil.
What is the major function of the cell wall is?
Protects plasma membrane by preventing osmotic lysis (bursting)
The cell wall of the bacterial cell consists of what?
Semirigid structures responsible for the shape of the cell. Almost all prokaryotes have a cell wall that surrounds the underlying fragile plasma membrane.
The bacterial cell was is composed of a macro molecular network called?
Peptidoglycan
Peptidoglycan is composed of what?
Its a repeating disaccharide connected by polypeptides to form a lattice that surrounds and protects the entire cell.
What are the molecules that are the main components to peptidoglycan?
N-acetylglucosamine (NAG)
N-acetylmuramic acid (NAM)
How is NAG and NAM arranged?
They are alternating and are linked in rows of 10 to 65 sugars to for a carbohydrate backbone that alternate in D and L forms
Adjacent rows are linked by polypeptides
What type of bacteria is peptidoglycan primarily found in?
Gram-positive
What drug is used against gram positive bacteria and why?
what is the result?
Penicillin
It interferes with the final linking of the peptidoglycan rows and helps to destroy the cell wall of peptidoglycan bacteria.
The disruption of the cell wall causes the bacteria to lyse
The gram-positive cell was has what specific features?
Many layers of peptidoglycan
Contains Teichoic Acids, there are two classes
Lipoteichoic acids
Wall teichoic acids
What is lipoteichoic acids?
what is the function of Teichoic Acids
Lipoteichoic acid- spans the peptidoglycan layer and is linked to the plasma membrane
The function of Teichoic Acids is they are negatively charged, so they regulate the movement of cations (+) across the cell
They play a role in cell growth
They are also used in lab experiments for identification, this tells us much of the walls’ antigenic specificity
What other type of acids can some cell walls contain
Mycolic acids
What are the major differences of the gram-negative cell wall from gram-positive cell wall?
- Fewer layers of peptidoglycan manly one or very few.
2. Contains an outer membrane
The outer membrane of gram-negative is made of?
Is made of lipopolysaccharides (LPS), Lipoproteins, and phospholipids
The peptidoglycan is bonded to what?
Bonded to lipoproteins in the outer membrane and in the periplasm
The outer membrane base several functions, what are they?
It has a strong negative charge which is an important factor in evading phagocytosis and the actions of the complement cascade, and antibiotics.
What gives the cell wall its permeability?
Due to the Porins that form channels which permits the passage of molecules like nucleotides, disaccharides, peptides, amino acids, vitamin B12, and iron