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
The Lipopolysaccharides a component of the cell wall consists of three compounds?
- Lipid A
- A core polysaccharide
- O polysaccharide
What is lipid A and what is its function?
Lipid portion of the LPS and its embedded in the top layer of the outer membrane.
When gram negative bacteria die, they release lipid A which function as an endotoxin. This ends toxin causes fever, dialation of blood vessels, shock, and blood clotting.
LPS is also responsible for?
Antigen identification, just like teichoic acid in gram +
What is the core polysaccharide?
Attached to lipid A and contains unusual sugars, it provides stability
What is the O polysaccharide?
Extends outward from the core polysaccharide and functions as an antigen, which is good for identification
Example is E.coli O157:H7
Gram positive cell wall vs Gram negative cell wall
+ Thick peptidoglycan - thin peptidoglycan
+ Teichoic Acids - no Teichoic Acids
- has outer membrane + does not
- has periplasmic space + does not
What color does Gram + and Gram - stain?
Gram + = purple
Gram - = red only if Safranin is applied
What is the primary stain that stains both + and - cells purple because?
The dye enters the cytoplasm of both types of cells. When the iodine is applied it forms large crystals with the CV, which are too large to escape. Meaning can’t get past the thick layer of peptidoglycan
What happens to the stain complex of CV-I when applied to Gram negative cells?
The CV-I washes out leaving the cell colorless because the alcohol wash dissolves the thin outer membrane and leaves holes in the thin layer of peptidoglycan
What are other ways damage can happen to the cell wall of both gram + and - cells?
+ has 2-ring basal body. - has a 4-ring basal body
+ cell wall is disrupted by lysozyme - cell releases endotoxins
+ is sensitive to penicillin. - sensitive to Tetracycline
What are some characteristics and organisms that have Atypical cell walls?
- Acid fast cell walls
- Mycoplasmas
- Archaea
Acid-fast cell walls have what characteristics?
Like gram-positive
Have a waxy lipid (mycolic acid) bound in peptidoglycan
Remember that acid fast stain is used to identify the genus Mycobacterium and Norcardia
Mycoplasmas also have Atypical cell walls, what are a few characteristics?
Lack cell walls
Have Sterols in the plasma membrane
What are the Atypical traits of Archaea’s cell wall
They are wall-less
Their walls of pseudomurein (lack NAM and D-amino acids)
What digests disaccharide in peptidoglycan (damages the cell wall)
Lysozyme- which also found in saliva and tears
The cellular contents that remain surrounded by the plasma membrane may remain intact if lysis dies not occur, this wall less cell is called?
Protoplast
Gram +
When lysozyme is applied to gram-negative the cell is not destroyed and some of the membrane and cellular contents , plasma membrane, and remaining outer wall layer are called?
Spheroplastl
Both protoplast and spheroplasts are susceptible to what?
Osmotic lysis
What are wall-less cells that swell into irregular shapes?
L forms
The inner membrane is referred to ?
The plasma (cytoplasmic) membrane
What are some structural features of the cytoplasmic membrane
phospholipid bilayer
- hydrophilic (polar) head
- hydrophobic (non-polar) tail
Has peripheral proteins that sit on the surfaces of the plasma membrane, can fxn as enzymes in Chem rxns, and also for structure and support.
Integral proteins that are used for structure, and passage of molecules, ions, and water that are unable to diffuse through the plasma membrane. These can be removed by interrupting the lipid bilayer
Describe the Fluid Mosaic Model
The lipid bilayer and protein molecules are not static they move freely
the membrane is said to be as viscous as Olive oil.
What is the most important function of the plasma membrane?
What is the term for this function
Serve as a selective barrier through which materials enter and exit the cell.
Selective permeability- allows the passage of some molecules. (Also called semipermeable).
What can and cannot pass the plasma membrane easily?
Large molecule cannot pass
Small molecules (water, O2, CO2, and simple sugars) and non-polar molecules can pass easily
How does the plasma membrane aid in the production of ATP?
Aids in the breakdown of nutrients and production of energy.
Plasma membrane of bacteria contain enzymes that aid in catalyzing the chemical rxns that break down nutrients that aid in the production of ATP
What are Chromatophores or thylakoids?
Where are they found
In some bacteria, there are pigments and enzymes that are involved in photosynthesis and are found in the folds of the plasma membrane
These structures are called Chromatophores
Bacterial membranes have some irregular folds that are referred to as ?
what are the proposed function
Mesosomes: are artifacts that are produced during preparation
What are the ways the plasma membrane can be damaged
Damage to the membrane by alcohols, quaternary ammonium (detergents), and polymyxin antibiotics causes leakage of cell contents
Movement of materials across membranes occurs by two processes:
Passive Transport-does not need energy
Active Transport-needs energy
What is passive transport and what are the three ways for moving thing across the membrane
- Simple diffusion- movement of molecules (solute) or ions from a high concentration to a low concentration
- Facilitated Diffusion- movement of large molecules via channels
- Osmosis- net movement of water molecules from an area of high concentration to low concentration
What is a solute?
What is a solvent?
The substance that dissolves in a liquid (salt)
The dissolving medium (the liquid) water
Define concentration gradient
Difference in the concentration of the two areas.
What does facilitated diffusion use to move salutes across a membrane?
Solute moves via transporter protein (or permeate) in the membrane
What are the two types of transporters and what are their functions?
Non-specific transporter
Specific transporter which is selective as to what it allows to pass
What is osmotic pressure
The pressure needed to stop the movement of water across the membrane until equilibrium is reached
What is a hypotonic solution?
Solution outside the cell contains less solute but more water, therefore water moves into the cell causing the cell wall to swell until equilibrium is reached.
What is a hypertonic solution?
The outside medium haven’t a higher concentration of solute and lower concentration of water than inside the cell, therefore water moves out of the cell to bring the system to equilibrium causing the cell to shrink
What is an isotonic solution
No net movement of water in or out of the cell.
What does active transport require for it to take place? And Why?
What it another name for the protein that facilitates this movement?
Requires a transporter protein and ATP to move substances from low concentration to high concentration which is referred to as against the concentration gradient.
It is also referred to as a pump
What is group translocation?
What it the key function of group translocation?
Requires a transporter protein and PEP for energy to transport substances across the membrane
The substance is chemically altered to move across the membrane (Ex. Phosphate attached to glucose to move across the membrane.
Where is group translocation seen?
Only in Prokaryotes
What is the cytoplasm?
What’s in it?
The substance inside the plasma membrane
About 80% water, contains proteins carbohydrates, lipids, and inorganic ions
What is the nucleoid or nuclear area of the cell?
What does it contain
The nucleoid of a bacterial cell contains a single long continuous circular DNA
Often called a bacterial chromosome
What are plasmids?
A small ring of DNA that is independent of chromosomal DNA
All eukaryotic and prokaryotic cells have these, and they are the site of protein synthesis?
Prokaryotes have this one
Eukaryotes have this one?
Ribosome
Prokaryotes have the 70s ribosome. (50s + 30s subunits)
Eukaryotes have the 80s ribosome
What does the S stand for in 70s?
Sedimentation
The rate of sedimentation during ultra high speed centrifugation.
Within the cytoplasm of prokaryotic cells are several kinds of reserve deposits know as?
What actually are they
Inclusions
The are the cells reserve deposits of nutrients when the environment is deficient.
What are Metachromatic granules?
What are Polysaccharide granules?
What are lipid inclusions?
Metachromatic granules are reserve of inorganic phosphate that’s used in ATO synthesis. Found in algae, fungi, and Protozoa as well as bacteria
Glycogen and Starch you see these in the presence of iodine. Glycogen appears reddish brown and starch appears blue
Energy reserves they are fats
What are sulfur granules?
What are the carboxysomes?
What is the function of gas vacuoles?
The genus Acidithiobacillus- derive energy by oxidizing sulfur for its energy reserves
Inclusions that contain the enzyme ribulose 1,5-diphospate This is needed during photosynthesis for carbon dioxide fixation.
Hollow cavities that are used to maintain buoyancy in water
What are manetosomes and what are their function?
Inclusions of iron oxide surrounded by invaginations of the plasma membrane.
They are formed by gram-negative bacteria
They destroy H2O2 done in Vitro
What are endospores?
Where do they come from,and what type of gram are they?
They are resting cells that can survive harsh conditions i.e. Resistant to desiccation, heat, chemicals.
Examples are: Bacillus, Clostridium
they are gram+
What is the process of endospore formation within a vegetative cell?
When does this happen?
Known as sporulation or sporogenesis
Happens when a key nutrient like carbon or nitrogen becomes unavailable.
An endospore can remain dormant for thousands of years but it can return to its vegetative state via a process called?
This is only found in what type of organisms
Germination
Only in Gram +
Endospores may be located?
- Terminally
- Subterminally
- Centrally
What are the steps of forming endospores
- Spore septum begins to isolate newly replicated DNA and a small portion of cytoplasm
- Plasma membrane starts to surround DNA cytoplasm, and membrane isolated in step 1.
- Spore septum surrounds isolated portion forming forespore
- Peptidoglycan layer forms between membranes
- Spore coat forms
- Endospore is freed from cell
The Eukaryotic cell
What are the projections that are for moving substances along the surface of the cell and for locomotion.
However some species use the opposite for locomotion
Moving substances= cilia
Locomotion = flagella
Both cilia and flagella are anchored to the plasma membrane how?
What are their configurations
What is this configuration Called?
Anchored by the basal membrane
Consist of 9 pairs called doublet microtubules arranged in a ring, plus two microtubules in the center of the ring
Called the 9 + 2 array
Some organisms have cell walls and some have a glycocalyx. Distinguish between the two.
Plants, algae, fungi have cell walls
Plants have cellulose
Fungi have chitin
Yeast have polysaccharides glucagon and mannan.
Some eukaryotic cells including animal cells the plasma membrane is covered with?
Glycocalyx- which is sticky carbohydrates that gives strength to the cell wall and allows for easy attachment to other cells
What are the components of the plasma membrane
They are similar to prokaryotes -have a phospholipid bilayer -peripheral proteins -integral proteins -transmembrane proteins Sterols (not found in prokaryotes except Mycoplasma) Glycocalyx (carbohydrates)
What are the functions of the plasma membrane
Selective permeability which allows passage of Rome molecules
Simple diffusion, facilitated diffusion, osmosis
Active transport
Endocytosis
What are the two forms of endocytosis and how do they work?
Phagocytosis - Pseudopods extend and engulf particles
Pinocytosis - membrane folds inward, bringing in fluid and dissolved substances
Eukaryotes
What is the cytoplasm?
What is the cytosol
What is the cytoskeleton and what are its components?
Substance inside the plasma and outside the nucleus
Fluid portion of cytoplasm
The cytoskeleton give the cell its shape and structure to it organelle. Made up of Microfilaments, intermediate filaments, and microtubules
What is cytoplasmic streaming?
Movement of cytoplasm from one part of the cell to another. It distributes nutrients throughout the cell
What are the two forms of ribosomes in a Eukaryotic cell?
Where are 70s ribosomes found?
Membrane bound- meaning attached to the ER. (60s and 40s)
Free- in the cytoplasm
70s are found in chloroplasts and in mitochondria only
What is the function of membrane bound ribosomes?
What is the function of free ribosome?
Synthesize proteins that are destine for insertion into the plasma membrane or for export out of the cell.
Synthesize proteins for inside the cell
What is the largest organelle within the cell and what does it contain?
The Nucleus.
Contains chromosomes
Has a porous double-layered envelope
What are the two forms of ER? What is the difference?
What is their function
Both are transport network
Rough ER- ribosomes are attached (for protein synthesis to be placed in the membrane or out the cell)
Smooth ER no ribosomes - it synthesizes phospholipids and also fats and steroids such as estrogen and testosterone
What is the golgi complex and what is its function?
The golgi complex is the first step in the transport process after proteins are synthesized by the Rough ER.
Made of flattened sacs, which consists of 3 to 20 cisternae. This is the delivery system of the cell
The golgi complex make these single membrane-enclosed spheres. What are they called and what is its function?
Lysosomes: Sacs that lack internal organelles but contain powerful digestive enzymes (lysozyme)
What is the main function of the Golgi complex
It’s a Delivery system- collects packages and distributes molecules
It also modifies some glycoproteins
What are the three ways the golgi complex moves molecules and proteins etc…
Transfer and transport vesicles when proteins are modified and moved from one cistern to another cistern
Secretory vesicles for transport of proteins to the plasma membrane
Storage vesicles like lysosomes
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