Chap 4 Flashcards
comes from the Greek words for prenucleus.
Prokaryote
comes from the Greek words for true nucleus.
Eukaryote
One circular chromosome, not in a membrane
Prokaryote
No histones
Prokaryote
No organelles
Prokaryote
Bacteria: peptidoglycan cell walls
prokaryote
Archaea: pseudomurein cell walls
Prokaryote
Divides by binary fission
Prokaryote
Paired chromosomes, in nuclear membrane
Eukaryote
has Histones
Eukaryote
Has organelles
Eukaryote
Polysaccharide cell walls, when present
Eukaryote
Divides by mitosis
Eukaryote
What is the main feature that distinguishes prokaryotes from eukaryotes?
Prokaryotic cells have genetic material that is not contained in a nucleus
Average size of bacteria
0.2 to 2.0 μm diameter × 2 to 8 μm length
monomorphic bacteria
single shape
pleomorphic bacteria
many shapes
Bacillus
rod-shaped
coccus
spherical-shaped
Types of spiral bacteria
Vibrio
Spirillum
Spirochete
Shapes of bacterial cells
1.Bacillus (rod-shaped)
2.Coccus (spherical-shaped)
3.Spiral
4.Star-shaped
5.Rectangular
See fig. 4.4 Draw types of spiral bacteria
diplococci, diplobacilli
pairs di-
di-
pairs
staphylo-
clusters staphylococci
Strepto-
Chains
tetrads
groups of 4
sarcinae
cubelike groups of 8
Bacillus scientific name and shape
scientific name: Bacillus
Shape:bacillus
vibrio
one curve
Spirilum shape
more curved than vibrio, thicker than spirochete
Spirochete
more slender than spirilum
How can you identify streptococci with a microscope?
it would look like a chain of spheres under the microscope
Glycocalyx is external to
External to the cell wall
Consistency of glycocalyx
viscous and gelatinous
Glycocalyx is made of
Made of polysaccharide and/or polypeptide
Two types of glycocalyx
1.Capsule
2. Slime layer
Capsule glycocalyx
Neatly organized and firmly attached
Slime layer glycocalyx
unorganized and loose
Glycocalyx contributes to
virulence
the relative capacity of a microbe to cause damage in a susceptible host
virulence
virulence
the relative capacity of a microbe to cause damage in a susceptible host
Cause of Pneumococcal Pneumonia
Streptococcus pneumoniae
Filamentous appendages external of the cell
Flagella
Function of flagella
Propel bacteria
Flagella is made of
protein flagellin
Filament of flagella
Outermost region
Hook of flagella
attaches to the filament
Basal body of flagella:
consists of rod and pairs of rings; anchors flagellum to the cell wall and membrane
Parts of flagella
- Filament
- Hook
- Basal body
Monotrichous
cells with a single flagellum
in monotrichous cells, what happens when the flagellum rotates counterclockwise?
The bacterium runs in a single direction
in monotrichous cells, what happens when the flagellum rotates clockwise?
The bacterium tumbles and changes direction
amphitrichous bacteria
have a flagellum at either end of the cell
lophotrichous
bacteria with a tuft of flagella at one end. Multiple tails at one end
in lophotrichous cells, what happens when the flagella rotate counterclockwise?
clockwise?
counterclockwise: the bacteria runs
clockwise: the bacteria tumbles
Peritrichous bacteria
have flagella covering the surface of the cell
When does Peritrichous bacteria run?
when all flagella rotate counterclockwise and become bundled.
When does Peritrichous bacteria tumble?
When flagella rotate clockwise and separate
Importance of flagella during taxis
Flagella allow bacteria to move toward or away from stimuli
Why do flagella rotate?
to “run” or “tumble”
Flagella proteins are what kind of antigens ?
Flagella proteins are H antigens
serovars
different strains of bacteria (called serovars, for serological variants)
Helps distinguish among serovars
flagella proteins
motility
The ability of an organism to move by itself
Why is motility of cells important?
Lets the cell move towards a desired environment or to flee from a harmful environment
Has axial filaments
spirochetes
Taxis
movement toward or away from a stimulus
phototaxis
light stimulus
chemotaxis
chemical stimulus
When do tumbles become less frequent?
positive taxis
positive taxis
move towards the stimulus
When do tumbles become more frequent?
When the cell moves away from the stimulus
Archaella
Another motility structure. Found on archaea. Are thinner and more flexible than flagella. Made of different proteins than flagella.
Archaella are made of
glycoproteins archaellins
Archaella are anchored to
the cell
motion of archaella
rotate like flagella
Axial filaments are also called
endoflagella
Axial filaments are found in
spirochetes
Where are axial filaments anchored?
at one end of the cell
What kind of movement do axial filaments create?
Rotation causes cell to move like a corkscrew
Group of bacteria that are spiral shaped. Move in corkscrew-like fashion
spirochetes
Use flagella that do not protrude from the cell wall like typical flagella
spirochetes
Lyme disease is caused by a
spirochete
Borrelia burgdorferi
spirochete that causes lyme disease
treponema pallidum
causes syphilis, spirochete
The axial filament is made of a bundle of flagella called
endoflagella
How does the endoflagella cause the spirochete to move?
rotation of the endoflagella around the bacterium causes the spirochete to corkscrew through the medium. Lets it move through mucus easily
Fimbriae
Hairlike appendages that allow for attachment
Pili involved in
Involved in motility (gliding and twitching motility)
Conjugation pili involved in
DNA transfer from one cell to another
Why are bacterial capsules medically important
Capsules often protect pathogenic bacteria from phagocytosis by the cells of the host.
How do bacteria move?
Conjugation, motility, taxis
conjugation
the process by which one bacterium transfers genetic material to another through direct contact
what does the cell wall prevent?
Prevents osmotic lysis and protects the cell membrane
In bacteria, the cell wall is made of
peptidoglycan
the cell wall contributes to
pathogenicity
Pathogenicity
the ability of an organism to cause disease
Peptidoglycan is made of
Polymer of a repeating disaccharide in rows:
N-acetylglucosamine (NAG)
N-acetylmuramic acid (NAM)
Row in peptidoglycan are linked by
polypeptides
Characteristics of Gram-positive Cell walls
1.Thick peptidoglycan
2.Teichoic acids
Peptidoglycan
A biopolymer consisting of amino acids and carbohydrates, forming the cell wall of most bacteria.
Teichoic acids
Bacterial polysaccharide. They are the major components of the cell walls and membranes of many bacteria.
Characteristics of gram-negative cell walls
1.Thin peptidoglycan
2.Outer membrane
3.Periplasmic space
Function of teichoic acids
Carry a negative charge
Regulate movement of cations
Lipoteichoic acid
links cell wall to plasma membrane
Wall teichoic acid
links the peptidoglycan
What provides antigenic specificity
Polysaccharides and teichoic acids
Periplasm is located between
between the outer membrane and the plasma membrane
Periplasm of gram-negative cell walls contains
peptidoglycan
Outer membrane of gram-negative cell walls is made of
polysaccharides, lipoproteins, and phospholipids
Gram-Negative Cell walls protect from
phagocytes, complement, and antibiotics
Made of lipopolysaccharide (LPS)
Gram-negative cell walls are made of
Antigen of gram-negative cell walls
O polysaccharide, E. coli O157:H7
endotoxin embedded in the top layer of gram-negative cell walls
Lipid A is an endotoxin
Porins
(proteins) form channels through membrane
Porins found in
Gram-negative cell walls
Crystal violet-iodine crystals form inside of
cell
What happens to gram-positive cells during gram stain?
Alcohol dehydrates peptidoglycan
CV-I crystals do not leave
How do gram-positive cells look during gram stain?
peptidoglycan forms about 90% of the cell wall in gram-positive bacteria. This causes them to appear blue to purple under a Gram stain.
What happens to gram-negative cells during a gram-stain?
Alcohol dissolves outer membrane and leaves holes in peptidoglycan
CV-I washes out; cells are colorless
Safranin added to stain cells
How do gram-negative cells appear during a gram stain?
gram negative bacteria do not retain the crystal violet so they look pink or red after adding safranin
gram positive cell walls have two rings in
basal body of flagella
gram positive cell walls produce
exotoxins
High susceptibility to penicillin
Gram-Positive Cell Walls
Disrupted by lysozyme
Gram-Positive Cell Walls
4 rings in basal body of flagella
Gram-Negative Cell Walls
Produce endotoxins and exotoxins
Gram-Negative Cell Walls
Low susceptibility to penicillin
Gram-Negative Cell Walls
Waxy lipid (mycolic acid) bound to peptidoglycan
Acid-fast cell walls
Like gram-positive cell walls
Acid-fast cell walls
Mycobacterium has what kind of cell walls
Acid-fast cell walls
Nocardia has what kind of cell wall
Acid-fast cell walls
What stain do you have to use on acid fast cell walls?
Carbolfuschins
Mycoplasmas
Lack cell walls
& Have Sterols in plasma membrane
Archaea walls
Wall-less, or
Walls of pseudomurein
pseudomurein lacks
(lack NAM and D-amino acids)
hydrolyzes bonds in peptidoglycan
Lysozyme
inhibits peptide bridges in peptidoglycan
Penicillin
is a wall-less gram-positive cell
Protoplast
is a wall-less gram-negative cell
Spheroplast
are susceptible to osmotic lysis
Protoplasts and spheroplasts
are wall-less cells that swell into irregular shapes
L forms
Why are drugs that target cell wall synthesis useful?
to prevent the formation of cell walls in bacteria. Without their cell walls, bacterial cells become very vulnerable to osmotic lysis, which kills them.
Why are mycoplasmas resistant to antibiotics that interfere with cell wall synthesis?
Mycoplasmas typically do not have cell walls or have little wall material. Therefore, drugs that target cell wall synthesis are not effective against mycoplasmas
How do protoplasts differ from L forms?
Protoplast: A gram-positive bacterium or plant cell treated to remove the cell wall.
L form: Prokaryotic cells that lack a cell wall; can return to walled state.
Phospholipid bilayer that encloses the cytoplasm
The Plasma (Cytoplasmic) Membrane
proteins on the membrane surface
Peripheral proteins
proteins that penetrate the membrane
Integral and transmembrane proteins
the _____ ________ of a prokaryotic cell is the main gateway for movement of molecules in and out of a cell
cytoplasmic membrane
structure of phospholipids
phosphate head, glycerol and two fatty acids
Charge on phosphate of phospholipids
negatively charged
hydrophilic part of phospholipids
head
Hydrophobic part of phospholipids
tails
span the entire bilayer and act as channels for molecules
integral proteins
loosely attached to membrane on one side
peripheral proteins
Proteins bound to a polysaccharide
Glycoproteins
Glycoproteins may function as
recognition sites, enzymes, receptors
Membrane is as viscous as olive oil
Proteins move freely for various functions
Fluid mosaic model
How does the fluid mosaic model allow the plasma membrane to be self-sealing?
Phospholipids rotate and move laterally
Self-sealing
allows the passage of some molecules, but not others
selective permeability
chromatophores
Some plasma membranes have photosynthetic pigments on foldings
_______ ____________Contains enzymes for ATP production
plasma membrane
Which molecules can pass through cell membrane by passive diffusion?
1.water,
2.dissolved oxygen,
3.simple alcohols
Which molecules cannot pass directly though cell membrane?
Charged molecules and large molecules
Which molecules tend to become stuck inside the hydrophobic interior of cell membranes?
hydrophobic molecules
occurs along EC gradient, Doest require use of ATP
passive transport
What can cause leakage of cell contents?
1.alcohols,
2. ammonium (detergents),
3. polymyxin antibiotics
substances move from high concentration to low concentration; no energy expended
passive processes
substances move from low concentration to high concentration; energy expended
Active processes
movement of a solute from an area of high concentration to an area of low concentration
simple diffusion
simple diffusion continues until
molecules reach equilibrium
Facilitated diffusion:
solute combines with a transporter protein in the membrane
Transports ions and larger molecules across a membrane with the concentration gradient
Facilitated diffusion
permeases
allow specific and nonspecific facilitated diffusion
nonspecific facilitated diffusion
allow wide range of molecules to pass through
contain a recognition element
specific facilitated diffusion
osmosis
movement of water across semipermeable membrane
water channels
aquaporins
Osmotic pressure
the pressure needed to stop the movement of water across the membrane
solute concentrations equal inside and outside of cell; water is at equilibrium
isotonic solution
solute concentration is lower outside than inside the cell; water moves into cell
Hypotonic solution
solute concentration is higher outside of cell than inside; water moves out of cell
Hypertonic solution
Group translocation:
requires a transporter protein and phosphoenolpyruvic acid (PEP); substance is altered as it crosses the membrane
requires a transporter protein and ATP; goes against gradient
Active transport
uniport
transport only one type of molecule in one direction AGAINST gradient; need ATP
antiport proteins
transport two types of molecules, but in opposite directions AGAINST their gradients; use ATP
Symport molecules
transport two different types of molecules at the same time, but is coupled with a uniport channel that uses ATP.
Example of antiport protein
Na K channel
Explain ATP usage in symport proteins
the uniport protein uses ATP to pump a molecule out of the cell against its concentration gradient. When that molecule’s concentration outside of the cell is high, it diffuses back through the symport protein into the cell. In the process, it moves another substance back into the cell against its concentration gradient.
Which agents can cause injury to the bacterial plasma membrane?
1.alcohol,
2. quaternary ammonium (detergents)
3.polymyxin antibiotics
How are simple diffusion and facilitated diffusion similar? How are they different?
simple diffusion and facilitated diffusion both don’t require energy to function. simple diffusion doesn’t need a protein to happen, while facilitated diffusion does.
The substance inside the plasma membrane
Eighty percent water plus proteins, carbohydrates, lipids, and ions
Cytoplasm
Microfilaments, intermediate filaments, and microtubules that provide support and movement for eukaryotic cytoplasm.
cytoskeleton
Bacterial chromosome
circular thread of DNA that contains the cell’s genetic information
Plasmids
extrachromosomal genetic elements; carry non-crucial genes (e.g., antibiotic resistance, production of toxins)
Ribosomes made of
protein and ribosomal RNA
Sites of protein synthesis
Ribosomes
70 S
ribosomes
measurements of ribosomal subunits
50S+ 30S
Metachromatic granules (volutin)—
phosphate reserves
Polysaccharide granules
energy reserves
Lipid inclusions
energy reserves
Sulfur granules
energy reserves
Carboxysomes
RuBisCO enzyme for CO2 fixation during photosynthesis
Gas vacuoles
protein-covered cylinders that maintain buoyancy
Magnetosomes
iron oxide inclusions; destroy H2O2
Endospores
Resting cells; produced when nutrients are depleted
Endospores are resistant to
1.desiccation,
2.heat,
3.chemicals,
4.radiation
Endospores are produced by
Bacillus and Clostridium
Sporulation
endospore formation
Germination
endospore returns to vegetative state
Where is the DNA located in a prokaryotic cell?
in the nucleoid
What is the general function of inclusions?
Reserve materials
Under what conditions do endospores form?
Endospores usually form under conditions where resources are limited or depleted, particularly key nutrients such as carbon and nitrogen sources.
Differentiate prokaryotic and eukaryotic flagella
Eukaryotic and prokaryotic flagella are different in that eukaryotic flagella possess microtubules made up of tubulin. In contrast, prokaryotic flagella are made up of flagellin.
long projections; few in number
Flagella
short projections; numerous
cilia
Flagella and cilia both consist of
microtubules made of the protein tubulin
Microtubules are organized as
9 pairs in a ring, plus 2 microtubules in the center (9 + 2 array)
Allow flagella to move in a wavelike manner
microtubules
Cell wall
Found in
plants, algae, and fungi
Made of carbohydrates (cellulose—plants, chitin—fungi, glucan and mannan—yeasts)
cell wall
Glycocalyx
Carbohydrates bonded to proteins and lipids in the plasma membrane
Glycocalyx Found in _______ cells
animal
Compare and contrast prokaryotic and eukaryotic plasma membranes.
1.Similar in structure to prokaryotic cell membranes
-Phospholipid bilayer
Integral and peripheral proteins
-Selective permeability
-Simple diffusion,
-facilitated diffusion, osmosis, active transport
Differences in structure
Sterols—complex lipids
Carbohydrates—for attachment and cell-to-cell recognition
Differences in function
-Endocytosis—phagocytosis and pinocytosis
-Phagocytosis: pseudopods extend and engulf particles
-Pinocytosis: membrane folds inward, bringing in fluid and dissolved substances
Compare and contrast prokaryotic and eukaryotic cytoplasms.
1.The cytoplasm of prokaryotes has a cytoskeleton, but its not capable of cytoplasmic streaming,
2. Eukaryotic cytoplasm has a cytoskeleton and exhibits cytoplasmic streaming.
The three basic bacterial shapes are
coccus (spherical), bacillus (rod-shaped), and spiral (twisted).
Cytoplasm
substance inside the plasma and outside the nucleus
Cytosol
fluid portion of cytoplasm
Cytoskeleton
made of microfilaments and intermediate filaments; gives shape and support
Cytoplasmic streaming
movement of the cytoplasm throughout a cell
Sites of protein synthesis
ribosomes
80 S
Ribosomes
Consists of the large 60S subunit and the small 40S subunit
Ribosomes
ribosomes that are 80S
Membrane-bound: attached to endoplasmic reticulum
Free: in cytoplasm
Ribosomes that are 70 S
In chloroplasts and mitochondria
The antibiotic erythromycin binds with the 50S portion of a ribosome. What effect does this have on a prokaryotic cell? On a eukaryotic cell
Erythromycin will affect the activity of ribosomes (interrupting protein synthesis) in prokaryotic cells since their ribosomes contain the 50S subunit. However, it will not affect eukaryotic ribosomes since they do not contain the 50S subunit.
nucleus
Double membrane structure (nuclear envelope) that contains the cell’s DNA
nuclear envelope
Double membrane structure
DNA is complexed with histone proteins to form
chromatin
During mitosis and meiosis, chromatin condenses into
chromosomes
Folded transport network
Endoplasmic reticulum
Rough ER
studded with ribosomes; sites of protein synthesis
Smooth ER:
no ribosomes; synthesizes cell membranes, fats, and hormones
Golgi complex
Transport organelle
Modifies proteins from the ER
Transports modified proteins via secretory vesicles to the plasma membrane
Golgi complex
Lysosomes formed in
Golgi complex
Lysosomes
1.Vesicles formed in the Golgi complex
2.Contain digestive enzymes
Vacuoles
Cavities in the cell formed from the Golgi complex
Function of vacuoles
Bring food into cells; provide shape and storage
organelle with double membrane
mitochondria
cristae of mitochondria
inner folds
fluid of mitochondria
matrix
Function of mitochondria
Involved in cellular respiration (ATP production)
Chloroplasts
Locations of photosynthesis
chloroplasts contain
flattened membranes (thylakoids) that contain chlorophyll
peroxisomes
Oxidize fatty acids; destroy H2O2
Centrosomes
Networks of protein fibers and centrioles
Function of centrosomes
Form the mitotic spindle; critical role in cell division
Compare the structure of the nucleus of a eukaryote and the nucleoid of a prokaryote.
nucleus- enclosed men within the cel containing the genetic material
nucleoid- nucleus-like, irregular shaped region in prokaryotes
4-19 How do rough and smooth ER compare structurally and functionally
Smooth ER is more tubular (less sacs) and there are no ribosomes on its outer side. Rough ER modifies proteins giving them 3D structure and tagging them – addressing where the vesicles should take them. RER is the sole producer of membrane proteins.
First eukaryotes evolved __.__ billion years ago
2.5
Life arose as simple organisms . to _ billion years ago
3.5 to 4
Endosymbiotic theory
Larger bacterial cells engulfed smaller bacterial cells, developing the first eukaryotes
Ingested photosynthetic bacteria became
chloroplasts
Ingested aerobic bacteria became
mitochondria
Which three organelles are not associated with the Golgi complex? What does this suggest about their origin?
The Golgi complex is not associated with the mitochondria, chloroplast, or flagella. This suggests that the Golgi complex may have originated from another cellular structure inside the cell and not from a symbiotic bacterium. Golgi complex did not originate from bacterial symbiosis.
Protoplast
Wall-less gram-positive cell
Protoplast
Wall-less gram-positive cell
Spheroplast
is a wall-less gram-negative cell
