Which are smaller, prokaryotic cells or eukaryotic cells?
prokaryotic cells; 100-1000 times smaller
What are the two most common shapes of prokaryotic cells?
Coccus (spherical)
Bacillus (rod)
What are the spiral shapes or prokaryotic cells?
Vibrio: looks like a noodle
Spirillum: shorter, rigid, external flagella
Spirochete: longer, flexible cell wall, axial filament
What are some other shapes a prokaryotic cell can have?
Star-shaped
Rectangular
What does it mean if a species has many shapes?
it is pleomorphic
Cocci can be in many arrangements, what are they?
-Diplococci
-Streptococci
-tetrads
-sarcinae
Diplococci
pairs of cocci
streptococci
chains of cocci
tetrads
groups of four
Sarcinae
cubelike groups of eight
Arrangement of bacilli?
-single bacillus
-diplobacilli- pairs of rods
-streptobacilli- chains of rods
-coccobacillus-oval shaped rods
Glycocalyx
sugar shell
What are the two types of glycocalyx?
capsule and a slime layer
Capsule
neatly organized and firmly attached
ex: streptococcus
Slime layer
unorganized and loose
Fimbrae
(shorter, few-100s per cell)
-adhering to cells or surfaces
Pili
(longer, 1-2 per cell)
-sex pilus for transfer of DNA
-Slight motility (twitching and gliding)
Bacterial flagella
-spin in both directions
-Powered by PMF
-mobility helps with photo and chemotaxis
Eukaryotic flagella and cilia
-used for mobility
-movement is whip-like
-powered by ATP
Spirochete (bacteria) flagella
-corkscrew motility
-made of endoflagella
ex: lyme disease (Borellia)
How might a corkscrew morphology and this inner flagella help infection?
allows virus to spread easily, through thicker tissues
What is peptidoglycan specific to?
bacteria
Gram Positive Bacteria
-stain purple
-have thick peptidoglycan layer
-granular layer
-Teichoic Acids: linked to cell wall and plasma membrane; have a negative charge
What is an example of antigenic specificity?
Lancefield grouping
Gram Negative Bacteria
-stain reddish pink
-thin peptidoglycan layer
-periplasm: layer between outer membrane and cell membrane
-Outer membrane: lipoproteins, porin proteins, and lipopolysaccharides.
What are lipoproteins used for in G.Neg?
anchors
Porin proteins in G.Neg?
allow some molecules to pass
Lipopolysaccharide in G.Neg?
triggers inflammation response
Lipid A is found where and what does it do?
It is an endotoxin found embedded in the membrane: inflammatory response
O polysaccharide is variable because
different strains of bacteria
Penicillin is an antibiotic that does what?
inhibits cell wall sythesis by preventing crosslinking of glycan chains.
-gram positives generally more susceptible.
because they cannot get across outer membrane of gram negative
Lysozyme
is an enzyme that breaks down the glycan chain
-found in sweat, tears, and saliva
-gram positive is again more susceptible because they cannot get across the outer membrane of gram negative.
Where is peptidoglycan found and why?
In the cell wall, not outer membrane to pass through in gram positive.
Differential staining
distinguishes between two groups of bacteria.
Gram positive: remain purple
Gram negative: counterstain pink
Acid Fast Bacteria
-small group of myobacterium
-more similar to gram positives
-waxy cell wall, mycolic acid: cannot gram stain
-cells that retain a primary red stain are "acid-fast" Blue is the counter stain.
What are two example of Acid Fast Bacteria?
mycobacterium TB
mycobacterium Leprosy
Mycoplasma
-bacteria lacking a cell wall
-pleomorphic and small
-have a stronger cell membrane containing alcohol
ex: mycoplasma pneumonia
Archaea
- Pseudomurein (no peptidoglycan)
-cannot be gram-stained
-some lack cell walls
-Surface layers (s-layers): sheets of proteins or glycoproteins
Eukaryotes have ___________ cell walls?
diverse
Algae cell wall
made of cellulose
Fungi cell walls
made of chitin
fluid mosaic model
-viscous like olive oil
-proteins move freely
-phospholipids can rotate and move laterally
-self-sealing
What are the functions of a cell membrane (prokaryotes)?
1. Selective barrier
2. Nutrient breakdown and energy production
Cell membrane is used to transport
water
Osmosis
movement of water across a membrane
Hypotonic environement
Lysis- water moving in
Hypertonic environment
plasmolysis
Passive transport
with the concentration gradient (high to low)
-Net movement until equilibrium is reached
Simple diffusion
type of passive transport
-across lipid membrane
Facilitated diffusion
type of passive transport
-transport proteins, permeases
Active transport
against concentration gradient
(low to high)
-NEED energy input
-IMP in bacteria
ABC transporters (primary)
use ATP energy
Co-Transport (secondary/coupled)
use energy from another gradient; bacteria often us H+
Light Driven
use light energy (some prokaryotes)
Group translocation
use energy from a high energy organic compound in the cell; molecule is chemically modified as it is imported. (ONLY in bacteria)
Secretion of what is important in bacteria to survive?
to survive in their particular environment bacteria need secretion of proteins, DNA, and other large molecules.
What has several complex secretion systems?
gram-neg
What is protein secretion directed by?
a specific amino acid tag or "signal sequence
Cytoplasm in a prokaryotic cell
Mostly (80%) water + proteins, carbohydrates, lipids, and ions
-Cytoskeleton -protein fibers
-Cell division, shape, growth, DNA movement, protein targeting, etc.
Inclusions and granules in prokaryotic cell?
Reserve deposits in the cytoplasm; usually protein bound or protein complexes.
Nucleoid contains what in a prokaryotic cell?
-chromosome
-plasmids
-Ribosomes
Chromosome
single, circular, double stranded DNA
tightly packed and supercoiled
Plasmids
-smaller circular, DNA molecules
-non-essential but can contain beneficial genes
-horizontal gene transfer
Ribosomes (70s)
-site of protein synthesis
-located in the cytoplasm
-made of proteins and RNA
-2 subunits
70s and 80s
Prokaryotic ribosomes are? While eukaryotic ribosomes are?
70s....80s
endosymbiotic theory
Larger bacterial cells engulfed smaller bacterial cells, developing the first eukaryotes
Ingested photosynthetic bacteria became chloroplasts
Ingested aerobic bacteria became mitochondria
Endospores and sporulation
-Differentiated cells produced by some bacterium
-Many species of Clostridiumand Bacillus
-Very resistant to heat, chemicals, radiation, etc.; can exist for years
-Formed during Sporulation-cued by starvation
Germination
endospore returns to vegetative state