Two basic cell types
Eukaryotic and Prokaryotic
All Living things (Multicellular/single) made of cells that share what characteristics?
Shape: Spherical, Cubical, Cylindrical, Internal Content: Cytoplasm, surrounded by membrane, DNA chromosome(s), Ribosomes, metabolic capabilities
Eukaryotic Cells
Originated about 2 billion years ago -Animals, Plants, Fungi, and Protists -Contain membrane-bound organelles that compartmentalize cytoplasm and perform specific functions -Contain double-membrane bound nucleus with DNA chromosomes
Prokaryotic Cells
Originate 3.5 Billion Years Ago -Bacteria and Archaea -NO nucleus or other membrane-bound organelles
6 Characteristics of Life
- Reproduction and Heredity 2. Growth and Development 3. Metabolism 4. Movement and/or Irritability 5. Cell Support, Protection, and Storage Mechanisms 6. Transport of Nutrients and Waste
Bacterial External Structures
Appendages 1. Motility - Flagella and Axial Filaments (Periplasmic Flagella) 2. Attachment or Channels - Fimbriae and Pili Glycocalyx (surface coating)
Flagella Parts
- Filament - Long, thin, helical structure composed of protein flagellin 2. Hook - Curved Sheath 3. Basal Body - Stack of rings firmly anchored in cell wall.
4 flagellar arrangements
- Monotrichous 2. Lophotrichous 3. Amphitrichous 4. Peritrichous
Monotrichous Flagella
Single flagellum at one end
Lophotrichous
Small bunches emerging from same site
Amphitrichous
Flagella at both ends
Peritrichous
Flagella dispersed over surface of cell
Periplasmic Flagella
Internal flagella, enclosed in the space between the outer sheath and the cell wall peptidoglycan
How do Periplasmic Flagella produce motility?
By contracting and imparting twisting or flexing motion
Fimbriae
Fine, proteinaceous, hairlike bristles emerging from the cell surface
What is the function of fimbriae?
Adhesion - to other cells and surfaces
Pili
Rigid tubular structure made of Pilin protein
What kind of cells are Pili found in?
Gram-Negative only
What is the function of Pili?
Join bacterial cells for partial DNA transfer called conjugation.
Glycocalyx
Coating of molecules external to cell wall made of sugars and/or proteins
Types of Glycocalyx
- Slime Layer - Loosely organized and attached 2. Capsule - Highly organized, tightly attached
What are the functions of Glycocalyx?
- Protect cell from dehydration/nutrient loss 2. Inhibit death by WBC’s via phagocytosis, contributing to pathogenicity 3. Attachment - formation of biofilms
Cell Envelope
External covering OUTSIDE cytoplasm 2 layers: Cell Wall and Cell Membrane
What is function of Cell Envelope?
Maintain cell integrity
Gram-Positive Bacteria
Thick cell wall composed primarily of peptidoglycan and cell membrane DYE PURPLE
Gram-Negative Bacteria
Outer cell membrane, thin peptidoglycan layer, and cell membrane DYE RED
Peptidoglycan
Primary component of bacterial cell walls. Unique macromolecule composed of repeating framework of long glycan chains cross-linked by short peptide fragments
Gram-Positive Cell Wall
- 20 to 80 nm thick peptidoglycan -Includes Teichoic Acid and Lipoteichoic Acid -Some cells have Periplasmic Space, between the cell membrane and cell wall
Teichoic Acid and Lipteichoic Acid functions in Gram + Cell Wall
Cell wall maintenance and enlargement during cell division ,move cations across the cell envelope; stimulate a specific immune response
Gram-Negative Cell Wall
Inner and outer membranes and periplasmic space between them contains a thin peptidoglycan layer -outer membrane contains Lipopolysaccharides (LPS)
Does Gram-Positive or Gram-Negative cell have Outer Membrane?
Gram-Negative
Is Gram-Positive or Gram-Negative Cell more permeable to molecules?
Gram-Positive
How many major layers does Gram-Positive Cell have?
1
How many major layers does Gram-Negative Cell have?
2
Gram Stain
Differential stain that distinguishes cells with a gram-positive cell wall from those with a gram-negative cell wall. -Important basis of bacterial classification and identification -Practical aid in diagnosing infection and guiding drug treatment
Which of the following is not found in the Gram-Negative cell wall structure?A. Porins B. Teichoic Acids C. Periplasmic Space D. Lipopolysaccharides E. Peptidoglycan
B. Teichoic Acids
Cell Membrane Structure
Phospholipid bilayer with embedded proteins
Functions of Cell Membrane
Provides site for energy reactions, nutrient processing, and synthesis -Passage of nutrients into the cell and discharge of wastes -cell membrane is selectively permeable
Bacterial Cell cytoplasm
-Dense gelatinous solution of sugars, amino acids, and salts. -70-80% water (serves as solvent for materials used in all cell functions)
Nucleoid of Prokaryotes contains
-Chromosome (Single, Circular, double-stranded DNA contains genetic info required by cell) -Plasmids (Free small circular, double-stranded DNA)
Bacterial Ribosomes
-60% rRNA, 40% protein -large and small subunit -Differ from eukaryotic in size and number of proteins -Site of protein synthesis -Found in all cells
Bacterial Internal Structures include:
Inclusions and granules (intracellular storage, vary in size, number and content. Bacteria use them when environmental sources are depleted)
Endospores
Inert, resting cells produced by some G+ genera -Hardiest of all life forms -Withstands extreme heat, drying, freezing, radiation and chemicals -NOT A MEANS OF REPRODUCTION
G+ genera that can produce endospores
Clostridium, Bacillus, and Sporosarcina
2-Phases of Endospore Life cycle
- Vegetative Cell - Metabolically active and growing 2. Endospore - Exposure to adverse environment; high resistance and long-term survival
Sporulation
Formation of endospores
Germination
Endospores returning to vegetative growth
What will destroy an endospore?
Pressurized steam at 120 C for 20-30 minutes
Coccus
Spherical
Bacillus
Rod
Coccobacillus
Very short and plump
Vibrio
Gently curved
Spirillium
Helical, comma, twisted rod
Spirochete
Spring-like
Bergey’s Manual of Determinative Bacteriology
Five volume resource covering all known prokaryotes 2 domains: Archaea and bacteria
Domain Archaea
Major Taxonomic group of Prokaryotes -Primitive, adapted to extreme habitats and modes of nutrition
Domain Bacteria
Major Taxonomic group of Prokaryotes
Diagnostic Scheme for Medical Use
Phenotypic qualities used in identification -Divide bacteria based on cell wall structure, shape, arrangement, and physiological traits
Species
Collection of bacterial cells which share an overall similar pattern of traits in contrast to other bacteria whose pattern differs significantly
Strain or Variety
A culture derived from a single parent that differs in structure or metabolism from other cultures of that species
Type
A subspecies that can show differences in antigenic makeup, susceptibility to bacterial viruses and in pathogenicity
Cyanobacteria
Blue-Green Algae -Gram Negative Cell wall -Photosynthetic Bacteria
Green and Purple Sulfur Bacteria
Photosynthetic, Do NOT give off oxygen as product of photosynthesis
Rickettsias
Obligate Intracellular Parasite -Very tiny, gram-negative bacteria -Most Pathogens -Cant survive outside host cell -Rocky Mountain Spotted Fever
Chlamydias
Obligate Intracellular Parasites -Tiny -Not transmitted by arthropods -Chlamydia Trachomatis = eye infection and one of most common STD’s -Chlamydia Pneumoniae = lung infection
Archaea
3rd Domain, The other prokaryotes -More closely related to eukaryotes than bacteria -Unique genetic sequence in rRNA -Unique membrane lipids and cell walls