Bacteriology Overview Flashcards
1
Q
Characteristics of BACTERIA
A
- No nuclear membrane
- Mitochondria ABSENT
- Endoplasmic reticulum is ABSENT
- NO sterols in cytoplasmic membrane
- Chitin, glucans and mannans ABSENT from cell wall
- NOT sensitive to anti fungals
2
Q
Characteristics of FUNGI
A
- Well defined nuclear membrane present
- Mitochondria PRESENT
- Endoplasmic reticulum is PRESENT
- Sterols are PRESENT in the cytoplasmic membrane
- Cell wall has chitin, glucans and mannans
- NOT sensitive to antibiotics
3
Q
BACTERIAL STRUCTURE
A
- The biochemical composition of these structures are macromolecules such
as DNA, RNA, protein, polysaccharide, phospholipid etc
4
Q
Macomolecules are made up of PRIMARY SUBUNITS
A
- PROTEINS: subunits are amino acids
- POLYSACCHARIDES: subunits are sugars (carbohydrates)
- PHOSPHOLIPIDS: subunits are fatty acids
- NUCLEIC ACIDS: subunits are nucleotides
5
Q
Where in the cell are AMINO ACIDS found?
A
- Flagella
- Pili
- Cell walls
- Cytoplasmic membranes
- Ribosomes
- Cytoplasm
6
Q
Where in the cell are POLYSACCHARIDES found?
A
- Capsules
- Inclusions (storage)
cell walls
7
Q
Where in the cell are PHOSPHOLIPIDS found?
A
- Membranes
8
Q
Where in the cell are NUCLEIC ACIDS found?
A
- DNA: nucleoid (chromosome), plasmid
- RNA:
Ribosomes: mRNA
tRNA: cytoplasm
9
Q
BACTERIAL CELL STRUCTURE
A
Appendages:
– Flagella
– Pili (or fimbriae)
Cell envelope:
– Capsule
– Cell wall
– Plasma membrane
Cytoplasmic content:
– Chromosomes
(DNA)
– Ribosomes
10
Q
Which structures are NOT PRESENT in all bacteria?
A
- Capsule
- Flagella
- Pili
11
Q
CELL WALL TYPES
A
- Gram POSITIVE
- Gram NEGATIVE
12
Q
FLAGELLA
A
- Swimming movement
- Predominant chemical composition is PROTEIN
13
Q
SEX PILUS
A
- Mediates DNA transfer
during conjugation - Predominant chemical composition is PROTEIN
14
Q
COMMON PILI or FIMBRIAE
A
- Attachment to surfaces
- Protection against phagocytic engulfment
- Predominant chemical composition is PROTEIN
15
Q
CAPSULES
A
- Attachment to surfaces
- Protection against phagocytic engulfment
- Occasional killing or digestion
- Reserve of nutrients or protection against dessication
Predominant chemical composition is POLYSACCHARIDES, rarely POLYPEPTIDES
16
Q
CELL WALL
A
- Prevents osmotic lysis of cell protoplast and confer rigidity and shape on cells
- Peptidoglycan prevents osmotic lysis and confer rigidity and shape on cells
- Outer membrane is a permeability barrier
- Associated LPS and proteins have various functions
17
Q
PLASMA MEMBRANE
A
- Permeability barrier
- Transport of solutes
- Energy generation
- Location of numerous enzyme system
- Predominant chemical composition is PHOSPHOLIPID and PROTEIN
18
Q
RIBOSOMES
A
- Sites of translation (Protein Synthesis)
- Predominant chemical composition is RNA and PROTEIN
19
Q
INCLUSIONS
A
- Reserves of nutrients
- Additional specialized functions
- Predominant chemical composition is highly variable
- Can be lipid, carbohydrate, protein or inorganic
20
Q
CHROMOSOME
A
- Genetic material of the cell
- Predominant chemical composition is DNA
21
Q
PLASMID
A
- Extrachromosomal genetic material
- Predominant chemical composition is DNA
22
Q
APPENDAGES
A
- Flagella
- Pili
23
Q
FLAGELLA
A
- Composed of a protein (FLAGELLIN)
- Usually much longer than the bacterial cell
- NOT PRESENT in all bacteria
- Bacteria that possess flagella are MOTILE
- Many Gram NEG bacteria have flagella
- Present in some species of enterococci
24
Q
Parts of Flagella
A
- Filament
- Hook (joint betw filament and basal body)
- Basal Body (anchored to cell wall and cytoplasmic membrane)
25
Variety of Number and Arrangement of Flagella
- Monotrichous flagellum (one "tail")
- Lophotrichous flagellum (multiple "tails" at one end)
- Amphitrichous flagellum (one "tail" at each end)
- Peritrichous flagellum ("tails" around entire flagella)
26
What is motility test medium?
- Semi soft medium inoculated with a straight needle
- Motile bacteria swim away from line of inoculation to find nutrients causing turbidity
- NON motile will only
grow along the line of inoculation
27
Fimbriae or Pili
- Short, hair-like structures on the surfaces of prokaryotic cells
- Shorter and stiffer than flagella
- Smaller in diameter than flagella
- Very common in Gram NEG bacteria
- Most often involved in adherence of bacteria to surfaces, substrates
and other cells or tissues in nature
28
F or Sex Pilus
- A specialized type of pilus
- Apparently stabilizes
mating bacteria during the process of conjugation
- Found in E. COLI
29
Common Pili
- Usually involved in specific adherence (attachment) of
| prokaryotes to surfaces in nature
30
Components of Cell Envelope
- Capsule
- Cell wall
- Plasma membrane
31
Gram POSITIVE Cell Wall
- Uniformly thick layer external to the plasma membrane
| - Composed mainly of peptidoglycan (murein)
32
Gram NEGATIVE cell wall
- Thin and multilayered
- Consists of a
relatively thin peptidoglycan sheet between the plasma membrane and a
phospholipid-lipopolysaccharide outer membrane
33
PERIPLASM
- The space between the inner (plasma) and outer membranes (wherein the
peptidoglycan resides)
34
CAPSULE
- Polysaccharide layer outside of the cell wall
35
TRUE CAPSULE
- Discrete detectable layer of polysaccharides deposited
| outside the cell wall
36
BIOFILM
- Less discrete structure or matrix which embeds the cells is a called a slime layer
37
Mucoid Colonies on
| Agar Media
- Indicate bacteria with well defined capsular material
38
Functions of The CAPSULE
* Adherence to surface, tissue or substrate in nature
* Resistance to engulfment by phagocytic cells
* Resistance to killing and digestion by phagocytic cells
* Resistance to attack by antibodies and drugs
* Protection against drying
* Reserve of nutrients
39
CELL WALL
- Most prokaryotes have
- Prevent damage to
the underlying protoplast
- Essential structure for cell
viability
- Composed of unique components found nowhere
else in nature
- One of the most important sites for attack by
antibiotics
- Provides ligands for adherence and receptor sites for drugs or viruses
- Components are responsible for symptoms of a
disease
- Provides for immunological distinction and
immunological variation among strains of bacteria
40
CELL WALL
- Bacteria usually live in relatively dilute environments
- The accumulation of solutes inside the cell cytoplasm greatly exceeds the total solute concentration in the outside environment
- Since the membrane is a delicate, plastic structure, it must be restrained by an outside wall made of porous, rigid material that
has high tensile strength
(murein)
41
CELL WALL
- Bacterial murein is a unique type of peptidoglycan
- Composed of chains of alternating subunits of N-acetylglucosamine
and N-acetylmuramic acid crosslinked by short tetrapeptide side chains and peptide cross-bridges.
• The cell walls of archaea may be composed of protein,
polysaccharides, or peptidoglycan-like molecules, but NEVER contain murein
- This feature distinguishes the bacteria from the archaea
42
Structure of the G+ve Bacterial Cell Wall
- Cell wall is thick (15-80
nm)
- Consists of several layers of peptidoglycan
- Running perpendicular to
the peptidoglycan sheets are a group of molecules called TEICHOIC ACIDS (unique to the Gram-positive cell wall)
43
Structure of the G-ve Bacterial Cell Wall
- Relatively thin (10 nm)
- Composed of a single layer of peptidoglycan surrounded by a membranous
structure (outer membrane)
- Outer membrane of Gram-negative bacteria invariably contains a unique component, lipopolysaccharide (LPS or
endotoxin)- TOXIC TO ANIMALS!!
- In Gram-negative bacteria the outer membrane is usually considered as part of the cell wall
