Ziegler-Microbial Structure Flashcards
(79 cards)
1
Q
What is a microbe?
A
British Petroleum Finds Vinegar
- Bacteria (prokaryotic)
- Protozoa (eukaryotic)
- Fungi (eukarytotic)
- Viruses (neither prokaryotic or eukaryotic
2
Q
What are the differences between Prok and Euk:
Chromosome?
A
Single circular
Paired linear
3
Q
What are the differences between Prok and Euk:
Chromosome location?
A
Nucleoid (no membrane)
Nucleus (membrane present)
4
Q
What are the differences between Prok and Euk:
Nucleolus?
A
Absent
Present
5
Q
What are the differences between Prok and Euk:
Extrachromosomal DNA?
A
Plasmid
Mitochondria and Chloroplast
6
Q
What are the differences between Prok and Euk:
Site of Cellular Respiration?
A
Cell membrane
Mitochondria
7
Q
What are the differences between Prok and Euk:
Ribosomes?
A
30S and 50S/70S
40S and 60S/80S in cytoplasm (70S in organelles
8
Q
What are the differences between Prok and Euk:
Locomotion?
A
Rotating flagella and gliding
Undulating flagella and cilia, and also amoeboid movement
9
Q
What are the differences between Prok and Euk:
Pili?
A
Sex or attachment pili
Absent
10
Q
What are the two basic shapes of bacteria?
A
Rod and cocci
11
Q
What are other bacterial shapes?
A
- Spirochetes
- Spirillum
- Diplococci
- Diplobacilli
12
Q
What are the various rod shapes?
A
- They’re also known as bacillus
- Two bacilli together–Diplobacilli
- Chains of bacilli–Streptobacilli
- Other arrangements–Palisades (side by side or X,V, or Y figures
13
Q
What is a spirochete?
A
A flexible undulating corkscrew?
14
Q
What is a spirillum?
A
A rigid corkscrew shape
15
Q
What are the components of bacterial structure?
A
- Flagella and pilli (fimbriae)
- Capsule–external to cell wall, protects bacteria from phagocytosis and plays a role in adherence
- Cytoplasmic membrane–gram staining
- Cell envelope-cell membrane, capsule, antigens
16
Q
What is a mesosome?
A
Convuluted invaginations at the plasma membrane–Chromosomal DNA attached to the bacterial membrane invaginated at the site of bacterial division
17
Q
What is plasmid DNA?
A
- Small, circular, distinct from chromosome
- capable of self replication
- Extrachromosomal but can become integrated into bacterial DNA
- FXN: Contain genes that can give bacteria antibiotic resistance or virulence factors
18
Q
Where are the characteristics of ribosomes in bacterial structure?
A
- Ribosomes are present but no endoplasmic reticulum
- Ribosomes that are active in protein synthesis are attached to the membrane
- Proteins that make up ribosomes are diff in prok and euk cells
19
Q
What are flagella?
A
- Used by bacteria for locomotion, movement
- Composed of flagellin
- Different arrangements of flagella
20
Q
What are the different arrangements of flagella?
A
- Montrichous flagellum–1 flagella, cause cholera
2. Multiple flagella (peritrichous arrangement)–Salmonella
21
Q
What is the flagellar motor?
A
- The mechanism by which locomotion occurs
- Made of the protein flagellin and consists of filament and basal region. Basal region has a hook and basal body which has a rod and rings.
22
Q
How is the difference in ring number for gram positive and negative organisms?
A
- (+) 2 rings–one in cell wall and one in cell membrane
2. (-) 4 rings–2 in the cell wall and 2 in the membrane
23
Q
How do pili (fimbriae) relate to flagella?
A
Shorter and finer than flagella
24
Q
How many types of pili are there?
A
- Adherence pili (adhesis)–attach bacteria to surfaces/cells, allows them to congregate multiply and divide (gram pos cell conjugation)
- Sex pili–important in bacterial conjugation (found in some gram negative bacteria), allows genetic exchange from 1 gram negative bacteria to another gram negative bacteria
25
What is the bacterial capsule?
1. A slimy outer coating not found in all bacteria
2. A complex of high molecular weight polysaccharides (slime or glycocalyx)
3. Can be antiphagocytic
4. Bacteria with glycocalyx/capsule have selected advantage to survive b/c capsule is antiphagocytic
26
What is the cytoplasmic membrane?
1. Encloses the bacterial cytoplasm
2. Phospholipid bilayer (selectively permeable)
3. Imbedded with proteins
4. Site of nutrient transport
5. No ER
6. Site of respirtion
27
What is peptidoglycan and how does it relate to the cell membrane of bacteria?
1. Unique to bacteria and external to cytoplasmic membrane
2. site of antibiotic action
3. if you inhibit peptidoglycan bacteria is less likely to maintain osmotic pressure and will break down
28
What are the elements of peptidoglycan structure?
1. External part of bacteria
2. Backbone of alternating Nam and Nag monomers
3. tetrapeptides hanging off
4. tetrapeptides linked to adjacent tetrapeptides through cross links or direct peptide bonds
29
What do gram positive/negative bacterial cell envelopes have in common?
1. Cytoplasmic/bacterial membranes
| 2. peptidoglycan (MORE in positive, LESS in neg)
30
Is it harder to get an antibiotic into a gram positive or gram negative cell?
1. Large antibiotics that inhibit protein synthesis only work on gram positive cells and can't penetrate gram negative.
31
What dose Gram stain depend on?
1. The amount of peptidoglycan
| 2. The permeability of the cell wall to purple colored iodine dye complexes
32
What is the difference between gram pos/neg bacteria when it comes to gram staining?
1. Pos: retain purple iodine dye complexes after treatment with decolorizing agent
2. Neg: do not retain complexes when decolorized (safranin is used for neg to counterstain)
33
What are the steps to gram staining?
1. Heat fixed to a slide
2. Add Crystal violet (all cell stained blue)
3. Fix: Iodine fixes stain to bacterial cell
4. Decolorizes gram negative bacteria w/ alcohol. Gram positive remain blue/purple. (Taxes away cell membrane and everything that is a phospholipid
5. Counterstain: Safranin stains the gram negative bacteria a pink color. So much peptidoglycan/cross linking, complexes that are formed can't get out so remains blue until stained with safrnanin.
34
What is teichoic acid?
1. WATER SOLUBLE POLYMER of ribitol or glycerol residues joined by phosphodiester linkages
2. Unique to gram POSITIVE
3. Teichoic acid--in cell walls chemically bound to peptidoglycan
4. Lipoteichoic acid--cell membranes bound to glycolipic
35
What is found ONLY in a gram positive cell wall?
1. Teichoic acids/teichuronic acids
2. Lipioteichoic acid
3. Polysaccharides
(PLaTe)
36
What is teichuronic acid?
Similar to teichoic acid, but made in phosphate limiting conditons
37
What is lipoteichoic acid (LTA)?
1. In cell membranes, chemicall bound to membrane glycolipid
38
How do polysaccharides relate to gram positive cell walls?
Composits of sugars released from teichoic and teichuronic acid
39
In gram pos cells, what percent of the cell wall is due to peptidoglycan?
88%
40
What is an endotoxin?
1. Found only in gram neg bacteria
2. Causes endotoxic shock (it can KILL people)
3. In outer membrane of cell envelope
4. found in the lipopolysaccharide of the outer membrane
41
What components are found ONLY in gram negative bacteria?
1. Lipoproteins- cross link peptidoglycan and OM
2. Periplasmic space
3. Outer membrane
4. Lipopolysaccharide-endotoxin/LPS
(POLL)
42
What is the periplasmic space?
1. Gel like matrix between cytoplasmic membrane and outer membrane
2. Contains enzymes for nutrient breakdown and substrate binding proteins, including penicillin and binding proteins
43
What is a lipoprotein?
1. Cross links outermembrane to peptidoglycan
2. IN the periplasmic space
(slide 44)
44
What are the components of the outer membrane in gram negative bacteria?
1. Phospholipid bilayer containing lipopolysaccharides (Lipid A, endotoxin, O antigen)
2. Porins (nonspecific pore proteins), anchor proteins and transport proteins
3. Protects the cell from hydrolytic enzymes
45
What are lipopolysaccharides?
1. Made of Lipid A covalently attached to a polysaccharide with core and terminal repeat units
2. LPS (lipid a) is called an endotoxin (extremely toxic to animals)
3. The lipid portion of LPS is attached to the outer membrane by hydrophobic bonds
4. O antigen: The polysaccharide chain of repeating units, exposed to the outside of the cell and is antigenic (unique for each species of gram negative bacteria)
46
What are Mycoplasma?
PNSS
1. Best known for causing pneumonia, hard to treat with antibiotics
2. the smallest free living organisms
3. No CELL WALL! **NO peptidoglycan, bacterial stains don't work well
4. The only barrier is the cytoplasmic membrane
5. Membranes contain sterols--required for growth (not synthesized by the bacterium)
47
What is an acid fast bacteria?
1. Myobacteria
2. Contain small amounts of peptidoglycan
3. Contain large amounts of glycolipids: Lipoarabinomman, MYCOLIC ACIDS in the cell wall (60% of the cell wall and make it IMPERMEABLE)
4. Have cell well but DONT stain pos/neg---ACID FAST STAIN shows that it's mycoplasmic
48
What is acid fast staining?
Staining with red carbolfuchsin and destaining with acid alcohol, only acid fast retain the staing after the decolorizing step
49
What are protein secretion systems (PSS)?
1. In addition to cell wall/envelope most bacteria have protein secretion systems
2. Gram neg--six classes, Gram pos- 7
3. Play a major role in how bacteria interact with their environment
4. help determine pathogeneicity
50
What are the structures of PSS?
1. Simple systems (T1SS): transporters, outermembrane factors, membrane fusion proteins
2. Complex (T3SS, T4SS, T6SS): have a transmembrane structure (injectosome) which consists of more than 25 proteins
3. Type of system they have depends on genes in bacteria
51
What are the functions of PS Systems?
1. Transport proteins or nucleic acids (T4SS) to outside the cell, periplasm or inside host cells
2. Transported proteins can be surface proteins (adhesins/toxins) that modify host cell physiology causing pathological consequences
3. adhesins- sit on outside of cells and help bacteria adhere to other cells
52
What are endospores?
1. Survival response to adverse nutrient conditions
2. Helpful in identifying some bacteria: made by bacillus and clostridum species in nutrient limiting conditions (starvation)
2. Resistant to heat, desiccation and chemical damage
53
Why are endospores heat resistant?
Calcium dipicolinate in the core (5-15% spore dry weight) aids in heat resistance
54
What is the spore wall?
1. It is the cell wall of the germinating bacterium
| 2. Contains normal peptidoglycan
55
What is the spore coat?
1. Contains keratin-like proteins
| 2. Impermeable to chemicals
56
What is the spore cortex?
1. The thickest part of the spore envelope
| 2. Contains peptidoglycan with fewer cross-links
57
What is the spore core?
1. Contains calcium dipicolinate
| 2. Contains all the nucleic acid for later growth
58
What are the 2 types of viruses?
1. Prokaryotic = bacteriophage
| 2. Eukaryotic
59
What are the general characteristics of a virus?
1. NEED A HOST!--can'at replicate on own so take over biosynthetic machinery of host to make more copies of themselves
2. Viral particle is DNA/RNA in a protein coat without a membrane
3. The outer coat protects the genetic material and facilitates adhesion/infection
4. has no enzymes, organelles, or other biosynthetic machinery
5. Nucleic acids code for proteins needed for viral replication
60
What are enveloped viruses?
Have acquired membrane from host
61
What are naked capsid viruses?
Consist of the nucleic material with a coat/capsid.
62
What are nucleocapsid/capsids?
Protects nucleic acids (DNA/RNA)
63
What is a capsomere?
Subunit of the capsid structure
64
What are polyhedral/helical structures?
Different capsid structures, used for viral classification
65
What are viroids?
1. Very small ss circles of RNA
2. Cause disease in plants
3. Replication strategy is unkown
4. HDV is similar to viroid
5. Obligate intracellular parasites
66
What are prions?
1. Cause "slow virus disease" (Scrapie, Kuru, Creutzfeltd-Jakob, mad cow
2. Resistant to heat inactivation (autoclaving), radiation damage and nucleases (contain no nucleic acids)
3. Can be inactivated by detergens, urea, phenol
4. Causative agent is the prion protein
5. Altered conformations of normal cell proteins that can autocatalytically form more copies of itself
67
What is kuru?
Human disease in cannibals in Papa new guinea
68
What is mad cow disease?
1. Problem with vCJD
| 2. For people there's CJD from unknown source and vCJD thought to be variant form of BSE infectious to people
69
What is unique about the PrPsc (PRION) proteins?
1. Has the same protein sequence as a normal cellular protein PrPc
2. Cellular protein and the prion protein have different folded conformations
3. PrPc protein is found in normal tissue and is degraded by proteases
4. PrPsc protein is NOT degraded by proteases
5. Prion protein catalyzes a different formation of itself!
70
What are the general characteristics of fungi?
EECO
1. eukaryotic organisms
2. have cell walls for protection
3. Erosterol is dominant membrane sterol rather than cholesterol (imp for therapy)
4. Requires preformed organic compounds for growth
71
What are the three types of fungi? Which produce disease?
1. Yeasts, molds, mushrooms
| 2. yeasts and molds produce disease
72
What are yeasts?
1. SINGLE cell fungi
2. Reproduce by BUDDING
3. Some strains (candida) produce speudohyphae
73
What are molds?
1. Grow in filamentous forms called hyphae
2. Many species produce cross walls of hypahe called septae
3. Nonseptate hyphae do exist
4. Masses of hypahe are called myelin
74
What are dimorphic fungi?
1. exist as yeast/ yeast like forms and filamentous forms (more like mold)
2. Form controlled by NUTRIENTS AND TEMPERATURE
75
Which form of dimiorphic fungi is found in the body and which in the environment?
YEAST--- BODY
| FILAMENTOUS- ENVIRONMENT
76
What are the different spores associated with different fungi?
CAB
1. Condida--asexual spores of molds
2. Arthroconidia--formed from joints in hyphae then fragmentation
3. Blastoconidia--yeast cell buds
77
Why are spores important to relate to fungi?
Help to identify some fungi--ex. barrel shaped arthrospore of coccidiodes immitis
78
What are protozoa?
S is TC FC
1. Single cells
2. Exist as trophozoites (motile form) and cysts (resting stage)
3. Some move by flagella (Giardia) and some by cilia (balantidum)
79
Which worms cause disease?
1. Trematodes (flukes)
2. Cestodes (tapeworms)
3. Nematodes (roudworms)
* *Infection usually involves ingestion of larval or cyst forms
