Unit 1 (Bacteria) Flashcards
1
Q
Infection
A
the successful invasion of host tissues by pathogenic micro-organisms, causing disease
2
Q
Name given to a micro-organism is based on the following (5):
A
- shape
- origin
- habitat
- related diseases
- discovery
3
Q
Autotrophs
A
manufacture their own food
4
Q
Heterotrophs
A
use organic matter from other sources to create energy
5
Q
Saprophytes
A
use dead animal and plant material as a source of nutrients (responsible for the breaking down of waste products)
6
Q
Commensals
A
live within/on organism and cause no harm
7
Q
Parasites
A
live on/in another organism at the expense of the host
8
Q
Bacteria
A
- single celled/unicellular
- pathogenic or non-pathogenic (flora)
9
Q
Non-pathogenic
A
- harmless
- can become pathogenic if removed from their normal site
10
Q
Morphology
A
the study of the structure and form
11
Q
Microbiology
A
the study of micro-organisms
12
Q
Coccus
A
- spherical/near round
13
Q
Staphylococci
A
clusters
14
Q
Diplococci
A
pairs
15
Q
Sarcinae
A
group of 8
16
Q
Bacillus
A
rod-shaped
17
Q
Vibrio
A
comma shaped
18
Q
Spirillum
A
spiral shaped
19
Q
Classifications of bacteria
A
- morphology
- staining
- growth
- nutrition
- physiology
- genetics
- biochemistry
20
Q
Staining
A
- Grams’ method
- Zieh Neelson method
21
Q
Grams method
A
- violet dye is positive and red dye is negative
- Gram positive cocci: violet + spherical round
- Gram negative cocci: red + round
- Gram positive bacillus: violet + rod
- Gram negative bacillus: red + rod
22
Q
Zieh Neelson method
A
- red dye + acid wash
- blue/green dye over
- bacteria stays red= acid fast bacteria
23
Q
Bacterial cell diagram and labels
A
in notes
24
Q
Cell wall
A
- responsible for the shape and rigidity of the cell
- prevents it from rupturing in a hypotonic solution
- composed of mainly peptidoglycan
- protection of cell contents
25
Cell membrane
- regulates the movement of materials into and out of the cell
26
Cytoplasm
- site of reactions
- semi-fluid substance
- contains ribosomes and RNA, vesicles, inclusions, granules that store glycogen and a nuclear region
27
Ribosome
makes protein
28
Chromatin network
genetic material
29
Capsule/slime layer
- protection
- drying out
30
Pilli
1) Pili
- allows exchange of DNA material
2) Fimbriae (attachment pili)
- helps bacteria to adhere to surfaces
31
Flagella
movement
32
Inclusion
storage where nutrients are held
33
Mesosome
an extension of the cell membrane that folds into the cytoplasm + increases the surface area
34
Plasmid
small, circular DNA molecules that carry genes
35
Cell division
1) Binary fission
2) Budding
36
Binary fission
- cell duplicates its components and divides into 2:
- when a septum grows between them the daughter cells becomes independent and separate
- DNA synthesis continues and the single chromosome is replicated before the cell divides again
- if the separation is incomplete linear chains of cuboidal groups of 4 (tetrads) occur
37
Budding
- a small, new cell develops from the surface of a bacterium cell
- the bud separates from the mother cell
38
Nutritional factors that influence bacterial growth
- all organisms require a food source which provides the basic elements H, O, N, S, P, M, Fe and supplies energy
- organisms obtain these these from organic sources (carbon containing) or inorganic matter or both
- some organisms show preference for specific organic matter and secrete enzymes that target these compounds: Lipolytic, Proteolytic and Saccharolytic
39
Lipolytic
organisms break down fat
40
Proteolytic
organisms break down proteins
41
Saccharolytic
organisms metabolize sugars
42
All bacteria require ?
CO2 but often generate it for themselves
43
The physical factors/environmental factors affecting the survival of micro-organisms are:
- Temp (exceeding minimum and maximum)
- Moisture
- Chemicals (salt, sugar, acids, alkalines)
- Oxygen
44
Moisture
- all living cells require water in the liquid phase to sustain them
- water particles in reactions within the cell, form its largest component, facilitates the passage of nutrients into and waste products out of the cell and prevents drying out
- when water is frozen or bound in concentrated salt and sugar solutions it becomes unavailable for use by micro-organisms
- strong solutions of salt and sugar may exert osmotic pressure on the cell, withdrawing water and causing dehydration and cell death
- these measures are often used in food preservation
45
Temperature
- Psychrophi/es
- Mesophiles
- Thermophi/es
46
Psychrophi/es
- found in very cold conditions (15-20 degrees Celsius)
47
Mesophiles
- survived best at temperatures between 30-37 degrees Celsius
- some are pathogenic (cause disease) and many have an optimum growth temperature equal to body temperature
48
Thermophi/es
- prefer high temperatures and grow best between 50-60 degrees Celsius
49
pH (potential hydrogen)
- the majority of organisms prefer a neutral pH (7) environment and are called neutrophiles
- Acidophiles prefer an acidic medium (below 7) whilst a few species prefer alkaline conditions (pH above 7)
- strong acidic or alkaline environments destroy microbes
50
Oxygen
- all organisms obtain energy by metabolizing sugar inside the cell
- aerobic organisms, anaerobic, facultative and micro-aerophilic organisms
51
Aerobic organisms
- micro-organisms which require oxygen for the release of energy (respiration)
52
Anaerobic organisms
- micro-organism which obtain energy in the absence of oxygen
53
Facultative organisms
- micro-organisms which release energy with or without oxygen
54
Micro-aerophilic organisms
- micro-organisms which require a minimum of oxygen
55
Spore formation
- when environmental conditions become unfavourable or nutrients such as C or N lack, endospores form inside of mother cells
- endospores can survive long periods of drought and are resistant to killing by extreme temps, radiation and destructive chemicals
- the endospore cannot divide itself and the parent cell can only produce 1 endospore, so sporulation is a protective mechanism of survival for the bacterium
- once conditions become favourable again an endospore develops into a vegetative cell again
- the living cell now takes in large quantities of water and looses its resistance to heat and staining
56
Virulence
- the ability of pathogenic organisms to cause disease varies
57
Virulence depends on:
-the ability to invade or penetrate the hosts defense mechanism ( invasiveness)
- the ability to damage host tissues (toxicity)
- the availability of all requirements for normal growth
- the ability to resist or evade the natural defense system of the host (resistance)
- the ability to produce toxins that are harmful to host tissues
58
Endotoxins
- produced inside Gram negative organisms and are only released when the cell is broken down, after its death
- less toxic than exotoxins
59
Exotoxins
- harmful chemicals which are released into the tissues that cause structural damage or functional disturbance in the body
60
Antigens
- complex substances, often protein-like which are normally contained within a cell
- either a macrophage, which has ingested a microbe or an abnormal cell
- antigens stimulate the production of specific antibodies
61
T-lymphocytes recognize these antigens and develop into ?
- Memory T-cells (provide immunity)
- Killer T-cells (destroy the cells carrying the antigens)
- Suppressor T-cells (moderate immune response)
- Helper T-cells (activate B-lymphocytes)
62
Activated B-lymphocytes produce ?
- plasma cells that secrete antibodies that destroy bacteria and neutralize bacterial toxins
63
Exotoxins and antigens
- highly antigenic
- the host produces specific antibodies that neutralize these toxins
- may be modified by heat and chemicals to loose their toxicity but retain the ability to produce antigens and are called toxoids
64
Toxoids
- exotoxins may be modified by by heat and chemicals to loose their toxicity but retain the ability to produce antigens
- capable of stimulating antibody production without causing disease
- used for immunization
65
Endotoxins and antigens
- only weakly antigenic and the intact organism is only partly destroyed by the hosts antibodies
- cannot be converted into toxoids
66
What type of toxin can be converted into a toxoid
- Exotoxin
67
Non-pathogenic bacteria
(Commensals)
- do not cause disease, often serve a useful purpose and are called commensals
- routinely found in the digestive and respiratory tract or on the skin
