Microbiology and Infection

Question 1

WHAT ARE BACTERIA

Answer 1

1) SINGLE CELLED MICROBES
2) PROKARYOTIC (NO NUCLEUS)
3) NO MEMBRANE BOUND ORGANELLES
4) HAVE A SINGLE LOOPED OF DNA CONTAINED IN THE NUCLEOIDS

Question 2

DRAW THE BASIC STRUCTURE OF A BACTERIA

Answer 2

PILUS
CAPSULE
CELL WALL
PLASMA MEMBRANE
NUCELOID
CYTOPLASM
RIBOSOMES
FLAGELLUM

Question 3

HOW IS BACTERIA GROUPED

Answer 3

ACCORDING TO DIFFERENT FACTORS
1)ONE FACTOR IS SHAPE
2)ANOTHER FACTOR IS ACCORDING TO MICROSCOPIC ARRANGEMENT AND LOOK
3) CAN BE ARRANGED INTO 2 GROUPS BASDED ON GRAM REACTION: POSITIVE/NEGATIVE
BASED UPON CELL STRUCTURE

Question 4

WHAT ARE THE 5 SHAPES OF BACTERIA

Answer 4

1) BACILLUS (ROD)
2)COCCUS (SPHERICAL)
3) SPIRILLUM (SPIRAL)
4) SPIROCHETE (CORKSCREW)
5) VIBRIO (COMMA)

Question 5

OUTLINE THE GRAM STAIN PROCESSES

Answer 5

1) CRYSTAL VIOLET - PRIMARY STAIN ADDED TO SLIDE
2) IODINE - MAKES DYE LESS SOLUBLE SO IT STICKS TO CELL WALLS
3) ALCOHOL - WASHES AWAY STAIN FROM GRAM NEGATIVE CELL WALLS
4)SAFRANIN - COUNTERSTAIN ALLOWS DYE TO STICK TO GRAM NEGATIVE CELLS

Question 6

EFFECT OF CRYSTAL VIOLET

Answer 6

STANS CELLS PURPLE OR BLUE

Question 7

EFFECT OF IODINE

Answer 7

CELLS REMAIN PURPLE OR BLUE

Question 8

EFFECTR FO ALCOHOL

Answer 8

GRAM POSTIVE CELLS = STAY PURPLE OR BLUE

GRAM NEGATIVE CELLS ARE COLOURLESS

Question 9

EFFECT OF SAFRANIN

Answer 9

GRAM POSITIVE = STAY PURPLE OR BLUE
GRAM NEGATIVE = PINK OR RED

Question 10

BACTERIAL VIRULENCE FACTORS

Answer 10

1) PLASMIDS
2) ENDOTOXINS
3)EXOTOXINS
4) FLAGELLUM
5)FIMBRAIE

Question 11

PLASMIDS?

Answer 11

ADDITIONAL CIRCULAR DNA
OBSTAINED BY GENE TRANSFER
CAN CONFER EXTRA GENES

CAN OFFER BACTERIA VIRULENCE TO OVERCOME DEFENCES

OFFER ANTIBIOTIC RESISTANCE

OFFER UNIQUE METABOLISM

Question 12

ENDTOXINS?

Answer 12

FOUND IN GRAM NEGATIVE CELLS

ALSO KNOWN AS : LIPOPOLYSACHARRIDES
—- composed of a lipid and o antigen

O ANTIGENS BRING ABOUT STRONG IMMUNE RESPONSES
- can lead too septic shock
- inflammatory mediators
- reactive oxygen specier (ROS) this destroys host cell membranes

Question 13

EXOTOXINS

Answer 13

A TOXIN WHICH CAUSES DAMAGE TO THE HOST
- destroying cells
- disrupting metabolism

CAN BE SECRETED OR RELEASED DURING LYSIS

EFFECT CAN BE LOCALISED OR SYSTEMIC

DIFFERENT CLASSES
- cell surface active
-membrane damaging
- intracellular
- matrix damaging

Question 14

EXOTOXIN - CELL SURFACE ACTIVE
(a class of exotoxin)

Answer 14

SUPER ANTIGENS:
- FOUND IN STAPHYLOCOCCUS AUREUS AND STREOTOCOCCIS PYOGENES

• CAUSES TOXIC SHOCK SYNDROME
• binds to immune cells allowing or them to constantly be switched on leading to over reactions
  this causes fevers, vomiting , liver inflammation, kidney failure

Question 15

EXOTOXIN - MEMBRANE DAMAGING
( a class of exotoxin)

Answer 15

damaging membranes FORM CHANNELS
means small molecules can leak out and water can leak in to retain osmotic pressure THIS IS BLEBBING

Enzymatically active toxins, produces PHOSPOLIPASE, CASUSES DESTRUCTION AND LYSIS OF CELL

this causes GAS GANGRENE

Question 16

EXOTOXINS

Answer 16

AB TOXINS
- cholera
COMPRISED OF 2 TYPES OF SUBUNITS A and B
- A1B5
BINDS TO THE CELLS OF THE SMALL INTESTINE
ENTERS THE CELL AND TRIGGERS A RECEPTOR WHICH OPENS THE CFTR PUMP

Question 17

ANTIBIOTICS

Answer 17

USED TO TREAT BACTERIAL INFECTIONS

CLASSIFIED IN SEVERAL WAYS

• by the target of action
• by chemical structure
• by overall function
• by specificity

Question 18

TWO CLASSES OF ANTIBIOTICS

Answer 18

BACTERIOCIDAL + BACTERIOSTATIC

Question 19

BACTERIOCIDAL ANTIBIOTICS

Answer 19

Target the cell wall: Penicillins and Cephalosporins

Target the cell membrane: polymyxins

Target bacterial enzymes: rifamycins, quinolones and sulfonamides

Question 20

BACTERIOSTATIC ANTIBIOTICS

Answer 20

Target bacterial protein synthesis: macrocodes, lincoasmides and tetracyclines

bacteria become quiescent and are eventually removed by detoxification mechanisms

Question 21

ANTIBIOTICS SPECIFICITY?

Answer 21

Can be NARROW RANGE

• effective only against a small specific group of bacteria

Can be WIDE RANGE

• Effective against a much broader range of bacteria

Question 22

FIVE TPES OF PLAGUES

Answer 22

Bubonic plague : cause bubos in lymph nodes

Septicaemia Plague : infection is found in blood stream and cause tissue necrosis

Pneumonic Plague : infects the lung tissue causing tissue necrosis

pharyngeal plague : affects the tonsils

meningeal plague : causes meningitis

Question 23

WHAT IS A VIRUS

Answer 23

small infectious particle

many different sorts

needs another cell to be able to replicate and grow

when not inside a host cell they are called visions

Question 24

what is the basic structure of a virus?

Answer 24

genetic material
capsid
envelope

Question 25

6 stages of viral replication

Answer 25

ATTACHMENT : virus binds to a specific site on a cell

PENETRATION : either injects or is endocytosed

UNCOATING : removal of envelope and capsid

REPLICATION : uses cells replication machinery

ASSEMBLY : uses cells protein synthesis machinery to assemble new viral particles

RELEASE : causes cell lysis and release of new phage

Question 26

what ar the effects on the host cells

Answer 26

the effects are called cytopathic

there are varied effects

but they normally results in cellular death

• cell lysis during viral release
• induced apoptosis
• cell cycle suppression

Question 27

Vaccination

Answer 27

designed to stimulate a person immune system

develops adaptive immunity which can be used during normal encounters with a virus

uses 1/4 methods:
- inactivated
- attenuated
- component
- mRNA

Question 28

4 METHODS OF VACCINATION

Answer 28

INACTIVATED - uses a whole viral particles but has been completely deactivated

ATTENUATED - uses whole viral particles but they have had infectivity reduced

COMPONENT - uses a purified specific compononet of a viral particle e.g capsid proteins

mRNA : Manmade mRNA which will cause cells to produce a protein from the virus