Lecture 1

Question 1

What is Microbiology

Answer 1

study of microscopic organisms also known as microbes

Question 2

four major groups of microorganisms(morgs)

Answer 2

Viruses
Bacteria
Fungi
Parasites(protozoa and metazoa)

Question 3

Branches of Microbiology

Answer 3

Industrial Microbiology
Agricultural Microbiology
Sanitary Micro
Veterinary Micro
Medical/Clinical  Micro

Question 4

Medical microbiology

Answer 4

study, identification and the control of microbes which can cause disease in humans

Question 5

microbes which can cause disease in humans

Answer 5

Pathogens

Question 6

Illness caused by pathogens is termed

Answer 6

infection or infectious disease

Question 7

four major disciplines:

Answer 7

Bacteriology: the study of bacteria
Mycology : the study of fungi
Parasitology : the study of parasites
Virology : the study of viruses

Question 8

Viruses

Answer 8

Are non-cellular particles
They are the smallest ,ranging in size from 0.01 to 0.3 µm (10-300 nm) They are observed only through an electron microscope
May not be living
Consists of a genomic core of DNA or RNA but never both,and a coat of protein around the core known as envelope
Produce progreny in host
No independent reproduction
Obligate intracellular parasites

Question 9

Bacteria:

Answer 9

They are prokaryotic microbes 2 to 6 µm in size.
Unicellular can reproduce independently by binary fission
Divide by fission- form colonies
Are able to live independently in nature, in the soil, water, on plants, animals and humans when live as companions with the humans known as Normal flora
When cause disease in humans known as pathogens
Most bacteria are free living or parasitic forms that can metabolize and reproduce by independent ways.

Question 10

Fungi

Answer 10

They are eukaryotic 2.0 to 100 µm in size
They are unicellular and multicellular
Unicellular-Yeast
Multicellular- molds,dimorphic fungi (Pathogenic fungi) Candida ( opportunistic pathogens)
Have all organelles found in human cells

Question 11

Protozoa

Answer 11

Most protozoa are single celled
They are eukaryotic
5.0 to 200 µm
They are motile by pseudopods ,flagella or cilia.
Are free living or live inside the human body for part of their life cycle
E.g amoeba

Question 12

General size of microorganisms

Answer 12

Amoeba  = 15 µm
Yeast       =   5 µm
Bacteria    = 2 µm
Virus          = 0.1 µm( 100 nm)
So,
amoeba >yeast>bacteria>virus

Question 13

Unusual forms of medically significant bacteria

Answer 13

Rickettsias, Chlamydias, Spirochetes
The rickettsias and chlamydias, however have adapted to life inside their host cells.
Eg.Chlamydia tracomatis

Therefore, are considered obligate intracellular parasites

Question 14

capsule:

Answer 14

it is a slime layer found in some bacteria outside the cell wall, not easily washed off, and,
Allows these microbes to resist phagocytosis by WBCs and increases the virulence (disease causing capacity ) eg.E.coli, Klabsiella pnemoniae,Haemophilus influenza

Question 15

Cell wall

Answer 15

it is a unique prokaryotic feature, resists shrinkage of the cell.
Bacterial cell walls gain their rigidity from a unique macromolecule called peptidoglycan.
one of the major basis for the classification of the bacteria. Gram positive and Gram negative cell walls are chemically different

Question 16

Cell membrane

Answer 16

it is a semi-permiable organelle ,which allows material in and out of the cell

Question 17

Flagella

Answer 17

they are whip like hairs/tails helps in the motility of the bacterium

Question 18

Pili/Fimbriae

Answer 18

are small hair like projections on the surface, allow bacteria to stick to the surface and also used to
move DNA plasmids between bacteria

Question 19

Plasmid

Answer 19

It is a DNA molecule that is separate from, and can replicate independently of, the chromosomal DNA.
They are double-stranded and, in many cases, circular. Plasmids usually occur naturally in bacteria.
Plasmids are responsible for the antibiotic resistance .

Question 20

Bacterial growth

Answer 20

Growth is the term applied to the process of increasing the number of bacteria.
Bacteria grown in the lab are referred to as a culture

Question 21

Conditions for growth

Answer 21

Temperature,moisture osmotic pressure,pH,nutrition (food) and gases

Question 22

Temperature

Answer 22

Bacteria can grow over a wide range of temperature and can survive in the range of -20 to 90oC.
However, for most pathogens 35-37 oC is the optimal temperature.

Question 23

Cryophiles

Answer 23

temp range -2 to 4 oC

Question 24

Psychrotrophs

Answer 24

temp range 20 -30 oC

Question 25

Mesophiles

Answer 25

temp range 25-40 oC

Question 26

Thermophiles

Answer 26

temp range 55-70 oC

Question 27

Hyperthermophiles

Answer 27

temp range 70 oC or greater

Question 28

Moisture

Answer 28

Moisture in the form of water and damper conditions favor bacterial growth. Dryness slows down the growth

Question 29

Osmotic pressure:

Answer 29

this is controlled by the amount of solute (normally salt )in the environment. Too much of salt stops the growth. However some organism can grow in higher concentrations of salt

Question 30

pH

Answer 30

bacteria can grow over a wide range of pH between 3 to 9
pH 2 to 4.5 is acidic
pH 7to 7.4 is neutral this is the ph of blood
pH 8 to 10 is alkaline
Most bacteria can grow in the range of pH 5 o 8,optimum being pH 7 to 7.5

Question 31

Nutrients

Answer 31

Main nutritional requirement are in the form of
Water
Proteins
Essential elements in the form of C,H,O,N,P,S ,and,
Some other trace elements
Medium is a form of providing all the required nutrients to the microbe in an artificial environment

Question 32

Gases

Answer 32

Mainly oxygen and carbon dioxide

Question 33

Obligate aerobes

Answer 33

Certain bacteria have an absolute or obligate requirement of oxygen are called Obligate aerobes Eg Micrococcus species,Bacillus species
growth in a tube would be at the top
enzymes such as catalase and superoxide dismutase allow toxic oxygen to be neutralized

Question 34

Obligate anaerobes

Answer 34

Certain bacteria can grow in the absence of oxygen and are called Obligate anaerobes
eg- Clostridium species
Growth in a tube at the bottom
lacks the enzymes to neutralize harmful forms of O2

Question 35

Facultative Anaerobes

Answer 35

Some bacteria grow better in the presence of O2 but can also grow without it they are called Facultative Anaerobes eg. E.coli
Growth in the top of the tube and then a little bit throughout
enzymes such as catalase and superoxide dismutase allow toxic oxygen to be neutralize

Question 36

Microaerophiles

Answer 36

Bacteria able to grow in a little amount of oxygen (i.e lower than atmospheric oxygen)are called Microaerophiles eg:Helicobacter pylori
growth in tube in the middle
produce lethal amounts of O2 if exposed to normal atmospheric oxygen

Certain microaerophiles can survive only if the carbon dioxide levels are high ,these are called capnophiles

Question 37

Aerotolerant anaerobes

Answer 37

only anerobic growth , but continues in prosence of oxygen
growth in tubes in clumps evenly
only presence of superoxide dimutase , o2 is partially neutralized . tolerates O2
Clostridium perfingens

Question 38

What is a medium

Answer 38

form of providing all the required nutrients to the microbe in an artificial environment .
individual components or by using dehydrated powder (basal medium) - more consistent prep.

Question 39

Shapes of bacteria

Answer 39

Coccus - round
Bacillus - rod - can be branched
Spiral bacteria -

Question 40

Gram postive

Answer 40

retain crystal violet and appear blue - purple

Question 41

Gram negative

Answer 41

do not retain the crystal and stain pink red

Question 42

Fastiidous bacteria

Answer 42

only grow on specialized medium

Question 43

What are two morphological forms of fungi

Answer 43

mold (reproduce by spores) and yeast(reproduce by budding and not spores)

Question 44

dimorphic fungi

Answer 44

Pathogenic fungi can grow in both yeast and mold forms, depending on culture conditions