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Introduction to disease and microbiology
Health – maintaining homeostasis (remaining healthy)
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Appropriate level of physical activity
Adequate nutrition (energy and components)
Good quality sleep
Strong Immune System
- Natural Defenses
- Quick response

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Stress management
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Environmental

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Social

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Biological

Mental stimulation
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Socialization

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Active brain

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Emotional

Disturbances in Homeostasis/ becoming ill
Exogenus – external factors – Pathogens, environment, diet
Endogenous – internal factors – Lifestyle choices, organ + system failure, genetics
Potential outcomes; Chronic or acute (Long lasting or severe)

Define disease
some definitions include:
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A disorder of structure or function in a human, animal, or plant, especially one that produces
specific symptoms or that affects a specific location and is not simply a direct result of
physical injury

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(an) illness of people, animals, plants, etc
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A disease is a particular abnormal condition, a disorder of a structure or function, that
affects part or all of an organism

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The type of disease that we are going to concentrate on over the next five weeks are the
diseases caused by microorganisms (pathogen)

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Pathogen: a microorganism that has the potential to cause disease
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Therefore the term ‘Microorganism’ is a broad term used to group a number of different
organisms together
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1688 ~Francesco Redi published his work to debunk spontaneous Generation
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3 pieces of neat, 1 exposed, on covered with paper and one with net
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Some people still believed microorganism came from spontaneous generation

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1748 - A priest John Needham proved spontaneous generation

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Boiled meat then placed it in flasks and put a stopper on it
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They are essential for all aspects of our lives:
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Health – Digestion, help produce vitamins in the gut like K and folic acid,
outcompete dangerous bacteria, genetic engineering
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Medicine – research, antibiotics, insulin production (in bacteria)

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Environment – Water waste systems, recycling dead animal and plants releasing
nutrients
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g
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It
creates an impermeable barrier to most molecules
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Prokaryotic structures
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Capsule – protection and helps keep bacteria together

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Cytoplasm – Liquid within cell holding nutrients etc

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Ribosomes – Free floating and helps with protein production

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Nucleoid – Contains DNA and used for replication

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Plasma membrane – acts as a barrier controlling what enters and leaves the cell

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Flagellum – controls the movement of the cell

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Cell Wall – Gives strength to the cell to stop it busting do to difference inside the cell and
outside

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Fimbriae – help gram negative bacteria stick to each other

Eukaryotic cells
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Includes all plants and animals as well as many single celled organisms: algae, amoebae,
fungi and moulds
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The most obvious being a nucleus
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Plant cells

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Surrounded by a rigid cell wall and contain a large membrane bound vacuole and
chloroplasts

Similarities and differences between prokaryotes and eukaryotes
Component

Prokaryote

Eukaryote

Size

2μm (2 x 10-6 m)

10 – 100 μm
(1x10-5 – 1x10-4 m)

Amount of DNA

1
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Prokaryotes also differ from eukaryotes in that they contain only a single loop of stable
chromosomal DNA, while eukaryote DNA is found on tightly bound and organised
chromosomes
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In prokaryotes many processes occur across the cell membrane; rather then within the cell
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Bacteria
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Found everywhere
Many cause illness
Some cause spoilage of food
Some essential → skin flora, gut flora
(skin & intestinal microbiota)
Many harmless, many mutualistic

Prokaryotic fission (Binary fission) → asexual reproduction → cells genetically identical
Virus
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Is a virus living or non-living?

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A virus is a simple microorganism consisting of either RNA or DNA surrounded by a coating
of either protein and fat, or glycoprotein
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This
immune response causes us to have symptoms such as the common cold
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Fungi
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Fungi are eukaryotes which means

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they have a defined nucleus and organelles
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three types
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1) moulds (filamentous) growth and multicellular structures,

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2) yeasts (non-filamentous) and tend to be single celled

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3) mushrooms which produces spores
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Not all reproduce by mitosis as with animal cells some do by binary fission like bacteria
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Examples: Giardia and malaria

Algae (blue/green)
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Algae are eukaryotic (nucleus-bearing) organisms
Photosynthetic organisms
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Does not always fit with definition of microorganism

Prions (a specific type of misfolded protein)
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Misfolded proteins with the ability to transmit their misfolded shape onto normal variants of
the same protein
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Different to other microorganism such as viruses, bacteria, fungi and parasites, as they all
contain nucleic acids (DNA, RNA or both)
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genetically as a dominant trait

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2
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Inherited – Familial Creutzfeldt-Jakob disease

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2

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