Intro to Microbiology

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Chapter 1: The Main Themes of Microbiology

What is Microbiology?
micron = small and biologia = study of living things

Microbiology = study of small living things
How small is “small”?
What do we really mean by living?

Working definition: Study of entities too small to be seen with the unaided human eye. •(< 0.2 mm = 200 µm = 200,000 nm)

Types of Microbes
Prokaryotes include Bacteria and Archaea
Eukaryotes include Protista (Algae and Protozoa), Fungi, and Animalia
Viruses are considered NON-LIVING

Size Range of Microbes

Relative Microbial Sizes

Characteristics of Living Organisms
Metabolism – enzyme-catalyzed chemical reactions
Bacillus cereus – YesBacteriophage T4 – No
Reproduction – progeny formed sexually or asexually
Bacillus cereus – YesBacteriophage T4 – Yes
Differentiation – different cell types can occur
Bacillus cereus – YesBacteriophage T4 – No
Communication – signaling within and between cells
Bacillus cereus – YesBacteriophage T4 – No
Locomotion – relative movement of cell or organism
Bacillus cereus – YesBacteriophage T4 – No
Evolution – genetic change over time
Bacillus cereus – YesBacteriophage T4 – Yes

Importance of Microbes
The study of microbiology is relevant to our everyday life in many different ways. 1.Microbes are the earliest organisms found in the fossil record 2.They perform essential reactions in the environment

3.Microbes can be harnessed to work for us
4.They sometimes cause infectious diseases

Microbes in the Fossil Record
The study of Evolutionary Biology
Microbes first appeared about 3.5 billion years ago
They were the only life forms on Earth for over 1.5 billion years

Microbes in the Environment
Study of Environmental Microbiology
Microbial photosynthesis account for most of the atmospheric oxygen on Earth
Microbes are essential for decomposition of dead organisms
Many biologically important elements (Sulfur, Nitrogen, Phosphorus) are cycled by microbes

Harnessing the Power of Microbes
Studies of Industrial Microbiology and Food Microbiology •Microbes can be used to make or preserve food products (e.g. yogurt, salami, cheeses) •Microbes can produce important compounds (e.g. antibiotics, MSG, ethanol)

Biotechnology
Studies of Recombinant Biology, Molecular Biology, and Agricultural Microbiology •Microbes can be altered or manipulated to produce useful products or modify other organisms.

Microbial Diseases
Some microbes cause infectious diseases
Only a few percent of all microbes are associated with disease

Sub-Disciplines by Organism
Microbiologists are sometimes referred to by the type of microbial system that they study •Bacteriology: Study of prokaryotes
Mycology: Study of fungi
Phycology: Study of algae
Protozoology: The study of protozoa
Virology: The study of viruses
Immunology: The study of the immune system

The Discovery of Microbes
People have long been aware of the effects of microbial growth •Spoilage, disease, decomposition
Microbes are too small to be seen even with hand lenses
Microscopes changed that

Robert Hooke
1664
English naturalist
and architect
May have been the first to see microorganisms
Coined the word “cell” to describe what he saw while viewing tree bark from a cork oak.

Antonie van Leeuwenhoek
1684
Dutch fabric merchant
First person to accurately describe living microbes
Used a simple microscope
Made and reported many detailed observations

The Spontaneous Generation Debate
Once microbes were discovered, early microbiologists were drawn into the debate over spontaneous generation. •Biogenesis: living things originate from other living things •Spontaneous generation (abiogenesis): life rapidly appears from non-living things.

Early Origins of Abiogenesis
Aristotle: 400 BC – Favored spontaneous generation
He was a...
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