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Flashcards in Introduction to Microbiology Deck (28):

What is microbiology?

The study of life and microorganisms that are too small to be seen with the naked eye


What is a prokaryote and which microbe groups are prokaryotes?

Prokaryotes lack a nucleus and any other membrane bound organelles. They include bacteria and archaea


What is a eukaryote and which microbe groups are eukaryotic?

Eukaryotic cells contain complex structures enclosed within membranes as well as a nucleus. Fungi, protozoa and algae.


What are non-living entities?

These are viruses. They are called non-living because they only reproduce in other organisms. They are microorganisms.


Why would life not exist without microorganisms?

Earth - 4.6 billion years old. 1st life was bacterial - 3.8 billion years ago. Anoxic atmosphere - anaerobic metabolism such as methanogens producing methane. Evolved to light harvesting organisms - purple bacteria. Evolved to cyanobacteria - oxygenated atmosphere. Eukaryotic cells evolved. Life exclusively microbial until 500-800 million years ago


Why can microbes be harmful?

Microorganisms can cause disease such as malaria (but few microbes are pathogenic) They can cause veterinary and agricultural problems They can cause food spoilage or contaminate water supplies


Why are microbes essential for life?

Release oxygen into the atmosphere Soil, marine and freshwater microbes form basis of foodchains In agriculture they recycle nutrients, carbon, sulphur and phosphorus Microbes in the gut of ruminant animals breakdown cellulose Fermented foods such as alcohol,vinegar, cheese Food additives such as citric acid Soil microbes break down organic matter Degrade or detoxify pollutants such as oil and mercury


How can microbes be used as biological insecticides?

Microbes that are pathogenic to insects can be used on agricultural crops. Bacillus thuringiensis infections are fatal in insects but harmless to humans and plants.


What industrial chemicals can be made by the help of microbes?

Vitamins, alcohols and solvents, organic acids, enzymes and drugs. Can also be manipulated to make substances not normally made by the microbe - e.g. digestive aids, insulin


Microorganisms are ubiquitous. What does this mean?

This means they are present everywhere. In all types of ecological niches.


List some examples of ecological niches where microbes may be found.

Soils, oceans, freshwater, Antarctica, hot springs, hydrothermal vent, nuclear reactors


What is an ecological niche?

An ecological niche is the role and position a species has in its environment; how it meets its needs for food and shelter, how it survives, and how it reproduces.


Microorganisms exist in interacting populations called...

Microbial communities


The environment in which a microbial population lives in is its...



The microbial communities and physical and chemical constituents in their environment is referred to as an...



What is the study of microbes in their natural environments called?

Microbial ecology


What is the diversity and abundance of microbes in a microbial community controlled by?

Resources such as food and conditions such as temperature, pH,


Microbes can interact with each other to...

Help microbes that can help each other and kill off any competition


Microbes interact with their chemical and physical environments in what ways?

Resources are utilised. Waste products are released and environmental conditions may be altered.


Microbial communities are dynamic, what does this mean?

They are constantly prone to change - they expand and contract


Describe one way in which a microbial community is dynamic

O2 is essential to some microbes but poison to others. O2 consuming microbes remove oxygen from a habitat. The habitat becomes anoxic. Conditions favour the growth of the anaerobic microbe.


Microbes can attach to solid surfaces and form...



How can biofilms be good?

They can protect mucous membranes from harmful microbes


How can biofilms be negative?

They can clot medical implants, joint prostheses and catheters. They can cause infections, e.g. endocarditis which is the inflammation of the heart


Why are biofilms such a problem?

They are often antibiotic resistant


What are microbial communities present in or on the human body called?

The normal microbiota / microflora


Why is the normal microbiota a good thing?

They prevent the growth of pathogens and produce growth factors such as folic acid and vitamin K.