Lecture 1: Introduction

Question 1

What are the 2 definitions of microbiology?

Answer 1

1. Based on organism size - the study of very small organisms that cannot be seen by the unaided eye (<1 mm)
2. Based on techniques used - the set of general techniques used to study very small organisms. If we use the same techniques, we put organisms in the same basket.

Question 2

Give 4 examples of the types of lab techniques used to study microorganisms.

Answer 2

1. Use of microscope
2. Isolation of microorganisms (to ensure you’re only studying the one you’re interested in)
3. Sterilization (need a clean environment to ensure we’re only working with one bug)
4. Growing pure cultures using different types of culture media

Question 3

What is the difference between microorganisms and microbes?

Answer 3

Microbes specifically refer to harmful human pathogens, while microorganisms are ubiquitous and are not necessarily harmful to humans.

Question 4

What are microbiota and how are they different from microorganisms?

Answer 4

They are a subset of microorganisms found at any site on or in the human body.

Question 5

Give 2 examples of uses of microorganisms to humans.

Answer 5

1. Food industry - yeast to ferment wine and beer
2. Biotechnology - antibiotics, vitamins, enzymes, etc.

Question 6

Name the three kingdoms of life in which microorganisms are found.

Answer 6

Bacteria, archaea, eucarya

Question 7

What are three broad groups of microorganisms? Give 2 examples of each.

Answer 7

1. Prokaryotes/prokaryotic cells - bacteria, archaea
2. Eucaryotes/eukaryotic cells - algae, fungi, protozoa
3. Non-living microorganisms (acellular entities) - prokaryotic and eukaryotic viruses

Question 8

Explain the difference between the three broad categories of microorganisms.

Answer 8

Prokaryotes have no nucleus, so their DNA, proteins, etc. are free-floating in the cytoplasm. There is no internal division.

Eucaryotes have a nucleus and are compartmentalized into organelles, and the DNA is stored in the nucleus.

Non-living microorganisms are merely viruses, as they cannot reproduce by themselves and only reproduce by infecting other cells.

Question 9

Name 5 common attributes of life that microorganisms share.

Answer 9

1. Can grow (increase in size)
2. Have a metabolism
3. Motion (either moves by itself or has internal motion of some kind)
4. Reproduction (creating identical but separate entities)
5. Response to stimuli

Question 10

Explain the purpose of microorganismal metabolism.

Answer 10

They need to consume nutrients in order to acquire energy to grow and excrete the waste.

Question 11

Most microorganisms are ________.

Answer 11

Unicellular

Question 12

What is meant by internal motion of a microorganism?

Answer 12

This is the movement of macromolecules like the ribosome, DNA polymerase, etc.

Question 13

Who were the first people to suggest the existence of microorganisms? What was their hypothesis?

Answer 13

Lucretius and Girolamo Fracastoro both independently suggested that invisible organisms cause disease

Question 14

Who was the first to develop the microscope and when? What was its magnification level?

Answer 14

Zacharias Janssen in 1608. It could magnify 3X to 9X.

Question 15

Who was the first to describe and depict a microorganism? What did they observe?

Answer 15

Robert Hooke in 1665. He observed the reproductive structures (Sporangia) of the microfungus Mucor, which he depicted in his book Micrographia.

Question 16

Describe the structure of sporangia and how they work.

Answer 16

There are stems with cells attached. Some of the cells are open, while others are broken open. The fungus grows the stems with cells at the top that contain a spore, which can then spread elsewhere once the cells are broken open.

Question 17

What did Anthony van Leeuwenhoek discover and when? How did he describe them? What impact did this have on the scientific community?

Answer 17

He discovered bacteria and protozoa in 1674, which he called “animalcules”. He described them as being everywhere and as appearing in certain materials. This revived the old theory of spontaneous generation.

Question 18

What is spontaneous generation?

Answer 18

It is an old theory that living organisms spontaneously appear or develop from inanimate matter. It was the prevailing theory up until the 17th century.

Question 19

Give 2 examples of spontaneous generation.

Answer 19

Dust generates mites, decaying meat generates fly larvae and flies.

Question 20

How was the spontaneous generation theory disproven? By whom?

Answer 20

In 1665, Francesco Redi designed and performed an experiment to address the theory that flies are spontaneously generated from decaying meat. It consisted of an unsealed flask of meat, a sealed flask, and a flask covered with gauze. Flies accumulated on the gauze of the third flask and not on the sealed flask, showing that fly larvae only develop in meat that flies can reach. He claiming that this disproved spontaneous generation, although it just prompted more questions.

Question 21

How big is a typical bacterial cell?

Answer 21

1 micrometer.