chapter 1 learning objectives

Question 1

define microorganisms

Answer 1

a large, diverse group of microscopic organisms that exist as single cells or in cell clusters. they are able to live alone in nature independently of multicellular organisms

Question 2

describe the role and impact of microbes on earth

Answer 2

deeply involved in the flow of energy and food through earth’s ecosystems. play a role in both anoxygenic and oxygenic photosynthesis: bacteria changed the atmosphere to one without oxygen to one with oxygen. photosynthetic microorganisms account for more than 50% of earth’s photosynthesis, contributing most of the oxygen to the atmosphere. also play a role in decomposition and nutrient recycling by breaking down dead matter and wastes into simple compounds

Question 3

explain how humans have manipulated microorganisms for their own uses over the millenia

Answer 3

examples are baker’s and brewer’s yeast, cheese production, and moldy bread on wounds. biotechnology. genetic engineering (manipulation of genetics of microbes, plants, and animals in order to create new products and GMO’s). recombinant DNA technology (altering DNA of one organism by transferring genetic material from another organism). bioremediation (the introduction of microorganisms into the environment to restore stability).

Question 4

summarize the relative burden of human disease caused by microbes

Answer 4

there are about 2000 microbes that cause disease (pathogens) which is less than 1% of microbes

Question 5

define prokaryotes and eukaryotes

Answer 5

prokaryotes have no membrane-bound nucleus. lack various organelles bound with phospholipid membranes, reproduce asexually, smaller than eukaryotes
eukaryotes have a membrane bound nucleus and are larger than prokaryotes with numerous organelles.

Question 6

list 6 groups of microorganisms and differentiate them from one another

Answer 6

1. bacteria- prokaryotic. cell walls with peptidoglycan and are unicellular
2. archaea- no peptidoglycan in cell walls and found in extreme environments.
3. fungi- eukaryotic. obtain food from other organisms. cell walls but no peptidoglycan. microscopic and macroscopic, can be useful or harmful. unicellular or multicellular. molds and yeasts included.
4. protozoa- eukaryotic. unicellular. no cell wall. live freely in water. mostly asexual reproduction but also sexual. most are capable of locomotion (flagella, cilia, pseudopodia)
5. algae- eukaryotic. unicellular or multicellular. photosynthetic. (unicellular algae produce most of the world’s oxygen). simple reproductive structures, categorized by pigmentation and composition of cell wall
6. viruses- non-living, not prokaryotic or eukaryotic. not independently living cellular organisms. much smaller and simpler than living cells. small amount of DNA OR RNA wrapped in protein and sometimes a protein-containing lipid membrane

Question 7

compare and contrast the relative sizes of microbes

Answer 7

eukaryotes-largest
prokaryotes-middle
viruses-smallest

Question 8

compare and contrast the scientists who studied spontaneous generation and explain why the debunking of this idea was so important to microbiology

Answer 8

Aristotle proposed spontaneous generation
Redi- when decaying meat was kept isolated from flies, maggots never developed
Needham- boiled beef gravy and infusions of plant material in vials and then sealed them with corks. vials were cloudy indicating microbial growth which reinforced the idea that microbes could arise spontaneously.
Spallanzani- boiled infusions and then sealed vials and his infusions stayed clear indicating that Needham either didn’t heat vials sufficiently or didn’t seal them tight enough. this proved spontaneous generation of microorganisms does not occur. microorganisms exist in the air and can contaminate experiments. this debate led to the development of the scientific method.

Question 9

explain the scientific method and why its important

Answer 9

ask a question, generate a potential answer, conduct experiment to test hypothesis, accept reject or modify hypothesis. this stopped scientists from explaining natural phenomena by a mixture of belief, superstition, and argument and start using observations and outcomes in carefully controlled experiments

Question 10

list and understand the significance of Koch’s Postulates

Answer 10

1. the agent must be present in every case of the disease
2. the agent must be isolated and grown in pure culture
3. the cultured agent must cause the disease when introduced to a healthy (experimental) host
4. the agent must be re-isolated from the diseased experimental host

Question 11

Correctly write the binomial name of a microorganism

Answer 11

the genus name followed by the species name. genus name is capitalized, species is lowercase. both are italicized or underlined (if italics aren’t available.