Microbiology Basics

MB 302

HOMEWORK #1: Intro, history

1) Microbes play major roles in our lives and the biosphere. Draw a simple microbially mediated carbon cycle that links organic carbon and carbon dioxide. In one or two sentences, explain how microbes mediate this cycle.

In this cycle microbes conduct processes like fermentation, which larger organisms cannot carryout themselves, but are hugely necessary in order to obtain organic carbon.

2) For each statement below determine if it is True or False.

There are no bacteria in seawater because the salinity is too high. False

There are no bacteria in toxic waste because the chemical compounds are too harsh. False

There are no bacteria in yogurt because they would make you sick. False

There are no bacteria in hydrothermal vents because it is far too hot. False

3) What is the approximate size of the average bacterium in m? ___2___

What is the approximate size of the average bacterium in mm?___0.002___

4) Why do viruses that cause disease invalidate Koch’s postulates?

Because they are Asymptomatic carriers. People/organisms can have the virus but show no symptoms (Postulate 1)

5) Draw a simple tree of life that shows the basic relationships between the three domains recognized today.

Bacteria Archea Eukaryota

6) Who is credited with redrawing the taxonomic tree into the three-domain system?

Carl Woese

7) What are “Prokaryotes” and how do they differ from “Eukaryotes?” Circle the domain(s) in your tree above that is/are considered prokaryotes.

Prokaryotes lack a nucleus & nuclear envelope whereas Eukaryotes DNA & RNA are contained in the nucleus.

Prokaryotes also lack a mitochondria

8) Go to: http://phenomena.nationalgeographic.com/2015/05/06/new-loki-microbe-is-closestrelative-to-all-complex-life/

Using information from this article, draw a simple diagram that illustrates the emergence of eukaryotes from an alphaproteobacterium and Lokiarchaeum.

“Loki”

“alpha”...