Chapter 1 lecture 1

Question 1

Definition of life.

Answer 1

Cells and organization.
Response to environmental changes.
Growth and development.
Biological evolution.
Energy use and metabolism.
Regulation and homeostasis.
Reproduction.

Question 2

What is microbiology?

Answer 2

Microbiology is the study of microbes.

• The field examines how microbes interact with humans, with food, and how they can be used BY humans (among other aspects).

Question 3

The Importance of Microorganisms

Answer 3

Most populous and diverse group of organisms.
Found everywhere on the planet.
Play a major role in recycling essential elements.
Source of nutrients and some carry out photosynthesis.
Benefit society by their production of food, beverages, antibiotics, and vitamins.
Some cause disease in people, plants, or animals.

Question 4

Characteristics of the Members of the Microbial World

Answer 4

Organisms and acellular entities too small to be clearly seen by the unaided eye.
Generally <1 mm, some macroscopic.
These organisms are relatively simple in their construction and lack differentiated tissues.

Question 5

Microbiology revolves around two themes:

Answer 5

1. Understanding basic life processes
   Microbes are excellent models for understanding cellular processes in unicellular and multicellular organisms
2. Applying that knowledge to the benefit of humans and planet Earth
   Microbes play important roles in medicine, agriculture, and industry

Question 6

Types of Microbial Cells

Answer 6

prokaryotic cells
eukaryotic cells

Question 7

prokaryotic cells

Answer 7

lack a true membrane-delimited nucleus
This is not absolute

Question 8

eukaryotic cells

Answer 8

have a membrane-enclosed nucleus
are more complex morphologically

Question 9

Classification Schemes

Answer 9

Two Group

Five Kingdom-Monera, Protista, Fungi, Animalia, Plantae

Three domain system – developed due to advances in molecular techniques

Carl Woese et al (1990 paper) based on a comparison of ribosomal RNA, divides microorganisms into:
Bacteria (true bacteria),
Archaea
Eukarya (eukaryotes)

Question 10

Evolution of the Three Domains of Life

Answer 10

Universal phylogenetic tree.

Based on comparisons of small subunit rRNA (SSU rRNA).
Aligned rRNA sequences from diverse organisms are compared and differences counted to derive a value of evolutionary distance.
Relatedness, but not time of divergence, determined this way.

Question 11

The 3 Classification Schemes

Answer 11

Three domain system, based on a comparison of ribosomal RNA genes, divides microorganisms into:
Bacteria (true bacteria).
Archaea.
Eukarya (eukaryotes).

Question 12

Domain Bacteria

Answer 12

Usually single-celled.
Majority have cell wall with peptidoglycan.
Most lack a membrane-bound nucleus.
Ubiquitous and some live in extreme environments.
Cyanobacteria produce significant amounts of oxygen.

Question 13

Domain Archaea

Answer 13

Distinguished from Bacteria by unique rRNA gene sequences.
Lack peptidoglycan in cell walls.
Have unique membrane lipids.
Some have unusual metabolic characteristics.
Many live in extreme environments.

Question 14

Domain Eukarya

Answer 14

1. Protists—generally larger than Bacteria and Archaea.
   Algae—photosynthetic.
   Protozoa—may be motile, “hunters, grazers”.
   Slime molds—two life cycle stages.
   Water molds—devastating disease in plants.
2. Fungi.
   Yeast—unicellular.
   Molds and mushrooms—multicellular.

Question 15

Acellular Infectious Agents

Answer 15

Viruses.
- Smallest of all microbes.
- Requires host cell to replicate.
- Cause range of diseases, some cancers.

Viroids.
- Infectious agents composed of RNA.

Satellites.
- Nucleic acid enclosed in protein shell.
- Must coinfect a host cell with a virus to complete life cycle.

Prions—Infectious proteins.

Question 16

Divisions and Types of Microbes

Answer 16

Cellular vs. Acellular Diagram

Question 17

Origins of Microorganisms

Answer 17

Last Universal Common Ancestor (LUCA)

• The root or origin of modern life is on bacterial branch but nature still controversial.
• Archaea and Eukarya evolved independently of Bacteria.
• Archaea and Eukarya diverged from common ancestry.

Question 18

What experiment was conducted to determine how the first microbial life arose?

Answer 18

In the 1950s, a grad student named Stanley Miller formed organic molecules from a primordial soup.

Question 19

What were the earliest molecules and what could they do?

Answer 19

original molecule-single molecule that could
1) do cellular work
2) replicate itself

Question 20

How did we get that perfect soup storm?

Answer 20

Mash of random and spontaneous combinations, maybe in water –> primordial soup

evolution of RNA molecules

Lipids in water create micelles, and water makes for association

removal of water –> disassociation and pressure

pieces together

Question 21

ribozymes

Answer 21

Discovered by Thomas Cech in 1981
RNA molecules that form peptide bonds
perform cellular work and replication