MCROBIO 1.1-1.3

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Questions and Answers

What is the old definition of microbiology?

study of organisms & agents too small to be seen by the naked eye

What is the new definition of microbiology?

the study of organisms that can exist as single cells and are capable of replicating their genome

Which of the following is not a field of microbiology?

Bacteriology

Zoology (correct)

Virology

Mycology

Viruses are excluded from the new definition of microbiology.

False Signup and view all the answers

What is one main benefit of microorganisms?

They can decompose organic material. Signup and view all the answers

What type of fermentation does yeast perform?

Ethanol and Carbon Dioxide production Signup and view all the answers

The Greeks attributed disease to bad air, known as ______.

miasmatic odors Signup and view all the answers

Which microorganism is responsible for making bread rise?

Saccharomyces cerevisiae Signup and view all the answers

The Romans ignored sanitation in their cities.

False Signup and view all the answers

What is primarily observed when microorganisms are cultured on solid media?

Cultural characteristics on agar plates Signup and view all the answers

Which of the following statements about microbial motility is accurate?

Some microorganisms do not exhibit motility. Signup and view all the answers

How is the term 'growth' defined in the context of microbiology?

The increase in cell number due to cell division Signup and view all the answers

What key factor influences the activities of microorganisms in their environments?

Interactions within microbial communities Signup and view all the answers

What is the primary purpose of using semi-solid media in microbiology?

To observe the motility of microorganisms Signup and view all the answers

What is one of the interconnected themes of microbiology?

Understanding microbial life processes for the benefit of humankind Signup and view all the answers

Which process describes the growth of a microbial cell on a solid nutrient medium?

Cell division Signup and view all the answers

Which of the following correctly describes a branch of microbiology?

Protozoology is the study of protozoa Signup and view all the answers

Which statement about the role of microorganisms in ecosystems is true?

Decomposition by microorganisms impacts global ecosystems. Signup and view all the answers

What characterizes exons in the context of a eukaryotic genome?

They are segments that encode proteins. Signup and view all the answers

Which of the following is a technique used to isolate colonies in microbiological studies?

Streak plate method Signup and view all the answers

Which statement about the new definition of microbiology is accurate?

Viruses are included in the study of microbiology. Signup and view all the answers

Which of the following is an application of microbiology?

Developing antibiotics from microorganisms Signup and view all the answers

Which characteristic is true regarding the genomes of bacteria compared to eukaryotes?

Bacteria do not have introns. Signup and view all the answers

What is the primary purpose of using a quadrant streaking method in microbiology?

To isolate pure colonies from mixed cultures. Signup and view all the answers

Which option represents a key characteristic of microorganisms in the new definition?

They can replicate their nucleic acid genome at some life stage. Signup and view all the answers

What role do microorganisms play in human society according to modern understanding?

They contribute to renewable energy sources. Signup and view all the answers

Which statement accurately describes the genome of viruses compared to cellular organisms?

Viruses have a genome that can be RNA or DNA. Signup and view all the answers

How do microorganisms influence global ecosystems?

Through their decomposition activities Signup and view all the answers

What defines the concept of 'pure culture' in microbiology?

A culture consisting of only one species. Signup and view all the answers

Which of the following statements is correct regarding introns and exons?

Introns are present only in eukaryotic cells. Signup and view all the answers

What happens to endospores when they survive in unfavorable conditions?

They germinate into new microorganisms Signup and view all the answers

How does the surface-to-volume (S/V) ratio change as the size of a rod-shaped organism increases?

The S/V ratio decreases with size Signup and view all the answers

What is a consequence of small cell size related to nutrient exchange?

Small cells exchange nutrients and wastes more rapidly Signup and view all the answers

Which mutation type is represented as beneficial?

Some mutations provide advantages in nutrient acquisition Signup and view all the answers

What is indicated about the efficiency of smaller cells compared to larger cells?

Smaller cells can synthesize more with a given mass of nutrients Signup and view all the answers

How does an increase in cell membrane affect nutrient absorption in cells?

More cell membrane allows for better nutrient absorption Signup and view all the answers

What factor is crucial for the growth of rod-shaped microorganisms concerning nutrient availability?

Higher nutrients require smaller S/V ratios Signup and view all the answers

What role do flagella play in certain microorganisms?

They serve for motility and propulsion Signup and view all the answers

What is the main reason a microorganism may change its genus classification?

It was found to be more closely related to another organism. Signup and view all the answers

Which taxonomic rank directly below Domain is represented in the example of Escherichia coli?

Phylum Signup and view all the answers

What is required for proper microbial characterization?

Study of multiple genetically identical cells. Signup and view all the answers

The term 'Taxon' refers to what in biological classification?

A group of organisms. Signup and view all the answers

Bergey’s Manual is important for which purpose?

It acts as a standard reference for identifying and classifying prokaryotes. Signup and view all the answers

Which of the following is true about the naming of bacteria?

Names must conform to the International Code of Nomenclature. Signup and view all the answers

In the context of microbial life, the three major groups include Bacteria, Archaea, and what other group?

Eukarya. Signup and view all the answers

Which of the following ranks is NOT part of the taxonomic classification of Escherichia coli?

Kingdom Signup and view all the answers

What are the two types of Bergey’s Manuals mentioned?

Systematic and Determinative. Signup and view all the answers

What is a prerequisite for the process of microbial characterization?

Use of pure culture. Signup and view all the answers

What is the role of the International Journal of Systematic & Evolutionary Microbiology?

It is the official publication of record for taxonomy and classification. Signup and view all the answers

Which classification system primarily relies on molecular identification in addition to morphological characteristics?

Bergey’s Manual of Determinative Bacteriology. Signup and view all the answers

What does the abbreviation 'PCOFGS' refer to in the context of domains?

It signifies a smaller group within the three major domains. Signup and view all the answers

Study Notes

Exploring the Microbial World

Microorganisms play a crucial role in global ecosystems, particularly in decomposition and the nitrogen cycle.
Old definition of microbiology limited to invisible organisms; new definition includes those replicating nucleic acid genomes, encompassing viruses.

Basic Microbiology

Fields of study:
- Virology for viruses
- Mycology for fungi
- Phycology for algae
- Protozoology for protozoa
- Bacteriology for bacteria.

The Science of Microbiology

Microbiology focuses on understanding living organisms and their application for humankind's benefit.
Microorganisms offer both positive and negative effects; most are harmless and beneficial, aiding in processes like food fermentation.

A Brief History of Microbiology

Microorganisms are considered the first forms of life, adapting and thriving in various environments, which significantly contributes to the oxygen supply on Earth.

Scope & Relevance of Microbiology

Key contributions of microorganisms include:
- Fermented foods and beverages, where yeast (e.g., Saccharomyces cerevisiae) converts carbohydrates to alcohol and carbon dioxide.
- Historical beliefs regarding disease: Ancient Greeks associated illness with "bad air" (mal’aria) and miasmas, prompting sanitation practices.
- Roman advancements in public health with aqueducts and sewage systems due to the miasma hypothesis.

Introduction to Microbiology

Global ecosystem heavily relies on microbes for various processes, including decomposition and nitrogen conversion.
Microorganisms influence human society, exemplified by the discovery of antibiotics like penicillin derived from fungi.

Definitions and Scope

Microbiology now defined as the study of organisms that exist as single cells or acellular forms with a nucleic acid genome capable of self-replication.
Inclusion of viruses in microbiology's definition reflects their importance in understanding microbial life.

Themes and Applications

The science of microbiology focuses on understanding microbial life and its applications for human benefit and the health of Earth.
Various culture media types include:
- Liquid media for large-scale microbial culture with easy nutrient access.
- Solid media for estimating cell counts and examining cultural characteristics.
- Semi-solid media to observe microbial motility.

Growth in Microbiology

In microbiology, "growth" refers to cell number increase through division rather than physical size.
A single microbial cell can proliferate into millions, forming visible colonies.
Endospores can survive extreme conditions and germinate into active microorganisms.

Cell Structure and Functions

All cells contain a DNA genome, which encodes essential proteins and RNA.
Prokaryotic cells lack introns, distinguishing them from eukaryotic cells.
Surface-to-volume (S/V) ratio affects nutrient exchange; smaller cells exhibit higher efficiency in nutrient uptake compared to larger cells.

Cell Size Implications

Microscopic examination reveals that smaller cells can exchange nutrients and wastes more rapidly, making them more efficient in free-living environments.
16S ribosomal RNA is used for prokaryotic classification, while 18S is used for eukaryotes.

Nomenclature and Taxonomy

Classifications based on new discoveries can lead to genus reassignments for organisms, reflecting evolutionary relationships.
The taxonomic hierarchy includes Domain (e.g., Bacteria), Phylum (e.g., Proteobacteria), Class (e.g., Gammaproteobacteria), Order (e.g., Enterobacteriales), Family (e.g., Enterobacteriaceae), Genus (e.g., Escherichia), and Species (e.g., Coli).
Two primary references for prokaryotic classification are Bergey’s Manual of Systematic Bacteriology and Bergey’s Manual of Determinative Bacteriology.

Characterization and Identification

Characterization of microorganisms typically involves studying populations of identical cells rather than individual cells.
Importance of pure cultures for accurate identification and characterization is emphasized.
Microorganisms are categorized into three domains: Bacteria, Archaea, and Eukarya, each representing major cell lineages.

Taxonomic Framework in Microbiology

International Code of Nomenclature for Bacteria regulates naming conventions.
Approximately 30 major phylogenetic lineages exist among Bacteria, with some species successfully cultured, but many remain uncharacterized.

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Description

Dive into the essentials of microbiology with this quiz, covering the significance of microorganisms in ecosystems, their various fields of study, and their historical context. Explore the dual nature of microbes as both beneficial and harmful to humanity.