MICRO -chp1

What is microbiology?

The study of organisms too small to be seen without magnification (a microscope).

What is a microorganism/microbe?

An organism too small to see with the naked eye — the actual thing that microbiology studies.

What are the major groups of microorganisms?

Bacteria

Viruses

Fungi

Protozoa (single-celled eukaryotes)

Algae

Helminths (worms).

What are the primary fields of microbiology, and what does each one do?

• Medical Microbiology / Public Health / Epidemiology – studies effects of microbes on humans; monitors/controls disease spread in communities (CDC, USPHS)

• Biotechnology / Genetic Engineering / Industrial Microbiology – uses microbes to make products (beer, vaccines) at large scale

• Immunology – studies the body's reactions to pathogenic microbes (blood testing, vaccination, allergies)

• Agricultural Microbiology – studies microbes and domesticated plants/animals (plant disease, soil fertility, livestock infections)

• Food Microbiology – studies microbes' impact on food supply (spoilage, foodborne disease, food production)

What are the basic characteristics of a prokaryotic cell?

Microscopic, single-celled, lacks a nucleus, lacks membrane-bound organelles.

What are the basic characteristics of a eukaryotic cell?

Has a true nucleus, has membrane-bound organelles, can be single-celled (microscopic) or multicellular.

How long have bacteria-like organisms (prokaryotes) existed on Earth, and what does this tell us about evolutionary origins?

About 3.5 billion years — this makes prokaryotes the ancestral cell type, with eukaryotes evolving later.

According to endosymbiotic theory, how did eukaryotic cells likely evolve? (Additional explanation, not in lecture slides)

Mitochondria and chloroplasts were once free-living prokaryotes that were engulfed by a larger cell and became permanent organelles.

What are the two major ecological roles of microbes in Earth's ecosystems?

Photosynthesis and decomposition.

What two big jobs do microbes do for Earth?

1. Photosynthesis – make oxygen and food from sunlight (over half of all photosynthesis on Earth is done by microbes!)

2. Decomposition – break down dead stuff and recycle nutrients back into nature

Real life: Ocean algae make about half the air you breathe.

What are the three basic structural categories of microbes?

Prokaryotes (no nucleus, no membrane-bound organelles)

Eukaryotes (true nucleus, membrane-bound organelles)

Viruses (acellular, made of DNA or RNA plus protein).

What is the general size order of microbes, from smallest to largest?

Viruses < prokaryotic cells < eukaryotic cells.

How do viruses differ from cellular microbes?

Viruses are not made of cells, contain only DNA or RNA (never both), and cannot reproduce independently — they require a host cell.

What are three everyday products humans make using microorganisms?

Bread, cheese, and alcoholic beverages (also antibiotics).

What is biotechnology, and what are two examples from lecture?

Large-scale manipulation of microorganisms for specific products (food, drugs, vaccines), including genetic engineering.

Examples: algae farmed for oil extraction as a petroleum substitute, and modified crops for drought/heat tolerance and insect resistance.

What is bioremediation, and what are examples of its use?

Using living organisms to remedy an environmental problem or contamination. Examples: oil spill cleanup, water and sewage treatment, degradation of solid waste in landfills, and cleaning soils contaminated with pesticides, heavy metals, or radioactive waste.

What is a parasite?

An organism that lives on or in the body of another organism (the host) and is harmful to that host.

What is a pathogen?

A disease-causing microbe.

Are most microbes harmful to humans?

No — most microbes are free-living and relatively harmless; many are beneficial.

What is the scale of human infectious disease, according to lecture?

Nearly 1,500 different microbes cause human diseases; about 10 million deaths per year worldwide from infections, with the majority occurring in developing countries where many cases are preventable or treatable with access to drugs and vaccines.

What are examples of noninfectious diseases caused by microbes?

Gastric ulcers (Helicobacter pylori), infertility (Chlamydia), cervical and other cancers (human papillomavirus), liver cancer (hepatitis viruses); the microbiome also affects overall human health.

Who first observed microorganisms using a microscope?

Leeuwenhoek.

What is the difference between spontaneous generation and the theory of biogenesis?

Spontaneous generation is the incorrect idea that life arises from non-living matter; biogenesis is the idea that life only comes from preexisting life.

Who proved biogenesis over spontaneous generation, and what else did they contribute to microbiology?

Louis Pasteur — his experiments supported biogenesis; he also developed vaccines against rabies and anthrax, described microbial fermentation in wine/beer, invented pasteurization, and was one of the first to show human disease could be caused by microbial infection.

Who developed the postulates for proving a microbe causes a specific disease, and what else did they contribute?

Robert Koch — his postulates were used to discover the causal agents of 20 diseases between 1875–1900 and are still used today; he also helped invent standard techniques like inoculation, isolation, growth, and maintenance of pure cultures.

What are Koch's Postulates?

1) The microorganism must be found in abundance in all diseased organisms and not in healthy ones.

2) It must be isolated from a diseased organism and grown in pure culture.

3) The cultured microorganism should cause disease when introduced into a healthy organism.

4) It must be re-isolated from that newly diseased host and identified as identical to the original agent.

What did Dr. Oliver Wendell Holmes observe about infection and childbirth?

Mothers who gave birth at home had fewer infections than those who gave birth in hospitals.

What did Dr. Ignaz Semmelweis discover about infection transmission?

He correlated infections with physicians coming directly from the autopsy room to the maternity ward without washing their hands.

What did Joseph Lister contribute to medicine?

He introduced aseptic techniques into surgery, including disinfecting hands with chemicals before surgery and using heat for sterilization, to reduce microbes and prevent wound infections.

What is the difference between sterilization and aseptic technique?

Sterilization requires eliminating all life forms, including endospores, viruses, and prions. Aseptic technique reduces the transmission of microbes but is not necessarily fully sterile.

What is the scientific method?

The process used to explain natural phenomena; inquiry driven by observation that leads to a hypothesis and testable predictions.

What makes a hypothesis valid?

It must be testable — capable of being supported or rejected by evidence.

What are examples of a testable versus non-testable hypothesis?

Testable: "Hemophilia is an inheritable disease." Non-testable: "Hemophilia is caused by a curse placed on the royal family."

What is the difference between a scientific fact, a hypothesis, and a theory?

A fact comes from direct and repeatable observations. A hypothesis is a tentative, testable explanation. A theory is a hypothesis supported by extensive data.

What is an example of a scientific theory from lecture, and why is it called a theory?

The Germ Theory of Disease — it's called a theory because it's supported by a large amount of evidence, not because it's uncertain.

What is taxonomy?

The organizing, classifying, and naming of living things.

What is the goal of nomenclature, and why are common names inadequate?

The goal is to give each organism one precise, universal name. Common names are non-descript and inconsistent — for example, Mountain Lion, Cougar, Panther, and Puma all refer to the same animal.

How is the binomial nomenclature system structured?

Two parts: the genus (first part, capitalized) and the specific epithet/species (second part, lowercase). Names are always italicized. The genus can be abbreviated after first use (e.g., P. concolor). Example: Panthera concolor.

What does it mean when organisms share the same genus name?

They are very similar — for example, Panthera pardus (leopard), Panthera leo (lion), Panthera onca (jaguar), and Panthera tigris (tiger) are all in the genus Panthera.

Can scientific names describe an organism's traits? Give an example.

Yes — for example, Micrococcus luteus: "micros" means small, "coccus" means berry, and "luteus" means yellow.

What does evolution explain about life on Earth?

The unity and diversity of life — all living organisms share a common ancestor, and new species originate from preexisting species.

What is the mechanism that drives evolution?

Natural selection — organisms most suited to their environment survive and reproduce at a higher rate. (happens in population)

How is evolutionary history used to study and classify organisms?

It's used to group species into phylogeny, based on shared morphological, biochemical, and physiological characteristics.

What are the three Domains of Life, and what defines each one?

Bacteria (true bacteria),

Archaea (bacteria-like organisms that live in extreme environments),

Eukarya (all eukaryotic organisms, which have a nucleus and organelles)

humans (eukaryotic cell) are closer to archea cells than bacteria