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1

the study of microbes

Microbiology

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forms of life too small to be seen with the naked eye (bacteria, fungi, algae, protists).

Microbes

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

Microbiology

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If microbiology is the study of microscopic life, what is the basis for life?

Metabolism
Growth
Reproduction
Genetic variation/evolution
Response/adaptation to the external environment
Homeostasis (maintaining internal organization and order, usually by expending energy)

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What is the subunit of polypeptides?

Amino Acids

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These function as enzymes which catalyze the vast majority of biochemical reactions in the cell. Other proteins are structural components of cells

Amino Acids, formed by the polypeptide macromolecule

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What are the two subunits of nucleic acids

Deoxyribonucleotides
Ribonucleotides

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These nucleic acid subunits are informational; they provide the instructions for assembly and reproduction of the cell

Deoxyribonucleotides

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These nucleic acids serve many functions, most of which are involved in the production of polypeptides. Some serve structural or catalytic functions.

Ribonucleotides

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Do the lipids have unitary or diverse substructures?

Diverse Structures

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The subunits of this macromolecule are structural and make up cellular membranes that form physical boundaries between the inside of the cell and surroundings and the membranes of internal organelles

Lipids

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What are the subunits of polysaccharides?

Sugars

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These subunits of polysaccharides are structural, form things such as cellulose and chitin, and are used as energy storage, like glycogen and starch

Sugars

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Which subunits of a cell take up the most weight (50-55%)?

What next (15-20%)?

What next (10%)?

What next (6-7%)?

What next (2-5%)

Amino Acids

Ribonucleotides

Lipids

Sugars

Deoxyribonucleotides

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These are also critical as storehouses of genetic information.

Nucleic acids (DNA/RNA)

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In fact, comparisons of DNA sequences are how we can break life into three large groups known as

Domains

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Up until the 1970s, organisms had been placed into one of two categories, depending upon whether or not they had an interior set of membrane bound structures (mitochondria, nucleus). What categories were these

Prokaryotes (no organelles)

Eukaryotes (organelles)

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In the 1970s, DNA sequencing was used to compare sequences of ribosomal RNA genes in different organisms. This led to a new scheme of organizing life into three domains:

Bacteria, Archea, Eukarya

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In which of the three domains can a nuclear membrane be found?

Eukarya

not bacteria or archea

20

Are membrane-bound organelles found in bacteria?

Are membrane bound organelles found in archea?

Are membrane bound organelles found in eukarya?

Rarely, a few found in a few species

Rarely, a few found in a few species

Yes, multiple distinct types found in all species

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Is the plasma membrane found in bacteria similar to eukarya?

Is the plasma membrane found in archea similar to eukarya?

Yes

No. Different than bacteria and eukarya

22

How frequently is a cell wall in bacteria? What is it made of?

How frequently is a cell wall in archea? What is it made of?

How frequently is a cell wall in eukarya? What is it made of?

Nearly all species. Peptidoglycan

Nearly all species. Various materials

Some species. Various materials.

23

What is the RNA polymerase like in bacteria?

What is the RNA polymerase like in archea?

What is the RNA polymerase like in eukarya?

Single polymerase

Single polymerase, eukarya like RNA pol II

Three main polymerases (RNA pol I, II, and III)

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Do bacteria contain histones?

Do archea contain histones?

Do eukarya contain histones?

No. Histone-like proteins.

Yes.

Yes.

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These microbes aren't considered to be alive

Viruses

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Do viruses have much activity outside of a host cell?

No. They are inert and non-reactive outside of a host cell..

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Why study microbes?

1) They are very fast, cheap, and easy to grow.
2) They can produces enzymes and other molecules for industrial/medical uses
3) Most of them have small numbers of genes, so they are easy to study
4) Genetic manipulation of single celled bacteria is usually much easier than multi-cellular bacteria

28

The very early environment on Earth was drastically different than it is today.
There was little ________ in the atmosphere, and the surface of the planet was a soup of chemicals in liquid form.

Oxygen

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The early atmosphere and environment of Earth led to the initial synthesis of the first forms of (and their use in primitive single-celled life)

Macromolecules

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In the 1950s, a grad student named Stanley Miller worked with his mentor, Harold Urey, to simulate the “spark” that might have started forming organic molecules from the primordial soup.

Miller-Urey Experiment

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Multicellular fossils dating to about _________ ybp (years before present) have been found—meaning microbes dominated the planet for approximately 3.5 billion years!

0.5 billion ybp

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Some microbial fossil records do exist, largely in fossilized mats discovered in

Australia

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But molecules alone aren’t life—so how did early organic molecules change into the four macromolecules of cells today?

Early iron-containing surfaces may have helped provide the right environments by “sticking” the molecules to their surfaces.

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any early life would still need to have genetic information, the ability to catalyze biochemical reactions, and a way of separating the cell interior from the external environment. Are there molecules or structures that might satisfy those requirements?

Yes. RNA!

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Some RNA molecules have the ability to catalyze reactions, these are known as

RNA could serve the dual purpose of genetic information storage AND catalyzing reactions!

Ribozymes, a combination of ribonucleic acid and enzymes

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Early compartmentalization may have had a single lipid layer as an early form of plasma membrane, called...

This could have formed a crude way of separating interior contents from the external environment

Micelle

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So then, the basic idea of how microbial life arose on Earth is:
Early conditions formed ____ and _______.
These came together into a primitive cell using ____ for storing genetic info and coding.
Primitive cells eventually changed from using RNA to ____ instead for storing their genetic information.

RNA and micelles
RNA
DNA

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A theory of eukaryotic evolution that Primitive prokaryotic microbes ingested other microbes, starting a symbiotic relationship, forming the first basic eukaryotes.

Endosymbiotic theory

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Under endosymbiotic theory, ingested microbes that could use oxygen for a respiratory process to produce chemical energy became

Mitochondria

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Under endosymbiotic theory, ingested microbes that could fix carbon dioxide into organic molecules using light energy became

Chloroplasts

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Name two reasons why bacteria and humans use double-stranded DNA for storage of genetic information, and not single-stranded RNA

1) DNA provides a backup copy of genetic info in case of a problem

2) DNA is more stable than RNA

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DNA is transcribed into a ‘working copy’ in the form of ____, which is translated into the proteins needed to make a cell work

messenger (m)RNA

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What are the other forms of RNA that show its versatilty?

tRNA, rRNA

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How do we use DNA and RNA information to study the genetics of microbes today? In other words, what are the 2 perspectives?

Examining effects of single mutations in DNA individually

Studying and comparing pieces of genomes to each other (bioinformatics) across domains

45

What is the classic example of microbial engineering, where humans massed produces molecules they wanted?

E.Coli, done in 1978 by Genentech in San Francisco

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In terms of microbial metabolism and energy, what is the term for a microbe that ingests pre-formed organic molcules?

What is the term of a microbe that produces organic molecules?

Which of these helped change the earth's early atmosphere over time?

Heterotroph

Autotroph

Autotrophs

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Regardless of how microbes GET organic molecules, they are then broken down by microbes to harness chemical energy in the form of

ATP

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Metabolism that doesn’t need oxygen but doesn’t yield much energy for microbes.

Metabolism that does require oxygen but yields MUCH more energy!

Fermentation

Aerobic Respiration

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This is a process in which inorganic molecules are cycled to organic molecules and back again, and microbes can aid it as they interact with the environment

Biogeochemical Cycling

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Do microbes exist as individual cells/populations?

No! Microbes live in diverse groups in nature, with many different members forming a microbial community and ecosystem.
Ex)
Microbes in the intestines
Plaque on teeth
Slime on rocks on beaches
Mold growths on bathroom surfaces

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Whose ideas changed the preconceived notions of microbes and their role in diseases?

Louis Pasteur and Robert Koch

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An old theory that microbes could form spontaneously as life from nonliving matter

Spontaneous generation theory

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This person performed a simple yet elegant experiment to disprove spontaneous generation theory in the late 1800s, explain it.

In a flask with a long curved neck, broth was boiled to sterilize it. The sterilized broth was allowed to cool. Microbes became trapped in the bent neck of the flask. The broth remained sterile. When the flask was tilted, it contacted microbes in the neck and microbes replaced the broth

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What diseases did Robert Koch discover the cause of?

Anthrax and Tuberculosis

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This person's experiments established basic rules which made it possible for others to determine which microbes caused which diseases. They are still in use to this day.

Robert Koch

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What caused the great change in deaths in the population from 1930 to 1950?

What is demonstrated by the trends in Africa and the rest of the world?

Antibiotics

Cultural/economic differences cause different disease rates

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Some microbial diseases have had a profound impact on humanity, like...

The plague

58

In the twentieth century, we have seen a dramatic drop in U.S. deaths from

but not

Infectious disease

Noninfectious causes

59

What has caused the reduction in deaths from infectious diseases?

Treatment (antibiotics)
Antiseptics (Joseph Lister)
Sanitation improvements (sewage treatment)
Food/water safety (pasteurization)
Personal hygiene improvements
Vaccination