Chapter 19

Question 0

Bacteria and Archaea

Answer 0

Prokaryotes; superficially similar in appearance, but striking structural and biochemical differences that reveal ancient evolutionary separation between the two groups.

Question 1

Which organisms are members of the domains Archaea and Bacteria?

Answer 1

Earth’s first organisms were prokaryotes, single-cell organisms that lack organelles such as nucleus, chloroplasts, and mitochondria. For the first 1.5 billion years, all life was prokaryotic. Predominant form of life.

Question 2

Peptidoglycan Molecules

Answer 2

Contained in cell walls of bacterial cells, a polysaccharide that also incorporates some amino acids, which helps strengthen the cell wall. Unique to bacteria, archaea does not have it on their cell walls.

Question 3

What is a structural and compositional differences between Archaea and Bacterial cells?

Answer 3

Their plasma membranes, ribosomes, and RNA polymerases, as well as mechanics of basic processes such as transcription and translation.

Question 4

Clades

Answer 4

Groups of species linked by descent from a common ancestor.

Question 5

Appearance of Colonies

Answer 5

Groups of individuals that descended from a single cell.

Question 6

The Gram Stain

Answer 6

A staining technique that distinguishes two types of cell-wall construction in bacteria. Depending on the results of the stain, these bacteria are classified as either gram-positive or gram-negative. Used as means of clade classification.

Question 7

How big are bacteria and archaea?

Answer 7

very small, ranging from .02 to 10 micrometers in diameter. (in comparison, the diameters of eukaryotic cells range from about 10 to 100 micro meters).

Question 8

Largest Known bacterium.

Answer 8

Thiomargarita namibiensis is 700 micrometers in diameter, visible to the naked eye.

Question 9

Cell wall that surround prokaryotic cells most common shapes are:

Answer 9

Spherical, rodlike, and corkscrew-shaped.

Question 10

How do prokaryotes survive and reproduce?

Answer 10

they adapt and both domains to inhabit and exploit a wide range of environments.

Question 11

Some prokaryotes are motile. What does this mean?

Answer 11

They can move about. - Many of these motile prokaryotes have Flagella and it may appear at one end of a cell, in pairs (one at each end of the cell), as a tuft at one end of the cell, or scattered over the entire cell surface.

Question 12

Flagella

Answer 12

Hair-like motile extension of the plasma membrane; it contains microtubules arranged in a 9+2 pattern. Propels some cells through fluids and allows to disperse into new habitats, migrate towards nutrients, and leave unfavorable environments.

Question 13

Anatomic differences between gram positive prokaryotes and gram negative prokaryotes

Answer 13

gram positive bacteria lack the outermost “wheels”

Question 14

Differences between bacterial flagella and archaeal flagella.

Answer 14

In bacterium flagella, a unique wheel-like structure embedded in the bacterial membrane and cell wall allows the flagellum to rotate. Archaeal flagella are thinner than bacterial and are constructed of different proteins. Archaeal flagella is still not well understood.

Question 15

Biofilms

Answer 15

Sticky layer of protective slime, composed of polysaccharide or protein, which protects the cells and helps them adhere to surfaces. Slime-secreting prokaryotes of one or more species aggregate in colonies to form communities known as biofilms. ex. Dental plaque, formed by bacteria that inhabits the mouth.

Question 16

Biofilms protection

Answer 16

Helps defend the embedded bacteria against a variety of attacks, including those launched by antibiotics and disinfectants. They are harmful to humans and very difficult to eradicate. Many infections of the body take the form of biofilms, including tooth decay, gum disease, and ear infections.

Question 17

Endospores

Answer 17

Rod-shaped protective structure bacteria that forms inside a bacterium that contains genetic material and a few enzymes encased within a thick protective coat that protects the bacteria. After an endospore is formed, the bacterial cell that contains it breaks open, and the spore is released to the environment. All metabolic activity ceases until the spore encounters favorable conditions, at which time metabolism resumes and the spore develops into an active bacterium.

Question 18

Prokaryotes are specialized for specific habitats

Answer 18

Even though they can occupy virtually every habitat, including extreme conditions, no single species of prokaryotes, however, is as versatile. Some stop growth at a specific temperature , and others survive for longer periods of time in other habitats.

Question 19

Prokaryotes have diverse metabolisms.

Answer 19

Able to colonize diverse habitats partly because they have evolved diverse methods of acquiring energy and nutrients from environment. ex anaerobic respiration.

Question 20

Anaerobs

Answer 20

an organism that can live and grown in the absence of oxygen. Some anaerobes are opportunists, engaging in anaerobic respiration when oxygen is lacking and switching back when oxygen becomes available. Many prokaryotes are strictly aerobic.

Question 21

Energy sources for prokaryotes.

Answer 21

Can extract energy from an array of substances. Not only the sugars, carbs, fats and proteins, but also on compounds that are inedible or even poisonous to humans including petroleum, methane (natural gas) and solvents such as benzene and toluene.

Question 22

Cyanobacteria

Answer 22

They use photosynthesis to capture energy directly from sunlight. -like green plants, photosynthetic bacteria possess chlorophyll. Most species produce oxygen as a by product of photosynthesis, but some known as the sulfur bacteria, use hydrogen sulfide instead of water in photosynthesis, releasing sulfur instead of oxygen. NO PHOTOSYNTHETIC ARCHAEA ARE KNOWN.

Question 23

How do prokaryotes reproduce?

Answer 23

Most prokaryotes reproduce asexually by Binary Fission, a form of cell division that is much simpler than mitotic cell division. Produces genetically identical copies of the original cell. Under optimal conditions, they can divide about once every 20 minutes.

Question 24

Rapid reproduction is beneficial how?

Answer 24

it allows bacterial populations to evolve quickly, many mutations happen which is the source of genetic variability due to errors in DNA replication during cell division. Thus, the repeated cell division of prokaryotes provides ample opportunity for new mutations to arise and also allow mutations that enhance survival to spread quickly.

Question 25

Conjugation- Prokaryotes may exchange genetic material without reproduction

Answer 25

Since reproduction is generally asexual and does not involve genetic recombination, some bacteria and archaea exchange genetic material. DNA is transferred from a donor to a recipient. The plasma membrane of two conjugating prokaryotes fuse temporarily to form a cytoplasmic bridge across which DNA travels.

Question 26

Sex Pili

Answer 26

In Bacteria, donor cells may use extensions that attach to a recipient cell, drawing it closer to allow conjugation.

Question 27

How is conjugation beneficial?

Answer 27

It produces new genetic combinations that may allow the resulting bacteria to survive under a greater variety of conditions. Some cases between different species.

Question 28

Plasmid

Answer 28

A small circular DNA molecule that is separate from the single bacterial chromosome that tis transferred during bacterial conjugation.

Question 29

How are plasmids beneficial for bacteria?

Answer 29

They carry genes for antibiotic resistance or alleles of genes also found on the main bacterial chromosome. Could be beneficial or malignant depending on circumstances.

Question 30

How do prokaryotes affect humans and other organisms?

Answer 30

-Crucial for life on Earth. Plants and animals utterly dependent on prokaryotes. Help obtain vital nutrients and help break down and recycle wastes and dead organisms. We could not survive without prokaryotes. Not always beneficial; most deadly diseases are from microbes (bacterium) .

Question 31

Prokaryotes capture the nitrogen needed by plants.

Answer 31

Humans can’t live without plants, and plants cant live without bacteria. Plants are unable to capture nitrogen from the element’s most abundant reservoir, the atmosphere. Plants need nitrogen to grow. They depend on nitrogen-fixing bacteria.

Question 32

Nitrogen-Fixing bacteria

Answer 32

Live both in soil and is specialized nodules, small rounded lumps on the roots of certain plants (legumes, alfalfa, soybeans, etc). They capture nitrogen gas from air trapped in the soil and combine it with hydrogen to produce ammonium, a nitrogen containing nutrient that plants use directly.

Question 33

Prokaryotes are nature’s recyclers how?

Answer 33

Obtain energy by breaking down complex organic molecules (carbon and hydrogen molecules). They find plentiful source of organic molecules in the waste products and dead bodies of plants and animals. By consuming, thereby decomposing waste and prevents from accumulating in the environment and release nutrients doing so.

Question 34

Prokaryotes can clean up pollution how?

Answer 34

Pollutants are human made by-products and are organic compounds. They can serve as food for archaea and bacteria. Nearly everything human made can be broken down by some prokaryote, including detergents, toxic pesticides, and harmful industrial chemicals such as benzene and toluene.

Question 35

Bioremediation

Answer 35

Is the practice of manipulating conditions to stimulate breakdown of pollutants by living organisms. (clean up toxic wastes and polluted groundwater).

Question 36

Pathogenic (disease-producing)

Answer 36

The feeding habits of certain bacteria threaten human health despite the benefits. Bacteria synthesize toxic substances that cause disease symptoms. (No pathogenic archaea has been identified). Tetanus, Bubonic plague “black death”, Lyme disease (borrelia burgdorferi), tuberculosis, gonorrhea and syphilis, Cholera. E.coli

Question 37

What are Viruses, Viroids, And Prions?

Answer 37

Viruses are generally found in close association with living organisms, but most do not consider them alive. They lack traits of life- they aren’t cells, nor they are composed of one. They cannot accomplish basic tasks on their own. They have no Ribosomes to make proteins, nor cytoplasm, nor the ability to synthesize organic molecules and no capacity to use the energy stored in such molecules. Not considered alive.

Question 38

What does a virus consist of?

Answer 38

A molecule of DNA or RNA surrounded by a protein coat. Smaller than the smallest prokaryotic cell. Assume variety of shapes. Two major parts: A molecule of hereditary material and a coat of protein surrounding the molecule. Parasites of living cells.

Question 39

Where does a virus reproduce?

Answer 39

Can reproduce only inside a HOST cell- the cell that a virus or other infectious agent infects. Reproduction begins when virus penetrates a host cell; the viral genetic material takes command. Highjacks the host cell and uses the instructions encoded in the viral genes to produce the components of new viruses. The pieces rapidly assembled, and an army of new viruses bursts forth to invade and conquer neighboring cells.

Question 40

Viruses are host specific

Answer 40

Different viruses attack specific host cells. NO organism is immune to all viruses. Bacteriophages infect bacteria. This could be beneficial since bacteria is increasingly becoming resistant to antibiotics. In plants and animals, (multi-cellular) they are responsible for common cold, herpes, AIDS. Difficult to treat viral infections. Antiviral drugs are limited due to most viruses quickly evolve resistance to drugs.

Question 41

Viroids

Answer 41

Infectious particles that lack a protein coat and consist of nothing more than short, circular strands of RNA. Able to enter the nucleus of a host cell and direct syntheses of new viroids. (crop diseases)

Question 42

Prions

Answer 42

More puzzling than viroids. Kuru culture, consist of only protein. Infectious protein particles. Protein produced by normal nerve cells. Some copies of this normal protein molecule for reasons poorly understood, become folded into the wrong shape and are thus transformed into infectious prions.