Chapter 27: Archaea and Bacteria (Part 1, Week 5) Flashcards Preview

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Flashcards in Chapter 27: Archaea and Bacteria (Part 1, Week 5) Deck (62)
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1
Q

T/F Bacter and Archaea are examples of macroorganisms that can be seen with the naked eye?

A

False. They are MICROorganisms and can only be seen with a microscope.

2
Q

What are, in phosphorous-rich bodies of water, some species of photosynthetic bacteria known as?

They can grow rapidly into large, visible population–known as blooms–that color the water blue-green or cyan.

A

Cyanobacteria

The individual cells release small amounts of toxins that help keep small aquatic animals away from eating them, but when blooms occur, toxins can rise to levels that poison humans, pets, livestock, and wildlife.

3
Q

How do you prevent blooms of cyanobacteria?

A

People can prevent the formation of harmful cyanbacterial blooms by reducing the flow of phosphorus-rich fertilizers, manure, and sewage into bodies of water.

4
Q

[Start 27.1 Diversity and Evolution]

What are all three domains of life and what structures do they have?

A

Eukarya, Archaea, and Bacteria.

Eurkarya have a eukaryotic structure. Archaea and Bacteria have a prokaryotic structure.

5
Q

What do archeal and bacterial cells lack?

A

Nuclei with porous envelopes and other cellular features typical of eukaryotes.

6
Q

Why can you not aggregate archaea and bacteria collectively as prokaryotes?

Definitions for Answer:

Monophyletic - consists of a most recent common ancestor and its entire descendants.

Paraphyletic - consists of a common evolutionary ancestor or ancestral group, but not including all the descendant groups.

A

Such an aggregation is not a monophyletic group, but rather a paraphyletic group—one that does not include all of the descendants of a single common ancestor.

That’s because domain Archaea is more closely related to domain Eukarya than either is to domain Bacteria.

Even so, archaea and bacteria display some common features in addition to a prokaryotic cell structure.

7
Q

What phylum within Archaea and its close relatives are more closely related to Eukarya than to Bacteria?

A

Lokiarchaeota

Bacteria and Archaea are the two domains featuring prokaryotic cells. Eukarya is the domain consisting of organisms whose cells are eukaryotic.

8
Q

T/F Many cases of horizontal gene transfer among phyla and domains are known.

A

True.

Some of these are depicted with blue bars and include the acquisition of mitochondria and chloroplasts by eukaryotes.

9
Q

Since Archaea and bacteria include the smallest known cells and are the most abundant organisms on Earth, how much does half of Earth’s biomass consist of?

A

An estimated 10^30 individual bacteria or archaea.

Just a pinch of garden soil can contain 2 billion prokaryotic cells, and about a million occur in 1 mL of seawater.

10
Q

Fun Facts about bacteria and archaea!

  • Live in nearly every conceivable habitat.
  • Most ancient organisms on Earth (3 bya)
  • Most diverse metabolic processes
  • Influence climate, atmosphere, soils, water quality, and tech.
  • They have CRISPR-Cas systems that combat viruses and have proven useful in genetic engineering.
A

N/A

11
Q

What, in DNA, is present in archaea and eukaryotes but not in bacteria? (2)

A

Histones!

Histones are biochemically basic proteins that provide a scaffold to wrap and condense DNA in the nucleus.

Archaea and eukaryotes share more than 30 ribosomal proteins that are not present in bacteria, and archaeal RNA polymerases are closely related to their eukaryotic counterparts.

12
Q

What differences does archaea have with eukarya?

A

Archaea possess distinctive membrane phospholipids, which are formed with ether bonds.

Ester bonds characterize the membrane phospholipids of bacteria and eukaryotes

13
Q

How do archaea withstand heat and extreme conditions?

A

Ether-bonded membranes are resistant to damage by heat and other extreme conditions, which helps explain why many archaea are able to grow inextremely harsh environments.

14
Q

What are the key differences between the biochemical composisiton of the cell wall between archaea and bacteria?

A

In most bacteria, the cell wall is composed of carbohydrates that are cross-linked by peptides, forming a substance called peptidoglycan, whereas the cell wall of archaea is usually a surface layer of proteins.

Some bacterial species alsohave an outer envelope (membrane) composed of lipids and polysaccharides.

15
Q

Where do most archaea occur?

A

In soils and surface ocean waters in moderate conditions, diverse archaea occupy habitats with very high salt content, acidity, methane levels, or temperatures that would kill most bacteria and eukaryotes.

16
Q

What is an organism that occurs primarily in extreme habitats?

A

Extremophile

One example is the methane producer
Methanopyrus, which grows best at deep-sea thermal vent sites where the temperature is 98°C. At this temperature, the proteins of mostorganisms would denature, but those of Methanopyrus are resistant to such damage.

Methanopyrus is so adapted to its extremely hot environment that it cannot grow when the temperature is less than 84°C.

17
Q

What is a type of extremophile that lives in thermal sea vents much like the Methanopyrus organism?

A

Hyperthermophile

18
Q

What do you call the species of archaea that are able to grow in higher than usual salt concentrations?

A

Halophiles

19
Q

T/F Archaea domain is more diverse than the Bacteria domain.

A

False. Bacter is CONSIDERABLY more diverse and has 50 or more bacterial phyla.

Archaea have 5.

20
Q

T/F Bacteria favor moderate conditions.

A

True. Since they form many symbiotic associations with eukaryotes.

21
Q

For Cyanobacteria, what does the blue-green pigmentation result from?

A

From the presence of photosynthetic pigments called phycobilins (FICO-be-lins) that help chlorophyll absorb light energy.

Cyanobacteria are the only bacteria known to generate oxygen as a product of photosynthesis.

Ancient cyanobacteria produced Earth’s first oxygen-rich atmosphere, which allowed the eventual rise of eukaryotes. The chloroplasts of eukaryotic algae and plants were derived from cyanobacteria.

22
Q

Within the phylum Cyanobacteria, they have the greatest diversity of body type among bacteria… What are some examples? (3)

A
  • Occur as single cells called unicells
  • Occur as colonies held together by a thick gluey substance called mucilage
  • Occur as branched and unbranched filaments

Some of the filamentous cyanobacteria display hallmarks of multicellularity: cellular attachment, specialized cells, intercellular chemical communication, and programmed cell death.

23
Q

What are the five major sub groups of genera in the phylum Proteobacteria?

A

alpha (α), beta (β),gamma (γ), delta (δ), and epsilon (ε).

24
Q

What subgroup of Proteobacteria can the ancestry of mitochondria be traced to?

Here are a plethora of more examples!

A

The ancestry of mitochondria can be traced to the α-proteobacteria, which also include several genera noted for mutually beneficial relationships with animals and plants.

For example, Rhizobium and related genera of α-proteobacteria form nutritionally beneficial associations with the roots of legume plants such as beans and peas and are thus agriculturally important.

Another α-proteobacterium, Agrobacterium tumifaciens, causes destructive cancer-like tumors called galls to develop on susceptible plants, including grapes and ornamental crops.

The genus Nitrosomonas, soil inhabitants important in the global nitrogen cycle, represents the β-proteobacteria.

Neisseria gonorrhoeae, the agent of the sexually transmitted disease gonorrhea, is one of the γ-proteobacteria.

Vibrio cholerae, another γ-proteobacterium, cause scholera epidemics when drinking water becomes contaminated with animal waste during floods and other natural disasters.

The γ-proteobacteria Salmonella enterica and
Escherichia coli strain O157:H7 also cause human disease, so food and water are widely tested for their presence.

The δ-proteobacteria include the colony-forming myxobacteria and predatory bdellovibrios, which drill through the cell walls of other bacteria in order to consume them.

Helicobacter pylori, which causes stomach ulcers, belongs to the ε-proteobacteria.

25
Q

What is the process in which an organism incorporates genetic material from another organism without being the offspring of that organism?

One reason why the domains of Bacteria and Archaea display an mazing level of diversity.

A

Horizontal gene transfer

Horizontal gene transfer is common among archaea and bacteria, occurring most frequently between species that are closely related or that live in close proximity.

26
Q

What is an example of horizontal gene transfer resulting in large genetic changes that confer new metabolic capacities?

A

For example, at least 17% of the genes present in the common human gut inhabitant E. coli
were horizontally transferred from other bacteria.

27
Q

How many of the 200 prokaryotic genome studies have been involved in horizontal transfer at some point in their history?

A

80%

Genes also move among the bacterial, archaeal, and eukaryotic domains. For example, salt-tolerant (halophytic) archaea originated after an ancient horizontal transfer of more than a thousand genes from bacteria.

28
Q

What are the three ways horizontal gene transfer occurs?

A

Transduction - transmission by virus

Transformation - transmission of naked DNA material from environment

Conjugation - direct contact transfer

29
Q

What is a way that horizontal gene transfer can occur in which one species, the endosymbiont, lives in the body or cells of another species, the host?

A

Endosymbiosis

30
Q

[Start 27.2 Structure and Movement]

Fun Fact: What is the largest dimension of most eukaryotic cells?

A

10 to 100 um.

Bacteria cells are normally much smaller, usually ranging from a few micrometers in diameter however, some can get as big as 600 to 800 um.

Small cell size limits the amount of materials that can be stored within each cell but allows much faster cell division. When nutrients are sufficient, many bacteria can divide many times within a single day.

This explains how bacteria can spoil food rapidly and why bacterial infections can spread quickly within the human body.

31
Q

What are able to use light energy to produce organic compounds because their cells contain large numbers of thylakoids, flattened tubular membranes that grow inward from the plasma membrane?

A

Cyanobacteria and other photosynthetic bacteria

32
Q

What does the extensive membrane surface of the thylakoids bear large amounts of?

A

Chlorophyll and other components that are needed for photosynthesis.

33
Q

Where did thylakoids descend from?

Where also are they abundant? Pretty easy, dude.

A

Descended from cyanobacterial ancestors.

Thylakoidsare also abundant in plant chloroplasts.

Thylakoids enable photosynthetic bacteria and chloroplasts to take maximum advantage of light energy in their environments.

34
Q

How do aquatic photosynthetic bacteria increase cell buoyancy and thus help the organisms float within well-illuminated surface waters?

A

Gas vesicles (a protein walled structure)

35
Q

What is an intriguing adaptation, which is sometimes called a bacterial organelle, that are tiny crystals of an iron mineral known as magnetite, each surrounded by a membrane and act as a compass needle that responds to the Earth’s magnetic field and helps the bacteria orient themselves in space and thereby locate the submerged, low oxygen habitats they prefer?

A

Magnetosomes (produced by invaginations of the plasma membrane)

These and other bacterial cells use flagella to move to more favorable locations.

Fun Fact: Like the bacterium Magnetospirillum magnetotacticum, birds such as homing pigeons and migratory fishes such as rainbow trout have the capacity to sense and respond to magnetic fields.

36
Q

What other invaginations of the plasma membrane allows an envelope composed of a double membrane enclosing all cellular DNA and some ribosomes from other cellular influences?

A

Nucleus-like bodies

37
Q

What are the five common shapes of prokaryotic cells?

A

Cocci - Sphere-shaped prokaryotic cells.

Bacilli - Rod-shaped prokaryotic cells.

Vibrios - Comma-shaped prokaryotic cells.

Spirochaetes - Flexible, spiral-shaped prokaryotic cells.

Spirilli - Rigid, spiral-shaped prokaryotic cells.

Cytoskeletal proteins similar to those present in eukaryotic cells control these cell shapes.

For example, helical strands of an actin-like protein are responsible for the rod shape of bacilli; if this protein is not produced, bacilli become spherical in shape.

Cellular shape is an important component of bacterial function in nature. Cocci tend to have a greater surface area/volume ratio, which facilitates exchange of materials with the environment, but bacilli can often store more nutrients.

38
Q

T/F In the case of unicellular bacteria and archaea, a single cell constitutes an entire organism.

A

True

39
Q

What does many bacteria excude a coat of?

A

Slimy mucilage, sometimes called a glycocalyx, capsule, or extracellular polymeric substance (EPS).

40
Q

What does glycocalyx, or the mucilage, varying in consistency and thickness, composed of?

A

Hydrated polysaccharides and proteins, as well as lipids and nucleicacids.

41
Q

What does the capsule, or mucilage, of a bacterial cell help it accomplish? (if it has one)

A

A capsule helps some disease-causing bacteria evade the defense system of their host.

You may recall that Frederick Griffith discovered the transfer of genetic material while experimenting with capsule-producing pathogenic strains and capsule-less nonpathogenic strains of the bacterium
Streptococcus pneumoniae.

The immune system cells of mice are able to destroy this bacterium only if it lacks a capsule.

42
Q

What other roles does mucilage play within bacteria? (4)

A
  • holding cells together closely enough for chemical communication and DNA exchange to occur
  • helping aquatic species to float in water
  • binding mineral nutrients
  • repelling attack
43
Q

What do pigmented slime sheaths coating some bacterial filaments in some bacteria help with?

A

Preventing UV damage

44
Q

What is an aggregation of microorganisms that secrete adhesive mucilage, thereby gluing themselves to surfaces?

A

Biofilms

Formation of a biofilm helps microbes remain in favorable locations for growth; otherwise body or environmental fluids would wash them away

45
Q

What is a mechanism by which prokaryotic cells are able to communicate by chemical means when they reach a critical population size?

A

Quorum sensing

This fosters biofilm formation.

46
Q

How does quorum sensing foster biofilm formation?

A

During quorum sensing, individual microbes secrete small molecules having the potential to influence the behavior of nearby microbes.

If enough individuals are present (a quorum), the concentration of signaling molecules builds to a level that causes collective behavior.

In the case of biofilms, populations of microbes respond to chemical signals by moving to a common location and producing mucilage.

47
Q

What are the beneficial and harmful consequences of biofilms to a human standpoint?

A

Benefit - In aquatic and terrestrial environments, biofilms help to stabilize and enrich sand and soil surfaces, and help form mineral deposits.

Harm - Biofilms that form on the surfaces of animal tissues, however, can be harmful. Dental plaque is an example of a harmful biofilm.

If allowed to remain, the bacterial community secretes acids that can damage tooth enamel. Biofilms may also develop in industrial pipelines, where the attached microbes can contribute to corrosion by secreting enzymes that chemically degrade metal surfaces.

48
Q

Mucilage or not, what do most prokaryotic cells possess outside the plasma membrane?

A

Cell wall

Cell walls maintain cell shape and help protect against attack by viruses or predatory bacteria. Cell walls also help microbes avoid lysing in hypotonic conditions, when the solute concentration is higher inside the cell than outside.

49
Q

Although some archaea lack cell walls, what do they sometimes possess?

In contrast, what is an important component of most bacterial cell walls?

A

A wall composed of protein.

Peptidoglycans - A polymer composed of carbohydrates crosslinked with peptides that is an important component of the cell walls of most bacteria.

50
Q

Bacterial cell walls occur in two major forms that differ in thickness of the peptidoglycan layer, staining properties, and response toantibiotics.

With that said, bacteria having these chemically different walls are called? (2)

A

Gram-positive and gram-negative.

After the staining process used to distinguish them. The stain is named for its inventor, Danish scientist Hans Christian Gram.

51
Q

Between gram-positive and gram-negative, which one has a relatively thick peptidoglycan layer, and which has a thinner peptidogylcan layer and are enclosed by a thin, outer envelope whose outer leaflet is rich in lipopolysaccharides (lipids that have polysaccharides covalently attached to them)?

A

Gram-positive is thicker which gram-negative is thinner.

This outer envelope of Gram-negative bacteria contains a phospholipid bilayer that surrounds the outside of the cell wall, whereas the plasma membrane is found inside the cell wall.

52
Q

What can peptigoglycan and lipopolysaccharides affect? (3)

A
  • disease symptoms
  • composition of vaccines
  • bacterial responses to antibiotics

For example, part of the peptidoglycan covering of the Gram-negative bacterial species Bordetella pertussis
is responsible for the extensive tissue damage to the respiratory tract associated with whooping cough, and whooping cough vaccines are improved by including antibodies that reduce the ability of the lipopolysaccharide layer to attach to host cells.

53
Q

What does the lipopolysaccharide-rich outer envelope of gram-negative bacteria help and impede?

A

The lipopolysaccharide-rich outer envelope of Gram-negative bacteria helps them to resist the entry of some antibiotics.

However, this outer envelope also impedes the secretion of proteins from bacterial cells into the environment, a process that normally allows cells to communicate with each other, as in quorum sensing.

54
Q

Why is it important in distinguishing Gram-positive from Gram-negative bacteria?

A

An important factor in choosing the best antibiotics for treating infectious diseases.

For example, Gram-positive bacteria are typically more susceptible than Gram-negative bacteria to penicillin and related antibiotics because these antibiotics interfere with synthesis of peptidoglycan, which Gram-positive bacteria require in larger amounts.

For this reason, penicillin and related antibiotics such as methicillin are widely used to treat infections caused by Gram-positive bacteria. However, it is of societal concern that some strains of bacteria have become resistant to some antibiotics, an example being methicillin-resistant Staphylococcus aureus, or MRSA.

55
Q

What is the ability of a cell to move or change position within its environment?

A

Motility

Diverse motility adaptations allow microbes to respond to chemical signals emitted from other cells during quorum sensing and mating, and to move to favorable conditions within gradients of light, gases, or nutrients.

For example, we have already learned that gas vesicles help cyanobacteria float into well-illuminated waters close to the surface, where photosynthesis can occur.

In addition, prokaryotic cells may move by twitching, gliding, or swimming by means of flagella.

56
Q

How do bacterial flagella and eukaryotic flagella differ? (3)

A

They lack a plasma membrane covering

internal cytoskeleton of microtubules made of the protein tubulin, and the motor protein dynein

—all features that characterize eukaryotic flagella

Additionally, eukaryotic flagella bend and straighten while prokaryotic SPIN.

57
Q

What are relatively long cell appendages that facilitate cellular movement or the movement of extracellular fluids?

A

Flagella (singular, flagellum)

58
Q

What is the structure of a bacterial flagella? And how does it work?

A

Filament, hook, and motor

Somewhat like a boat’soutboard motor and propeller

The hook links the filament with the motor that contains a set of protein rings at the cell surface.

Hydrogen ions (protons), which have been pumped out of the cytoplasm, usually via an electron transport chain, diffuse back into the cell through channel proteins within the motor. This proton flow powers the turning of the hook and filament at rates of hundreds of revolutions per second.

59
Q

What is the protein that makes up the extern filament on the bacterial flagellum?

A

Flagellin

60
Q

What creates the motion of the motor?

A

The conformation change of the channel proteins via the protons (H+)

61
Q

How does archaeal flagella different from bacterial flagella?

A
  • They rotate but are much thinner.
  • The flagella is composed of different proteins
  • Flagella are powered by hydrolysis of ATP
62
Q

What are threadlike surface appendages that allow bacteria to attach to each other during conjugation or to move across surfaces?

A

Pili (singular, pilus)

Myxococcus xanthus cells, for example, move by alternately extending and retracting pili from one pole or the other. This process allows directional movement toward food materials. If nutrients are low, cells of these bacteria glide together to form tiny treelike colonies, which are part of a reproductive process

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