Archaea Facts and Characteristics

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Questions and Answers

Which statement is true about Archaea?

Archaea are exclusively found in extreme environments.

All Archaea have a two-layer lipid membrane.

Archaea have larger sizes than most bacteria.

Archaea possess a circular DNA genome. (correct)

What type of environments do Halophiles thrive in?

Anaerobic environments.

High salt concentrations. (correct)

Extremely hot and acidic waters.

Extreme temperatures and pressures.

What is a primary characteristic of Methanogens?

They rely on sunlight for energy.

They produce oxygen as a byproduct.

They produce methane using carbon dioxide and hydrogen. (correct)

They are found only in aquatic environments.

Which statement about bacterial reproduction is accurate?

Bacteria replicate their genome through binary fission. Signup and view all the answers

What structure do motile bacteria use for locomotion?

Flagella Signup and view all the answers

Which is NOT a main type of Archaea based on unique habitats?

Psychrophiles Signup and view all the answers

What is a common shape of bacteria?

Spherical Signup and view all the answers

What is a plasmid?

An accessory ring of DNA in bacteria. Signup and view all the answers

How many pounds of bacteria approximately live on or in the human body?

2 pounds Signup and view all the answers

Which of the following sequences best represents the stages of evolution leading to living cells?

Organic monomers, Protobionts, Organic polymers, Living cells Signup and view all the answers

What hypothesis suggests that RNA was the first genetic material to evolve?

RNA-First Hypothesis Signup and view all the answers

Which experiment is famously associated with the production of organic monomers under prebiotic conditions?

Miller-Urey Experiment Signup and view all the answers

What is indicated as a possible source of organic monomers in addition to the Miller-Urey experiment?

Hydrothermal vents Signup and view all the answers

What component is described as being essential for protobionts' ability to divide?

Fatty acid membranes Signup and view all the answers

What term is used to describe the last universal ancestor of all life forms?

Last Universal Common Ancestor (LUCA) Signup and view all the answers

Which hypothesis states that the first living entities were simple polypeptides formed from amino acids?

Protein First Hypothesis Signup and view all the answers

What is one method by which bacteria can exchange genetic material?

Conjugation through a sex pilus Signup and view all the answers

Which type of bacteria can use inorganic chemicals to fix carbon dioxide into organic form?

Chemoautotrophs Signup and view all the answers

Which bacterium is primarily responsible for strep throat?

Streptococcus pyrogenes Signup and view all the answers

What are bacterial endospores primarily used for?

Survival in harsh conditions Signup and view all the answers

Which of the following is a virulence factor that pathogenic bacteria may possess?

Genes for toxins Signup and view all the answers

What is MRSA known for?

Being insusceptible to methicillin Signup and view all the answers

What typically characterizes food poisoning caused by certain bacteria?

Usually self-limiting with vomiting and diarrhea Signup and view all the answers

Which bacteria can cause an autoimmune response leading to heart damage?

Streptococcus pyrogenes Signup and view all the answers

Which type of food poisoning is likely to cause symptoms two hours after eating?

Released toxins into the food. Signup and view all the answers

What is the primary way that antibiotics inhibit bacterial growth?

Interfering with a unique metabolic pathway. Signup and view all the answers

What is a potential consequence of antibiotic therapy?

Overgrowth of harmful bacteria. Signup and view all the answers

Which of the following statements is true regarding viruses?

They contain a capsid and nucleic acid core. Signup and view all the answers

Which mechanism allows viruses to infect specific host cells?

Compatibility of viral spikes with host cell receptors. Signup and view all the answers

What occurs during antigenic shift in viruses?

New combinations of surface spikes from co-infecting viruses. Signup and view all the answers

Which characteristic is commonly associated with rhinoviruses?

They are responsible for the common cold. Signup and view all the answers

What is a potential consequence of bacterial resistance to antibiotics?

Difficulty in treating certain bacterial infections. Signup and view all the answers

Which hypothesis suggests that organic monomers evolved from a primordial soup?

Oparin-Haldane Hypothesis Signup and view all the answers

What is indicated as a possible result of the Miller-Urey experiment?

Formation of amino acids and other organic acids Signup and view all the answers

Which stage of microbial evolution involves the development of a cell membrane?

Stage 3: Protobionts Signup and view all the answers

How do protobionts differ from simple organic molecules?

Protobionts possess an outer membrane made of fatty acids Signup and view all the answers

Which statement best describes the RNA-first hypothesis?

RNA was the first hereditary material with enzyme-like functions Signup and view all the answers

What is a significant implication of the presence of anaerobic conditions in early Earth?

Synthesis of amino acids was supported Signup and view all the answers

What does the evolution of living cells entail according to the studies discussed?

Presence of membranes and three types of macromolecules Signup and view all the answers

Which of the following successfully demonstrates organic synthesis in the context of early Earth conditions?

The Miller-Urey Experiment Signup and view all the answers

What is the primary purpose of endospores in bacteria?

For survival in harsh conditions Signup and view all the answers

Which process involves bacteria taking up DNA from their environment?

Transformation Signup and view all the answers

What distinguishes chemoautotrophs from other bacteria?

They derive energy from inorganic chemicals Signup and view all the answers

What is a common characteristic of pathogenic bacteria?

They possess genes for virulence factors Signup and view all the answers

What type of illness can Clostridium botulinum cause?

Food poisoning with severe symptoms Signup and view all the answers

Which of the following diseases is typically caused by Staphylococcus aureus?

Impetigo Signup and view all the answers

Which mechanism of genetic recombination involves a virus?

Transduction Signup and view all the answers

What can be a consequence of an untreated streptococcal throat infection?

Autoimmune heart damage Signup and view all the answers

How do antibiotics primarily inhibit bacterial growth?

By disrupting bacterial metabolic pathways Signup and view all the answers

What potential issue can arise from antibiotic therapy?

Leads to allergic reactions Signup and view all the answers

Which of the following components is NOT part of a virus?

Ribosomes Signup and view all the answers

What best describes the process of antigenic drift in viruses?

Small mutations leading to slight changes in the virus Signup and view all the answers

What is a consequence of two viruses infecting the same host cell?

Increased likelihood of antigenic drift Signup and view all the answers

Which statement is true about the size of viruses compared to bacteria?

Viruses are smaller than bacteria Signup and view all the answers

Which two terms describe the mechanisms by which antibiotics can work?

Inhibit protein synthesis and disrupt cell membrane integrity Signup and view all the answers

What is a key feature of viruses that allows them to infect specific host cells?

Presence of spikes that match cell receptors Signup and view all the answers

What is a significant characteristic of the genome of Archaea?

It is a single, closed, circular DNA molecule. Signup and view all the answers

Which of the following accurately describes the plasma membrane of Archaea?

It contains a single lipid layer with branched side chains. Signup and view all the answers

What is a primary energy source for Methanogens?

Carbon dioxide and hydrogen. Signup and view all the answers

How do bacteria primarily reproduce?

Asexually by binary fission. Signup and view all the answers

Which type of environment do Thermoacidophiles thrive in?

Hot springs and geysers. Signup and view all the answers

What is a key feature of the flagella found in motile bacteria?

They are structurally different from eukaryotic flagella. Signup and view all the answers

What type of habitats do Halophiles typically occupy?

Salty habitats such as the Dead Sea. Signup and view all the answers

What role do fimbriae play in bacteria?

They enable bacteria to attach to surfaces. Signup and view all the answers

Study Notes

Chapter 28: Microbiology

About 2 pounds of bacteria live in or on your body. This is true.
Microbiology is the study of microbes, including bacteria, archaea, protists, fungi, viruses, and prions.
Microbes are abundant in air, soil, water, and on objects.
Some bacteria and fungi are decomposers.
Photosynthetic protists and bacteria are primary producers.
Microbiota are on our bodies.
Pasteur's experiment disproved spontaneous generation.

Pasteur and Spontaneous Generation

In his first experiment, Pasteur boiled broth in flasks to sterilize it. The flasks were opened briefly to the outside air, and 89% showed growth.
In Pasteur's second experiment, the flask was open to the air, allowing air to enter, and only 32% showed growth.
Pasteur's experiments concluded that all organisms come from preexisting organisms.

Origin of Microbial Life

All life traces back to a single common ancestor called the last universal common ancestor (LUCA).
Stage 1: Organic monomers (evolution of monomers) - Primordial Soup
Oparin-Haldane hypothesis
Miller-Urey Experiment
Stage 2: Organic polymers (evolution of polymers)
Stage 3: Protobionts (evolution of protobionts)
Development of the cell membrane
Stage 4: Living cells (evolution of living cells)

The Evolution of Monomers

Miller-Urey experiment (1953)
Early Earth had a reducing atmosphere.
After a week, water turned brown.
Amino acids and other organic acids were produced.
Tested over the decades.
Even greater numbers of organic molecules were produced.
Other sources of organic monomers include hydrothermal vents and meteors/comets. - Other sources are also possible based on scientific studies.

The Evolution of Polymers

Protein First Hypothesis
Solar energy causes amino acids at the shoreline to form simple polypeptides with catalytic properties.
RNA-first hypothesis
RNA evolved first and acted as hereditary material and enzyme.

The Evolution of Protobionts

Protobionts have outer membranes made of fatty acids, proteins, and other polymers inside.
Larger "Vesicles" able to divide.

The Evolution of Living Cells

Cells with membranes and DNA, RNA, and proteins.
RNA first hypothesis supports this theory.
Codon Chart seems optimized to deal with mutations.
May have been natural selection on codons.

Prokaryotic Diversity: Archaea

Domain Bacteria and domain Archaea are both prokaryotes.

Archaeal Size and Structure

Archaea are small.
Their genome is a single, closed, circular DNA molecule.
Their plasma membrane is a single lipid layer with branched side chains.
Three main types based on unique habitats and metabolism.

Organic Monomers

Organic monomers (like amino acids and sugars) could form without the presence of life. - This is supported by evidence.

Types of Archaea

Halophiles: love salt. Live in highly saline environments (Great Salt Lake, Dead Sea, etc.).
Thermoacidophiles: thrive in extremely hot and acidic environments (hot springs, geysers).
Methanogens: produce methane. Live in anaerobic environments (swamps, intestines). (cows and other animals, including humans)

Domain Bacteria

Bacteria are the most common type of prokaryote on Earth.
Over 11,000 different species; millions are likely present.
Most bacteria are between 0.2-10µm.
Three basic shapes: rod (bacillus), spherical (coccus), and spiral (spirillum)

Bacterial Size and Structure

Motile bacteria have flagella for locomotion (structurally different from eukaryotic flagella).
Some bacteria have fimbriae used to bind to surfaces.
Certain bacteria that infect the urinary tract use fimbriae to attach to cell surfaces.
Most bacteria have a single circular chromosome located in the nucleoid region. - Many bacteria also possess plasmids. (accessory DNA rings that carry certain genes).

Bacterial Reproduction and Gene Transfer

Bacteria reproduce asexually, by binary fission.
One bacterial cell splits into two daughter cells.
Some bacteria form resistant endospores for survival in harsh environments.
Mechanisms of genetic recombination include conjugation (transfer by a sex pilus), transformation (DNA uptake from environment), and transduction (viral transfer).

Bacterial Metabolism

Most bacteria are heterotrophic (require organic carbon for food).
Some bacteria are chemoautotrophs (use inorganic chemicals to fix carbon dioxide into organic form).
Cyanobacteria are photoautotrophs (have chlorophyll and perform photosynthesis).

Bacterial Diseases in Humans

Most bacteria do not cause disease.
Pathogenic bacteria often have genes for virulence factors (toxins or factors for tissue attachment).
Streptococcus infections (strep throat, impetigo, rheumatic fever, scarlet fever)
Staphylococcus aureus and MRSA (skin infections, often antibiotic-resistant).
Food poisoning (some produce toxins while others cause infections).

Viruses and Prions

Viruses are acellular structures that are parasites.
Viruses use the host cell's replication machinery (like ribosomes) and certain enzymes.
Viruses are smaller than bacteria (0.03-0.2µm).
Two main components are the capsid (outer protein layer) and nucleic acid core (DNA or RNA).
Some viruses have an envelope.

Viral Reproduction

Viruses are specific to a particular host.
Spikes on a virus configure exactly to receptor molecules on the host cell membrane.
The reproductive cycle of an enveloped animal RNA virus typically has six steps (attachment, entry, uncoating, replication, assembly, and budding).

The Common Cold and Influenza

Colds are mainly caused by rhinoviruses (over 100 species).
Flu is caused by influenza viruses.
Antigens on viruses can change, resulting in antigenic drift (mutation) or antigenic shift (new combinations of surface spikes).

Prions

Prions are protein infectious particles.
Normal proteins change shape, causing other proteins to change shape.
This causes degenerative diseases in the nervous system.
Prions can be passed through ingestion of infected tissue (e.g., mad cow disease, chronic wasting disease).

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Test your knowledge on the characteristics and facts about Archaea. This quiz covers various aspects of Archaea, helping you understand their significance in biology and ecology.