romikgosai/squad_modified_2 huggingface dataset:
Bacteria do not have a membrane-bound nucleus, and their genetic material is typically a single circular DNA chromosome located in the cytoplasm in an irregularly shaped body called the nucleoid. The nucleoid contains the chromosome with its associated proteins and RNA. The phylum Planctomycetes and candidate phylum Poribacteria may be exceptions to the general absence of internal membranes in bacteria, because they appear to have a double membrane around their nucleoids and contain other membrane-bound cellular structures. Like all living organisms, bacteria contain ribosomes, often grouped in chains called polyribosomes, for the production of proteins, but the structure of the bacterial ribosome is different from that of eukaryotes and Archaea. Bacterial ribosomes have a sedimentation rate of 70S (measured in Svedberg units): their subunits have rates of 30S and 50S. Some antibiotics bind specifically to 70S ribosomes and inhibit bacterial protein synthesis. Those antibiotics kill bacteria without affecting the larger 80S ribosomes of eukaryotic cells and without harming the host.

Q1: What is genetic make of bacteria?
A1: a single circular DNA chromosome
Q2: Where is DNA chromosome of bacteria located?
A2: in the cytoplasm
Q3: How does nucleoid look?
A3: irregularly shaped body
Q4: What are the exceptions of non-internal membrane bacteria?
A4: phylum Planctomycetes and candidate phylum Poribacteria
Q5: What is the purpose of polyribosomes in bacteria?
A5: production of proteins
Some bacteria produce intracellular nutrient storage granules for later use, such as glycogen, polyphosphate, sulfur or polyhydroxyalkanoates. Certain bacterial species, such as the photosynthetic Cyanobacteria, produce internal gas vesicles, which they use to regulate their buoyancy – allowing them to move up or down into water layers with different light intensities and nutrient levels. Intracellular membranes called chromatophores are also found in membranes of phototrophic bacteria. Used primarily for photosynthesis, they contain bacteriochlorophyll pigments and carotenoids. An early idea was that bacteria might contain membrane folds termed mesosomes, but these were later shown to be artifacts produced by the chemicals used to prepare the cells for electron microscopy. Inclusions are considered to be nonliving components of the cell that do not possess metabolic activity and are not bounded by membranes. The most common inclusions are glycogen, lipid droplets, crystals, and pigments. Volutin granules are cytoplasmic inclusions of complexed inorganic polyphosphate. These granules are called metachromatic granules due to their displaying the metachromatic effect; they appear red or blue when stained with the blue dyes methylene blue or toluidine blue. Gas vacuoles, which are freely permeable to gas, are membrane-bound vesicles present in some species of Cyanobacteria. They allow the bacteria to control their buoyancy. Microcompartments are widespread, membrane-bound organelles that are made of a protein shell that surrounds and encloses various enzymes. Carboxysomes are bacterial microcompartments that contain enzymes involved in carbon fixation. Magnetosomes are bacterial microcompartments, present in magnetotactic bacteria, that contain magnetic crystals.

Q1: What types of intracellar nutrient can bacteria produce?
A1: glycogen, polyphosphate, sulfur or polyhydroxyalkanoates
Q2: What gas vacuoles are respoonsible for in bacteria?
A2: to control their buoyancy
Q3: What are the most common nonliving compositions in bacteria?
A3: glycogen, lipid droplets, crystals, and pigments
Q4: How does gas vesicles produced by Cyanobacteria help her to move in water?
A4: move up or down into water layers with different light intensities
Q5: What are chromatophores used for?
A5: photosynthesis
In most bacteria, a cell wall is present on the outside of the cell membrane. The cell membrane and cell wall comprise the cell envelope. A common bacterial cell wall material is peptidoglycan (called "murein" in older sources), which is made from polysaccharide chains cross-linked by peptides containing D-amino acids. Bacterial cell walls are different from the cell walls of plants and fungi, which are made of cellulose and chitin, respectively. The cell wall of bacteria is also distinct from that of Archaea, which do not contain peptidoglycan. The cell wall is essential to the survival of many bacteria, and the antibiotic penicillin is able to kill bacteria by inhibiting a step in the synthesis of peptidoglycan.

Q1: What composes the cell envelope?
A1: cell membrane and cell wall
Q2: What is most common cell wall material?
A2: peptidoglycan
Q3: Are cell walls of bacteria similar to cell walls of plants and fungi?
A3: Bacterial cell walls are different
Q4: How can antibiotic penicillin destroy bacteria?
A4: by inhibiting a step in the synthesis of peptidoglycan
Q5: What are the main materials of cell walls of plants and fungi?
A5: cellulose and chitin
Gram-positive bacteria possess a thick cell wall containing many layers of peptidoglycan and teichoic acids. In contrast, gram-negative bacteria have a relatively thin cell wall consisting of a few layers of peptidoglycan surrounded by a second lipid membrane containing lipopolysaccharides and lipoproteins. Lipopolysaccharides, also called endotoxins, are composed of polysaccharides and lipid A that is responsible for much of the toxicity of gram-negative bacteria. Most bacteria have the gram-negative cell wall, and only the Firmicutes and Actinobacteria have the alternative gram-positive arrangement. These two groups were previously known as the low G+C and high G+C Gram-positive bacteria, respectively. These differences in structure can produce differences in antibiotic susceptibility; for instance, vancomycin can kill only gram-positive bacteria and is ineffective against gram-negative pathogens, such as Haemophilus influenzae or Pseudomonas aeruginosa. If the bacterial cell wall is entirely removed, it is called a protoplast, whereas if it is partially removed, it is called a spheroplast. β-Lactam antibiotics, such as penicillin, inhibit the formation of peptidoglycan cross-links in the bacterial cell wall. The enzyme lysozyme, found in human tears, also digests the cell wall of bacteria and is the body's main defense against eye infections.

Q1: What does gram-positive bacteria have?
A1: thick cell wall containing many layers of peptidoglycan and teichoic acids
Q2: Why gram-negative cell bacteria is more toxic than gram-positive bacteria?
A2: polysaccharides and lipid A
Q3: What can be endotoxins called?
A3: Lipopolysaccharides
Q4: What can different structure of the cell walls of bacteria effect?
A4: differences in antibiotic susceptibility
Q5: What is the main defense of human body against eye infections?
A5: enzyme lysozyme, found in human tears
Acid-fast bacteria, such as Mycobacteria, are resistant to decolorization by acids during staining procedures. The high mycolic acid content of Mycobacteria, is responsible for the staining pattern of poor absorption followed by high retention. The most common staining technique used to identify acid-fast bacteria is the Ziehl-Neelsen stain or acid-fast stain, in which the acid-fast bacilli are stained bright-red and stand out clearly against a blue background. L-form bacteria are strains of bacteria that lack cell walls. The main pathogenic bacteria in this class is Mycoplasma (not to be confused with Mycobacteria).

Q1: What is the most typical staining technique used to identify acid-fast bacteria?
A1: Ziehl-Neelsen stain
Q2: What is mycolic acid is responsible for in Mycobacteria?
A2: staining pattern of poor absorption followed by high retention.
Q3: What helps Mycobacteria be resistant to decolorization?
A3: high mycolic acid content
Q4: What is the main pathogenic bacteria in L-form class ?
A4: Mycoplasma
Fimbriae (sometimes called "attachment pili") are fine filaments of protein, usually 2–10 nanometres in diameter and up to several micrometers in length. They are distributed over the surface of the cell, and resemble fine hairs when seen under the electron microscope. Fimbriae are believed to be involved in attachment to solid surfaces or to other cells, and are essential for the virulence of some bacterial pathogens. Pili (sing. pilus) are cellular appendages, slightly larger than fimbriae, that can transfer genetic material between bacterial cells in a process called conjugation where they are called conjugation pili or "sex pili" (see bacterial genetics, below). They can also generate movement where they are called type IV pili (see movement, below).

Q1: What are fimbriae?
A1: fine filaments of protein
Q2: What are fimbriae liable for?
A2: involved in attachment to solid surfaces or to other cells
Q3: What is the diameter of fimbriae?
A3: 2–10 nanometres
Q4: What are pili?
A4: cellular appendages
Certain genera of Gram-positive bacteria, such as Bacillus, Clostridium, Sporohalobacter, Anaerobacter, and Heliobacterium, can form highly resistant, dormant structures called endospores. In almost all cases, one endospore is formed and this is not a reproductive process, although Anaerobacter can make up to seven endospores in a single cell. Endospores have a central core of cytoplasm containing DNA and ribosomes surrounded by a cortex layer and protected by an impermeable and rigid coat. Dipicolinic acid is a chemical compound that composes 5% to 15% of the dry weight of bacterial spores. It is implicated as responsible for the heat resistance of the endospore.

Q1: What are highly resistant dormant structures of certain gram-positive bacteria called?
A1: endospores
Q2: Is creating endospore a reproductive process?
A2: is not a reproductive process
Q3: What are ribosomes in endospores are enclosed in?
A3: cortex layer
Q4: What chemical compound comprises 5% to 15% of the dry weight of bacterial spores?
A4: Dipicolinic acid
Endospores show no detectable metabolism and can survive extreme physical and chemical stresses, such as high levels of UV light, gamma radiation, detergents, disinfectants, heat, freezing, pressure, and desiccation. In this dormant state, these organisms may remain viable for millions of years, and endospores even allow bacteria to survive exposure to the vacuum and radiation in space. According to scientist Dr. Steinn Sigurdsson, "There are viable bacterial spores that have been found that are 40 million years old on Earth — and we know they're very hardened to radiation." Endospore-forming bacteria can also cause disease: for example, anthrax can be contracted by the inhalation of Bacillus anthracis endospores, and contamination of deep puncture wounds with Clostridium tetani endospores causes tetanus.

Q1: Is there a metabolism in endospores?
A1: show no detectable metabolism
Q2: What extreme physical and chemical stresses can endospores endure?
A2: UV light, gamma radiation, detergents, disinfectants, heat, freezing, pressure
Q3: How long can endospores of bacteria stay alive in dormant state?
A3: for millions of years
Q4: What endospore-forming bacteria can cause tetanus disease?
A4: Clostridium tetani
Bacteria exhibit an extremely wide variety of metabolic types. The distribution of metabolic traits within a group of bacteria has traditionally been used to define their taxonomy, but these traits often do not correspond with modern genetic classifications. Bacterial metabolism is classified into nutritional groups on the basis of three major criteria: the kind of energy used for growth, the source of carbon, and the electron donors used for growth. An additional criterion of respiratory microorganisms are the electron acceptors used for aerobic or anaerobic respiration.

Q1: What is commonly used to determine taxonomy of bacteria?
A1: The distribution of metabolic traits
Q2: How is bacterial metabolism determined?
A2: nutritional groups
Q3: What are electron acceptors accountable for?
A3: aerobic or anaerobic respiration
Q4: What are three main criterias of bacterial metabolism?
A4: the kind of energy used for growth, the source of carbon, and the electron donors
Carbon metabolism in bacteria is either heterotrophic, where organic carbon compounds are used as carbon sources, or autotrophic, meaning that cellular carbon is obtained by fixing carbon dioxide. Heterotrophic bacteria include parasitic types. Typical autotrophic bacteria are phototrophic cyanobacteria, green sulfur-bacteria and some purple bacteria, but also many chemolithotrophic species, such as nitrifying or sulfur-oxidising bacteria. Energy metabolism of bacteria is either based on phototrophy, the use of light through photosynthesis, or based on chemotrophy, the use of chemical substances for energy, which are mostly oxidised at the expense of oxygen or alternative electron acceptors (aerobic/anaerobic respiration).

Q1: How does heterotrophic carbon metabolism occur?
A1: organic carbon compounds are used as carbon sources
Q2: When carbon metabolism is called autotrophic?
A2: cellular carbon is obtained by fixing carbon dioxide
Q3: What category do parasitic bacteria fall into?
A3: Heterotrophic bacteria
Q4: Green sulfur-bacteria is typical representative of what type of bacteria?
A4: autotrophic bacteria
Q5: What is chemotrophy ?
A5: the use of chemical substances for energy
Bacteria are further divided into lithotrophs that use inorganic electron donors and organotrophs that use organic compounds as electron donors. Chemotrophic organisms use the respective electron donors for energy conservation (by aerobic/anaerobic respiration or fermentation) and biosynthetic reactions (e.g., carbon dioxide fixation), whereas phototrophic organisms use them only for biosynthetic purposes. Respiratory organisms use chemical compounds as a source of energy by taking electrons from the reduced substrate and transferring them to a terminal electron acceptor in a redox reaction. This reaction releases energy that can be used to synthesise ATP and drive metabolism. In aerobic organisms, oxygen is used as the electron acceptor. In anaerobic organisms other inorganic compounds, such as nitrate, sulfate or carbon dioxide are used as electron acceptors. This leads to the ecologically important processes of denitrification, sulfate reduction, and acetogenesis, respectively.

Q1: What do lithotrophs use ?
A1: inorganic electron donors
Q2: What type of electron donors organotrophs use?
A2: organic compounds
Q3: In what organisms is oxygen used as eelectron acceptor?
A3: anaerobic organisms
Q4: What do respiratory organisms use as electron donors?
A4: chemical compounds
These processes are also important in biological responses to pollution; for example, sulfate-reducing bacteria are largely responsible for the production of the highly toxic forms of mercury (methyl- and dimethylmercury) in the environment. Non-respiratory anaerobes use fermentation to generate energy and reducing power, secreting metabolic by-products (such as ethanol in brewing) as waste. Facultative anaerobes can switch between fermentation and different terminal electron acceptors depending on the environmental conditions in which they find themselves.

Q1: What is sulfate-reducing bacteria accountable for?
A1: the production of the highly toxic forms of mercury
Q2: What is the by-product of non-repiratory anaerobes?
A2: ethanol
Q3: How can anaerobes adjust to the surrounding environment?
A3: can switch between fermentation and different terminal electron acceptors
Lithotrophic bacteria can use inorganic compounds as a source of energy. Common inorganic electron donors are hydrogen, carbon monoxide, ammonia (leading to nitrification), ferrous iron and other reduced metal ions, and several reduced sulfur compounds. In unusual circumstances, the gas methane can be used by methanotrophic bacteria as both a source of electrons and a substrate for carbon anabolism. In both aerobic phototrophy and chemolithotrophy, oxygen is used as a terminal electron acceptor, whereas under anaerobic conditions inorganic compounds are used instead. Most lithotrophic organisms are autotrophic, whereas organotrophic organisms are heterotrophic.

Q1: What are hydrogen and carbon monoxide for Lithotrophic bacteria?
A1: Common inorganic electron donors
Q2: How can gas methane be used in exceptional set of conditions by methanotrophic bacteria?
A2: both a source of electrons and a substrate for carbon anabolism
Q3: What is the main element for aerobic photorophy?
A3: oxygen
Regardless of the type of metabolic process they employ, the majority of bacteria are able to take in raw materials only in the form of relatively small molecules, which enter the cell by diffusion or through molecular channels in cell membranes. The Planctomycetes are the exception (as they are in possessing membranes around their nuclear material). It has recently been shown that Gemmata obscuriglobus is able to take in large molecules via a process that in some ways resembles endocytosis, the process used by eukaryotic cells to engulf external items.

Q1: What chemical process  helps bacteria to absorb raw materials?
A1: diffusion
Q2: How can bacteria obtain raw materials from the environment?
A2: in the form of relatively small molecules
Q3: What process is used by eukaryotic cells to absorb external items?
A3: endocytosis
Q4: What part of bacteria cell is used during diffusion?
A4: molecular channels in cell membranes
Unlike in multicellular organisms, increases in cell size (cell growth) and reproduction by cell division are tightly linked in unicellular organisms. Bacteria grow to a fixed size and then reproduce through binary fission, a form of asexual reproduction. Under optimal conditions, bacteria can grow and divide extremely rapidly, and bacterial populations can double as quickly as every 9.8 minutes. In cell division, two identical clone daughter cells are produced. Some bacteria, while still reproducing asexually, form more complex reproductive structures that help disperse the newly formed daughter cells. Examples include fruiting body formation by Myxobacteria and aerial hyphae formation by Streptomyces, or budding. Budding involves a cell forming a protrusion that breaks away and produces a daughter cell.

Q1: How size and reproduction are linked in bacteria?
A1: Bacteria grow to a fixed size and then reproduce
Q2: How does bacteria reproduce?
A2: through binary fission
Q3: If the conditions are right how long does it take for bacteria to reproduce?
A3: divide extremely rapidly
Q4: What are produced in cell division?
A4: two identical clone daughter cells
In the laboratory, bacteria are usually grown using solid or liquid media. Solid growth media, such as agar plates, are used to isolate pure cultures of a bacterial strain. However, liquid growth media are used when measurement of growth or large volumes of cells are required. Growth in stirred liquid media occurs as an even cell suspension, making the cultures easy to divide and transfer, although isolating single bacteria from liquid media is difficult. The use of selective media (media with specific nutrients added or deficient, or with antibiotics added) can help identify specific organisms.

Q1: In what environment are bacteria being cultivated in labs?
A1: solid or liquid media
Q2: What is typical solid setting?
A2: agar plates
Q3: What can help to indentify specific bacteria?
A3: The use of selective media
Q4: Which environment is better to isolate a single example of bacteria strain?
A4: agar plates
Q5: Which media is preffered to grow larger volumes of bacteria?
A5: liquid growth media
Most laboratory techniques for growing bacteria use high levels of nutrients to produce large amounts of cells cheaply and quickly. However, in natural environments, nutrients are limited, meaning that bacteria cannot continue to reproduce indefinitely. This nutrient limitation has led the evolution of different growth strategies (see r/K selection theory). Some organisms can grow extremely rapidly when nutrients become available, such as the formation of algal (and cyanobacterial) blooms that often occur in lakes during the summer. Other organisms have adaptations to harsh environments, such as the production of multiple antibiotics by Streptomyces that inhibit the growth of competing microorganisms. In nature, many organisms live in communities (e.g., biofilms) that may allow for increased supply of nutrients and protection from environmental stresses. These relationships can be essential for growth of a particular organism or group of organisms (syntrophy).

Q1: What is the simple way of producing large volume of bacteria cells?
A1: high levels of nutrients
Q2: What caused the evolution of different growth strategies in bacteria?
A2: nutrients are limited
Q3: What can create a subsequent increase of nutrients in natural environment?
A3: biofilms
Q4: What do algal bacteria if nutrients are available?
A4: grow extremely rapidly
Bacterial growth follows four phases. When a population of bacteria first enter a high-nutrient environment that allows growth, the cells need to adapt to their new environment. The first phase of growth is the lag phase, a period of slow growth when the cells are adapting to the high-nutrient environment and preparing for fast growth. The lag phase has high biosynthesis rates, as proteins necessary for rapid growth are produced. The second phase of growth is the log phase, also known as the logarithmic or exponential phase. The log phase is marked by rapid exponential growth. The rate at which cells grow during this phase is known as the growth rate (k), and the time it takes the cells to double is known as the generation time (g). During log phase, nutrients are metabolised at maximum speed until one of the nutrients is depleted and starts limiting growth. The third phase of growth is the stationary phase and is caused by depleted nutrients. The cells reduce their metabolic activity and consume non-essential cellular proteins. The stationary phase is a transition from rapid growth to a stress response state and there is increased expression of genes involved in DNA repair, antioxidant metabolism and nutrient transport. The final phase is the death phase where the bacteria run out of nutrients and die.

Q1: What is the first stage of bacteria adaptation?
A1: lag phase
Q2: What is the second phase of bacteria growth known for?
A2: rapid exponential growth
Q3: The absence of what causes the last stage of bacteria growth?
A3: nutrients
Q4: What is called the third statge of growth of bacteria?
A4: stationary phase
Q5: How many phase are in the growth of bacteria?
A5: four phases
Most bacteria have a single circular chromosome that can range in size from only 160,000 base pairs in the endosymbiotic bacteria Candidatus Carsonella ruddii, to 12,200,000 base pairs in the soil-dwelling bacteria Sorangium cellulosum. Spirochaetes of the genus Borrelia are a notable exception to this arrangement, with bacteria such as Borrelia burgdorferi, the cause of Lyme disease, containing a single linear chromosome. The genes in bacterial genomes are usually a single continuous stretch of DNA and although several different types of introns do exist in bacteria, these are much rarer than in eukaryotes.

Q1: What shape is chromosome of bacteria?
A1: circular chromosome
Q2: What bacteria is an exception to single circular chromosome rule?
A2: Spirochaetes of the genus Borrelia
Q3: What bacteria is responsible for Lyme disease?
A3: Borrelia burgdorferi
Q4: How does chromosome of Borrelia burgdoferi look like?
A4: single linear chromosome