Questions and Answers
What is the process called when a prokaryotic cell takes up and incorporates foreign DNA from the surrounding environment?
Prokaryotes can only obtain energy from light.
False
What is the term for the movement of genes among individuals from different species?
Horizontal gene transfer
In conjugation, a donor cell attaches to a recipient by a ______________, pulls it closer, and transfers DNA.
Signup and view all the answers
Match the following prokaryotes with their modes of nutrition:
Signup and view all the answers
What is the term for the process by which some prokaryotes convert atmospheric nitrogen (N2) to ammonia (NH3)?
Signup and view all the answers
Obligate anaerobes can survive with or without O2.
Signup and view all the answers
Facultative anaerobes can survive with or without ___________________.
Signup and view all the answers
What type of archaea live in highly saline environments?
Signup and view all the answers
Chlamydia are Gram-positive bacteria.
Signup and view all the answers
What is the byproduct of methanogens' metabolic process?
Signup and view all the answers
Cyanobacteria are _______________ that generate O2.
Signup and view all the answers
Match the following bacteria with their characteristics:
Signup and view all the answers
What is the role of prokaryotes in the recycling of chemical elements?
Signup and view all the answers
Mycoplasms are the largest known cells.
Signup and view all the answers
What is symbiosis in the context of ecology?
Signup and view all the answers
What is the main function of fimbriae in prokaryotes?
Signup and view all the answers
All prokaryotes have complex compartmentalization.
Signup and view all the answers
What is the main component of bacterial flagella?
Signup and view all the answers
Many bacteria exhibit __________, the ability to move toward or away from a stimulus.
Signup and view all the answers
What is the function of pili (or sex pili) in prokaryotes?
Signup and view all the answers
Match the following terms with their functions:
Signup and view all the answers
Bacteria can reproduce sexually.
Signup and view all the answers
What is the function of endospores in bacteria?
Signup and view all the answers
What is the outermost layer of a bacterium that enables binding to cell surfaces and evasion of phagocytosis?
Signup and view all the answers
Gram-negative bacteria have a thick peptidoglycan layer and one cell membrane.
Signup and view all the answers
What is the function of flagella in bacteria?
Signup and view all the answers
Bacteria can have different shapes, including coccus (circular), bacillus (rod-shaped), and _______________________.
Signup and view all the answers
What is the function of pili in bacteria?
Signup and view all the answers
The plasma membrane of bacteria is impermeable, allowing no substances to enter or leave the cell.
Signup and view all the answers
Match the following bacterial layers with their descriptions:
Signup and view all the answers
Gram-positive bacteria have _______________________, which enables binding to cell walls and recognition by macrophages.
Signup and view all the answers
What is the purpose of fixing cells to the slide in the Gram stain procedure?
Signup and view all the answers
What is the function of Graham's iodine in the Gram stain procedure?
Signup and view all the answers
Why do Gram-positive bacteria retain the crystal violet iodine complex during the Gram stain procedure?
Signup and view all the answers
What is the result of decolorization with ethanol on Gram-negative bacteria during the Gram stain procedure?
Signup and view all the answers
What is the purpose of safranin in the Gram stain procedure?
Signup and view all the answers
Why do Gram-negative bacteria lose the crystal violet iodine complex during the Gram stain procedure?
Signup and view all the answers
What is the correlation between the Gram stain and the cell wall structure among bacteria?
Signup and view all the answers
What is the result of adding ethanol to the slide during the Gram stain procedure?
Signup and view all the answers
What is the primary reason for the evolution of 'super bugs'?
Signup and view all the answers
What is the significance of Alexander Fleming's discovery of penicillin?
Signup and view all the answers
What is the consequence of using broad-spectrum antibiotics?
Signup and view all the answers
What was the purpose of the Mega-Plate experiment?
Signup and view all the answers
How do bacteria reproduce rapidly, leading to the evolution of antibiotic resistance?
Signup and view all the answers
What is the warning that Alexander Fleming gave regarding the use of antibiotics?
Signup and view all the answers
What is the result of antibiotic resistance spreading from animal populations to humans and crops?
Signup and view all the answers
What is the significance of the Mega-Plate experiment's results?
Signup and view all the answers
Bacterial DNA exists in two parts: bacterial ______ and bacterial plasmid
Signup and view all the answers
The process of extracting a small part of the bacterial ______ to become a plasmid or reintegration of the plasmid into the bacterial ______ is called transposition
Signup and view all the answers
In conjugation, F+ bacteria link with F- bacteria, creating a mating ______, and transfer a copy of their plasmid to the F- bacteria
Signup and view all the answers
Transformation is the ability of bacteria to take up ______ DNA from the environment and use it
Signup and view all the answers
In transduction, a bacteriophage carrying its own DNA injects this DNA into a bacterial cell, and the viral DNA is integrated into the bacterial ______
Signup and view all the answers
Lysogenic phage gives bacteria new abilities, such as producing ______
Signup and view all the answers
What is the significance of the phylogenetic tree of life in relation to domains of life?
Signup and view all the answers
Domain Archaea and Eukarya are sister taxa, meaning they did not share a common ancestor.
Signup and view all the answers
What are the types of environments where Archaea are typically found?
Signup and view all the answers
The domain _______________________ includes all single-celled prokaryotic organisms.
Signup and view all the answers
Match the following groups of archaea with their characteristics:
Signup and view all the answers
What is the function of histones in Archaea and Eukarya?
Signup and view all the answers
Cyanobacteria are Gram-positive bacteria.
Signup and view all the answers
What are some beneficial functions performed by domain Bacteria?
Signup and view all the answers
What is the primary mechanism by which bacteria evolve resistance to antibiotics?
Signup and view all the answers
Why are broad-spectrum antibiotics problematic?
Signup and view all the answers
What was the purpose of the Mega-Plate experiment?
Signup and view all the answers
What is the consequence of the misuse of antibiotics?
Signup and view all the answers
What is the significance of Alexander Fleming's discovery of penicillin?
Signup and view all the answers
How do bacteria spread antibiotic resistance?
Signup and view all the answers
What was Alexander Fleming's warning regarding the use of antibiotics?
Signup and view all the answers
What is the result of the rapid reproduction of bacteria?
Signup and view all the answers
Study Notes
Prokaryotic Characteristics
- Prokaryotes have fimbriae, allowing them to stick to their substrate or other individuals in a colony
- Pili (or sex pili) are longer than fimbriae and enable prokaryotes to exchange DNA
Locomotion
- Many bacteria exhibit taxis, the ability to move toward or away from a stimulus
- Chemotaxis is the movement toward or away from a chemical stimulus
- Most motile bacteria propel themselves using flagella, which are composed of a motor, hook, and filament
Internal Organization
- Prokaryotic cells usually lack complex compartmentalization
- Some prokaryotes have in-foldings of the plasma membrane that perform metabolic functions
- The genome consists of a circular chromosome located in the nucleoid region
- Some species of bacteria also have smaller rings of DNA called plasmids
Prokaryotic Reproduction
- Prokaryotes reproduce by binary fission, with short generation times
- Many prokaryotes form metabolically inactive endospores, which can remain viable in harsh conditions for centuries
- Three factors contribute to genetic diversity in prokaryotes: rapid reproduction, mutation, and genetic recombination
- Mutation rates during binary fission are low, but rapid reproduction allows mutations to accumulate rapidly in a population
Domain Archaea
- Archaea share certain traits with bacteria and other traits with eukaryotes
- Some archaea live in extreme environments and are called extremophiles
- Extreme halophiles (Clade Euryarchaeota) live in highly saline environments
- Extreme thermophiles (Clade Crenarchaeota) thrive in very hot environments
- Methanogens (Clade Euryarchaeota) live in swamps and marshes and produce methane as a waste product
Domain Bacteria
- Proteobacteria include photoautotrophs, chemoautotrophs, and heterotrophs
- Chlamydia are parasites that live only within animal cells
- Spirochetes are helical heterotrophs, with some being parasites
- Cyanobacteria are photoautotrophs that generate O2
- Gram-positive bacteria include Actinomycetes, Bacillus anthracis, Clostridium botulinum, and some Staphylococcus and Streptococcus
Ecological Importance
- Prokaryotes play a major role in the recycling of chemical elements between the living and nonliving components of ecosystems
- Chemoheterotrophic prokaryotes function as decomposers, breaking down dead organisms and waste products
- Prokaryotes can increase the availability of nitrogen, phosphorus, and potassium for plant growth
Symbiosis and Genetic Recombination
- Symbiosis is an ecological relationship in which two species live in close contact: a larger host and smaller symbiont
- Genetic recombination occurs through transformation, transduction, and conjugation
- Conjugation is the process where genetic material is transferred between prokaryotic cells
Metabolism and Nutrition
- Prokaryotes can be categorized by how they obtain energy and carbon
- Phototrophs obtain energy from light, chemotrophs obtain energy from chemicals, autotrophs require CO2 as a carbon source, and heterotrophs require an organic nutrient to make organic compounds
- Energy and carbon sources are combined to give four major modes of nutrition
- Nitrogen metabolism is essential for the production of amino acids and nucleic acids
- In nitrogen fixation, some prokaryotes convert atmospheric nitrogen (N2) to ammonia (NH3)
Bacteria Structure
- Bacteria are the largest group of microorganisms with medical significance.
- They come in three main shapes: coccus (circular), bacillus (rod-shaped), and spiral.
- Other shapes include coca bacillus (in between coccus and bacillus) and vibrio (spiral and bacillus).
Bacterial Movement and Appendages
- Some bacteria have flagella, thin rigid filaments made of proteins, allowing for bacterial movement.
- Hair-like appendages called fimbriae and pili are used for binding to cell surfaces and causing disease.
- Pili are shorter than fimbriae but perform the same function.
- Pili are also involved in bacterial conjugation, the transfer of genetic material between bacteria.
Bacterial Layers
- The outermost layer is the capsule, which has polysaccharides and enables binding to cell surfaces and evasion of phagocytosis.
- The innermost layer is the plasma membrane, a semi-permeable membrane allowing transportation of substances in and out of the cell.
- The plasma membrane is a phospholipid bilayer with proteins, similar to those found in human cells.
- The cell wall is a semi-rigid structure that enables bacteria to be classified into gram-positive and gram-negative groups.
Gram-Positive and Gram-Negative Bacteria
- Gram-positive bacteria have a thick peptidoglycan layer and one cell membrane.
- Gram-negative bacteria have a thin peptidoglycan layer and two cell membranes.
- Gram-positive bacteria have lipoteichoic acid, which enables binding to cell walls and recognition by macrophages.
- Gram-negative bacteria have lipid-like structures on the outer cell membrane, including lipoproteins and lipid A, which can cause diseases and shock syndromes.
Cytoplasm and DNA
- Cytoplasm contains water, enzymes, ribosomes, and circular DNA.
- Ribosomes are the site of protein synthesis.
- The DNA in bacteria is circular, unlike the linear DNA found in humans (except in mitochondria).
- Plasmids are small, circular genetic information found in the cytoplasm, which can be incorporated into the circular DNA or transferred between bacteria through conjugation.
Gram Stain Procedure
- A thin film of cells from a fresh culture is prepared on a clean slide and allowed to dry.
- Cells are fixed to the slide by brief heat fixation using a Bunsen burner flame.
- The slide is stained with crystal violet for 30-40 seconds, resulting in all cells appearing purple under the microscope.
- Excess crystal violet is removed by rinsing with water, and then the slide is treated with Graham's iodine for about one minute.
- Decolorization is achieved by washing the slide with ethanol or acetone, which removes the crystal violet from Gram-negative bacteria but not from Gram-positive bacteria.
- The ethanol or acetone is added drop-wise to the slide until the colour just starts to run clear.
- Excess ethanol is washed off with water, and the slide is counter-stained with safranin for 20-30 seconds, which stains Gram-negative bacteria pink.
Gram Stain Mechanism
- The Gram stain method is based on the differences in bacterial cell wall structure.
- In Gram-positive bacteria, the ethanol treatment shrinks the thick peptidoglycan layer, which retains the crystal violet iodine complex.
- The thick peptidoglycan layer in Gram-positive bacteria acts as a permeability barrier, preventing the loss of the crystal violet iodine complex.
- In Gram-negative bacteria, the thin peptidoglycan layer has large pores, allowing ethanol to extract lipids and increase porosity, resulting in the loss of the crystal violet iodine complex.
Antibiotics and Microbes
- Antibiotics are natural substances produced by microbes to kill other microbes, with a history of use spanning billions of years.
- Alexander Fleming discovered antibiotics in 1928 by isolating penicillin from a contaminated bacterial culture.
- Penicillin revolutionized medicine, saving millions of lives from infections.
- Most commercial antibiotics are broad-spectrum, capable of destroying beneficial microbes in the gut, leading to microbiome imbalance.
Problems with Antibiotics
- Overuse and misuse of antibiotics have led to the evolution of resistant bacteria, also known as "super bugs."
- Antibiotic resistance occurs when bacteria evolve to resist antibiotics, making them ineffective.
- Misuse of antibiotics destroys beneficial microbes, increasing susceptibility to infections.
The Mega-Plate Experiment
- The Mega-Plate experiment involved growing E. coli bacteria in agar jelly with increasing concentrations of antibiotics.
- The results showed that E. coli mutants evolved resistance to antibiotics in just 11 days.
Evolution of Antibiotic Resistance
- Bacteria reproduce rapidly, allowing them to evolve resistance quickly.
- Exposure to antibiotics selects for bacteria with resistant mutations, leading to the spread of resistant microbes.
- Antibiotic resistance can spread from animal populations to humans and crops.
Fleming's Warning
- Alexander Fleming warned that overusing antibiotics would lead to the evolution of resistant bacteria, making them ineffective against infections.
- Fleming advocated for judicious use of antibiotics to prevent unintended consequences on the microbiome.
Smart Use of Antibiotics
- Antibiotics should only be used to treat bacterial diseases, not viral diseases.
- Unnecessary antibiotic use leads to the evolution of resistant bacteria and disrupts the microbiome.
- Wise and moderate use of antibiotics is essential to prevent the spread of antibiotic resistance.
Bacterial Genetics
- Bacterial DNA consists of two parts: a larger, more complex bacterial chromosome and a smaller bacterial plasmid that floats inside the bacteria.
Transposition
- Involves the extraction of a small part of the bacterial chromosome, which can become a plasmid or reintegrate into the chromosome.
- Only affects plasmid DNA, not chromosome DNA.
- Enables bacteria to share DNA with other bacteria through plasmid transfer.
Conjugation
- Occurs between F+ bacteria (possessing a sex pilus) and F- bacteria (lacking a sex pilus).
- The sex pilus is encoded by the plasmid, not the chromosome.
- F+ bacteria form a mating bridge with F- bacteria and transfer a copy of their plasmid, resulting in both bacteria becoming F+.
Transformation (Competence)
- The ability of certain bacteria to take up naked DNA from their environment and utilize it.
- Allows bacteria to acquire new traits, such as antibiotic resistance.
- Exclusively observed in Streptococcus pneumoniae, H.influenza, and Neisseria.
- Requires the uptake of free DNA from the environment.
Transduction
- The process in which a bacteriophage (bacterial virus) injects its DNA into a bacterial cell.
- The viral DNA integrates into the bacterial DNA and begins replicating.
- Can result in bacterial death (lytic phage) or not (lysogenic phage).
- Lysogenic phages can grant bacteria new capabilities, such as producing exotoxins.
Phylogenetic Tree of Life
- Emphasizes domain levels of organization, showing three main domains: Eukarya, Archaea, and Bacteria
- Domain Eukarya and Archaea are sister taxa, sharing a common ancestor, despite differences in cellular structure
Similarities between Archaea and Eukarya
- Share RNA polymerase with multiple subunits
- Have methionine as the start amino acid during protein synthesis
- Possess histones, which organize DNA
- These similarities suggest a closer evolutionary relationship between Archaea and Eukarya
Domain Archaea
- Found in extreme environments, such as high temperatures and high salinity
- Examples include Halophiles, Thermophiles, and Methanogens
- Five groups of archaea: URI Archaea and Crenarchaeota, among others
Domain Bacteria
- Includes all single-celled prokaryotic organisms
- Found in almost every environment on earth
- Perform beneficial functions: nitrogen fixation and decomposition
- Can cause disease: stomach ulcers and Lyme disease
Subdivisions of Domain Bacteria
- Proteobacteria:
- Alpha Proteobacteria (Rhizobium)
- Beta Proteobacteria
- Gamma Proteobacteria (Pseudomonas fluorescens)
- Delta Proteobacteria
- Epsilon Proteobacteria (Helicobacter pylori)
- Chlamydiae:
- Gram-negative bacteria that live within animal cells
- Examples: Chlamydia trachomatis
- Spirochetes:
- Gram-negative bacteria with a helical shape
- Examples: Borrelia and Treponema
- Cyanobacteria:
- Gram-negative bacteria that perform photosynthesis
- Examples: Oscilloria
- Gram-positive bacteria:
- Examples: Bacillus and Staphylococcus
Bacterial Diversity
- Found in almost every environment on earth
- Play important roles: nitrogen fixation and decomposition
- Can cause disease, but many are harmless or beneficial to humans
Antibiotics and Microbes
- Antibiotics are natural substances produced by microbes to kill other microbes, with a history of use spanning billions of years.
- Alexander Fleming discovered antibiotics in 1928 by isolating penicillin from a contaminated bacterial culture.
- Penicillin revolutionized medicine, saving millions of lives from infections.
- Most commercial antibiotics are broad-spectrum, capable of destroying beneficial microbes in the gut, leading to microbiome imbalance.
Problems with Antibiotics
- Overuse and misuse of antibiotics have led to the evolution of resistant bacteria, also known as "super bugs."
- Antibiotic resistance occurs when bacteria evolve to resist antibiotics, making them ineffective.
- Misuse of antibiotics destroys beneficial microbes, increasing susceptibility to infections.
The Mega-Plate Experiment
- The Mega-Plate experiment involved growing E. coli bacteria in agar jelly with increasing concentrations of antibiotics.
- The results showed that E. coli mutants evolved resistance to antibiotics in just 11 days.
Evolution of Antibiotic Resistance
- Bacteria reproduce rapidly, allowing them to evolve resistance quickly.
- Exposure to antibiotics selects for bacteria with resistant mutations, leading to the spread of resistant microbes.
- Antibiotic resistance can spread from animal populations to humans and crops.
Fleming's Warning
- Alexander Fleming warned that overusing antibiotics would lead to the evolution of resistant bacteria, making them ineffective against infections.
- Fleming advocated for judicious use of antibiotics to prevent unintended consequences on the microbiome.
Smart Use of Antibiotics
- Antibiotics should only be used to treat bacterial diseases, not viral diseases.
- Unnecessary antibiotic use leads to the evolution of resistant bacteria and disrupts the microbiome.
- Wise and moderate use of antibiotics is essential to prevent the spread of antibiotic resistance.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
This quiz covers the surface structures and locomotion mechanisms of prokaryotes, including fimbriae, pili, taxis, chemotaxis, and flagella.