Earth’s first organisms were likely _.
Prokaryotes
Most prokaryotes are _, although some species form colonies.
Unicellular
Unlike eukaryotes, prokaryotes do not have _.
Membrane-bound organelles
Prokaryotic cells are _ than eukaryotic cells.
Smaller
Prokaryotic cells have a variety of _.
Shapes
What are the two major bacteria groups?
Photoautotrophs (ex: algae) and chemoheterotrophs (ex: E. coli)
How do antibiotics like penicillin work?
By puncturing holes in the cell wall of a bacterial cell
What is quorum sensing?
How bacteria communicate with one another
Prokaryotes thrive almost everywhere, including places too _, _, _, or _ for most other organisms (especially archaea, AKA extremophiles).
Acidic, salty, cold, or hot
Prokaryotes are divided into two domains: _ and _.
Bacteria and Archaea
An important feature of nearly all prokaryotic cells is their _.
Cell wall
What are the functions of the cell wall of a prokaryotic cell?
Maintains cell shape, protects the cell, and prevents it from bursting in a hypotonic environment
Eukaryotic cell walls are made of _ or _.
Cellulose (plants) or chitin (exoskeletons and fungi)
Bacterial cell walls contain _, a network of sugar polymers cross-linked by polypeptides (very rigid).
Peptidoglycan
Archaea contain _ and _ but lack peptidoglycan.
Polysaccharides, proteins
What is one way that scientists divide Bacteria and Archaea into two different domains?
Bacterial cell walls contain peptidoglycan whereas archaea cell walls do not
Scientists use the _ to classify bacteria by cell wall composition.
Gram stain
_ bacteria have simple cell walls with a large amount of peptidoglycan.
Gram-positive
_ bacteria have more complex cell walls with an outer membrane and less peptidoglycan (these are the “mean” bacteria).
Gram-negative
Which type of bacteria stains purple? Which type stains red?
Gram-positive; Gram-negative
Many antibiotics trap _ and damage bacterial cell walls
Peptidoglycan
Which type of bacteria is more likely to be antibiotic resistant?
Gram-negative
A polysaccharide or protein layer called a _ covers many prokaryotes (outside of the cell).
Capsule
Many prokaryotes form metabolically inactive _, which can remain viable in harsh conditions for centuries.
Endospores
How do endospores remain viable in harsh conditions for centuries?
By entering a dormant state
Some prokaryotes have _, which allow them to stick to their substrate or other individuals in a colony.
Fimbriae
_ are longer than fimbriae and allow prokaryotes to exchange DNA.
Pili (or sex pili)
Most motile bacteria propel themselves by _ that may be concentrated at one or both ends.
Flagella
Flagella of bacteria, archaea, and eukaryotes are composed of different _ and likely evolved _.
Proteins; independently
Prokaryotic cells usually lack _.
Complex compartmentalization
Some prokaryotes have specialized _ that perform metabolic functions.
Membranes
Membranes in prokaryotes are like _ in eukaryotes.
Organelles
Membranes in a prokaryotic cell are usually _.
Infoldings of the plasma membrane
The prokaryotic genome has _ than the eukaryotic genome.
Less DNA
Most of the prokaryotic genome consists of a _.
Single circular chromosome
The chromosome of a prokaryotic genome is not surrounded by a membrane; it is located in the _.
Nucleoid region
Some species of bacteria also have smaller rings of DNA called _.
Plasmids
Prokaryotes reproduce quickly by _ and can divide every _.
Binary fission; 1-3 hours
Because binary fission does not allow for genetic variation in prokaryotic cells, there are three other factors that contribute to genetic diversity:
Rapid reproduction, mutation, and genetic recombination
There are some differences between prokaryotes and eukaryotes in DNA _.
Replication, transcription, and translation
_ rates during binary fission are low, but because of rapid reproduction, they can accumulate rapidly in a population.
Mutation
Their short _ allows prokaryotes to evolve quickly.
Generation time
The combining of DNA from two sources (contributes to diversity)
Genetic recombination
Prokaryotic DNA from different individuals can be brought together by three processes: _, _, and _.
Transformation (take DNA from the environment), transduction (viruses move DNA from one organism to another), and conjugation (like sex)
Movement of genes among individuals from different species is called _.
Horizontal gene transfer
Prokaryotes can be categorized by how they obtain _ and _.
Energy and carbon
_ obtain energy from light.
Phototrophs (think plants)
_ obtain energy from chemicals.
Chemotrophs (think animals)
_ require CO2 as a carbon source (from the air).
Autotrophs
_ require an organic nutrient to make organic compounds (usually from other organisms).
Heterotrophs
_ require O2 for cellular respiration.
Obligate aerobes
_ are poisoned by O2 and use fermentation or anaerobic respiration.
Obligate anaerobes
_ can survive with or without O2.
Facultative anaerobes
Facultative anaerobes are _ compared two obligate aerobes/anaerobes.
Highly evolved
_ is essential for the production of amino acids and nucleid acids.
Nitrogen
Prokaryotes can _ nitrogen in a variety of ways.
Metabolize
In _, some prokaryotes convert atmospheric nitrogen (N2) to ammonia (NH3).
Nitrogen fixation
In the cyanobacterium Anabaeana, photosynthetic cells and nitrogen-fixing cells called _ exchange metabolic products.
Heterocysts (or heterocytes)
_ between prokaryotes allows them use environmental resources they could not use as individual cells.
Metabolic cooperation
Metabolic cooperation occurs between different prokaryotic species in surface-coating colonies called _.
Biofilms
Give an example of a biofilm.
Plaque on teeth
_ bacteria and _ bacteria on the ocean floor use each other’s waste products.
Sulfate-consuming; methane-consuming
Advances in _ are beginning to reveal the extent of prokaryotic diversity.
Genomics
Scientists continue to work on the _ of prokaryotes.
Phylogeny
_ made possible the division of prokaryotes into two domains: Bacteria and Archaea.
Genetic analysis
_ include the vast majority of prokaryotic species familiar to most people.
Bacteria
Diverse _ type are represented among bacteria.
Nutritional
Which type of bacteria do we come in contact with the most?
Proteobacteria
Proteobacteria are _ and include photoautotrophs, chemoautotrophs, and heterotrophs.
Gram-negative
Some proteobacteria are _, and others _.
Anaerobic, aerobic
Give three examples of proteobacteria.
- Rhizobium (wihich fixes atmospheric N2)
- Agrobacterium (which is used in genetic engineering)
- Helicobactor pylori (which causes stomach ulcers)
_ share certain traits with bacteria and other traits with eukaryotes.
Archaea
Some archaea live in extreme environments and are called _.
Extremophiles
Extreme _ live in highly saline environments.
Halophiles
Extreme _ thrive in very hot environments.
Thermophiles
_ live in swamps and marshes and produce methane as a waste product.
Methanogens
Methanogens are strict _.
Anaerobes (which means they are poisoned by O2
What are some prokaryotic roles?
Chemical recycling, ecological interactions, research and technology, and bioremediation
Chemoheterotrophic prokaryotes function as _, breaking down dead organisms and waste products.
Decomposers
Prokaryotes can sometimes increase the availability of _, _, and _ for plant growth.
Nitrogen, phosphorus, potassium
Symbiosis
An ecological relationship in which two species live in close contact
What are the two roles in symbiosis?
A larger host and a smaller symbiont
How many species of bacteria live in our intestines?
About 500-1,000
Many of the species of bacteria living in our intestines are _ and break down food that is undigested by our intestines.
Mutualists
The bacteria within humans that aid in digestion and defense is termed the _.
Microbiome
Bacteria cause about half of all _.
Human diseases
Some _ are transmitted by other species.
bacterial diseases
Experiments using prokaryotes have led to important advances in _.
DNA technology
What can we now make using bacteria?
Natural plastics, vitamins, antibiotics, and hormones