Biology: Chapter 27 (Bacteria and Archaea) (copy)

bacteria and archaea

What two domains include prokaryotes?

unicellular

Are prokaryotes multicellular or unicellular?

0.5-5 µm v. 10-100 µm

Compare the relative size of prokaryotes to eukaryotes

spherical
rod shaped
spiral

What three shapes are most common for prokaryotes?

peptidoglycan

What is the composition of the typical bacterial cell wall?

maintains cell shape

protects cell

prevents it from bursting in a hypotonic environment

What three functions does the prokaryotic cell wall provide for the cell?

cellulose or chitin

What materials comprise the cell wall of eukaryotes?

lack peptidoglycan
contain proteins and polysaccharides

Cell walls of archaeans are different because they...

Peptidoglycan

a type of polymer in bacterial cell walls consisting of modified sugars cross-linked by short polypeptides

gram stain

A staining method that distinguishes between two different kinds of bacterial cells walls

May be used to help determine medical response to an infection

gram-positive bacteria

Group of bacteria that have a cell wall that is structurally less complex and contains more peptidoglycan than the cell wall of gram-negative bacteria

gram-negative bacteria

Group of bacteria that have a cell wall that is structurally more complex and contains less peptidoglycan than the cell wall of gram-positive bacteria

Gram-negative bacteria

Which gram-stained bacteria is more likely to be antibiotic resistant?

capsule

The sticky layer of polysaccharide or protein that enable prokaryotes to adhere to their substrate or to other individuals in a colony

slime layer

less organized capsule

Protects against dehydration
Shields from attacks by host's immune system

What functions does the capsule or slime layer serve?

fimbriae

hairlike appendages prokaryotes use to stick to their substrate or to one another

pili

appendages that pull two cells together prior to DNA transfer from one cell to another

taxis

a directed movement toward or away from a stimulus

chemotaxis

the movement towards or away from a chemical stimulus

flagella

What structure makes movement of bacteria possible?

plasmids

A small circular double stranded DNA molecule that carries accessory genes separate from those of a bacterial chromosome

nucleoid

region of cytoplasm that appears lighter than the surrounding cytoplasm and is where the chromosomes in a prokaryote are located

endospores

A thick coated resistant cell produced by some bacterial cells when they are exposed to harsh conditions

binary fission

a single cell divides into two identical cells

exhausted nutrient supply
poisoned by metabolic waste
competition
consumed by other organisms

What conditions check prokaryotic reproduction?

every 20 minutes

Under ideal conditions, how quickly can E coli divide?

They are small

They reproduce by binary fission

They have short generation times

What three features allow prokaryotic populations to consist of trillions of individuals?

recombination

combining DNA from two sources, contributes to diversity

• Rapid reproduction

• Mutation

• Genetic recombination

What three factors have caused prokaryotes to have considerable genetic variation?

• Transformation

• Transduction

• Conjugation

What are the three ways prokaryotic DNA from different individuals can be brought together?

transformation

a process where a prokaryotic cell takes up and incorporates foreign DNA from the surrounding environment

genotype altered by foreign DNA

Streptococcus pneumonia can transform from a harmless bacteria to one that causes pneumonia due to non-pathogenic cells picking up DNA with a pathogenic gene from the environment and replacing the harmless version of the gene via recombination

Give an example of change through transformation.

transduction

the movement of genes between bacteria by bacteriophages

phages carry genes rom one host to another

Occurs as an accident during a phage’s reproductive cycle. A virus may mistakenly incorporate bacterial DNA in place of some or all of its own into new virus particles. The new DNA may get incorporated into cells infected by the altered virus.

Explain how transduction occurs in a cell.

horizontal gene transfer

movement of genes from one organism to another

Conjugation

Direct transfer of DNA between two cells that are temporarily joined by pilus

When two cells are members of different species, _______ results in horizontal gene transfer

F factor

a piece of DNA required for the production of pili; can occur in either the chromosome or plasmid

DNA donors

As a plasmid, cells containing the F-plasmid function as _____

DNA recipients

As a plasmid, cells without the F-factor function as ______

during conjugation

When is the F-factor transferrable?

R plasmids

A bacterial plasmid carrying genes that confer resistance to certain antibiotics

Antibiotics are kill sensitive bacteria but not bacteria with specific r plasmids

through natural selection the fraction of bacteria with genes for resistant increases in a population exposed to antibiotics

antibiotic resistant strands of bacteria are becoming more common

light and carbon

Prokaryotes can be categorized by how they obtain ______ & _______

Phototrophs

obtain energy from light

Chemotrophs

obtain energy from chemicals

Autotrophs

require CO2 as a carbon source

Heterotrophs

require an organic nutrient to make organic compounds

• Photoautotrophy

• Chemoautotrophy

• Photoheterotrophy

• Chemoheterotrophy

Four major modes of nutrition

Obligate Aerobes

require O2 for cellular respiration

Obligate Anaerobes

poisoned by O2, use fermentation or anaerobic respiration

Facultative Anaerobes

can survive with or without O2

Nitrogen

_____ is essential for the production of amino acids and nucleic acids

Nitrogen Fixation

converts atmospheric nitrogen (N2) to ammonia (NH3)

Proteobacteria

gram-negative bacteria that includes photoautotrophs, chemoautotrophs, and heterotrophs

some are aerobic, others are anaerobic

• Alpha Proteobacteria - Rhizobium (formes root nodules in legumes and converts atmospheric N2) & Agrobacterium

• Beta Proteobacteria - Nitrosomonas (soil bacterium that converts ammonium into nitrite)

• Gamma Proteobacteria - Thiomargarita manibiensis. And pathogens like: Legionella, Salmonella, & Virbiro Cholerae. And Escherichia coli (E. coli)

• Delta Proteobacteria

• Epsilon Proteobacteria - many pathogens including: Campylobacteria & Helibacter pylori

What are the subgroups of Proteobacteria? Name an example for each.

Bacteria Group: Chlamydias

parasites that live within animal cells and can’t make ATP

Bacteria Group: Spirochets

helical heterotrophs

Bacteria Group: Cyanobacteria

phototrophs that generate O2, may be responsible for the original presence of atmospheric O2 on earth

• Actinomycetes - decompose soil

• Bacillus anthracis, the cause of anthrax

• Clostridium botulinum, the cause of botulism

• Some Staphylococcus and Streptococcus, which can be pathogenic

• Streptomyces used to produce streptomycin

• Mycoplasms, the smallest known cells

Give some examples of Gram-Positive Bacteria

Extremophiles

archaea that live in extreme conditions

Extreme Halophiles

live in highly saline environments

Extreme Thermophiles

thrive in very hot environments; have structural adaptions that make their DNA and proteins stable at high temperatures, stopping them from denaturing.

Methanogens

type of archaea that live in swamps and marshes and are poisoned by O2

some species live in the anaerobic guts of termites and cattle, helping them break down cellulose

Euryachaeota clade

All known methanogens and many extreme halophiles belong to the ______

Chemical Recycling

recycling of chemical elements between the living and nonliving components of ecosystems

Symbiosis

an ecological relationship in which two species live in close contact: a larger host and a smaller symbiont

• Mutualism

• Commensalism

• Parasitism

What are the three types of symbiosis?

Mutualism

both symbiotic organisms benefit

Commensalism

one organism benefits while neither harming nor helping the other in any significant way

Parasitism

an organism called a parasite harms but (usually) does not kill its host

Pathogens

parasites that cause disease

endotoxins or exotoxins

Pathogenic prokaryotes typically cause disease by releasing ______ or _______

Endotoxins

released only when bacteria die and their cell walls break down

Exotoxins

secreted and cause disease even if the prokaryotes that produce them aren’t present

virulence - turns something harmless into potent pathogens

ex. pathogenic strains of E. coli contain genes acquired through transduction

Give an example of horizontal gene transfer spreading genes associated with virulence.

Bioremediation

the use of organisms to remove pollutants from the environment.