Bacteria and Archaea Flashcards
What kind of group are Prokaryotes?
non-monophylitic
Four postulates that prove a casual relationship between a microorganism and a disease
- The microorganism must be present in every case of the disease and absent from healthy individuals.
- The putative causative agent must be isolated and grown in pure culture.
- The same disease must result when the cultured microorganism is used to infect a healthy host.
- The same microorganism must be isolated again from the diseased host.
What does Gut bacteria do?
Affect obesity (shown in mice)
Sexual behavior (shown in flies)
Affect stress, depression (shown in mice)
May affect OCD (in humans)
Bacteria mutualism with humans
direct inhibition of pathogens Digestive processes Development of the immune system Antibiotics can harm your mutualists Facilitate absorption of minerals Synthesize certain vitamins
Digestive processes
Short chain fatty acids from bacterial fermentation
Metabolize drugs
Development of the immune system
Fine control of cytokines (inflammatory response)
Three most common shapes of bacteria
spheres (cocci), rods (bacilli), and spirals
Gram positive bacteria
Thick, complex network of peptidoglycan
Also contains lipoteichoic and teichoic acid
Gram negative bacteria
thin layer of peptidoglycan
Second outer membrane with lipopolysaccharide
Both Eukaryotes and Archaea contain ______ and ______ but lack _______
Polysaccharides, proteins, peptidoglycan
Gram stain
used to make bacteria visible
classifies many bacterial species
Characteristics of gram-negative bacteria
have less peptidoglycan
Have outer membrane
more likely to be antibiotic resistant
fimbriae (attachment pili)
allow some bacteria to stick to their substrate or other individuals in a colony
Flagella
allows for taxis - the ability to move in response to stimuli
what is flagella composed of
the protein flagellin
Both bacteria and archaea cells usually lack complex __________
Compartmentalization.
Membranes in bacteria and archaea that perform metabolic funtions
Respiratory membranes in aerobic bacteria
Thylakoid membranes in photosynthetic bacteria
What kind of chromosome does the genome have
circular
plasmids
smaller rings of DNA that some species of bacteria have
where is the bacterial genome located
the nucleoid region
what kind of bacterial genome do bacteria have
a ring of DNA that is not surrounded by a membrane
Endospores
Internal to the bacterium
resistant to heat, UV radiation, desiccation, alcohol, and chemicals
Can survive for extended periods of time
Bacteria causing tetanus, botulism, and anthrax
Exospores
formed differently
Less robust
How do bacteria reproduce
binary fission, can divide every 1-3 hours
What causes variation in offspring
Mutations
Factors that contribute to genetic variation
Rapid reproduction
Mutation
Genetic recombination
How can DNA from different individuals be brought together
Transformation, transduction, conjugation
transformation
a bacterial cell can take up and incorporate foreign DNA from the surrounding environment in a process called transformation
Transduction
the movement of genes between bacteria by bacteriophages (viruses that infect bacteria)
Bacteria that can transform are
competent
Generalized transduction
virtually any gene can be transferred
occurs via accidents in the lytic cycle
viruses package bacterial DNA and transfer it in a subsequent infection
Specialized transduction
Occurs via accidents in the lysogenic cycle
Imprecise excision of prophage DNA
The phage carry both phage genes and chromosomal genes
Conjugation
the process where genetic material is transferred between bacterial cells
Sex pili
allow cells to connect and pull together for DNA transfer
F factor
a piece of DNA that is required for the production of sex pili
where can the F factor exist
a separate plasmid or as DNA within the bacterial chromosome
What is the process of the F plasmid transfer
F+ cell produces F plus that connects it to F- cell
Transfer of F plasmid occurs through conjugation bridge
F plasmid copied through rolling circle replication
The end result is two F+ cells
R plasmids
carry genes for antibiotic resistance
Reasons for antibiotic resistance
Agricultural uses
Patients demanding for antibiotics for nonbacterial infections
Antibiotic products
Lateral gene transfer allows multiple resistance
Phototrophs
obtain energy from lifht
Chemotrophs
obtain energy from chemicals
Autotrophs
require CO2 as a carbon source
Heterotrophs
require an organic nutrient to make organic compounds
Obligate aerobes
require O2 for cellular respiration
Obligate anaerobes
poisoned by O2 and use fermentation or anaerobic respiration
Facultative anaerobes
can survive with or without O2
Notrogen fixation
some bacteria convert atmospheric nitrogen (N2) to ammonia (NH3).
Proteobacteria
gram-negative, include photoautotrophs, chemoautotrophs, and heterotrophs.
Some are anaerobic and others are aerobic
Subgroup: Alpha Proteobacteria
closely associated with eukaryotic hosts
mitochondria evolved from aerobic alpha proteobacteria through endosymbiosis
Subgroup: Gamma Proteobacteria
include sulfur bacteria such as chromatic and pathogens such as Legionella, salmonella, and vibrio cholera
Subgroup: Epsilon Proteobacteria
contains many pathogens including Campylobacter, which causes blood poisoning and Helicobacter pylori, which causes stomach ulcers
Gram-Positive Bacteria
Include:
Actinobacteria - decompose soil
Bacillus anthraces - the cause of anthrax
Clostridium botulinum - the cause of botulism
Some staphylococcus and streptococcus - can be pathogenic
Mycoplasms - smallert known cells
Streptomyces - the source of many antibiotics
Pathogens
Parasites that cause disease
Benefits of bacteria
Fermentation Waste Management Toxic spill cleanup Genetic Engineering Antibiotics
Archaea
share certain traits with bacteria and other traits with eukaryotes
extremophiles
live in extreme environments
Extreme halophiles
live in highly saline environments
Extreme thermophiles
thrive in very hot environments
Methanogens
live in swamps and marshes and produce methane as a waste product
Methanogens are strict anaerobes and are poisoned by O2
Archaea and humans
produce methanols in the digestive tract
found in mouth and can influence tooth health
Many found in intestine
