Once the density is reached, they communicate with each other through "quorum sensing" which signals the bacteria to work as a community rather than as individuals.
bacteria produce a polysaccharide that glues them together
holds population at stationary growth
antibiotics can't get into biofilms.
rise in nutrients
increase in combined metabolism of aerobic bacteria
kills obligate aerobes
What are extremophiles? (5)
microorganisms that can survive extreme conditions
a category of extremophile
adapted to survive in cold temps
more fluid, unsaturated lipis in cell wall and altered proteins that work in cold.
prefer middle, normal temperatures
Pathogens are mesophiles
optimum around 37 degrees
heat loving; grow at elevated temps
altered lipid make up to withstand high temps. Cross linked or saturated lipids.
Most thermophiles fall into Archea
heat killing bacteria
What are the parts of a virus? (6/11)
capsule (protects genome)
enveloped viruses: membrane comes from last host. Not all viruses have an envelope.
Steps of a typical virus life cycle (6/11)
Uncoating (sheds capsid to release genetic info)
Replication of genome
Release (often lyses)
What are the four deoxynucleotides? (7)
How do DNA strands base-pair with each other? (7)
DNA replication enzymes
Helicase unzips helix
Primase lays down primer
DNA polymeraselays down DNA
RNase H removes RNA primer laid down by primase
DNA ligase rezips strands
RNA polymerase makes complimentary RNA strand
Sigma factor directs to the right gene.
Promoter recognized by sigma factor.
RNA made from gene is mRNA
70 s Ribosome
takes mRNA and synthesizes a protein.
tRNA brings animo acids
What antibiotics affect protein synthesis? (8)
the transfer of DNA through plasmids
horizontal gene transfer
the uptake of free DNA
horizontal gene transfer
transfer of genetic data via bacteriophage
horizontal gene transfer
the partial breakdown of organic food without net electron transfer to an inorganic terminal electron acceptor.
substrate level phosphorylation
complete breakdown of organic molecules with electron transfer to a terminal electron acceptor such as O2
How do aerobic and anaerobic respiration differ?
Anaerobic respiration has an inorganic final electron acceptor other than oxygen
Aerobic respiration has a final electron acceptor of oxygen
What is a proton motive force and how is it made?
A difference in charges across a membrane
made by pumping out cations (H+) using ETC
Ways to start ETC
a reduced form of some inorganic molecule is used to start this ETC
ETC is energized by loght with electrons donated by a chlorophyll
energy carrying molecule
energy can be used pretty much anywhere in the cell
carries 2-3 times more energy than ATP
used in redox reactions
NAD+ to NADH
Embden-Meyerhoff-Parnas (EMP) Pathway
Net gain: 2 ATP, 2 NADH
more evolutionarily advanced
Entner-Doudoroff (ED) Pathway
net gain: 1 ATP, 1 NADH, 1 NADPH
most common in the GI tract
induces immune response
is bound by antibody
two types: humoral and cell-mediated
Basic antibody structure
immunoglobulin or IgG
4 protein chains; (2 identical heavy chains and 2 identical light chains). If you pulled out two, the tail end would most likely be the same or CONSTANT which is why it’s called Fc. The top half is the variable region or Fab (fragment with antigen binding)
Primary vs Secondary Response
IgG will respond immediately and more will be produced during the secondary immune response.
B cell is activated
differentiates into plasma cells (secrete antibodies) and memory cells.
Humoral immune response
Needs an antigen presenting cell with MHC-II.
Needs a helper T cell with CD4 and a TCR (t-cell receptor) on its surface. CD4 recognizes the MHC-II and the TCR binds the antigen. Helper t secretes cytokines.
Needs a B cell which must bind the antigen (has antibody on surface) and undergo clonal selection.
A microbe is always present in a diseased host, but absent in a healthy subject.
Grow microbe in pure culture
Introduce pure microbe to health host, and host gets sick.
Same microbe re-isolated from now-sick individual.
Means of spreading infection: Direct Contact
come into direct contact with diseased individual
Means of spreading infection: Indirect Contact
fomites (innanimate objects)
vectors (such as blood sucking insects)
allow pathogen to adhere to surface without pili
Classes of Bacterial Endotoxins
protein synthesis inhibitors
signaling pathway disrupters
survives in stomach using urease to protect itself from acid
infects soft tissue/skin
nosocomial pathogen know for antibiotic resistence (MRSA)
virulence factors: afimbrial adhesins and toxins (see below)
alpha toxin (a membrane disruptor)
exoliatin protease (a protease)
TSST (super antigen)
Staph enterotoxin (superantigen)
infects respiratory tract; causes whooping cough.
Afimbrial adhesins (pertactin)
Toxins (pertussis toxin kills ciliated cells; a messenger disrupter)
Vaccine protects against pertactin and pertussis toxin.
infects GI tract; causes dysentery and can lead to kidney failure.
VF: Uses type III secreteion system to invade cells.