CH6 Part 1 Flashcards
Hooke Cell Theory
- All living organisms are composed of one or more cells
- Cells are the monomer of any organism
- New cells arise from pre-existing, living cells
Additions to Hooke cell theory
- No matter the species, chemical composition of cells is similar
- DNA is source of heredity
- Biochemical energy flows within cells
- organisms activity is product of cell activity
Major difference between Prokaryotes and Eukaryotes
Prok. dont have membrane-bound organelles (“before the nucleus”)
Prokaryotes
Bacteria, archaea, blue green algae
Largest taxonomic division and the three recognized
Domain: Archaea, Bacteria (preceding are Prok.), Eukarya
Taxonomic division under domain
Kingdom, Eukaryotes: Animalia, Plantae, Fungi
What genetic elements can be found in a prokaryote
- Single double stranded DNA
- Polyribosome
- plasmid (circular peice of ds-DNA much smaller than genome) also known as an extrochromosal genetic element. Typically confer an advantage. Also facilitate conjugation - prokaryotic sharing of info.
Bacteria Shapes and proper name?
- Round - Cocci
- Rod-shaped - Bacilli
- spiral-shaped - Spirochetes or spirillia
Bacterial Cell Wall
Rigid, composed of peptidoglycan which also contains D-alanine (both are unique to prokaryotes).
Note: lysozyme destroys the cell wall resulting in a protoblast
Gram Staining
Gram-positive: stains dark purple. Has thick wall of peptidoglycan.
Gram-negative: stains pinkish. Thin wall of peptidoglycan but additional exterior wall of lipopolysaccaride. Space between two walls = periplasmic space (can contain enzymes that degrade antibiotics)
Endotoxins
Found in outer membrane of gram-negative bacteria
Not inherently toxic, but cause strong immune reaction
if many bacteria die, releasing endotoxins, can cause a patient to experience septic shock. Aqueous blood is leaked into tissue causing large drop in blood pressure.
Exotoxins
Secreted by both gram(+) and gram(-). Help bacteria compete against other - sometimes natural bacterias.
Disease examples: Botulism, diptheria, tetanus, toxic shock syndrome
Capsule
Also known as glycocalyx.
Sticky layer of polysaccaride surrounding bacteria/colony
Prevents immune detection and improves adhesion to surfaces.
Flagella Distribution
Monotrichous - flagella at one end
Amphitrichous - flagella at both ends
Peritrichous - multiple flagella
Flagella Structure
Filament
Hook - like a 90o bend
Basal Structures - anchor to inner and outer membrane, and rotate rod
Powered by diffusion of H+ down proton gradient across inner membrane
*Note: different microtubule formation than in eukaryotes
Chemotaxis
Orienting toward or away from food or toxins respectively. Detected by chemoreceptors.
Pili
Long projections involved in attaching to different surfaces.
Sex pilus
Facilitates Conjugation Bridges between F+ (male) and F- (female) bacteria.
Fimbrae
Facilitate adhesion to surfaces.
Bacteria and Temperature
Can be used to classify bacteria.
Mesophiles: Prefer mild temperatures (30oC)
Thermophiles: survive up to 100oC
psychrophiles: near 0oC
Bacteria classification with Nutrition
Autotrophs - CO2 as carbon source
Heterotrophs - organic nutrients
Chemotrophs - energy from chemicals
Phototrophs - energy from light
But all bacteria are either Autotroph or Heterotroph and Chemotroph or Phototroph
4 Types of Bacteria
Chemoautotrophs: Build organic molecules from CO2 using chemical energy derived from inorganic molecules like H2S
Chemoheterotrophs: Require organic material as carbon source and energy
Photoautotrophs: CO2 as carbon source and energy from the sun
Photoheterotrophs: Energy from sun, but require organic molecule from other organism
Minimal Medium
Contains only glucose
Lawn and Plaque
Lawn is a dense growth of bacteria. Plaque is a gap in growth.
Auxotroph
A bacteria that cannot survive in minimal media, because can’t produce a molecule it needs to survive. Requires AUXillary Trophic substance to survive. Ex. Arginine
Obligate Aerobes
require oxygen
Anaerobes
Do not require oxygen
Faculative Anaerobes
Use O2 when around, but not needed
Tolerant Anaerobes
Do not O2 in metabolism but can have present
Obligate Anaerobes
Poisoned by oxygen
Fermentation v. Respiration
Respiration: Glucose catabolism with inorganic molecule
Fermentation: Glucose catabolism without an electron acceptor - produces a byproduct
Anaerobic Respiration
Glucose metabolism with electron transport and oxidative phosphorylation without oxygen (ex. SO4, H2S, CO2, CH4)
Log Phase
Exponential growth phase of bacteria (Log of exponential curve is linear), following lag phase and stationary phase)
Lag phase
precedes exponential growth and occurs for bacteria that were not previously growing, Result of needing to produce components for cell division ex. dNTPs
Stationary phase
Cease to divide due to lack of nutrients
Endospores
Formed by gram-positive bacteria under poor growth conditions.
Contains genome, ribosomes, and RNA in hard shell of peptidoglycan. Can withstand up to 100oC. Cannot divide during this period.
Metabolic reactivation = germination.
Bacterial means to acquire new genetic info
Transduction - Transfer of DNA by a lysogenic phage
Transformation - Under certain conditions, pure DNA will simply be integrated into cell.
Conjugation -
Conjugation
Two bacteria form conjugation bridge and one cell dopies DNA and transfers to other cell.
F (fertility) factor is key. If have F factor = F+ and male. If not F- and female.
F factor is exchanged during conjugation, so “sex” is transferred.
F factor
Fertility factor: singular circular DNA molecule. Contains many genes involved in conjugation ex. to form sex pili.
Hfr Cell
High Frequency Recombination Cell - F factor can become integrated into genome through recombination. Can still drive conjugation.
Note recombination can occur during conjugation as some genes in the F- cell will now be duplicate.
Conjugation Mapping
Can be performed using Hfr cells.
Review pg. 157 for more detail
Archaea
Live in most extreme environments. Have cell wal without peptidoglycan.
Similar traits to Eukaryotes: introns, mRNA sequences that are similar.
Reproduce via fusion or fission.
Extremely beneficial for industrial research.
Parasitic Bacteria
Obligate - must be inside a host to replicate
Faculative - can replicate inside or outside a host cell
Symbiotic Bacteria
Ex. Rhizobia - fixes nitrogen in the roots of legumes
Ex 2. Cyanobacteria in marine environments fix nitrogen
