Chapter 22 Flashcards
3 bacteria shapes
bacillus, coccus, spirilla
bacillus are shaped like
rods
coccus are shaped like
spheres
staphylococci are shaped like
grape clusters
streptococcus are shaped like
lines of grapes
prokaryote structure
- have a cell wall
- many have a capsule or slime layer
- some have hairlike protein fimbriae
- many can form sex pilus
- no membrane bound organelles
lies outside of plasma membrane, protects and prevents cell lysis, maintains osmotic pressure, made up of peptidoglycan
bacterial cell wall
what is the bacterial cell wall made of
peptidoglycan
gram stain reflects the
type of cell wall
gram positive (purple)
bacteria with thick peptidoglycan layer
gram negative (pink)
bacteria with thinner peptidoglycan layer plus outer lipid bilayer membrane
- sticky carbs and proteins secreted outside of cell wall
- adheres cells together or to surface
- resists attack from immune system
- holds in moisture
capsule or slime layer
help cells stick to surfaces and each other
hairlike protein called fimbriae
pulls two bacteria cells together for DNA transfer, forms mating bridge
sex pilus
the process by which one bacterium transfers genetic material to another through direct contact
conjugation
movement directed towards or away from a stimulus
taxis
movement away or towards chemicals
chemotaxis
movement away or towards light
phototaxis
align with earth’s magnetic field with crystals
geotaxis
movement is produced by
rotating flagellum protein fibers
where is DNA located in prokaryotes?
the nucleoid
functions of folded-in plasma membrane
aerobic cellular respiration, invagination, or oxygen-producing photosynthesis
prokaryote DNA
genome, no histones, one chromosome, plasmids
single double-stranded DNA that is circular
genome
extra tiny DNA rings with few genes, replicate independently and add diversity
plasmid
asexual reproduction by a separation of the body into two new bodies, yields two identical cells
binary fission
A differentiated cell formed within cells of certain Gram-positive bacteria that are extremely resistant to heat and other harmful conditions and agents
endospores
importance of DNA mutations
- Point mutations rare per division
- High rate of cell division –> many mutations
- One mutation can change phenotype
- Mutation (except lethal) are passed on in clones
- Selection favors best clones
Short generation times –> rapid evolution - Rapid- evolution, more divisions=more mutations
type of reproduction where:
no babies, genes go one direction, plasmids are exchanged
conjugation produces
Type of recombination: DNA bits from ruptured donor cell are absorbed directly by recipient, homologous DNA exchanges with DNA in chromosome
Example of horizontal gene transfer
recombination by transformation
type of recombination where DNA is carried by the bacteriophage, phages inject viral DNA into bacteria, and uses the cell’s resources to make more phages
recombination by transduction
primary producer in a food web
autotroph
most important decomposers on earth
chemoheterotrophic bacteria
secretes enzymes that hydrolyze dead material/waste, monomers enter by diffusion/active transport, and metabolism releases Co2, N,P,K
chemoheterotrophic bacteria
normally use O2 but switch to anaerobic processes if O2 is not present
facultative anaerobes
require O2 for cellular respiration
obligate anaerobes
