Bacteria Flashcards
What two domains do bacteria appear in?
bacteria and archaea
How are bacteria “masters of adaptation”?
asexual rapid reproduction through binary fission (MRSA) - see genetic diversity
What are bacteria measured in?
micrometers
What is the genetic material of bacteria?
single chromosome (DNA) found in the nucleoid, plasmids (separate circular strips of DNA, used in recombinant DNA technology as a vector)
What makes bacteria prokaryotes?
no nucleus (nucleoid instead), no membrane bound organelles - no mitochondria or chloroplasts but do have ribosomes
Why are bacteria important?
biotechnology (plasmids and recombinant DNA), finding antibiotics, understanding genetics, ecological decomposers, found in intestines as good bacteria (ecoli)
What are the 3 forms of bacteria?
bacillus (rod-shaped), coccus (spherical, can be found in clusters or chains), spiral (corkscrew)
What are the 3 outer layers of bacteria?
capsule, cell wall, cell membrane
capsule
structure- made of polysaccharides and proteins, also called slime coat because it is sticky for the bacteria to stick to objects as well as other cells (has fimbrae)
function- prevents dehydration, protection
cell wall
structure: made of peptidoglycan (complex carbohydrate that aids support)
function: rigid and thick, keeps shape and structure, protection
cell membrane
function: selectively permeable (regulates what goes in and out of the cell), protection
What are the 3 projections from the bacteria?
flagellum, pilus, fimbriae
flagellum
function: locomotion, motility (an organism’s ability to move)
structure: motor is made of 42 different proteins that must be in just the right place to work
irreducible complexity
proves intelligent design, every little part is necessary for correct use, ex. mouse trap
pilus/sex pilus
tubes in which bacteria pass DNA to another bacterial cell
fimbriae
front end of bacteria, for attachment, help stick to surfaces and each other
nucleoid
where genetic material is found (DNA)
ribosome
translates
mesosome
infolding of the plasma membrane where aerobic cellular respiration occurs (like membranes in mitochondria), ETC’s and oxygenated phosphorylation, can also do photosynthesis (light reactions)
granule
starch storage
endospores
spores inside the bacteria that respond to harsh environmental conditions like dry soil, protective covering surrounds the DNA and the rest of the cell disintegrates
Gram stain
dye used to differentiate between different types of bacteria
gram positive
purple, coccus, lots of peptidoglycan
gram negative
pink, bacillus, little peptidoglycan
antibiotics and how the gram stain applies to them
function: destroy cell wall to let out the contents bringing bacterial death, the amount of peptidoglycan shown by the gram stain determines antibiotics needed
Binary Fission
how one cell divides into two clones (not called mitosis), new cell goes through growth and replicates the one chromosome to 2, 61 minutes taken altogether (in order to divide, it must have the right nutrients, temperature, sunlight, and oxygen)
the importance of genetic diversity
Natural selection can only work if there is genetic variation. If all bacteria were the same, one thing can destroy all of them at the same time! It’s for survival
3 types of genetic diversity
rapid reproduction, mutation and genetic recombination
3 types of genetic recombination
transformation, transduction, conjugation
transformation
uptake of foreign DNA (lysed) from the surroundings (foreign DNA only gets in the bacteria by specific receptors. Many times, this foreign DNA gives resistant, beneficial genes)
transduction
carrying of bacterial DNA from one bacteria to another by bacteria phage viruses. Process: Viral DNA is injected into the bacteria and breaks apart the bacteria DNA. Then, the viral DNA is expressed and forms new phages, and these phages burst apart the cell (normal lytic cycle). Sometimes, one of these new phages have the bacterial DNA (infected with the virus), and this then infects another cell. So now, this other cell (recipient cell) has the recombinant DNA
Conjugation and 2 types
transfer of DNA between 2 temporarily joined (joined by the pilus) bacteria cells
- plasmid transfer
- chromosome transfer
Plasmid transfer
- There are 2 cells. The donor cell is F+, meaning that it has the fertility plasmid and the gene to make the pilus
- The pilus is made by the donor cell to make the bridge/channel to connect to the recipient cell.
- The donor cell replicates its plasmid.
- The donor cell sends the plasmid through the pilus.
- Now, the recipient cell has the plasmid and becomes F+ (so now it can be a donor cell). Many times, the plasmid gives beneficial genes.
Chromosome transfer
The donor cell duplicates its chromosome and sends it to the recipient cell through the pilus.
- Hfr (High frequency of recombination) cell has the F+ gene, but this F+ gene is part of a single chromosome (not a plasmid). The DNA replicates, and the pilus is formed
- F factor enters the recipient cell along with a part of the bacterial chromosome (through the pilus)
- The piece of chromosome gets duplicated, but the F+ factor is broken down, so the recipient cell remains F negative
2 types of plasmids
F and R plasmid
R plasmid
antibiotic resistance, sometimes in bacteria
3 types of metabolism
obligate aerobes, obligate anaerobes, and facultative anaerobes
obligate aerobes
require oxygen for survival (cellular respiration)
obligate anaerobes
poisoned by oxygen and use fermentation or anaerobic respiration
facultative anaerobes
survive with or without oxygen
What kind of reaction is cellular respiration?
catabolic - glucose broken down
2 ways living things can get glucose
eating it, photosynthesis
autotrophs
make food energy
- phototrophs- sunlight energy (photosynthesis)
- chemotrophs- chemicals (chemosynthesis)
heterotrophs
absorb nutrients by diffusion
compare and contrast archaea and bacteria
Similarities:
1. prokaryotes
2. no membrane bound organelles
3. no nuclear envelope
Differences:
1. bacteria have peptidoglycan and archaea don’t
2. bacteria are found in normal habitats but archaea live in extreme habitats (extremophiles)
3. molecular/structural differences (DNA, RNA, enzymes)
3 types of extremophiles
halophiles- salty habitats
thermophiles- hot habitats (geysers, volcanoes)
methanogens- produce methane into the environment as waste product (anaerobes, swamps/marshes)
ecology
the study of living things and their interaction between other living themes/environment
decomposers
break down dead organisms/waste products and enable chemical recycling
chemical recycling
recycle the chemicals in the environment needed by other living things
symbiosis and 3 types
2 organisms live together in close contact in a relationship for survival
- mutualism
- parasitism
- commensalism
mutualism
both organisms benefit from the relationship (bacteria in our intestines: they receive food, shelter from predators, and a warm, moist environment and they break down our food for us)
commensalism
one is benefitted and the other is neither harmed nor benefitted
parasitism
one benefits and one is harmed
pathogens
parasites that cause disease
2 ways pathogens make you sick
exotoxins- secreted outside of a bacterial cell (sick immediately)
endotoxins- released when bacteria dies and wall breaks down
