Chapter 27.1 - 27.2 Flashcards
What domains do prokaryotes make up?
2 out of 3 (archaea and bacteria)
What are the three most common shapes of prokaryotes?
Spheres, rods, and spirals
How do cell walls benefit prokaryotes?
- Maintain shape
- Provide protection
- Prevent cell from bursting (hypotonic environment)
What makes up bacterial cell walls? Archaean cell walls?
Bacteria: peptidoglycan
Archaea: many polysaccharides and proteins (no chitin, cellulose, peptidoglycan)
Why are foods soaked in salt?
Prokaryotes will plasmolyze in hypertonic environments, thus killing them
What technique separates bacteria into 2 types? How are they separate (by what)?
- Gram staining
- Separated based on composition of cell walls
What are the 2 types of bacteria caused by gram staining?
Gram-positive (simpler, more peptidoglycan)
Gram-negative (complex, lipopolysaccharides)
What type of bacteria is more dangerous in an infection?
Gram-negative
What is a capsule?
Sticky layer of polysaccharide or protein that surrounds most prokaryotic cell walls
What’s the purpose of a capsule?
- Allows adhering to substrate/others
- Protects against dehydration (hypotonic environment)
- Protects against immune system attacks
What are fimbriae?
Protein appendages that allows prokaryotes to stick to substrates or others
What are sex pili?
Long protein appendages which pulls cells together for DNA transfer
What is the most common feature that makes motility possible?
Flagellum
In a uniform environment, how do prokaryotes move by flagella?
In random movements
How do prokaryotes move in diverse environments?
They exhibit taxis, moving toward or away from stimulus
Prokaryotes that exhibit chemotaxis do what?
Change movement pattern in response to chemicals
Difference between positive and negative chemotaxis?
Positive: moving towards nutrients or oxygen
Negative: moving away from toxic substance
What do prokaryotes have instead of a nucleus? How is DNA composition different?
- Region of cytoplasm called nucleoid
- Circular with fewer proteins (may have plasmid)
How are ribosomes different in prokaryotes and eukaryotes?
Smaller and differ in protein/RNA content in prokaryotes
What conditions make prokaryotic reproduction limited?
- Exhausting nutrient supply
- Poisoned by metabolic wastes
- Competition from other microorganisms
- Being consumed by other organisms
What three features allow prokaryotic populations to be very large?
- Small
- Reproduce by binary fission
- Have short generation times
How are endospores created?
In harsh conditions, cell copied chromosome and surrounds it with tough wall (endospore formed). Water is removed by endospore to halt metabolism and cell disintegrates, leaving only endospore.
What 3 factors create genetic diversity among prokarytes?
- Rapid reproduction
- Mutation
- Genetic recombination
What 3 processes bring together prokaryotic DNA from different individuals (recombination)?
- Transformation
- Transduction
- Conjugation
What is transformation
Uptake of foreign DNA
What is transduction
Phages carry bacterial DNA to donor cell; exchange of genes at homologous segments
What is conjugation?
Transfer of genetic material between 2 bacterial cells that are temporarily joined
What is the basic mechanism of conjugation?
Donor cell uses sex pili to attach to recipient; upon contact, sex pili is retracted, pulling cells together; mating bridge is then formed for DNA transfer
What are Hfr cells?
Cells with F factor built into chromosome (donor cell)
What is homologous gene transfer?
DNA is exchange at homologous gene segments
What are resistant genes? What is an R plasmid?
- Genes that code for enzymes that destroy or hinder specific antibiotics
- Plasmid with resistance genes
