Chapter 22: Microbial Life - Prokaryotes Flashcards
What two domains are prokaryotes?
Archaea and Bacteria and appeared 3.5 billion years ago
- they are ubiquitous, living in extreme conditions hot and cold
- beneficial and harmful to life.
What is the structure of prokaryotes?
- no membrane bound organelles
- cell wall
- plasma membrane
- ribosome
- some have flagella/cilia for locomotion
- some have pili to attach to other cell surfaces
- one circular double stranded DNA chromosome
- have many plasmids
What are plasmids?
- small circular dna molecules
- these can be acquired from other bacterial cells or from the environment
- they replicate independent of the bacteria’s chromosome
- contain only a few genes that are not present in the bacteria’s own chromosome
What are the three shapes of prokaryotes?
- coccus (spherical)
- bacillus (rod)
- spirillus (spiral)
Bacteria cell wall contain _______.
- peptidoglycan, polysaccharide chains linked by both L- and D- amino acids. Most amino acids are L-
Kingdom Bacteria are divided into two groups based on the composition of their cell wall:
- gram positive
- gram negative
What is gram positive?
- all gram positive bacteria belong to the same phylum
- have thick cell wall, 90% is peptidoglycan, 10% is teichoic acid
- one lipid bilayer
What is gram negative?
- All other bacteria phyla are gram negative
- Have thin cell wall, 10% peptidoglycan, 90% teichoic acid
- outside the cell wall is a capsule layer of lipopolysaccharide and lipoproteins
- two lipid bilayer
How does a bacteria reproduce asexually through binary fission?
- The circular bacterial chromosome is replicated through dna synthesis
- the bacteria grows
- then pinches inward until it separates into two separate cells which results in cloning, not mitosis
- does not include genetic recombination, mutation of DNA provides variation
What are the 3 ways bacteria can share genes with other bacteria(genetic recombination)?
- transformation
- transduction
- conjugation
Transformation:
- bacteria absorbs plasmid or bacterial DNA shed by another bacteria, plasmid always remains as plasmid.
- absorbed bacterial DNA can be incorporated into bacterial chromosome of recipient bacteria.
Transduction:
- bacteriophages move bacterial DNA from one bacteria to another
- Bacterial DNA is accidentally assembled along with viral
nucleic acid
Conjugation:
- DNA is transferred from one bacteria to another through the pilus.
- Can transfer plasmid or parts of bacterial chromosomal
genome - Only bacteria with an F+ factor gene can produce pili and
donate DNA, Hfr cell has F+ gene
Bacteria are both helpful and harmful to humans (and our pets and
livestock) such as:
- E. coli - good and bad
- Lactobacillus plantarum - immune system
- Streptococcus pneumonia causes pneumonia
_____ is a disease affecting a high percent of population in a specific
area.
Epidemic , ex. cholera, yellow fever
