Microbes Flashcards
Archaea
Definition: A domain of single celled organisms
Cell membranes:
fatty acids linked to glycerol by ether linkages, no peptidoglycan
Asexual reproduction
offspring arise from a single organism
Autoinducer
- bacteria and archaea communicate with chemical signals (autoinducers) that are species specific or universal
- initiate group behavior genes once concentration is high enough
Bacteria
Definition: A large domain of prokaryotic microorganisms
Cell membrane: They have a peptidoglycan layer in their cell walls (gram+ or gram-)
Binary Fission
1) asexual, rapid division
2) no cell cycle
3) no membrane-bound organelles
Biofilm
communities of organisms that are irreversibly bound to a substrate; they secrete extracellular polymers (slime)
It works as a means of communication between prokaryotic cells; enables them to function like a multicellular organism
Key features:
- Extracellular polysaccharide matrix
- Surface attachment
- solid surface OR
- soft tissues in living organisms - Structural heterogeneity AND diversity (bacteria, archaea, protists, fungi, algae, etc.)
Chloroplast
An organelle bounded by a double membrane containing the enzymes and pigments that perform photosynthesis. Chloroplasts occur only in eukaryotes.
Also, organelles that work to convert light energy of the sun into sugars that can be used by cells
Origin: derived from endosymbiotic cyanobacteria
Conjugation
Bacteria and Archaea can directly exchange parts of their genome through a conjugation pilus (like a bridge). The transferred DNA is a plasmid.
Cyanobacteria
- Photolithoautotrophic
- Many can fix nitrogen
- contain internal membrane system
Diploid
2n; 2 sets of chromosomes
Endosymbiosis
Explains the origins of eukaryotic cell organelles such as mitochondria and chloroplasts
evidence:
- mitochondrial/chloroplast size
- mitochondrial/chloroplast structure and presence of DNA; their DNA is similar in structure, size and shape to bacterial DNA
Eukarya
Nucleus present, linear DNA, haploid or diploid or more, membrane-enclosed organelles present, cytoskeleton, mitosis
features: metabolically limited,
Extremophile
organisms that can live in extreme conditions. freezing/boiling temperatures, acidic environments
also called halophiles, thermophiles, acidophiles
Gram Stain
reveals the complexity of bacterial cell walls & separates bacteria into two distinct groups.
gram negative= thin cell walls and an outer membrane
gram positive= have dense cell wall consisting of primarily peptoglycan
Halophile
a microorganism that grows in or can tolerate high salty conditions.
Haploid
n; has a single set of chromosomes
Heterotrophy
Carbon source is organic
Lateral Gene Transfer LGT
- Conjugation - Bacteria and Archaea can directly exchange parts of their genome
- Transformation - Bacteria and Archaea can pick up DNA from their environment
- Transduction - Viruses can transmit DNA between hosts.
Similarities:
- both create new genetic combinations
- both may involve recombination
Differences (LGT):
- only involves small part of genome
- not reproduction
- multiple mechanisms
- can occur across large phylogenetic differences
Mitochondria
Facilitates aerobic cellular respiration in the cell.
Mitochondria arose from alpha-proteobacterium; all these bacteria are gram-
Meiosis
cell division that results in a reduction of ploidy
Nitrogen Fixation
Some cyanobacteria are able to fix atmospheric nitrogen and can convert it into a molecule to make available to other living organisms.
Mitosis
cell division that results in no reduction of ploidy
Peptidoglycan
bacteria membrane, cell wall; a special polymer of amino sugars
- gram+: peptidoglycan is outside of cell wall
- gram-: peptidoglycan is between plasma membrane and outer membrane of cell wall
only bacteria have peptidoglycan
Phagocytosis
The ingestion of bacteria or other material by phagocytes and amoeboid protozoans.