1. Microbiology: The Microbial World (2) Flashcards
Microorganisms are divided into what 2 catagories?
prokaryotes eukaryotes
What is the meaning of “prokaryotes”?
“pre nucleus” karyon= nucleus
What is a prokaryote?
A cell whose genetic material is not enclosed in a nuclear membrane.
What are characteristics of prokaryotes?
They are smaller and simpler than eukaryotes (~1 micrometer in diameter). DNA is one circular chromosome with a length of about 1 mm. The ability to exchange small packets of genetic information (may be carried on plasmids). Do not possess separate internal membrane-bound organelles (All internal structures are extensions of the cytoplasmic membrane).
What is a nucleoid?
The region of the cell containing the DNA.
What are plasmids?
Are small, extrachromosomal genetic elements that are capable of replication within prokaryotic cells. In some cases, may be transferred from one cell to another and thus may carry sets of specialized genetic information through a population.
What are the divisions within the prokaryotes?
Bacteria Archaea
What are bacteria?
Prokaryotes that possess peptidoglycan cell walls.
What is the meaning of eukaryotes?
“true nucleus”
What are eukaryotes?
Cells or organisms having a unit membrane-bound nucleus and usually membrane-bound organelles.
What are archaea?
Prokaryotes that lack peptidoglycan cell walls. Are often found in extreme environment.
What is the meaning of eukaryotes?
“True nucleus”
What are microbial eukaryotes?
They are cells or organisms having a unit membrane-bound nucleus and usually membrane-bound organelles.
What are characteristics of eukaryotes?
Their DNA is enclosed in a nuclear membrane and is found in multiple chromosomes. Cell division occurs via mitosis. Genetic transfer depends upon fusion of haploid gametes to form a diploid cell containing a full set of genes derived from each gamete. They possess membrane-bound organelles, including mitochondria, endoplasmic reticulum, etc.
What are the divisions within the Eukarya?
Algae. Fungi. Protozoa.
What are Algae?
They are photosynthetic eukaryotes (contain chlorophyll).and the cell walls are composed of cellulose
What is mitosis?
chromosomes replicate and an identical set is distributed into each of two nuclei
What are Fungi?
They are immotile, nonphotosynthetic, unicellular or multicellular eukaryotes. They produce asexual and sexual spores.
What are Protozoa?
These are unicellular, motile eukaryotes that lack the cell walls of algae and fungi. Many are free-living microorganisms or parasites that absorb or ingest organic compounds from their environment. They can reproduce sexually or asexually.
What is a Prion? (Proteinaceous infectious particles)
Is a small (30nm), infectious, abnormally folded protein, with no nucleic acid.
The prion protein (PrP) is encoded by what?
The host’s chromosomal DNA.
An abnormal isoform of the PrP is the only known component of the prion and is associated with what?
transmissibility.
The abnormal isoform of the PrP differs physically from the normal cellular isoform by what?
Its high Beta-sheet content. its insolubility in detergents. its propensity to agregate, its relative resistance to proteolysis by proteases.
What kind of prions are protease-sensitive?
Normal prions
What are transmissible spongiform encephalopathies?
Several neurodegenerative diseases in humans and animals that prions are responsible for. The diseases are irreversible and uniformly fatal.
What are some diseases from the basic lesion (spongiform degeneration in the gray matter of the brain)?
scrapie bovine spongiform encephalopathy kuru Creutzfeld-Jakob disease
What are the differences in the sizes of prokaryotes to eukaryotes?
prokaryotes- small, 0.5-3.0 micrometers eukaryotes- larger, >5 micrometers
What are the differences in the nucleus of prokaryotes to eukaryotes?
prokaryotes- no nuclear membrane eukaryotes- true nucleus, consists of nuclear membrane and nucleoli
What are the differences in the chromosomes of prokaryotes to eukaryotes?
prokaryotes- single, circular DNA haploid genome eukaryotes- multiple, DNA diploid genome
What are the differences in the membrane-bound organelles of prokaryotes to eukaryotes?
prokaryotes- absent eukaryotes- many types always present
What are the differences in the cytoplasmic membrane of prokaryotes to eukaryotes?
prokaryotes- does not contain sterols (except Mycoplasma spp.) eukaryotes- contains sterols
What are the differences in the cytoplasm of prokaryotes to eukaryotes?
prokaryotes- no cytoskeleton eukaryotes- has a cytoskeleton
What are the differences in the cell wall of prokaryotes to eukaryotes?
prokaryotes- usually present, chemically complex eukaryotes- present in fungi, absent in others
What are the differences in the ribosomes (sedimentation co-efficient) of prokaryotes to eukaryotes?
prokaryotes- 70S (50S+30S) eukaryotes- 80S (60S+ 40S)
What are the differences in the respiratory system of prokaryotes to eukaryotes?
prokaryotes- located in cytoplasmic membrane eukaryotes- via mitochondria or chloroplast
What are the differences in the reproduction of prokaryotes to eukaryotes?
prokaryotes- asexual (binary fission) eukaryotes- sexual and asexual (mitosis)
