Podcast Beta
Questions and Answers
What is the primary function of the field of systematic biology?
Who is credited with dividing the living world into two kingdoms, plants and animals?
What was the third kingdom established in the 19th century to accommodate single-celled organisms?
In the three-domain system, which domain comprises all eukaryotic organisms?
Signup and view all the answers
What is the main characteristic that distinguishes prokaryotes from eukaryotes?
Signup and view all the answers
What is the naming system devised by Carolus Linnaeus?
Signup and view all the answers
What is the correct sequence of the eight classification levels of living things?
Signup and view all the answers
What is the scientific name for the gray wolf?
Signup and view all the answers
What is the approximate percentage of water in the cytoplasm of a prokaryotic cell?
Signup and view all the answers
What is the function of mesosomes in prokaryotic cells?
Signup and view all the answers
What is the characteristic of the DNA in a prokaryotic cell?
Signup and view all the answers
What is the function of plasmids in prokaryotic cells?
Signup and view all the answers
What is the name of the process by which plasmids are passed on from one bacterial cell to another?
Signup and view all the answers
What is the role of the nucleoid in a prokaryotic cell?
Signup and view all the answers
What is the characteristic of the chromosome in a prokaryotic cell?
Signup and view all the answers
What is the function of some plasmids in relation to antibiotics?
Signup and view all the answers
What is the primary function of plasmids in genetic engineering?
Signup and view all the answers
What is the composition of the 50S subunit of a 70S ribosome?
Signup and view all the answers
What is the function of inclusion granules in bacterial cells?
Signup and view all the answers
What is the characteristic of endospores that makes them resistant to adverse conditions?
Signup and view all the answers
What is the purpose of Bacillus stearothermophilus spores in quality control?
Signup and view all the answers
What is the site of protein synthesis in all organisms?
Signup and view all the answers
How do mRNA and tRNA molecules interact with ribosomes during protein synthesis?
Signup and view all the answers
What is the characteristic of ribosomes that distinguishes them from other cell organelles?
Signup and view all the answers
What is the purpose of calcium dipicolinate in the formation of endospores?
Signup and view all the answers
What is the final stage of endospore formation?
Signup and view all the answers
What is the function of the cortex in the endospore?
Signup and view all the answers
What is the process by which a single endospore forms within a bacterium?
Signup and view all the answers
What is the structure that forms between the DNA and the rest of the cell during endosporulation?
Signup and view all the answers
What are the unique surface layers found in endospores that are not found in vegetative cells?
Signup and view all the answers
Study Notes
Systematic Biology
- Provides scientific names for organisms
- Describes them
- Preserves collections of them
- Provides classifications for the organisms, keys for their identification
- Investigates their evolutionary histories
- Considers their environmental adaptations
History of Classification
- Aristotle (384-322 BC) divided the living world into two kingdoms: plants and animals
- This system persisted for over 2000 years
- By the 19th century, the microscope revealed tiny single-celled organisms, leading to the creation of a third kingdom: Protista
- In 1938, Protista was divided into two kingdoms: Monera (unicellular prokaryotic microorganisms) and Protista (eukaryotic microorganisms)
Prokaryotes and Eukaryotes
- In the 1940s, biologists divided living organisms (except viruses) into two distinct groups: Prokaryotes (bacteria) and Eukaryotes (all other organisms)
- Prokaryotes (bacteria) have cells that lack a nucleus and other cell organelles
- Eukaryotes consist of cells that contain nuclei and other kinds of organelles
Three Domains of Life
- The three-domain system is currently used, replacing the old five-kingdom system
- Domain Bacteria and Domain Archaea comprise the prokaryotes
- Domain Eukarya includes all eukaryotic organisms
Classification Levels
- There are eight classification levels of living things:
- Domain
- Kingdom
- Phylum
- Class
- Order
- Family
- Genus
- Species
Binomial Nomenclature
- Carolus Linnaeus devised a naming system for organisms: Binomial Nomenclature
- Rules:
- Gray wolf (Canis lupus) is native to North America and Eurasia
Bacterial Internal Structures
- Cytoplasm: a gel-like matrix composed of 80% water, containing nucleic acids (DNA and RNA), enzymes, amino acids, carbohydrates, lipids, inorganic ions, and many low molecular weight compounds.
- Functions of cytoplasm: site of most bacterial metabolism, leading to growth and replication.
Mesosomes
- Mesosomes: plasma membrane infoldings.
- Functions of mesosomes:
- Role in the formation of cell walls.
- Replication of DNA in prokaryotes.
- Increase plasma membrane surface area and enzymatic content.
- Aid in the transfer of chromosomes to daughter cells.
- Analogous to cristae in the mitochondria of eukaryotic cells.
Nucleoid
- Nucleoid: also known as chromatin body, no nuclear membrane or nucleoli.
- Characteristics of nucleoid:
- Single circular chromosome of double-stranded, supercoiled DNA.
- No nuclear membrane.
- No nucleolus.
- No mitotic spindle.
- No histones.
- Size: 580,000 base pairs in Mycoplasma gallinarum to 9,140,000 bp in Myxococcus xanthus.
Plasmids
- Plasmids: small, nonessential, extra-chromosomal DNA, circular (linear in a few species).
- Characteristics of plasmids:
- Present in cytoplasm, but may become incorporated into chromosomal DNA.
- Often confer protective traits such as drug resistance or the production of toxins and enzymes.
- Passed on in conjugation.
- Replicate independently.
- Examples: antibiotic resistance, virulence factors, and conjugative plasmids.
Ribosomes
- Ribosomes: the most abundant in the cytoplasm, up to 15,000 ribosomes.
- Characteristics of ribosomes:
- 70S ribosomes in prokaryotes, composed of 50S and 30S subunits.
- 50S subunit contains 23S and 5S rRNA, and 30S subunit contains 16S rRNA.
- Chemically composed of ribosomal RNA (rRNA) and protein.
- Function as a workbench for protein synthesis – translation of mRNA into proteins.
Inclusion Granules
- Inclusion granules: nonliving components, not bounded by membranes, several kinds of reserve deposits.
- Examples: volutin granules, polysaccharide granules, lipid inclusions, sulfur and nitrogen granules, and gas vacuoles.
Endospores
- Endospores: dormant, resistant structures, produced intracellularly upon starvation.
- Characteristics of endospores:
- Resistant to adverse conditions: high temperatures, irradiation, cold, and organic solvents.
- Contain calcium dipicolinate.
- Not a mechanism of reproduction.
- Examples: Bacillus and Clostridium species.
- Formation: through endosporulation, involving DNA replication, spore septum formation, peptidoglycan cortex, and spore coat formation.
- Structure: cortex, core, and inner membrane, leading to resistance against UV light and harsh chemicals.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
Test your knowledge of biological classification systems, from systematic biology to Aristotle's early contributions.
