chapter 3 bacte

• Prokaryotes are organisms that do not contain a true nucleus and do not contain organelles such as mitochondria, endoplasmic reticulum, and Golgi apparatus.
• All the functions of these organisms take place in the cytoplasm or cytoplasmic membrane.
• The term "prokaryote" is formed by the words "pro," which means before, and the Greek word "karyon," which means nucleus, nut, or kernel.
• A common example of these cells are the bacteria.
• These organisms are classified as aerobes, facultative anaerobes, or obligate anaerobes.
• Examples of cell envelope organisms include Methanospirillum, Halobacterium, and Sulfolobus.
• These organisms may be stained either as Gram-positive or Gram-negative organisms in various shapes such as spherical, rod, and spiral (pleomorphic).
• These organisms can grow and survive under extreme environmental conditions.
• The cell envelope is the outermost structure of the bacterial cell, composed of an outer membrane, cell wall, periplasm, and plasma membrane.
• These organisms reproduce through binary fission, fragmentation, or budding.
• The cell wall, also referred to as the peptidoglycan or murein layer, is a rigid structure that maintains the shape of the cell and is composed of disaccharide-pentapeptide subunits and teichoic acid or lipoteichoic acid.
• Common/Somatic Pili are the organ of attachment and aid in the attachment of bacteria to tissues and surfaces.
• The movement of bacteria toward or away from a particular stimulus is called taxis.
• Survivability and pathogenic ability in bacteria are important factors.
• Gliding motility is exhibited by cyanobacteria, myxobacteria, and Capnocytophaga.
• Sex Pili are an essential part of the genetic transfer/conjugation process.
• Gram-positive bacteria have two basal rings while Gram-negative bacteria have four basal rings in the flagellar structure.
• Eukaryotes are microorganisms that contain a true nucleus (with chromosome bound by a nuclear membrane).
• Sterols are absent in prokaryotes, except in Mycoplasmataceae, and are present in Eukaryotes.
• Motile bacteria include Alcaligenes, Bacillus cereus, Bacillus subtilis, Campylobacter, Clostridium tetani, Bacillus anthracis, Bordetella, Clostridium, Streptococcus pneumoniae, Corynebacterium, Mycobacterium, Nocardia, and Actinomycetes.
• Pili and fimbriae are present in prokaryotes.
• Flagellar arrangement includes atrichous (without flagellum), monotrichous (single flagellum on one end), amphitrichous (single flagellum on both ends), lophotrichous (tuft/group of flagella on one end or both ends), peritrichous (spread over the whole surface), and pili (fimbriae) which are hair-like, proteinaceous structures, about 2 gm in length, that extend from the cell membrane to the external environment.
• The cytoskeleton and cytoplasmic streaming are present in Eukaryotes, but absent in prokaryotes.
• With Brownian movement, the bacteria bounce back and forth rapidly due to the bombardment of water molecules.
• Cell division in prokaryotes is asexual (binary fission), while in Eukaryotes it can be sexual and asexual.
• With true motility, the bacteria seem to be going in a definite direction.
• The size of a prokaryotic cell is typically between 0.20 pm - 2.0 pm, usually with a cell wall, and is absent in most fungi.
• True motility and Brownian movement are best observed through the hanging drop method.
• Gas vesicles are absent in prokaryotes, but present in Eukaryotes.
• Lysosomes and peroxisomes are absent in prokaryotes, but present in some species.
• Chromosomal DNA in prokaryotes is a single, circular chromosome complexed with RNA and without histones.
• Flagella in prokaryotes are simple, consisting of two protein-complex (multiple microtubules) building blocks.
• The location of the genome in prokaryotes is in the nucleoid or at the mesosome.
• Introns are present in genes in Eukaryotes, but absent in prokaryotes.
• In prokaryotes, ribosomes are present in a smaller size (70S) and larger size (80S).
• The nucleus is absent in prokaryotes, and the absence of a nuclear membrane or nucleoli is present, indicating a true nucleus with nuclear membrane and nucleoli.
• Cells of higher plants, animals, fungi, protozoa, and other morphologically complex and larger organisms than prokaryotes contain many membrane-bound organelles such as nucleus, endoplasmic reticulum, Golgi body, mitochondria, and lysosomes, in which cellular functions are performed.
• Subterminal spore is found in Clostridium botulinum.
• Germination is the end of the spore's dormant stage.
• Examples of endospore-forming bacteria include Bacillus and Clostridum.