Ch.4 Part 2 Flashcards
what is a decolorizing agent?
breaks down the gram negative cell wall, allows the primary stain and mordant to be washed away (colorless again)
what is a counterstain?
stain of a contrasting color
describe the differential stains (gram stains)
1.) all cells are stained
2.)iodine acts as a mordant; all cells remain purple
3.) smear is decolorized; gram-positive cells remain purple, but gram-negative cells are now colorless
4.) gram-positive cells remain purple; gram-negative cells are pink
what are acid fast bacteria?
myobacterium and nocardium
what does acid fast staining use?
carbolfuschin dye
what is an endospore?
An endospore is a dormant, highly resistant form of a bacterium, capable of surviving harsh conditions like heat, UV radiation, and chemicals.
in endospore stain the spores and vegetative cells are what colors?
spores are green
vegetative cells are red
Why is endospore staining important?
It helps identify spore-forming bacteria, which are often associated with severe infections (e.g., Clostridium tetani or Bacillus anthracis).
what is a capsule?
A protective layer around some bacteria made of polysaccharides or peptides.
what is a negative cell?
A stain that colors the background, leaving the capsule clear.
what is the result of a negative stain?
A dark background with clear halos around the bacterial cells (capsules).
why is neagtive staining important?
capsules protect bacteria from immune attack
Why do we need to know about the number and arrangement of flagella?
The number and arrangement help identify bacterial species, as different bacteria have characteristic flagellar patterns (e.g., monotrichous, lophotrichous, peritrichous).
How do we stain flagella?
Flagella are stained using carbolfuchsin and mordants, which help thicken the flagella for better visibility under the microscope.
what is taxonomy?
the sciene of classifying and naming organisms
what is taxonomy used for?
-allows large amounts of information to be organized
-make predictions on where to place newly discovered organisms
What is binomial nomenclature?
The system of giving each organism a two-part Latin name: Genus (capitalized) and Species (lowercase), e.g., Homo sapiens.
who created taxonomic scheme
carolus linnaeus
How are organisms classified?
Based on similarities in physical traits, genetic information, and evolutionary relationships.
Why is this system important?
It provides a universal language for scientists to clearly identify and categorize organisms across the world.
what is phylogenetic hierarchy
how organisms are evolutionary related, lead to comparisons of genetic materia;
Who is Carl Woes?
proposed a new classification system based on genetic data, particularly ribosomal RNA (rRNA) sequences.
what did woes propose?
introduced the concept of domains as a higher taxonomic level than kingdoms.
What are the three domains?
Bacteria: Single-celled organisms without a nucleus.
Archaea: Similar to bacteria but genetically distinct and often found in extreme environments.
Eukarya: Organisms with a nucleus, including animals, plants, fungi, and protists.
