Week 2 Flashcards
(25 cards)
What are the 3 Domains of Life?
Bacteria (Prokaryotes)
Archaea (Prokaryotes)
Eukarya (Eukaryotes)
What is the difference between prokaryotic and eukaryotic cells?
Prokaryotes: Single-celled organisms, no nucleus, and lack membrane-bound organelles.
Eukaryotes: Can be single-celled or multi-celled, with a nucleus and membrane-bound organelles.
What do prokaryotic cells and eukaryotic cells have in common?
Both have a cell membrane, ribosomes, and nuclear material (DNA).
How do prokaryotic cells and eukaryotic cells differ in their organization of DNA?
Eukaryotic cells: Have paired chromosomes within a nucleus.
Prokaryotic cells: Have a single, circular chromosome located in the nucleoid.
What is the role of histone proteins in DNA organization?
Eukaryotic cells have histone proteins that help organize DNA, while prokaryotic cells lack histones.
What is the difference in cell wall composition between prokaryotic and eukaryotic cells?
Prokaryotic cell walls: Contain peptidoglycan.
Eukaryotic cell walls: In plants and fungi, they contain cellulose and chitin.
What are the most common bacterial shapes?
Cocci (spherical)
Bacilli (rod-shaped)
Spirilla (spiral-shaped)
What is the glycocalyx?
polysaccharide layer that can be a capsule or slime layer. It helps bacteria attach to surfaces, prevents dehydration, and is a virulence factor by preventing phagocytosis.
What is the difference between a capsule and a slime layer in bacteria?
Capsule: Highly organized and tightly attached to the bacterial cell.
Slime layer: Loosely attached and less organized.
What is the role of the bacterial cell wall?
gives the cell shape, stability, and protection from osmotic pressure, and contains peptidoglycan, which forms a protective “armor” around the cell.
What is the function of the cell membrane in prokaryotes?
cell membrane acts as a selective barrier, controlling the movement of substances into and out of the cell. It is also the site of ATP production in prokaryotes.
How do prokaryotic cells produce ATP?
produced in the cell membrane using ATPase, as prokaryotic cells lack mitochondria.
What are inclusions in the cytoplasm of prokaryotic cells?
Storage structures such as gas-filled vesicles for buoyancy or granules that store substances like glycogen or phosphate.
What is the difference between 70S and 80S ribosomes?
70S ribosomes are found in prokaryotes and mitochondria
80S ribosomes are found in eukaryotic cells.
What is the structure of bacterial DNA?
single, circular chromosome located in the nucleoid area of the cell, without a nuclear membrane.
What are plasmids in prokaryotic cells?
extrachromosomal DNA molecules that are circular and double-stranded. They often carry genes for antibiotic resistance.
What are pili in bacteria?
appendages that help bacteria attach to surfaces (attachment pili) and facilitate DNA transfer during conjugation (sex pili).
What are the types of flagella arrangements in bacteria?
Polar flagellum: Flagellum at one end.
Peritrichous flagella: Flagella distributed around the cell surface.
What is the importance of a Gram stain?
distinguishes between Gram-positive and Gram-negative bacteria based on differences in their cell wall structure.
What is the process of performing a Gram stain?
Apply crystal violet (stains both types).
Add Gram’s iodine to form complexes.
Wash with alcohol, which removes the complex from Gram-negative cells.
Apply safranin counterstain to turn Gram-negative cells red/pink.
What is the difference between Gram-positive and Gram-negative bacteria?
Gram-positive bacteria have a thick peptidoglycan layer, which retains the crystal violet dye, making them purple.
Gram-negative bacteria have a thin peptidoglycan layer and an outer membrane, making them pink after the Gram stain.
What is antimicrobial chemotherapy?
using chemical agents (antibiotics, synthetic, or semisynthetic drugs) to treat diseases caused by microbes.
What is the difference between bactericidal and bacteriostatic agents?
Bactericidal agents kill bacteria (e.g., penicillin).
Bacteriostatic agents inhibit bacterial growth (e.g., tetracyclines).
What is selective toxicity in antimicrobial drugs?
refers to the ability of antimicrobial drugs to harm microbes without causing harm to the host’s cells.
