Ch 27 Bacteria archaea Flashcards
Prokaryotes are divided into What two domains:
Bacteria and archea
Prokaryotic cells have a variety of shapes
The three most common shapes are
spheres (cocci), rods (bacilli), and spirals
An important feature of nearly all prokaryotic cells is their cell wall, which
maintains cell shape, protects the cell, and prevents it from bursting in a hypotonic environment
Eukaryote cell walls are made of…
cellulose or chitin
Bacterial cell walls contain what…
peptidoglycan
what is peptidoglycan
a network of sugar polymers cross-linked by polypeptides
what does Archaea contain and lack?
contains polysaccharides and proteins but lack peptidoglycan
Scientists use the Gram stain to classify…
bacteria by cell wall composition
_ _ bacteria have simpler walls with a large amount of peptidoglycan
Gram-positive
_ _ bacteria have less peptidoglycan and an outer membrane that can be toxic
Gram-negative
Many_ _ target peptidoglycan and damage bacterial cell walls
antibiotics
_ _ bacteria are more likely to be antibiotic resistant
Gram negative
A polysaccharide or protein layer called a_ _ covers many prokaryotes
capsule
Some prokaryotes have_ _ , which allow them to stick to their substrate or other individuals in a colony
fimbriae
_ _ are longer than fimbriae and allow prokaryotes to exchange DNA
Pili (or sex pili)
In a heterogeneous environment, many bacteria exhibit ,_ _ the ability to move toward or away from a stimulus
taxis
What is Chemotaxis ?
the movement toward or away from a chemical stimulus
what are Bacterial flagella are composed of
a motor, hook, and filament
Flagella likely evolved as existing proteins were added to an _ _
ancestral secretory system
