Chapter 27 Flashcards
__________ thrive almost everywhere, including places too acidic (pH of 0.03), salty, cold, or hot for most other organisms
Prokaryotes
The two domains of prokaryotes
1) Bacteria
2) Archaea
The three most common shapes of prokaryotic cells
1) Spheres (cocci)
2) Rods (bacilli)
3) spirals
T/F: All bacteria are harmful
False; Some bacteria cause infections, but most species are harmless or perform beneficial functions
Beneficial bacteria are called _________ bacteria
commensal
An important feature of nearly all prokaryotic cells is their…
cell wall, which maintains shape, provides protection, and prevents bursting in hypotonic environments
Eukaryote cell walls are made of _______ or _______
cellulose; chitin
Bacterial cell walls contain _________
peptidoglycan
Peptidoglycan
a network of sugar polymers cross-linked by polypeptides
T/F: Archaea contain polysaccharides, proteins, and peptidoglycan
False; they contain polysaccharides and proteins, but lack peptidoglycan
Scientists use the __________ to classify bacteria by cell wall composition
Gram stain
Gram-positive
bacteria have simpler walls with a large amount of peptidoglycan
Gram-negative
bacteria have less peptidoglycan and an outer membrane that can be toxic
Many __________ target peptidoglycan and damage bacterial cell walls
antibiotics
__________ bacteria are more likely to be antibiotic resistant
Gram-negative
Fimbriae
Short, hair-like protein structures on bacterial cell surfaces; allow some prokaryotes who have them to stick to their substrate or other individuals
Pili (or sex pili)
longer than fimbriae and allows prokaryotes to exchange DNA
taxis
movement toward or away from a stimulus exhibited by many bacteria
__________ is the movement toward or away from a chemical stimulus
Chemotaxis
Flagella
Found in bacteria, archaea, and eukaryotes; are composed of different proteins and allow for mobility; likely evolved independently
Bacterial flagella are composed of a ______, ______, and ______
motor; hook; filament
Prokaryotic cells usually lack _____________
complex compartmentalization
Transformation
A prokaryotic cell takes up and incorporates foreign DNA from the surrounding environment
Transduction
the movement of genes between bacteria by bacteriophages
Bacteriophage
viruses that infect bacteria
Conjugation
the process where genetic material is transferred between prokaryotic cells
In bacteria, the DNA transfer is _________
one way
In conjugation, a donor cell attaches to a recipient by a ______, pulls it closer, and __________
pilus; transfers DNA
R plasmids
carry genes from antibiotic resistance
Antibiotics kill sensitive bacteria, but not bacteria with specific __________
R plasmids
biofilms
surface-coating colonies; often partake in metabolic cooperation between individuals in the biofilm
Cyanobacteria
Photoautotrophs that generate O₂
Plant chloroplasts likely evolved from _________ by the process of __________
cyanobacteria; endosymbiosis
Pathogenic Bacteria
Bacteria that cause diseases
T/F: Bacteria cause about a third of all human diseases
False; cause about half
