Topic 4 Flashcards
All cells are related by their…
descent from earlier cells
Cell structure is correlated to
cellular function
Prokaryotic Cells
- No nucleus
- DNA is an unbound region called the nucleoid
- No membrane-bound organelles
- Cytoplasm bound by plasma membrane
Eukaryote cell walls are made of
cellulose or chitin
Bacterial cell walls contain peptidoglycan
a network of sugar polymers cross linked by polypeptides
Gram stain
can be used to classify bacteria by cell wall composition
Gram-positive bacteria
- Simple, thick peptidoglycan
- > crystal violet gets trapped
- > cell appear purple/violet
Gram-negative bacteria
- Complex: thin peptidoglycan layer + outer membrane
- > does not trap crystal violet
- > appear red or pink
Many antibiotics target…
peptidoglycan and damage bacterial cell walls
Capsule
A polysaccharide or protein layer that covers many prokaryotes. (type of glycocalyx)
fimbriae
which allow them to stick
to their substrate or other individuals in a colony
Pili
longer than fimbriae and allow prokaryotes
to exchange DNA (plasmid)
In heterogenous environment, many bacteria exhibit
taxis (directed movement) -negative -> away -positive ->toward chemotaxis phototaxis
Bacterial flagella are composed of a…
motor, hook and filament
Chemoheterotrophic prokaryotes
decomposers, breaking down dead organism and waste products.
hydrothermal vents depend on…
chemoautotrophic bacteria for energy
Symbiosis
an ecological relationship in which two specied live in close contact: a larger host and smaller symbiont
interactions
mutualistic
commensalism
parasitism
