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.
