DDT 13 - Structure and Funciton of Bacteria Cell Flashcards
size range of bacteria
1-10 µm in length
0.2-2µm in diameter
3 basic shapes of bacteria
rod shaped -bacillus
round shape - coccus
spiral - spirillus
are bacteria eukaryotic or prokaryotic cells and what does that mean
prokaryotic cells
lack membrane enclosed organelles - no nucleus, mitochondria, chloroplasts
example of bacillus bacteria
salmonella
example of coccus bacteria
micrococcus - found in skin
example of spirillus bacteria
sprioplasma
what features do ALL bacterium have
cytoplasm
ribosomes
plasma membrane
nucleoid containing DNA
Describe cytoplasm in bacteria and its function
dense and contains ribosomes and storage granules that hold glycogen, lipid or phosphate compounds
Describe nucleoid in bacteria
bacteria contain a single, circular, double-helical strand of DNA containing between
how many genes are in nucleoid in DNA
3,000 - 6,000 genes within the cytoplasm.
Describe plasmid and its function
small circular, double stranded DNA molecule
Carries genes separate from the main DNA of cell, usually genes that are of a selective benefit to the bacterium
what features of the bacteria are similar to the human and what are different
ribosomes - same 2 subunits that makeup ribosomes - contain protein and RNA
different subunit composition
Like humans - DNA are tightly packed but don’t contain histones
how does one resistant bacteria transfer its resistance to sensitive bacteria
send copy of plasmid through conjugation bridge
Resistant bacterium is in close contact with sensitive bacterium
copy of plasmid in resistant bacterium is made and conjugation bridge is formed
Plasmid copy is transferred through conjugation bridge
describe capsule and its function in bacteria
thick sticky gelatinous layer made of polysaccharides
prevent phagocytosis
More difficult for macrophages to undergo phagocytosis because its sticky and to stimulate an immune response
describe flagellum and its function
anchored through all layers of bacteria by protein rings
3 parts - basal body, hook - propeller allows filament to move/rotate, filament
allow movement
describe pili
hair like appendage
ordinary pili - clump bacteria together
sex pili - transfer genetic info
2 types of bacteria cell walls
gram positive
gram negative
describe gram positive cell wall
peptidoglycan - Think|
/
plasma membrane|
describe gram negative cell wall
thicker outer membrane
peptidoglycan
plasma membrane
dyes and stains used to test cell wall type of bacteria
crystal violet
iodine
alcohol
safranin
describe how penicillin works against gram positive bacteria
+ive depends on thick layer
penicillin destroys layer - inhibits enzyme involved in peptidoglycan synthesis – Gram positive bacteria more susceptible
what colour does Gram positive bacteria go
purple
what colour does Gram negative bacteria go
pink
function of endospores
bacteria in dormant state
will activate when conditions are favourable to grow and multiply
when do endospores form and how do they form
in unfavourable condition s
plasma membrane then 2 spore septums surround endospores
example of endospore
tetanus
binary fission
one bacterial genome
duplicate genetic material
septum forms between genetic info and clone
cells pinch in 2 and separate
how long can bacteria reproduce
in 20 minutes
3 types of bacteria DNA exchange
Transformation
Conjugation
Transduction
how does bacteria transfer DNA via transformation
Fragments of DNA are taken in after the disruption of another cell.
how does bacteria transfer DNA via conjugation
Two cells exchange genetic material via a sex pilus.
conjugation pilus form
cells come in contact w/ each other
one strand of plasmid move to sensitive cell
both donor and recipient form complementary strand of plasmid to be F+
how does bacteria transfer DNA via transduction/horizontal gene transfer
Genes are carried from one cell to another by a virus called a bacteriophage
DNA of phage/virus penetrate bacteria cell
phage DNA can integrate w/ host’s DNA = prophage
becomes lytic - DNA is degraded and new phages are made
cell wall is ruptured - phages ready in penetrate other bacteria
detailed recount of transformation in bacteria
uptake of DNA fragments or plasmid from environment from dead bacteria
in plasmid usually just stable transformation of plasmid
in DNA fragments - it can be unsuccessful and degrade
