Bacterial structure and function Flashcards
5 examples of microorganisms
viruses bacteria algae fungi protozoa
three points about archae
prokaryotes
no peptidoglycan
often extremophiles
3 points about eukaryotes
eukaryotic
if they have cell walls, they dont contain peptifoglycan
not sensitive to traditional antibiotics
5 points about bacteria?
prokaryotic
cell walls have peptidoglycan
sensitive to traditional antibiotics
include cyanobacteria, gram positive and gram negative bacteria
include majority of pathogenic microorganisms
3 points of bacteria strucutre?
cytoplasmic membrane surrounded by peptidoglycan cell wall and maybe membrane
fluidcytoplasm with nuclear regions
various external structures like a capsule, flagella and pili
what are 4 examples of bacteria morphology
straight rod
club shaped rod
branching rod
spore-forming rod
what are three bacteria cell arrangements?
division in plane - to form chain
division in two planes- to give tetrad
division in three planes- to give cluster
how does cell wall protect bacteria?
protects from osmotic lysis
how do penicillin adn lysozome enzymes worl
inhibits cell wall synthesis
attacks peptidoglycan
what is peptidoglycan
a thick rigid layer fround in G+ and G_ cells
composed of overlapping lattice of 2 sugars and crosslinked by amino acid bridges
how is rigidity determined in peptidoglycan?
amount of peptide cross linking
what two sugars are found only in cell walls?
NAG and NAm; side chain attached made of four amino acids forming a cross link
explain the basis of crosslinking (3)
peptidogylcan is rigid mesh due to peptide crosslinking
a tetrapide attached to NAM
tetrapeptode is unusal because contains both D and L amino acids
4 points about G_ bacteria
outer and inner membrane
in membrane is peptidoglycan
periplasmic space
much more difficult to hit antibiotics
3 points about G+
one membrane
thick layer of peptidoglycan
other molecules linked to cell membrane
why are G- and G+ important?
diagnostics
virtual tool for diagnosing disease
G+ show darker staining
how does gram strain process happen
fix bacteria onto slide
fix crystal violet using iodine
add acetone
strips dye away from outer periplasmic space of only G+ cells
what are 5 microorganism classification growth characteristics?
shape gram stain atmosphere spores biochemical test; genetic/ antigenic
3 points about nuceloid
contains singe chromosome
most bacteria have single continous giant circular molecule
supercoiling due to enzyme called DNA gyrase
what are the 3 stages of bacteria chromosome replication?
at origin of replication, helicase unwinds to expose single-stranded DNA
primase synthesis ,primers and DNA dependent DNA polymerase synthesises DNA semi-conservative
two idnetical daughter chromosomes are formed
what are 4 facts about binary fission?
divide assexually be binary fission where one bacterium split into two
benefit of rapid population expansion but drawback pf binary fission is theres no genetic recombination
no genetic diversity
what are the 6 stages of binary fission?
chromosomes replication is initaed at membrane
DNA replication starts at origin
there is extension of cell wall and membrane
septum formation
membrane attachment of chromosomes pulls each daughter chromosome into a new cell
cell seperation; cytokinesis
what are 4 other bacterial structures?
spores
capsules
pili
flagella
what are endospores
dormant survival structures inly present in G+ organisms, never G-
resistant to high temperatures
how do we achieve sterilisation?
kill spores hence autoclaving
what are capsules made from
viscous polysaccaride or polypeptide slime
how do capsules work
protects bacteria from drying, traps nutrients- enable certain bacteria to adhere to surfaces
what are pili
has a shat composed of protein pilin, end of shaft adhesive tip callede lectin whihc binds sugars to host
