Microbiology Flashcards
how is a virus different from bacteria
not living
lack organelles or nucleus
substantially smaller
what is a bacteriophage
any virus that infects bacteria
has a head with genetic material and tail to attach to surface of bacterium
viral life cycle
attach to host cell and enter
bacterial ribosomes replicate and transcribe viral DNA
new viruses are formed and released by cell lysis
how do most animal viruses enter the cell
receptor mediated endocytosis
retrovirus life cycle
enter host cell by fusion and use reverse transcriptase to form DNA from RNA
the DNA is integrated into the host genome and exists by budding
difference between lytic and lysogenic cycle
lytic - active/virulent producing viral components that can infect other cells
lysogenic - dormant/temperate inserted into host cell allowing it to be replicated. will enter the lytic cycle when host chromosome is stressed
organisms are classified by how they acquire carbon and energy, what are the different groups
autotroph- can fix carbon
heterotroph - rely on autotrophs to synthesis organic compounds
photo - uses light for energy
chemo - uses chemical energy
difference between archaea and bacteria
archaea have no nucleus or organelles and live in extreme environments
3 bacteria shapes
cocci - sphere
bacilli - rod
spirilli - spiral
what is the DNA in bacteria and where is it located
single circular chromosome of double stranded DNA
localized in the nuclei region because there is no membrane bound nucleus
do prokaryotes have ribosomes
yes
what are plasmids
extra chromosomal Dna that may contain genes for antibiotic resistance (r factors )
how do bacteria reproduce
binary fission (asexual) where the circular DNA is replicated and grows. divides into two cells that are genetically identical ** exponential growth
what are flagella
made of flagellin to help bacteria move *bacteria only
describe the cell wall of a bacteria
bacteria have a plasma membrane which is surrounded by a cell wall and sometimes a capsule. the cell wall prevents the protoplast (plasma membrane + everything inside) from bursting
staining in gram negative vs positive bacteria
** where is the peptidoglycan located
positive - thick peptidoglycan wall on the outside of the cell = purple
negative - thin wall located between two membranes = pink
binary fission has no genetic recombination , what are the 3 ways bacteria undergo genetic recombination
conjugation
transformation
transduction
describe bacterial conjugation
F+ plasmid has the sex pilius and attaches to the recipient cell
a single strand of DNA is transferred to the recipient and both synthesize the double stranded circular plasmid and produce new pili
what is an R plasmid
contain gene for sex pills but they bestow different types of antibiotic resistance to their recipient cells
what is bacterial transformation
bacteria incorporate dna plasmids from external environment into their genome
what is bacterial transduction
bacteria accidentally encapsulates host DNA fragment then infects a new bacterium with some of that DNA
the virus that mediates this is called a vector
difference between bacterial conjugation, transformation, and transduction
conjugation is like sex, transformation gets DNA from external environment, transduction gets DNA from a host cell then a the virus brings it to new host cells
what are transposons
genetic elements that can jump around by inserting or deleting themselves from the genome. contain a gene for transposes protein
3 different types of transposons
IS elements - transposes gene flanked by inverted repeated sequences
complex -
composite - two transposes sequences
this is dumb
