chapter 3 microbiology Flashcards
autotrophs
use carbon dioxide as carbon source
heterotrophs
use organic substances like sugars as their source of carbon
binary fission
how bacteria reproduce. This results in a logarithmic growth rate
phases of the bacterial growth cycle
lag phase, log phase, stationary phase, decline phase
lag phase
Bacteria undergo a period of adaptation with vigorous metabolic activity
log phase
rapid division which is determined by environmental conditions
stationary phase
is reached when nutrient depletion or toxic products cause growth to slow until death rate equals the binary fission rate
decline phase
decline of live bacteria
What is end product inhibition?
the end product of a pathway inhibits the first enzyme of the same pathway
catabolite repression
when catabolites inhibit synthesis
what are some extracellular factors that modify bacterial growth?
temperature- mesophiles like 25-40C, thermophiles like 55-80 C, psychophiles like under20C
PH- 7.2-7.4 for optimal growth
obligate aerobes
require oxygen to grow because their ATP generating system is dependent on oxygen as the hydrogen acceptor
facultative anaerobes
use oxygen to generate energy if oxygen is present. They also can use the fermentation pathway for energy
obligate anaerobes
lack superoxide dismutase or catalase so they dont need oxygen to make energy
microaerophiles
work best at low oxygen concentration
name the 2 bacterial enzymes that oxygen
superoxide dismutase and catalase
replication bubble
strand between the replicating forks
semiconservative replication
each daughter cell receives a parental strand and a newly synthesized strand
polymerase
main enzyme in DNA replication
restriction enzymes
cleave double stranded DNA at specific sequences thus deleting foreign nucleotides
What is a mutation?
a change in a base sequence of DNA
what is base substitution and the 3 types
when the incorrect base is inserted.
missense mutation is when the base substitution results in a different amino acid
nonsense mutation- base substitution results in a premature stop
frame shift mutaiton
when one or more base pairs are added or deleted which shifts the reading frame and results in a inactive protein
insertion
insertion of additional pieces of DNA or bases and cause profound changes in the reading frame
what induces mutations?
chemicals, radiation, or viruses
conjugation
mating of bacteria which is controlled by a F plasmid that creates the sex pilus
transduction
transferring DNA via a virus
generalized transduction
when a bacteriophage has a piece of its old hosts bacterial chromosome
specialized transduction
when phage DNA that is integrated into bacterial DNA is excised and carries with it an adjacent part of bacterial DNA
transformation
“natural” when a bacterium dies and another picks up some of its DNA
transposition
jumps from one to another
homologous recombination
2 pieces of DNA with extensive homologous regions pair up and exchange pieces by the processes of breakage and reunion
non- homologous recombination
not much homology so they use a lot of enzymes inrecombination process
plasmids
extrachromosomal DNA molecules. They are in both gram negative and positive bacteria
Transmissible plasmids
transferred by conjugation and contain the sex pilus genes
non transmissible plasmids
they dont move but can if there is another plasmid in the same bacteria that is transmissible( they pretty much catch a ride)
what are some clinical relevance of plasmids?
antibiotic resistance, resistance to heavy metals, pili which mediate adherence of bacteria to epithelial cells, exotoxins
transposons
“jumping genes”, Can code for metabolic or drug resistance enzymes and toxins, Need host to replicate , hide in plasmids,
Restriction enzymes
break DNA at a specific nucleotide sequence. This creates a “sticky end” which can be combined with a wanted gene and incorporate it into the DNA of the host.
DNA probes
radioactive markers
PCR
uses Taq ( watch youtube)
multiplex PCR
more than one locus are amplified with multiple primers
Why is PCR so widely used?
for miniscule quantities of DNA, rapid clinical diagnostic procedures, amplification of RNA, comparison of different genomes
genomics
study of identity of all genes within the chromosomes of a cell
proteomics
study of proteins expressed by the genome of either an organism, cell, or tissue type.
metabolomics
study of chemical processes involving metabolites of a cell or an organism
