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