9.5 Genetic material Flashcards
(40 cards)
What is polymorphism in mo
Polymorphism is ability of some microorganisms to alter their morphology, biological functions, or reproductive modes in response to environmental conditions. Pleomorphism is particularly prevalent in certain groups of bacteria, yeasts, rickettsias, and mycoplasmas, which can exhibit irregular and variant forms within the same species or strain
How long is bacterial chromosome
More then length of bacterium. DNA is supercoiled and packed with help of Nucleoid-associated proteins (NAPs)
What are NAPs influencing
They shape DNA structure and function. Aside from influencing their topology( by wrapping it) they constrain supercoiling and contribute to nucleoid formation. They regulate gene expression, participate in short-range interactions, impact processes like transcription, translation and transfer
Compare Archaeal chromosome and proteins with bacterial
Archaeal chromosome is circular and some species are polyploid( more than one copy of the chromosome per cell)
Associated proteins are different from the bacterial ones, though some have similar function. Some archaea have eukaryotic-like histones
What are characteristics of bacterial DNA replication
*semi-conservative
*bidirectional replication
*two replication forks
What does it semi-conservative replication mean
During replication, each DNA strand contains one original( parental) strand and one newly synthesized( daughter) strand. Parental strands serve as templates for the synthesis of complementary daughter strands
What do replication forks do
Unwind double-stranded DNA
Where does initiation of replication starts
At oriC( origin of replication)
Who starts replication
Initiator proteins. Origin recognition complex( ORC) binds to the origin marking it as a starting point
What do initiator proteins do
Break hydrogen bonds between the strands, forming replication bubble
Who binds to the template DNA in replication bubble
SSB: single stranded binding proteins
What happens in replication after SSB connect to the strands
Helicase and primase connect to replication forks and form primase
What does helicase do at replication fork
Unwinds DNA strands
What does primase do
Attaches RNA primers which allows DNA polymerase III to synthesize DNA on the leading strand in 5’ to 3’ direction
What does DNA Polymerase III do on the lagging strand?
As RNA primase leaves primers, DNA polymerase III makes Okazaki fragments and DNA polymerase I removes DNA primers on the lagging strand and replaces it with DNA
Who joins Okazaki fragments together
DNA ligase
What happens at the end of replication
Each strand of DNA will consist of 1 parental strand and 1 daughter strand
What is replisome
The replisome is a complex molecular machine responsible for DNA replication.
What holds 2 DNA polymerase assembles and helicase together
Tau subunits
What does gyrase do
It’s ahead of replication fork and relieves the torsional stress that builds up. It does this by introducing negative supercoils in DNA, allowing helicase to function better
In what direction is synthesis done
In opposite directions
What is ter
Terminus of replication. When replication fork hit it and collide, it releases 2 chromosome copies. One set of Ter sites arrest DNA forks progressing in clockwise direction, a second set arrests forks in the counterclockwise directions
What binds to the Ter sites
Tus protein-a monomer. It inhibits replication fork progression by directly contacting DNA-B helicase, thus inhibiting DNA unwinding
What are plasmids
Extra-chromosomal elements with self-replicating ability. They are usually dsDNA with variable length. Pool of extrachromosomal DNA for horizontal gene transfer
