-
-
replicates the DNA of the organism. A duplicate strand of DNA is
synthesized
-
Transcription is what and creates what? (what type of RNA?)
- Transcription
- DNA directed RNA synthesis, template strand is
- transcribed, transcription gives you 3 kinds of RNA: t, m and r.
-
Translation what is it and what does it do?
- genetic info in the form of
- mRNA is decoded into an amino acid chain.
-
Describe the structure of DNA
- A,G,C,T has a deoxy ribose sugar, missing its hydroxyl group at
- carbon 2. 5 carbon sugar ring.
-
Describe structure of RNA
- Has two hydroxyl groups. 5
- carbon sugar ring
-
Compare and contrast the organization of DNA in the chromosomes of:
Bacteria, Archaea, and Eukaryotes
- Bacteria has circular double helix or twisted supercoiled DNA,
- complexed with basic proteins,
ArchaeaCircular double helix, twisted into supercoiled DNA, contains histone and forms nucleosomes., and Eukaryotes. Associated with histones to form nucleosomes. Double stranded linear.
-
Describe Bidirectional replication
you synthesize in both directions along the DNA, and you get a replication fork.
-
Rolling Circle
- E.coli do this, observed
- during plasmid replication. One strand is nicked and the free 3’ hydroxyl end
- is extended by replication enzymes. The 3’ end grows while the 5’ end is
- displaced, like an apple peel.
-
Characterize the function of DNA polymerase
catalyze DNA synthesis, in the 5’ to 3’ direction (REPLICATION)
NEEDS: Template, primer, dNTPs
DNA poly 3 plays the major role in replication
-
DnaA protein
proteins that bind to DnaA boxes within the origin of replication and use ATP to break H-bonds between DNA strands
-
Helicase
- separate and unwind DNA
- strands, they use ATP to unwind short stretches of helix ahead of the fork.
-
SSB
- keep the strands apart and
- stop them from binding together.
-
Topoisomerases
proteins that relieve tension generated by the rapid unwinding of the double helix.
-
primase
an enzyme that forms a short RNA sequence that is complementary to the DNA strand, allowing the DNApoly 3 to jump on.
-
Events at the replication fork
5 Steps
- 1. 40 DnaA proteins bind to OriC and hydrolyze ATP, separating the DNA strand
- 2. Helicase unwind the helix using topoisomerase like DNA gyrase.SSBs hop on
- 3. Primase synthesizes RNA primers. DNA poly III hops on and makes both leading and lagging strand.
- 4. Lagging strands form Okazaki fragments. DNA poly I removes RNA primer with 5' to 3' exonuclease activity.
- 5.Fragments are joined together by DNA Ligase
-
Synthesis of the lagging strand: who does it?
made discontinuously with okazaki fragments by DNA poly III
-
Proofreading-who does it? what end of the DNA?
Carried out by DNA poly III, removes mismatched base from the 3' end by exonuclease activity (not 100% efficient)
-
Termination of replication: who is involved and what happens
replisome reaches the termination site (on DNA) and ends replication. Catenanes form when 2 circular chromosomes do not separate. Topoisomerases temporarily break DNA molecules so strands can separate.
-
-
-
tRNA genes-describe the organization and structure. What structures does it have?
- can code for more than a single tRNA molecule or type of tRNA,
- spacers separate coding region and are removed after transcription.
Ribozymes: special ribonuclases that remove spacers.
- CONTAINS: promoter, leader,
- coding spacer, and trailer regions which are removed during maturation
-
rRNA genes- describe the organization and structure. What structures does it have in it?
Have a promoter, leader, terminator, coding spacer, and trailer region. Spacer and trailer regions may encode tRNA molecules
|
|
