Dna Flashcards
Name the 2 major types of proteins
Histones- basic proteins with a positive charge that binds to dna
Non Histones- all other proteins associated with dna
Conservative replication
2 strands of dna are replicated without strand replication
Semi conservative replication
Every new helix has one old and one new strand
Dispersive replication
After replication every helix contains parts of old and new strands all over the Dna molecule
When was meleson and stahls experiment
1958
What did there experiment determine about the mechanism of dna replication
DNA replicates semi conservatively
Starting point
Origin of replication
What does the helicase do?
Breaks hydrogen bonds and unwinds strands of DNA
Replication fork
Is the point of separation
Single strand binding proteins (ssbs)
Bind to exposed bases
DNA grass (topoisomerase)
Relieves tension from unwinding DNA
Leading strand
Built continuously toward the replication fork
Lagging strand
Built away from replication fork in a short (Okazaki) fragments
Human cells copy and error rate
Copies DNA in few hours, and it’s error rate is 1 per billion nucleotide pairs
2 types of errors
Mispairing, and strand slippage
Similarities in eukaryotes and prokaryotes
Elongation in the 5’ to 3’ direction
Requires a origin of replication
Uses DNA polymerase enzymes
Differences in eukaryotes and prokaryotes
Replication is faster in prokaryotes
DNA polymerase enzymes are different in structure and number
Linear chromosomes contain telomeres
Initiation
Starts when RNA polymerase binds to the DNA
Elongation
RNA polymerase binds to the DNA and opens up the helix
Termination
mRNA strand is synthesized until it reaches the end of the gene
Gene expression
Transfer of genetic info from DNA to RNA to protein
tRNA
Transfer RNA (anticodon loop)
