Chapter 9 Flashcards
Know the key features of DNA structure
Right-handed helix
Explain the difference between the major groove and the minor groove of the DNA double helix
The major grove is larger/ wider while the minor groove is smaller or narrow
Apply Chargaff’s rules
(A=T and G=C)
Explain what “semiconservative DNA replication” means
After replication, each new helix is a HYBRID, one new strand paired with one old strand
Define/identify an “origin of replication,” “replication forks,” and bidirectional replication
Origen of replication: starting point at which double-stranded DNA first separates Replication fork: ‘Split’ parental strands where new DNA is being made Bidirectional replication: Replication forks move in opposite directions away from replication origin
What are some of the important proteins needed for the process of DNA replication to occur? What are their functions? –
DNA Helicase: Unwinds DNA DNA Plymerase: Synthesizes the new strand of DNA using the old strand as a template Primase: Gives DNA polymerase a ‘place to start’ Ligase: Seals ‘gaps’ between DNA strands Telomerase: repairs ends of linear chromosomes
Describe the basic mechanism of DNA polymerase (what does it do, specifically?)
Catalyzes the addition of free nuscleotides, Always adds nucleotides to the 3’ end of a DNA strand. Thus, DNA polymerase always ‘writes’ in the 5’ > 3’ direction
What are 2 limitations of DNA polymerase? How are they solved?
DNA polymerase can only extend off of an existing chain of DNA and DNA polymerase can only ‘write’ in the 5’ > 3’ direction. As the replication fork opens, DNA polymerase can only continuously synthesize ONE STRAND (this strand is known as the LEADING STRAND), the other strand is discontinuously synthesized(called the lagging strand), primase needs to reprime DNA every few hundred bases, resulting fragments are called Okazzki fragments
