Genetics Lecture 2
Describe the molecular anatomy of genes and genomes
Watson and Crick created a model of DNA that featured two strands of intertwining nucleotides
that allowed for separation and reformation of the DNA within the cell – allowed for the
replication of genetic material
DNA replication isn’t just seen with one simple mechanism – there are many enzymes that are
active in the replication of genetic material within organisms
o Topoisomerase is the enzyme responsible for the initiation of unwinding of the DNA –
takes advantage of the tension between the strands; a single nick at the end of the DNA
can start unravelling DNA.
o DNA Helicase unwinds the original double strand - the strands have high affinity for
each other due to hydrogen bonding – ATP is needed to keep the strands apart.
o DNA Polymerase runs along the single-stranded molecule of DNA – forms a covalent
phosphodiester bond - energy in triphosphate is used toward the growing second
strand. A primer (3’OH) group is added onto the forming strand. DNA polymerase II is
responsible for forming the new DNA strand
o Primase attaches an RNA primer to the single-stranded DNA (sub for 3’OH) – Removed
by RNase H, gap is filled by DNA polymerase I
o Ligase catalyzes formation of phosphodiester bond – fills the unattached fap left when
the DNA primer is removed, and filled in. DNA Polymerase can organize the bond on the
5’ end, but ligase makes bonds on the 3’.
o Single-stranded binding proteins bind to the DNA while it’s single-stranded to keep it
from being degraded.
DNA polymerase can only act from 5’ to 3’
Discuss the hallmark features and organization of chromosomes
Describe the hallmark features and organization of genes and explain the role of each of these features
Describe the hallmark organization of genomes
Describe the cytological anatomy of chromosomes
Discuss different types of DNA sequence organization
Define key terms and solve problems.
Crime scene evidence, used the protein in forensic test from seminal stains,
phosphoglucomutase (PGM+1) Secretor A Status that was attributed to about 10% of the
population in Britain.
o First case to find someone guilty using DNA forens