chapter 16

mismatch repair of DNA (done by DNA polymerase 2)

repair enzymes correct errors in base pairing

nucleotide excision repair

a nuclease cuts out and replaces damaged stretches of DNA

mutations

are source of new alleles (genetic variation upon which natural selection operates)

linear chromosomes

no way to complete 5' end as repeated rounds of replication produce shorter ends

telomere

-eukaryotic chromosomal DNA molecules have special nucleotide sequences at their ends
-do not prevent shortening of DNA (postpone erosion of genes near DNA ends)
-shortening of telomeres might protect cells from cancerous growth by limiting cell division

telomerase

catalyzes the lengthening of telomeres in germ cells (gametes)

chromatin

in eukaryotic cell DNA is precisely combined w proteins in chromatin complex
-@internphase packed together into 10nm fiber

euchromatin

loosely packed chromatin

heterochromatin

-during interphase a few regions of chromatin (centromeres+telomeres) are highly condensed into heterochromatin
-dense packing of heterochromatin makes it difficult for cell to express genetic info coded in regions

Who demonstrated that DNA is the genetic material of the T2 phage?

Hershey and Chase did a series of classic experiments demonstrating that DNA is the genetic material of the T2 phage.

The radioactive isotope 32P labels the T2 phage's _____.

The T2 phage consists of a protein coat and DNA. It is the DNA that contains P.
The phage's protein coat is not labeled by P.

Hershey and Chase used _____ to radioactively label the T2 phage's proteins.

Hershey and Chase used radioactive sulfur to label the phage's proteins. Uranium is not a component of phages.

After allowing phages grown with bacteria in a medium that contained 32P and 35S, Hershey and Chase used a centrifuge to separate the phage ghosts from the infected cell. They then examined the infected cells and found that they contained _____, which dem

Since the phage DNA entered the infected cell, it makes sense that DNA is the genetic material.
A molecule does not have to be labeled in order to be the genetic material.

helicase

The role of helicases is to unwind the duplex DNA in order to provide a single-stranded DNA for replication, transcription, and recombination for instanc