test 2 Flashcards
In the classic experiment by Griffith, evidence of the action of a hereditary biomolecule was identified by
transformation (phenotypic change) of the R strain by biomolecules
Oswald Avery and colleagues strengthened scientific support that DNA was the transforming factor by replicating the Griffith experiment with some important differences in experimental design. The key difference was:
systematically eliminating the impact of classes of S strain biomolecules using enzymatic digestion before mixing with R strain live cells.
Oswald Avery and colleagues strengthened scientific support that DNA was the transforming factor by replicating the Griffith experiment with some important differences in experimental design. They found that the enzyme ______________ was effective at destroying the transforming capacity of S strain biomolecules.
DNase (DNA destruction)
Chargaff’s rules do NOT hold for which of the following genome types?
single-stranded DNA virus
Of the three key building blocks of DNA, which type(s) of building block is/are negatively charged and oriented on the outside of the double helical structure?
phosphate
Which statement BEST describes the arrangement of components in a DNA molecule?
Nucleotides are located toward the inside of the strands and the phosphates toward the outside.
Which statement below BEST describes the situation between nucleotides on opposite strands in a DNA molecule?
A-T bonding between opposite strands involves two hydrogen bonds, whereas G-C bonding between strands involves three hydrogen bonds.
The replisome contains a protein subunit responsible for unwinding the double helix to enable DNA replication. This subunit/enzyme is named
helicase
Why does DNA with a high G + C content require higher temperatures to melt?
G–C base pairs have three hydrogen bonds.
When comparing the three key models of DNA replication, the model that included the separation of the two strands of the original DNA (template) and using those strands as templates to synthesize two new DNA strands is called
semiconservative replication
Topoisomerase and helicase have distinct functions that include which of the following?
Helicase is responsible for unwinding the double helix (separating strands).
The complexity of lagging strand replication is necessary because
as polymerization occurs only in the 5’-to-3’ direction, the lagging strand must be synthesized in consecutive small fragments.
Initiation of replication occurs at an “origin of replication” site that typically includes an AT-rich region. Initiation benefits from these AT-rich regions because
adenine-thymine pairs are held together by two H-bonds, making them easier to separate during unwinding.
When replicating the end of a chromosome, the lagging strand cannot copy the last ~10 nucleotides at the end of the chromosome. As a result, chromosomes contain telomere sequences at their ends, which are defined as
noncoding, repetitive sequences that can be copied independent of the replisome.
Primase and telomerase enzymes are both considered types of
reverse transcriptases
Template strand DNA and encoded RNA are
complementary of one another with antiparallel orientation.
If the DNA template 5′-ATGCATGC-3′ were transcribed to RNA, the RNA would read
3′ UACGUACG 5′
RNA synthesis is always 5′ to 3′ because
nucleotides can only be added to an available 3′-OH group on the transcript terminus.
