Lecture 3 - DNA Structure & Replication Flashcards
What is the basic unit of chromatin?
a nucleosome - consists of 147 bp and a histone octamer
What does remodeling of nucleosomes allow proteins to do?
Access DNA for gene expression, replication, repair
Which type of bonds join the 3’ carbon of one deoxyribose or ribose to the 5’ carbon of the next?
Phosphodiester bonds
What type of bonds hold two strands of DNA together?
Hydrogen bonds
How many hydrogen bonds connect adenine and thymine base pairs?
2 H bonds
Provide two physical descriptors for DNA:
- Helical structure (coiled around a common axis)
2. Anti-parallel strands
The complementary strand of the DNA is also called the __________ strand.
Antisense
A DNA strand within a gene is called the __________ strand if its sequence is the same as that of the messenger RNA copy that is translated into protein.
Sense strand
Both strands of DNA are synthesized in the ____ –> ______ direction.
the 5’ to 3’ direction
What is the term for the site at which DNA replication is occurring - between the unwound parental duplex and the newly replicated daughter duplexes?
Replication fork
What enzymes catalyze the addition of a deoxyribonucleoside monophosphate to the free 3’ hydroxyl group of the growing DNA strand such that the DNA is replicated in a 5’ to 3’ direction?
DNA polymerases
What is the ribonucleoprotein complex that extends the TG-rich strand of telomeres by DNA synthesis using an internal RNA template?
Telomerase
What are telomeres?
Repeated DNA sequences at the ends of chromosomes
