Genetics - Part A Flashcards
What is the backbone of DNA?
The backbone is sugar phosphate with phosphodiesterase bonds.
WHat is the directionality of DNA and what does it mean?
The directionality of DNA is antiparallel : 5’-3’ and 3’-5’. This makes a double helix.
What are the bonds between the backbone and the nitrogenous bases
The bonds are Covalent phosphodiester.
What is the structure of a nucleotide?
Sugar, Phosphate group, Nitrogenous base.
What is the main difference between nitrogenous bases?
Adenosine and Thymine have a double H-bond. Where Guanine and Cytosine have a triple H-bond.
What is complementary base pairing?
Nitrogenous bases pair up with each other in a consistent way. A-T, G-C
Why do telomeres shorten?
Telomeres shorten due to cell division issues, and telomerase inactivity.
What is the relationship between telomerase and age?
As people get older telomeres reach their limit and it makes it harder for healthy cells to function.
What enzyme is associated with telomeres?
The telomerase enzyme.
What happens in strand separation?
at origin(there’s multiple) helicase breaks the hydrogen bonds and unwinds the double helix. As the helix breaks it forms something called the replication fork, to maintain this the single stranded binding protein bin to the separated strands to prevent hydrogen bonds from reforming. While this is happening topoisomerase is releaving the tension to make DNA replication easier.
What happens in building complementary strands step?
Primase lays down RNA primers to the strands, Rna is used as a starting point for the DNAP3. DNAP3 starts laying down complementary nucleotides. Every strands is built in a 5’-3’ direction, this makes a leading strand and a lagging strand. in the lagging strand once the fragments tough the primer DNAP 1 comes in a replaces the primer with nucleotides, the lugase joins them together.
What happens in the fixing errors step?
DNAP 1 and 3 go along each strands and proof read them checking for any mistakes. If any are they are removes and replace with the proper nucleotides which are then sealed with ligase.
Why is the lagging strand slower than the leading strand?
The lagging strand is slower because it isn’t one fluid motion, its multiple stress going back and forth to fill in gaps.
What is helicase?
Enzyme that unzips DNA
What is RNA primase?
Tells DNAP 3 where to start the replication process
What is ligase?
a protein used to join different DNA fragments
What are single stranded binding proteins?
SSB proteins prevent the recreation of hydrogen bonds
What is DNAP 1?
Removes RNA primers and replaces them with the proper nucleotides.
Whatis toposisomerase?
Stays in front of the replication fork preventing overwinding making the replication process easier.
What is DNAP 3?
Lays down complementary nucleotides using RNA primers.
