Structure
What are the three components that make up DNA?
2' Deoxyribose sugars, phosphate groups, and nitrogenous bases (A, T, G, C)
What did the key experiments all help discover about DNA?
DNA is the genetic material of all cellular life!!!
Which phase of the cell cycle does replication take place?
S phase
What is the replication fork?
The replication fork is the site where DNA unwinds to expose the nitrogenous bases.
What is Chargaff's rule for nitrogenous bases? How many hydrogen bonds are between them?
Adenine = Thymine (2 hydrogen bonds)
Guanine = Cytosine (3 hydrogen bonds)
Hersey and Chase used bacteriophage T2 virus to determine if DNA (32P) or protein (35S) is the genetic material. What did he discover?
He discovered that DNA is the genetic material that enter a bacterial cell and directs the assembly of new viruses.
Where is the place on a chromosome that begins DNA replication? How does it differ between prokaryotes and eukaryotes?
Origin of replication. Prokaryotes have only one, but eukaryotes have many.
What is the leading strand?
The leading strand is one of the new strands oriented to grow at 3' end, towards replication fork.
What are the 5 atoms found in DNA?
Hydrogen, oxygen, nitrogen, carbon, and phosphorus
Oswald Avery treated a virulent strain with RNase, Protease, and DNase with nonvirulent strain to target hydrolysis of RNA, protein, and DNA. What did he discover?
The results showed only DNase destroying the transforming activity of the virulent strain, so the transforming substance is DNA.
How do DNA strands grow?
New nucleotides are added to the strand at the OH on 3' end, determined by complementary base pairing. The DNA grows in 5' --> 3'.
What is the lagging strand?
The lagging strand is a new strand oriented to grow so its 3' end moves farther in opposite direction from the replication fork. It is opposite of leading strand. It occurs in Okazaki fragments.
What direction is the sugar-phosphate backbone in DNA? Include their numbered polarity (5' vs 3')
The sugar-phosphate backbone is antiparallel with a 5' --> 3' strand paired with 3' <-- 5' strand. The strands opposite polarity is defined by the deoxyribose sugar-phosphate bonds.
What did Franklin's X-ray crystallography and Watson and Crick discover about the structure of DNA?
Franklin convinced Watson and Crick that DNA was helical, and they discovered the general structure of DNA as a double helix.
Conservative is original helix is a template for synthesis of new helix.
Dispersive is fragments of original helix are templates, assembling DNA as mixture of old and new parts.
Semiconservative is original serves as template and new DNA has one old and one new strand. This is correct model.
How does DNA replication begin? What type of sequence is needed and by what enzyme?
DNA replication begins with short RNA primer complementary to DNA template. It is synthesized by a primase.
What components of DNA is exposed in the major and minor groves? How is this beneficial?
The nitrogenous bases (A, T, C, G) are exposed in the major and minor grooves. This is beneficial because they are accessible to proteins.
He discovered that a denatured virulent strain can genetically transform a nonvirulent strain killing the mouse. The bacteria can change their function and form by a transforming principle of the virulent strain genetic information.
What is the bond between 5' carbon and OH of 3' carbon? What enzyme does this?
The enzyme DNA polymerase III creates a phosphodiester bond, releasing 2 phosphate ions.
What 4 enzymes are needed for the DNA replication complex?
The DNA helices unwinds the DNA, single-stranded binding proteins prevent strands from rewinding, primase synthesizes RNA primers, and DNA polymerase III synthesizes the leading and lagging strands.