Chapter 12 Flashcards
Why were proteins a choice to be the heritable gene?
It could carry information, be transmissible, could replicate in the cell, and there was variation.
What are bacteriophages?
Viruses which attack bacteria, made up of DNA and protein; Hershey and Chase used them to determine if the hereditary material was DNA or proteins.
What is the Lytic Cycle?
Phages are bacterial viruses, phage attaches to bacterial cell, phage injects DNA, phage DNA directs host cell to make more phage DNA and protein parts, new phages assemble. Cell lyses and releases new phage.
What is Chargaff’s Rule?
The amount of purines (double ringed Adenine and Guanine) were equal to the amount of pyrimidines (one ring Thymine and Cytosine).
A + G = C + T
A = T
G = C
Describe the Double Helical Structure of DNA
Anti-parallel DNA strands wind around each other, with the purine and pyrimidine bases facing each other; held together by hydrogen bonds. 3’ -> 5’ bonds.
What is Semiconservative Replication?
Saves half the parent.
What is Conservative Replication?
Conserves original parent.
What is Dispersive Replication?
Little bits get copied at different times.
What is the difference between bacterial chromosome replication and eukaryotic replication?
Bacterial has one origin of replication, meaning one replication complex per chromosome.
Eukaryotes have multiple points of origin, meaning DNA is replicated from multiple points at once.
What is Polymerase Chain Reaction?
Copying DNA in vitro to make billions of copies of DNA in a few hours.
What are the three main steps of PCR?
Heating (to 95 degrees) to separate the DNA molecule strands, cooling (to 55 degrees) so that DNA primers can base pair with the DNA template, heating (to 72 degrees) for the Taq polymerase.
What is Transformation?
The conversion of a cell’s hereditary type by the uptake of DNA released by the breakdown of another cell.
What is the Polynucleotide Chain?
A sugar-phosphate-sugar-phosphate backbone with a phosphate group bridged between the 3’ carbon of one sugar and the 5’ carbon of another.
What is a phosphodiester bond?
The phosphate group bound to the 5’ carbon end and the hydroxyl group bonded to the 3’ carbon end.
What are DNA Polymerases?
The primary enzymes of DNA replication; dATP, dGTP, dCTP, dTTP. DNA polymerase can only add a nucleotide to the 3’ end - it writes the copy in the 5’ -> 3’ direction.
What is the Sliding DNA Clamp?
A protein that encircles the DNA and binds to the rear of the DNA polymerase in terms of the enzyme’s forward movement during replication. Tethers the DNA polymerase to the template strand.
What is the Origin of Replication?
The small, specific, sequence in the chromosome where the unwinding of the DNA for replication begins.
What is DNA Helicase?
The enzyme that catalyzes the unwinding of DNA template strands.
What is the Replication Fork?
The region of DNA synthesis where the parental strands separate and two new daughter stands elongate.
What are Single-Stranded Binding Proteins? (SSBs)
Proteins that coat single-stranded segments of DNA, stabilizing it for the replication process and keeping the two strands from pairing back together.
What is Topoisomerase?
An enzyme that relieves the over-twisting and strain of the DNA molecule ahead of the Replication Fork by cutting DNA and twisting it and rejoining it.
What are RNA Primers?
A short nucleotide chain made up of RNA that is laid down as the first series of nucleotides in a new DNA strand or made of DNA for use in the polymerase chain reaction; synthesized by primase.
What is Discontinuous Replication?
Replication in which a DNA strand is formed in short lengths that are synthesized in the opposite direction of DNA unwinding - the lagging strand.
What are Okazaki Fragments?
Relatively short segments of DNA synthesized on the “lagging” stand.
