DNA Rep. (Notes)
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DNA is made up of
Nucleotides
Nucleotides are composed of
• Phosphate group • 5-carbon sugar • Nitrogenous base
Nitrogenous bases; Purines
• Adenine (A) • Guanine (G)
Nitrogenous bases; Pyramidines
• Thymine (T) • Cytosine (C) • Uracil (U)
Chargaff’s rule
Adenine (A) must pair with Thymine (T) Guanine (G) must pair with Cytosine (C)
When and where does DNA replication take place?
When: S phase in interphase of cell cycle Where: nucleus of eukaryotes
☆ The origins of replication ☆
• Replication forks • Replication Bubbles
☆ Helicase ☆
Enzyme that Unwinds the DNA strands -> zipper
☆ Single strand binding proteins (SSBP’s) ☆
Keeps separated strands apart -> tug-a-war with zipper
☆ Topoisomerase ☆
Enzyme that allows the DNA molecules to rotate
☆ Primase ☆
Enzyme that makes the RNA primer
☆ RNA Primers ☆
Anchor Point present to start addition of new nucleotides
☆ DNA polymerase ☆
With RNA in place; starts the making of a new DNA strand in the 5’ to free 3’ direction
☆ Leading strand ☆
Single polymer in 5’ -> 3’ direction
☆ Lagging strand ☆
Polymer 5’ -> 3’ direction discontinuously against overall direction
☆ Okazaki fragments ☆
Series of short segments on the lagging strand
☆ DNA ligase ☆
Linking enzyme that starts formation of covalent bond from 3’ -> 5’ end of joining strands
☆ Phases of protein synthesis ☆
• Transcription • RNA processing • Translation
Products of protein synthesis
DNA -> RNA -> Protein
How does RNA differ from DNA
RNA; DNA; - Ribose. - deoxyribose - Uracil (U) - Thymine (T) - single-stranded - double str.
☆ Transcription ☆
The transfer of information from a DNA molecule To an (m)RNA molecule
Where does transcription start and stop?
Start: promoter DNA (TATA BOX) Stop: terminator DNA
What enzyme is responsible for the production of the RNA molecule?
RNA polymerase
RNA base pairing
Adenine (A) -> Uracil (U) Guanine (G) -> Cytosine (C)