BIO 1140 Lecture Notes - Lecture 13: Eukaryote, Viroid, Protease
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Cell Bio Lecture 13
Monday February 24, 2014
DNA and RNA Structure:
Chapter 12.1-12.2, pages 257-264
Objective – to understand structure-function relationships
Structure of DNA and RNA
Key Questions that we will try to answer:
-What is the structure of DNA and how do we know?
-Is DNA always the genetic material?
-Is the DNA structure always the same?
-Is the DNA structure in the cell relevant?
-Is the genome what we think it is?
-Without chromatin, would it be necessary to invent it?
DNA is made up of Purines and Pyramidines
-They’re heterocyclic and aromatic rings
-AGTC in DNA
-Deoxyribose so there’s no oxygen there
-If it was RNA, what would change would be uracil replaces thymine (no –Me group); ribose
would replace deoxyribose (2’ OH)
-It’s hard to determine the structure of a certain DNA or RNA unless we know the modifications
that took place
DNA is the genetic material (at least most times)
(A brief summary of the evidence)
-Phage infection experiment
-Role of Model Building
-The modern “synthesis” – DNA structures
The basic or archetypal structural forms for DNA and RNA
Bacterium: dsDNA(s) – Circular ; Protein/DNA nucleoid
Eukaryote: dsDNA – Linear ; Protein/DNA chromosome
Mitochondrion: dsDNA – Circular ; Protein/DNA
Chloroplast: dsDNA – Circular ; Protein/DNA
Virus: ss or ds DNA – Circular or Linear, ss or ds RNA – circular or linear (can be segmented genomes) ;
Protein or DNA
Viroid: ssRNA, circular ; None?
Note: Except for viroids, why nucleic acid and protein? Structural reason
Prion diseases/infectious proteins, the form of the protein recruits other proteins to become that form
Cells that can take up DNA are referred to as competent
R and S strands of the pneumonia – rough and smooth
S strand is virulent – multiplies within host and kills it
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