Introduction to Molecular Biology
Module 1
‘Introduction to Molecular Biology’
Learning Objectives
(Chapter 6) Molecular Biology, DNA, chromosomes, and the central dogma.
Understand Nucleic Acid Structure and properties (including alternate forms of DNA structure and supercoiling, and renaturation)
Explain the nature of Prokaryotic Chromosome
Understand the differences in re-association kinetics of single-copy vs. repeated sequence
Understand how DNA re-association provides a measure of genome size in base pairs
Functions of DNA
REM
Replication: genotypic function
Expression: phenotypic function
Mutation: evolutionary function
DNA Structure
Base Pair Rules - Adenosine=Thymine, Guanine≡Cytosine
Chargaff’s rule: (Purine + Pyrimidine)A+C=T+G, ‘any cell of all organisms should have a 1:1 ratio of pyrimidine and purine bases’
DNA is a double helix in a right handed manner. There is no relation between genome size and animal size.
Central Dogma of Genetics: All DNA flows from DNA > mRNA > protein
Size: The helix has a 2nm diameter, and for each helical turn, there is ~10 nucleotides. (note that the smallest viruses are~60nm)
It is named DNA because:
D: Deoxyribo- The pentose sugar doesn’t have any oxygen on position 2.
N: Nucleic- These molecules were first found in the nucleus of the cell (prior mitochondrial discovery), and in cytoplasm of prokaryotes.
A: Acid Two acid groups of phosphoric acid are used in forming DNA bonds.
DNA consists of a long chain of nucleotides which consist of
1. Deoxyribose (a 5-carbon pentose)
2. Phosphoric Acid
3. Nitrogenous Bases (nucleosides; either Purines, or Pyrimidines)
Each strand has opposite polarity (5’ -> 3’ and vice versa)
Supercoiling
In vivo, DNA is naturally negatively supercoiled (slightly unwound), when it’s ends are covalently joined, DNA free end is wound in the opposite direction to the DNA helix
Positively supercoiled: overwound, also depends on handedness. Free end of DNA is wound in the same direction as
‘Introduction to Molecular Biology’
Learning Objectives
(Chapter 6) Molecular Biology, DNA, chromosomes, and the central dogma.
Understand Nucleic Acid Structure and properties (including alternate forms of DNA structure and supercoiling, and renaturation)
Explain the nature of Prokaryotic Chromosome
Understand the differences in re-association kinetics of single-copy vs. repeated sequence
Understand how DNA re-association provides a measure of genome size in base pairs
Functions of DNA
REM
Replication: genotypic function
Expression: phenotypic function
Mutation: evolutionary function
DNA Structure
Base Pair Rules - Adenosine=Thymine, Guanine≡Cytosine
Chargaff’s rule: (Purine + Pyrimidine)A+C=T+G, ‘any cell of all organisms should have a 1:1 ratio of pyrimidine and purine bases’
DNA is a double helix in a right handed manner. There is no relation between genome size and animal size.
Central Dogma of Genetics: All DNA flows from DNA > mRNA > protein
Size: The helix has a 2nm diameter, and for each helical turn, there is ~10 nucleotides. (note that the smallest viruses are~60nm)
It is named DNA because:
D: Deoxyribo- The pentose sugar doesn’t have any oxygen on position 2.
N: Nucleic- These molecules were first found in the nucleus of the cell (prior mitochondrial discovery), and in cytoplasm of prokaryotes.
A: Acid Two acid groups of phosphoric acid are used in forming DNA bonds.
DNA consists of a long chain of nucleotides which consist of
1. Deoxyribose (a 5-carbon pentose)
2. Phosphoric Acid
3. Nitrogenous Bases (nucleosides; either Purines, or Pyrimidines)
Each strand has opposite polarity (5’ -> 3’ and vice versa)
Supercoiling
In vivo, DNA is naturally negatively supercoiled (slightly unwound), when it’s ends are covalently joined, DNA free end is wound in the opposite direction to the DNA helix
Positively supercoiled: overwound, also depends on handedness. Free end of DNA is wound in the same direction as