Please enable JavaScript.
Coggle requires JavaScript to display documents.
Molecular Base of Inheritance - Coggle Diagram
Molecular Base of Inheritance
DNA as genetic material
(Def) DNA is the hereditary material in organisms; it stores and transmits genetic information from one generation to the next
Chromosomes are made of DNA and protein, but multiple experiments showed DNA, not protein, is the genetic material.
Griffith’s Expiriment
(Def) Transformation: a change in genotype and phenotype caused by uptake of external DNA by a cell.
Griffith mixed heat-killed pathogenic S bacteria with living nonpathogenic R bacteria; some R cells became heritable S-type, showing a “transforming principle.”
Base pairing
Complementary base pairing:
A pairs with T (2 hydrogen bonds).
G pairs with C (3 hydrogen bonds).
Purine + pyrimidine pairing keeps the double helix diameter uniform.
Sequence: the order of bases along a strand; each gene has a unique base sequence encoding specific information.
Structure of DNA
Nucleotide components
Deoxyribose: the 5-carbon sugar in DNA.
Phosphate group: links sugars in the backbone via covalent bonds.
Nitrogenous bases:
Purines (two rings): adenine (A), guanine (G).
Pyrimidines (one ring): cytosine (C), thymine (T).
DNA strand and backbone
DNA strand: a polynucleotide with a sugar-phosphate backbone and bases projecting from it.
5' end: end of a DNA strand with a phosphate group.
3' end: end of a DNA strand with a free hydroxyl (–OH) on the sugar.
Double helix and antiparallel strands
Double helix: DNA structure with two strands twisting around each other like a spiral staircase.
Antiparallel: the two sugar-phosphate backbones run in opposite 5'→3' directions.
Sugar-phosphate backbones face outward toward the aqueous environment; bases face inward.
Hershey-Chase phage experiment
Bacteriophage (phage): a virus that infects bacteria.
Virus: genetic material (DNA or RNA) enclosed in a protein coat that must infect cells to reproduce.
Hershey and Chase labeled phage protein with radioactive sulfur and phage DNA with radioactive phosphorus. Only DNA entered the E.coli showing that DNA is the genetic material of phages
Chargaff’s Rule
Rule : DNA nucleotide: deoxyribose sugar + phosphate group + nitrogenous base (A, T, G, or C).
DNA nucleotide: deoxyribose sugar + phosphate group + nitrogenous base (A, T, G, or C).