Measles caused by a contagious virus, identifiable by a red rash.
The virus was almost eradicated in the U.S. until a 2014 outbreak.
Understanding of DNA and RNA is crucial in combating viruses.
The Structure of Genetic Material
DNA Replication
Flow of Genetic Information: DNA → RNA → Protein
Genetics of Viruses and Bacteria
Early 20th century: The basis for inheritance was unclear.
Frederick Griffith's Experiment (1928):
Mixed dead pathogenic bacteria with live harmless bacteria.
Result: Some harmless bacteria became pathogenic, inheriting this trait.
Hershey and Chase Experiment:
Used phages (bacterial viruses) to show DNA, not protein, is the genetic material.
Phage DNA directed the host cell to produce more phages.
Nucleic Acids (DNA/RNA): Long chains of nucleotides.
Nucleotide Structure:
Nitrogenous base, five-carbon sugar, phosphate group.
DNA vs RNA:
DNA: Uses deoxyribose, bases include A, C, T, G.
RNA: Uses ribose, base uracil (U) instead of thymine (T).
Watson and Crick discovered DNA is a double-stranded helix.
Base pairing:
A with T
G with C
The structure allows for the storage and replication of genetic information.
Nobel Prize awarded in 1962 to Watson, Crick, and Wilkins.
Rosalind Franklin's contributions are acknowledged posthumously.
Begins with separation of DNA strands.
Enzymes create complementary strands using each original strand as a template.
Semiconservative Model:
Each new helix has one old strand and one new strand.
Parental DNA molecules serve as templates for new daughter strands.
Results in two identical DNA molecules.
Genes (sequences of DNA) are transcribed into RNA, then translated into proteins.
Transcription: DNA → RNA synthesis.
Translation: RNA → Proteins synthesis.
Codons: Triplet code that corresponds to amino acids.
The same genetic code is used across nearly all organisms.
Mutations: Changes in genetic information due to DNA replication errors or environmental factors.
Effects vary based on nucleotides substituted, inserted, or deleted.
Viral Structure:
Consist of nucleic acids (DNA/RNA) encased in a protein coat (capsid).
Lytic Cycle: Virus replicates its DNA, assembles new virions, bursts host cell.
Lysogenic Cycle: Viral DNA integrates into host chromosome, replicates with host cell's DNA, remains dormant.
Emerging viruses can quickly become significant health threats (e.g., HIV, Coronavirus).
Understanding of genetic principles critical for response.
Griffith, Hershey, and Chase's experiments all support that DNA is the genetic material.
Structural differences between DNA and RNA are crucial for understanding their functions.
The DNA structure enables effective replication essential for heredity.