week 1

• INTRODUCTION TO MOLECULAR BIOLOGY & GENETICS

  
• HISTORY OF MOLECULAR BIOLOGY

  • biochemistry, genetics, microbiology and virology.

  
• CHROMOSOMES & INHERITED TRAITS
• FRANCIS CRICK'S FIRST SKETCH OF DNA DOUBLE HELIX PATTERN
• HELIX STRUCTURE
• COMPLEMENTARY NUCLEOTIDES
• WHOM WOULD YOU MEET?

  • James Watson
  • Rosalind Franklin
  • Xray diffraction
  • Wilkins
  • Francis Crick
  • Maurice
  • Nobel Prize
  • reconstructed
  • National Science
  • Museum
  • Meselson-Stahl experiment
  • Har Gobind
  • Khorana
  • genetic
  • molecular biology
  • code
• Molecular biology


  The study of biology at the molecular level
• Molecular biology


  The study of gene structure and functions at the molecular level to understand the molecular basis of hereditary, genetic variation, and the expression patterns of genes
• The Molecular biology field overlaps with other areas, particularly genetics and biochemistry
• Genome


  The totality of genetic information encoded in the DNA (or, for some viruses, RNA)

  
• The genome database is organized in six major organism groups: Eukaryotes, Bacteria, Archaea, Viruses, Viroids and Plasmids
• Three domains of life

  • Eukaryotes
  • Prokaryotes
  • Archaea
• Cell


  The smallest living unit, the basic structural and functional unit of all living things
• Some organisms, such as most bacteria, are unicellular (consist of a single cell). Other organisms, such as humans, are multicellular
• Functions of cells


  • Secretion (Produce enzymes)
  • Store sugars or fat
  • Brain cells for memory and intelligence
  • Muscle cells to contract
  • Skin cell to perform a protective coating
  • Defense, such as white blood cells
• Eukaryotic cell


  Cells with a true nucleus, where the genetic material is surrounded by a membrane
• Eukaryotic cell


  • Eukaryotic genome is more complex than that of prokaryotes and distributed among multiple chromosomes
  • Eukaryotic DNA is linear
  • Eukaryotic DNA is complexed with proteins called "histones
  • Numerous membrane-bound organelles
  • Complex internal structure
  • Cell division by mitosis
• Prokaryotic cell


  Unicellular organisms, found in all environments. These include bacteria and archaea
• Prokaryotic cell


  • Without a nucleus; no nuclear membrane (genetic material dispersed throughout cytoplasm
  • No membrane-bound organelles
  • Cell contains only one circular DNA molecule contained in the cytoplasm
  • DNA is naked (no histone)
  • Simple internal structure
  • Cell division by simple binary fission
• Archaea are prokaryotes; organisms without nucleus but some aspect of their molecular biology are more similar to those of eukaryotes
• Eukaryotic cell cycle phases

  • G1 = Growth and preparation of the chromosomes for replication
  • S = Synthesis of DNA
  • G2 = Preparation for mitosis
  • M = Mitosis
• The central dogma of molecular biology is the flow of genetic information from DNA to RNA to protein

  
• Nucleic acid


  DNA and RNA are long chain polymers of small compound called nucleotides. Each nucleotide is composed of a base, sugar (ribose in RNA or deoxyribose in DNA) and a phosphate group
• DNA structure


  The structure of DNA was described by British Scientists Watson and Crick as long double helix shaped with its sugar phosphate backbone on the outside and its bases on inside; the two strand of helix run in opposite direction and are anti-parallel to each other. The DNA double helix is stabilized by hydrogen bonds between the bases
• The G+C content of a natural DNA can vary from 22-73% and this can have a strong effect on the physical properties of DNA, particularly its melting temperature
• DNA nucleotides


  A is for adenine; G is for guanine; C is for cytosine and T is for thymine. Adenine and guanine are double ringed structure termed purine, thymine and cytosine are single ring structures termed pyrimidine. Adenine A pairs with thymine T (two hydrogen bonds) and guanine G pairs with cytosine C (three hydrogen bonds)
• In contrast to DNA; RNA is a single stranded, the pyrimidine base uracil (U) replaces thymine and ribose sugar replaces deoxyribose
• • the name was coined by Warren Weawer
• DNA


  The genetic material of all cellular organisms and most viruses, the gigantic molecule which is used to encode genetic information for all life on Earth
• 64 codons in mRNA
• Rna is single strand
• When T. H. Morgan's group showed that genes are located on chromosomes, the two components of chromosomes—DNA and protein—became candidates for the genetic material

  
• The role of DNA in heredity was first discovered by studying bacteria and the viruses that infect them
• Frederick Griffith's experiment showed that the heat-killed remains of the pathogenic strain could transform the harmless strain, a phenomenon now defined as transformation
• mRNA regions that are not translated; 5' untranslated region, 3' untranslated region, 5' capand poly-A tail
• Oswald Avery, Maclyn McCarty, and Colin MacLeod identified the transforming substance as DNA
• Alfred Hershey and Martha Chase showed that DNA is the genetic material of the bacteriophage T2
• Erwin Chargaff reported that DNA composition varies from one species to the next, making DNA a more credible candidate for the genetic material
• Chargaff's rules state that the base composition of DNA varies between species, and in any species the number of A and T bases is equal and the number of G and C bases is equal