Introduction to Genetics - E1

• history of genetics:

  • 1600-1850: the dawn of modern biology
  • William Harvey: theory of epigenesis and observed that body organs do not form in the embryo until later on
  • Schleiden and Schwann: the cell theory (1830)
  • Darwin traveled on the HMS Beagle that provided geographical, biological, and geological observations which helped formulate his theory on evolution
• history of genetics:

  • Charles Darwin published his ideas of evolution in the origin of species in 1859
  • existing species developed from other ancestral species by descent with modification
  • Alfred Wallace proposed the idea of natural selection
  • natural selection is the driving force for evolutionary change
• Genetics progressed from Mendel to DNA in less than a century
• genesis

  study of birth or study of heredity
• three branches of genetics?

  • transmission
  • molecular
  • population
• TRANSMISSION GENETICS:

  Gregor Mendel: the "father" of genetics and studied inheritance and genes

  Mendel published his work on the transmission of genetic information from parents to offspring

  Mendel worked with peas and used quantitative ideas about genes
• TRANSMISSION GENETICS:

  Inheritance:

  • each parent contributes particles
  • phenotype ~ appearance
  • factors/genes
• TRANSMISSION GENETICS:

  Gene:

  • exists in two different forms ~ alleles
  • dominant and recessive
• TRANSMISSION GENETICS:

  diploid: two pairs (mitosis)

  haploid: half of a pair (meiosis ~ resulting cells = gametes)
• TRANSMISSION GENETICS:

  genes are transmitted through gametes which maintain genetic continuity
• TRANSMISSION GENETICS:

  mutations produce alleles of genes which is genetic variation

  EX: down syndrome
• TRANSMISSION GENETICS:

  set of alleles for given trait is called genotype

  genotype is an observable trait and phenotype
• TRANSMISSION GENETICS:

  genetic information has DNA only NOT protein
• TRANSMISSION GENETICS:

  Thomas Hunt Morgan (1910):

  • researched fruit flies (drosophila melanogaster)
  • found information on sex chromosomes, autosomes, mutants, genotype, sex, eye color, and wild/normal standard type
  • wild standard type is normal
  • standard type is abnormal
• TRANSMISSION GENETICS:

  A H Sturtevant: found the space between genes
• TRANSMISSION GENETICS:

  in 1930, genetic mapping with eukaryotes like peas, humans, neurospora (a mold found in prokaryotes)
• TRANSMISSION GENETICS:

  recombinants = crossing over
• TRANSMISSION GENETICS:

  Barbara McClintock:

  • first one to discover the relation of a gene, how meiosis takes place, demonstrated crossing over in 1931, and the direct region of chromosome of gene
• the discovery of the double helix launched the era of molecular genetics
• MOLECULAR GENETICS:

  Friedrich Miescher (1869): the nucleus is a mixture of compounds called nuclein

  • found nuclein from a small circle of a pus of band-aid
• MOLECULAR GENETICS:

  Oswald Avery and colleagues (1944): found the pieces of DNA
• MOLECULAR GENETICS:

  Fredrick Griffith (1920s): rediscovered genetic material of DNA
• MOLECULAR GENETICS:

  the relationship between proteins and genes dates back to 1902
• MOLECULAR GENETICS:

  Archibald Garrod: studied human diseases and found out that defective genes lead to defective enzymes

  • recessive trait disease
  • accumulation of black
  • acaptonuria
  • pigment in the urine
• MOLECULAR GENETICS:

  an abnormal buildup of an intermediate chemical compound is called a biochemical pathway
• MOLECULAR GENETICS:

  biochemists show the several chemical reactions carried out by cells
• MOLECULAR GENETICS:

  reactions are accelerated by organic catalysts enzymes - proteins
• MOLECULAR GENETICS:

  Garrod had a conclusion that defective genes give rise to defective enzymes
• MOLECULAR GENETICS:

  George Beadle and E.L. Tatum:

  both proved the relationship between genes and enzymes and found out that genes are susceptible to mutagens; also, the first people to use the word mutagens

  Beadle and Tatum worked with a fungus - Neurospora
• MOLECULAR GENETICS:

  what do genes do?

  • replicate
  • direct productions of RNAs and proteins
  • gene sequence is altered that leads to mutations and evolution
• MOLECULAR GENETICS:

  James Watson and Francis Crick (1951-1953):

  in 1953, both discovered the structure of DNA and they understood the DNA molecules

  explained how DNA replicates

  used the data from Rosalind Franklin and Maurice Wilkins to learn more about the DNA

  in 1962, both Watson and Crick won a nobel prize
• MOLECULAR GENETICS:

  Rosalind Franklin made a mistake that majorly helped Watson and Crick understand the DNA structure
• MOLECULAR GENETICS:

  Marshall Nirenberg and Har Gobind Khorana:

  • generated the genetic code
  • synthesized DNA molecules in a test tube
• chromosome I - longest

  chromosome II - shortest
• 22 chromosomes are autosomes and the 23 chromosome is the X/Y chromosomes

  • autosomes are any chromosomes that are not a sex chromosome
• POPULATION GENETICS:

  examines:

  • the extent of genetic variations within and among populations
• POPULATION GENETICS:

  description of genetic differences between different species
• RNA - antiparallel and is a single stranded helix

  DNA - antiparallel and is a double stranded helix
• the monomer (a molecule that can be bonded to other identical molecules to form a polymer) for DNA is a nucleotide that consists of a sugar (deoxyribose) that is bonded to a phosphate and also bonded to the bases:

  • adenine (A) A-T
  • thymine (T) T-A
  • guanine (G) G-C
  • cytosine (C) C-G
• nucleotide is a phosphate and a sugar