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Learning objectives

  • Describe the discovery of nucleic acid and nucleotides
  • Explain the historical experiments that led to the characterization of DNA
  • Describe how microbiology and microorganisms have been used to discover the biochemistry of genes
  • Explain how scientists established the link between DNA and heredity

Part 1

Alex is a 22-year-old college student who vacationed in Puerta Vallarta, Mexico, for spring break. Unfortunately, two days after flying home to Ohio, he began to experience abdominal cramping and extensive watery diarrhea. Because of his discomfort, he sought medical attention at a large Cincinnati hospital nearby.

  • What types of infections or other conditions may be responsible?

Jump to the next Clinical Focus box.

Through the early 20th century, DNA was not yet recognized as the genetic material responsible for heredity , the passage of traits from one generation to the next. In fact, much of the research was dismissed until the mid-20th century. The scientific community believed, incorrectly, that the process of inheritance involved a blending of parental traits that produced an intermediate physical appearance in offspring; this hypothetical process appeared to be correct because of what we know now as continuous variation, which results from the action of many genes to determine a particular characteristic, like human height. Offspring appear to be a “blend” of their parents’ traits when we look at characteristics that exhibit continuous variation. The blending theory of inheritance asserted that the original parental traits were lost or absorbed by the blending in the offspring, but we now know that this is not the case.

Two separate lines of research, begun in the mid to late 1800s, ultimately led to the discovery and characterization of DNA and the foundations of genetics, the science of heredity. These lines of research began to converge in the 1920s, and research using microbial systems ultimately resulted in significant contributions to elucidating the molecular basis of genetics .

Discovery and characterization of dna

Modern understanding of DNA has evolved from the discovery of nucleic acid to the development of the double-helix model. In the 1860s, Friedrich Miescher (1844–1895), a physician by profession, was the first person to isolate phosphorus-rich chemicals from leukocytes (white blood cells) from the pus on used bandages from a local surgical clinic. He named these chemicals (which would eventually be known as RNA and DNA) “ nuclein ” because they were isolated from the nuclei of the cells. His student Richard Altmann (1852–1900) subsequently termed it “ nucleic acid ” 20 years later when he discovered the acidic nature of nuclein. In the last two decades of the 19th century, German biochemist Albrecht Kossel (1853–1927) isolated and characterized the five different nucleotide bases composing nucleic acid. These are adenine, guanine, cytosine, thymine (in DNA), and uracil (in RNA). Kossell received the Nobel Prize in Physiology or Medicine in 1910 for his work on nucleic acids and for his considerable work on proteins, including the discovery of histidine .

Questions & Answers

a solvent isopropyl myristate is use for the pre-treatment of?
Nasir Reply
what is microbiology
Ayeniyi Reply
microbiology is the study of all living organisms that are too small to be visible to the naked eyes, examples bacteria and fungi etc
Iheme
study of microorganism such as becteria etc
Muhammad
study of microorganisms and their effect on organisms life
Aqsa
characteristic of Gram negative bacteria
jane Reply
Characteristics of Gram Negative Bacteria As with Gram positive bacteria, Gram negative bacteria also contain the peptidoglycan polymer in their cell wall. While this polymer is thin (2 to 4 nanometers in thickness with just about 3 layers of peptidoglycan) in Gram negative bacteria, it's also com
Kaviya
it's also composed of long glycan strands that are cross-linked by peptide molecules. This composition serves a number of functions including protecting the bacterial cell from lysis
Kaviya
Good shot
Enoch
Thanks 😊
Kaviya
what was Hans Christian Gram's supported in the modern Microbiology?
Wilson Reply
what is microbial growth
Chisa Reply
The organism responsible for vulva ulcers
nyiter Reply
Why are vascular pathogen poorly communicable from person to person?
Aj Reply
Most vascular pathogens are poorly communicable from person to person because they need a medium to be communicated i,e a vector that would carry them from one person to other
Kaviya
what's the habit of protista
Afieahngwi Reply
They show both autotrophic and heterotrophic mechanisms...
Swetha
thanks
Afieahngwi
welcome...
Swetha
let me mention some water. Air .Food and so on
Gattiek Reply
causes of infectious diseases
Afieahngwi Reply
water.Air
Gattiek
infectious disease are caused by pathogenic micro organisms like bacteria ,fungi..
Swetha
What is pasteurization?
Wilson
are fungi prokaryote or eukaryotes?
Afieahngwi Reply
fungi are eukaryotes.
Swetha
All fungi are eukaryotes. Even micro fungi.
Lad
have..complex cellular organization and membrane bound nucleus ...and..also... having loops of DNA( like plasmids) as.bacteria
Swetha
what enzyme replaces rna nucleotides with dna nucleotides during replication?
Remi Reply
an enzyme called DNA ligase.
Jael
describe the acid fast staining procedure used in the diagnosis of tuberculosis
Salma Reply
bacterial morphology
lf_ Reply
what is the difference between biogenesis & abiogenesis
Mayuri Reply
biogenesis is when living comes out from other living things as a result of reproduction while a biogenesis is the process where living things comes out from non living things
Usman
living things come form other form living things is biogenesis. ....right?
Mayuri

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Source:  OpenStax, Microbiology. OpenStax CNX. Nov 01, 2016 Download for free at http://cnx.org/content/col12087/1.4
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