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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

what is biochemistry
Isaac Reply
Biochemistry, sometimes called biological chemistry, is the study of chemical processes within and relating to living organisms. Biochemical processes give rise to the complexity of life. ... The mechanisms by which cells harness energy from their environment via chemical reactions are known as meta
Dejene
what is pathogenic
kelvin Reply
biological pathogen is anything that can produce disease. a pathogen may also be referred to as an infectious agent, or simple a germ.
Dejene
Thanks
kelvin
explain 3 points why gender is relevant to health.
kelvin
wat causes sor throat
Ezeama Reply
Streptococcus
Rajat
Streptococcus
Panda
Gram positive
shamim
streptococcus pyrogenes
Sherma
group A streptococcus pyogenes. But not the only one.
Carlos
does the bac of s.aures gives choronic diseas in bone?
Elyas
causes virus bac group A strep allergies smoking
Elyas
truth also virus
Shania
what z microbiology
Mwelwa Reply
microbiology is all about the scientific study of microorganisms, their life changes, their life span, structural punctuality and their phenomenon.
Ridwan
thanks
micah
Best scope in microbiology
Rahul
wat abut skin
Elyas
whatis scope
Amare
what is scope
Funmi
what happened when someone died and what happened to the blood
Franca Reply
nice question
Attari
when you die you have no memory and the blood dry off
Falere
what microorganisms is all about?
Ridwan
And how many does the microorganisms is classified?
Ridwan
How are microbs organized
Saskia
what is endoparasites and exo parasite and their example
OGEDE Reply
Endo : inside the body Exo/ecto : outside or on the body
Paul
examples please
OGEDE
Louse for exo/ecto Helminths (worms) for endo
Paul
what's prokaryotic
mohaiminul Reply
A prokaryotic cell is a cell with no membrane bounds organelles
Paul
what are the main effect of parasite?
yunusa Reply
nutritional group of micro organism
Mana Reply
what are the charateristic bacteria, eukaryotes, and viruses have in commom
Ami Reply
what type of bacteria ismor serious
Amare
D N A ar purno rup ki
Ruba Reply
বাংলায় দেখবো DNA এর পূর্রন্যরুপ কি
Ruba
what's microbiology
micah
micro biology is the study of micro organisms,those being unicellular multicellular or a cellular
aniisha
deoxyribonucleic acid is a long molecule that contains our unique genetic code.
aniisha
Does the parasite/parasitology are under microbiology or not
yunusa
Define bacteria
Kainat
Bacteria are a type of biological cell & they constitute a large domain of prokaryotic microorganisms.
raisa
what kind of microbiology
Mira
hello what is main function of T and B cells
Ishaq Reply
T cells are involved in cell-mediated immunity while B cells are primarily responsible for humoral immunity (relating to antibodies)
Janet
what is hepatitis B
Sunday
it's viral infection that attacks the liver and can cause both acute and chronic diseases. the virus is most commonly transmitted from mother to child during birth and delivery, as well as through contact with blood or other body fluids...
Dejene
What are fundamental experiment of microbiology?
Lucky Reply
study of microscopic organisms, unicellular and multicellular
Falere
what are the characteristics of bacteria, viruses, and eukaryotes
Ami
bacteria-are living organism. contain a peptidoglycan/lipopolysaccharide cell wall. VIRUS-are considered as organic structure which interact with living organism don't have acell wall. they have many differents like bacteria size -large(1000nm) virus size-smaller(20-400nm). bacteria ribosomes presen
Dejene
virus ribosomes absence. bacteria living organism. virus b/n living and non-living things
Dejene
eukaryotic cell has a true membrane bond nucleus and has other membranous organelles that allow for compartmenalization of function
Dejene
This answer is wrong
Jeffrey Reply
who discovered the growth curve
Joy Reply

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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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