The Hereditary Material - MT3 - Part 1 Flashcards
What is the only molecule recognizable from its shape?
DNA
- double helix
What lead to the discovery of the structure of DNA?
History of the study of the hereditary material
What 2 streams consisted from the DNA?
- Genetic function
2. Structure of macromolecules
What was the DNA structure very suggestive for?
Function
What was the function they proposed from the structure of DNA?
Replication
Who discovered DNA?
Friedrich Miescher
How did Miescher discover DNA?
He isolated nuclei from pus and found a new kinda of molecule called nuclein
Who discovered the shape of DNA?
Watson
What does pus have a lot of?
RBC
What does DNA have? (2)
- Both acidic and basic parts
- but mostly acidic - Lots of phosphorus
What did Miescher suspect was involved in heredity? And why?
Thought that nuclein might be involved in heredity because the significance of nuclei in hereditary had been established
What did Miescher think might be hereditary variants?
Isomers of nuclein
What did Albrencht Kossel find out?
That there are 5 kinds of bases
What are the 5 kinds of bases?
- Adenine
- Guanine
- Cytosine
- Thymine
- Uracil
What did Phoebus Aaron Leven do? (3)
- Elucidated the structure of nucleotides
- Determined the difference between DNA and RNA and their sugars
- Proposed the tetranucleotide model of DNA
What did Leven’s analysis suggest?
That the 4 bases of DNA were present in equimolar amounts
- in equal numbers
What was discovered about Leven’s model?
That it was wrong
- thought it was proteins instead of DNA
- proteins are not hereditary
What did Archibald Garrod study?
Alcaptonuria
- soon after the rediscovery of Mendels law
What did studying family pedigrees show?
That alcaptonuria is inherited as a Mendelian recessive trait
Alcaptonuria
Is a rare inherited genetic disorder in which the body cannot process the amino acids phenylalanine and tyrosine, which occur in protein
What are alcaptonuria not able to get ride of?
Homogentisic acid
What happens when homogentistic acid builds up? (2)
- It is excreted in the urine
2. Turns black upon exposure to air
What did Garrod suspect about alcaptonuria?
A deficiency in a pathway which lacked enzymatic function since it could not encode for that enzyme
What did Garrod conclude?
That a normal allele somehow produced an enzyme for the metabolism of homogentisic acid
- the alcaptonuric allele produced a defective or missing enzyme
What did Franz Moewus study?
The genetics of sexuality in chlamydomonas eugametos
- which is a green unicellular alga
What did Moewus associated with Mendelian mutations?
With an inability to produce sex hormones, thus associating genes with biochemical functions
- same as Garrod had done
What was Moewus accused of?
Making up data
What were mutations in Neurospora Crassa (a fungus) associated with?
Deficiencies in pathways that synthesize amino acids from precursor molecules
Mutagenesis
Ia a process by which the genetic information of an organism is changed, resulting in mutation
How might mutagenesis occur in nature? (2)
- Spontaneously
- As a result of exposure to mutagens
- can also be achieved in the lab
Genetic dissections
A major tool of developmental geneticists is the ordering of gene in functional pathways
What did George Beadle and Edward Tatum perform?
The famous experiment of mutants having deficiencies in certain precursor pathways to synthesize amino acids for later precursor molecules
- one gene = one enzyme (idea)
What was the first protein to be studied in structural and functional detail?
Hemoglobin (Hb)
- modle molecule
Why is Hb a model molecule? (3)
- Can get a lot of it in pure substance
- Easily accessible
- Ability to quickly purify
What could Pauling and co-workers show?
That a disease known to be inherited in simple Mendelian fashion, sickle cell anemia, was associated with a malformed version of a protein, Hb
What do mutated proteins have? (3)
- Different structures
- Different functions
- Can move at different migration speeds
