Oswald Theodore Avery (1877-1955)

Oswald Theodore Avery was a Canadian-born U.S. bacteriologist. He studied at Colgate University but the major part of his career was spent at the Rockefeller University Hospital in New York City. He discovered Transformation, a process by which a change could be introduced into bacteria and passed to later generations of cells. Avery took exract from heated smooth bacteria and treated it with DNAase (digested DNA) then mixed it with rough bacteria and injected it into rats. He found out by doing this that the rats lived. Avery then took extract and treated it with Pretease (digested proteins) and mixed it with rough bacteria and injected it into rats, the rats died. This experiment showed that DNA, not protein, has the ability to transform cells.

Forensics

Only one tenth of a single percent of DNA (about 3 million bases) differs from one person to the other. Any type of organisms can be identified by there DNA. To identify human beings, scientists scan 13 different DNA regions to create a DNA profile (also known as a DNA fingerprint)
Some examples of Forensic DNA:

• help identify a suspect using evidence from a crime scene 
• fraternity and finding family relationships  
• to match organ donors with the receiver
• identify victims where there physical appearance is severally change in an indecent

In forensics DNA is collected from a crime scene can bring up or eliminate a suspicious suspect. Scientists collect DNA from blood, bone, hair. and different types of body tissue. The scientists would use that DNA collected from the crime scene and create a DNA profile. The DNA profile is then compared to the other DNA profiles from previous crimes to find a match.

These DNA profiles is the number of repeats of an individual has in both copies of all STR markers, plus AMEL. Crime labs use CODIS (Computer Software and DNA Profile Database) there are two different sets of profiles: criminal indexes and missing persons index. Criminal indexes are in all 50 states, because DNA collection is legal. Missing persons indexes is used for missing persons, unidentified human remains and relatives of missing persons. When there's a match between a suspect and forensic evidence, a follow up DNA analysis is held to confirm the match. When they don't match they eliminate the suspect from the investigation. Proper handling of the evidence is key to maintain the evidence for the current case, future cases, and even help solve past cases.

ornl.gov

dna.gov

Ehow

Central Dogma

Replication:
DNA synthesis bind to specific regions of the chromosomes which is the replication origin.In prokaryotes there is only one origin for replication. The small chromosomes can replicate rapidly. Eukaryote although contain several chromosomes. Once the DNA double helix is at the origin and separates, an enzyme starts for preparation of each of the individual strands of DNA for synthesis. When the replisome moves away from the replication origin it starts to unwind the double helix. The replisomes move away from the replication origin along the DNA in both directions. The results of the process replaces the old DNA double helix with 2 identical ones. After adding a new nucleotide to the chain it goes through a check point to see if everything is correct. And if there is an error in the enzyme, the enzyme will put everything in a stand still and it'll remove the nucleotide and replace it with a correct one. If there is a mutation the enzyme would bind it to DNA and it'll break the sugar phosphates bonds of the mutation and fix it correctly.

Transcription:
(is the process of the making of a mRNA molecule) Happens in three stages the Initiation is the 1st stage. Its occurs when the enzyme RNA polymerse attaches to a specific region of the DNA. This are is known as the promteter region. But in the eukaryote cells the proteins need to present for the RNA polymerse to join itself with the prometer region. The 2nd stage is known as the Elongation. The Elongation is when the RNA polymerse begins to break the DNA. The enzyme travels with the DNA away from the prometer. A strand of RNA is created known as the primary transcript. The 3rd stage is known as Termination. Its when the RNA polymerse reaches at the end of the DNA to be transcribed. The primary transcript and the enzyme id then released.
Translation: When the protein synthesis moves the codon sequence of the mRNA to the amino acid sequence of a protein. One end of the RNA molecule carries a specific amino acid and the other side is the anti codon. The anti codon pairs with the mRNA . When the correct amino acid conbines with tRNA is called tRNA charging. Each enzyme bonds a different amino acid to its match tRNA by the energy from ATP. The tRNA and mRNA and the polypeptide chain come together at a specific region on the ribosomes. The tRNA leaves the E site after its amino acid is added to the polypeptide chain. The ribosomes move along the mRNA strand at a time.

 

Science Biology Text Book

Pictures:

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wiki 

Structures of DNA, tRNA and mRNA

Structure of DNA
DNA's backbone is based on a repeated pattern of a sugar and phosphate group. The Genetic parts of the DNA are found in the "Steps" of the structure. (nitrogen bases) The Bases are on the inside and the backbone is on the outside.(1)

It also has two strands of nucleotides that form a spiral stair case looking figure. Each nucleotide contains three parts; Phosphate group, sugar molecule and one of four bases. Those four bases are admine, guanine, cytosine and thymine. The bases link up using hydrogen bonds; Admine to Thymine and Cytosine to Guanine. The pairs never change but the pattern can very depending on the species.(2)

Structure of tRNA
Transfer RNA brings out the amino acids to a growing polypeptide chain at the ribosomal site of protein synthesis during translation. All tRNA's have a similiar sequences of 73-93 nucleotides. The image of tRNA is in a compact "L" shape. (4) Transfer RNA has three structures; A primary, secondary and a tertiary. Each one contains a specific anticodon triplet sequence that can be a base pair to one or more codons for an amino acid. (3)

Structure of mRNA

Messenger RNA allows the genetic coding in DNA.(5) mRNA is always singly stranded. It contains bases Adenine, Guanine, Cytosine and Uracil. There is random coiling in messenger RNA and there is no specific base pairing. In fact Base Pairing actually destroys its biological activity.(6)

Resources:

1.Chem Guide - DNA Structure

2. You Tube - DNA structure
3. Wikipedia - tRNA

4. Bass.Bio.Uci.edu - tRNA

5. eHow - mRNA
6. Micro Biology - mRNA

J.Craig Veneter and Francis Collins

J Craig Veneter was born on October 14, 1946 in Salt Lake City, Utah. He is an American Biologist. Veneter founded the institute for genomic research. He served in the United States Navy during the Vietnam war (where he working with intensive care ward of a field hospital. Veneter attended school at Mills High school. He went to a community college, College of San Mateo. Where he received his BS degree in biochemistry and his PhD in physiology and pharmacology. AT UCSD ( University of California San Diego) he was mentored by Nathan D Kaplan a biochemist. Francis Collins was raised on a small farm in Virgina's Shenandoah Valley. Collins didn't attend school but rather he was home schooled by his mother until he hit the 6th grade. Collins earned his BS in chemistry at the University of Virgina. He received his PhD in physical chemistry at Yale university.

    J Craig Veneter on the left and  Francis Collins on the right

The human genome project is an international reserch project with the goal of finding out the sequence of chemical base pairs of DNA. THe project began in the early 1990's. The project mostly focused on the genetic make up of human beings. The project also researched/ studied on E Coli, fruit flies, and lab mice. For the human side of the research , there were willing blood donors of male and females. The project was very expensive so they decided to use the ''shotgun theory'' which was to breakup the genome into smaller pieces into ''Vectors''. These vectors can be inserted into bacteria so that they could be copied using DNA replication. The genome that were broken apart are mapped out to chromosomes.

The contributions of Veneter and Collins to the Human Genome project toward DNA are still increasing now. A better understanding of DNA for new advancements in medicine and biotechnology, Genetic tests to find diseased genes such as breast cancer and liver disease.

Resources:

Wikipedia - Human Genone project

Wikipedia - Francis Collins

Jcvi

Nature

Watson & Crick 1953 - Double Helix Structure of DNA

James Watson and Francis Crick studied at the University of Cambridge. They became interested in Linus Pauling's work of a proton having an alpha helix structure, that spiraled in a coil. Watson also became interested in Rosalind Franklins research of DNA existing in two forms and an X-ray diffraction image of DNA.(1)

Watson and Crick found that there are two chains of nucleotide; one going up and one going down, each containing a long chain of monomer nucleotides.(2)

With the help of Erwin Chargaffs findings, they added that matching bases pairs interlocked in the middle of the double helix to keep the distance between the chains constant. Each strand of the DNA molecule was a template for the other.(1) DNA replicated itself and separating into two different strands. Those strands then became templates for new double-helix.

Resources
1.PBS- Watson and Crick

2. Nature - Watson and Crick

3. History

Martha Chase and Alfred Hershey

Martha Chase was born on 1927 in Clevelend, Ohio. Chase's career was an american geneticis. She attended the college of Wooster where she recieved her bachelors degree in 1950. She also attended the University of Southern Carolina where she recieved her PhD. Alfred Hershey was born on December 4,1908 in Owosso Michigan. He attended Michigan State College where he recieved his BS and his PhD. He was hired as the director of the genetics research unit in Cold spring harbor, New York.

Biologists thought that proteins are carried there information through inheritance since 1869. Chase and Hershey created there experiments on a virus known as "T2 phage". This virus infects baceterium by connecting its outer membrane and injecting its genetic material and leaving the empty shell on the bacterium. First they allowed the virous to infect E.Coli (in this experiment they observed that there was a transfer of P32 labeled virous its DNA was in the cytoplasm of the bacterium. in there second experiment they conducted they labeled the virous with radioactive Sulfur-35. After the seperation the radioactive S35 tracer was in the protein shells, but not in the infected bacteria. This in conclusion they found that the genetic material that infected the bacteria was DNA not protein. Chase and Hershey recieved the Nobel peace prize for their ''discovers concerning the genetic structure of virouses.''

Martha Chase and Alfred Hershey's findings that DNA is genetic material contributes to the better understand of virouses. With having a better understanding of virouses helped other scientests to develop vaccines against diseases such as polio.With there new information about DNA; Chase and Hershey creates ther blender experiment. A year after there blender experiment James Dewey Watson and Francis Harry Compton Crik deterimined that DNa is in a double helix type structure.

Resources:

Bookrags
 Wikipedia

Nobelprize

Thomas Hunt Morgan

Thomas was born on September 25,1866 at Lexington,Kentucky in the Unites States. He went to study at the University of Kentucky, and later studied morphology at John's Hopkins University. Thomas Hunt Morgan was awarded the noble peace prize for his discoveries concerning the role played by the chromosomes in heredity.

He had a fly room in Colombian University. Thomas experimented with male and female flies. Both the female and male flies were placed into the jar to mate. When the white eyed flies mates with the red eyed flies, they created red eyed offspring. Morgans first papers demonstrated that the sex was linked by the genes for the white eyed flies.With this fly room he concluded that genes are carried on chromosomes and are the mechanical basics of hereditary.

George Wells beadle and Hermahn Joesph Muller won the Nobel peace prize as students of Thomas Hunt Morgan. Morgans constributions of study helped Mendel's ideas of heredity. Morgan made other contributions to experimental embryology and to regeneration. In embryology, Morgans discoveries demonstrated that gravity is not important to the development to the egg as Roux suggested.

Resources:

Nobelprize

Wikipedia

Geneticstv

Erwin Chargaff 1905-2002 - "Chargaffs Rule

Erwin Chargaff was a biochemist who migrated to the united states to get away from all the Nazi troubles. He studied at Yale University, but he didnt like Connecticut so he moved back to Europe and studied at the University of Berlin. (1)
Chargaff read Oswald Avery's report that heredity unites and genes were composed of DNA. This led him to do more research, "Avery gave us the first text of a new language."(2) The rules state that DNA from any cell should have a 1:1 ratio of pyrimidine and purine bases. The amount of quanine is equalt to cytosine as well as the amount of adenine is eqaul to thymine.(1)
- A double-stranded DNA molecule globaly has a percentage base pair equality: %A = %T and
%G = %C (1)
-Both %A ~ %T and %G ~ %C are valid for each of the two strands. (1)

Chargaffs work was useful to other scientists like James Watson and Francis Crick in 1953. They concluded that DNA exists in a 3-D double helix. (Image to the right.)




Resources
1. Wikipedia: Erwin Chargaff
2. Chargaff and Avery

Rosalind Franklin - X-Ray Diffraction Image of DNA

Rosalind Franklin graduated from Cambridge University with a Ph.D. She then went and worked for John Randall as a research associate at Kings College in London. There, Franklin discovered that DNA can be in A form or B form. She developed a method to seperate the two forms providing the first DNA crystals pure enough to yield interpretable diffraction patterns. With this method a crystal is exposed to x-rays in order to produce a diffraction pattern.
Franklin discovered that the DNA helical structure has two strands not three sugar-phosphate backbones. Franklin gave details about the structures shape and size in her research. She could not find the bases paired on the inside of the helix; heredity. Rosalind left off here for Watson and Crick to discover the TOTAL DNA structure.(1)

Resources
1. Rosalind Franklin - access exellence