Frederick Griffith
A mouse injected with live smooth bacteria died. A mouse injected with live rough bacteria survived. A mouse injected with dead smooth bacteria survived. A mouse injected with live rough bacteria AND dead smooth bacteria died.
Did the capsule kill the mice?
There was a part of the heat-killed smooth bacteria that was able to make the live rough bacteria dangerous.
Transformation
a change caused when cells take up foreign DNA.
Erwin Chargaff
Determined base pairing rules. Amount of adenine = amount of thymine. Amount of cytosine = amount of guanine.
Rosalind Franklin and Maurice Wilkins
Used Franklin and Wilkins’ x-ray pictures to determine the structure of DNA.
1962 Nobel Prize Winners
Wilkins, Perutz, Crick, Steinbeck, Watson.
Where is DNA located?
Nucleus.
What type of organic molecule (biomolecule) is DNA?
Nucleic Acid.
What is DNA?
The function of DNA is to store genetic information. It contains a complete set of instructions for manufacturing all of the proteins for an organism.
Why do we need proteins?
Structure. Enzymes.
DNA is a polymer
The monomer of DNA is a nucleotide.
Nucleotides are made up of
Sugar → deoxyribose. Phosphate → one phosphorus atom and 4 oxygen atoms. Nitrogen base → carbon ring structure containing 1 or more N atoms.
There are four different N bases
Adenine. Thymine. Cytosine. Guanine.
DNA is made of two chains of nucleotides joined together by N bases
The two strands twist together to make a double helix. The sugar and phosphate make up the backbone. N bases make up the rungs.
Base pairing rules
Adenine pairs with thymine. Cytosine pairs with guanine. N bases are held together by hydrogen bonds. N bases that bond are called complementary bases.
Label the diagram
Phosphate. Sugar. Nitrogen Bases. C. GG. A. A. T. G.
There are two distinct ends to a strand of DNA
On the 3’ end, the sugar is attached to a hydroxyl group (OH). On the 5’ end, the sugar is attached to a phosphate group (PO4). The strands are antiparallel. The sugar phosphate backbones run in opposite directions.
Fun Facts!
If you wrote down all the bases in ONE cell, you would fill a stack of 1,000 phone books with As, Ts, Cs, and Gs. If you unraveled all your chromosomes from all your cells and laid out the DNA end to end, the strands would stretch from the Earth to the Moon about 6,000 times.
Universal Code
All organisms use the same genetic code. They all speak the same language, made up of A, T, C, and G. Differences in organisms are a result of the differences in the genome, or the sequence of the four nucleotides along the DNA strands. The sequence forms unique genetic information. This information tells the cell what specific proteins to make. The closer the relationship between two organisms, the greater the similarity in the order of their DNA nucleotides. Scientists use nucleotide sequences to determine evolutionary relationships among organisms.
