DNA It’s a nucleic Acid…specifically it’s Deoxyribonucleic Acid. This is the material that determines inherited characteristics.

What does DNA look like? A little history Watson & Crick found through X-ray images, that DNA looks like two threads twisted around each other & held together by many bridges in between, like a spiral staircase.   This structure is called a double helix. These scientists won a Nobel Prize in 1962 for work on the DNA’s structure. Rosalind Franklin was actually the 1st scientist to produce the pictures of DNA , but died before the Nobel Prize was given.

Where is DNA found? Eukaryotic cells it is stored in the nucleus. Eukaryotic cells have more DNA than prokaryotic cells. Prokaryotic cells store their DNA in a nucleoid.

The Parts of DNA DNA is made up of NUCLEOTIDES NUCLEOTIDES are made of three parts: A Pentose Sugar: Deoxyribose…it’s a sugar with 5 carbons (penta=5, -ose=sugar). A Phosphate Group…that’s a compound with a PO4 group. One of four different Nitrogenous Bases: Adenine Thymine Cytosine Guanine A T C G

Visuals of the THREE Parts of a nucleotide: Nitrogenous base Pentose Sugar Phosphate group

The Structure of DNA The DNA molecule looks like a ladder that has been twisted. This shape is called a DOUBLE HELIX. 1950 Irwin Chargaff figures out that there is always the same amount of adenine as thymine, and there was the same amount of cytosine as guanine. Therefore, A always bonds with T and C always bonds with G.

The Structure of the Double Helix The Rails of the ladder are alternating sugars and phosphates. (***Remember from your DNA candy lab. This was the red and black twizzlers) The Rungs of the ladder are the nitrogen (nitrogenous) bases that are attached to the sugars. (***These were the gummy bears.)

Here’s What it Looks Like

Purines and Pyrimidines The two different structures of nitrogenous bases. Purines= two rings with 9 carbons(A and G) Pyrimidines= a single 6 carbon ring (C and T) Notice: Every base pair contains one purine bonded to one pyrimidine!

Here’s a more detailed description of what it looks like…

Genes are… A GENE is a set of chemical instructions for assembling a protein. DNA is the molecule that carries these genetic instructions. Within a gene, each group of three nitrogenous bases codes for one amino acid. A sequence of amino acids is linked to make a protein. Proteins are fundamental to the function of cells and the expression of traits.

What is a genetic code?  The genetic code is the set of rules by which information encoded in DNA is translated into proteins by living cells. The code defines how sequences of three nucleotides specify which amino acid will be added next during protein synthesis. The order of the bases tells the cell what types of proteins to make! The genetic code is the specific order and number of nitrogen bases of an organism’s DNA!

Here’s The Relationship To Chromosomes

Replication When DNA copies (every time a cell divides), it splits down the middle separating in between the base pairs. The new strand of bases is complementary…that means that where there’s an A (adenine), there will be a T (thymine) to match with it. Where there is a C (cytosine), there will be a G (guanine) to match with it. There are two DNA strands formed through replication. Each new strand contains one copy of the original strand. Write the complementary strand for this sequence: GAATTCGCGGAT

Here’s What You Should Have  GAATTCGCGGAT CTTAAGCGCCTA

Enzymes (an enzyme is a protein…look for the –ase) *There are a number of enzymes that are involved in this process: DNA helicase: unzips the DNA (breaks the hydrogen bonds between the nitrogenous bases) DNA polymerase: lines up the new bases DNA ligase: “glues” sections together Amoeba Sisters DNA replication: https://www.youtube.com/watch?v=5qSrmeiWsuc