DNA Deoxyribonucleic Acid
Watson and Crick Remember them? James Watson and Francis Crick are credited with the discovery of the secret of the double stranded helix of DNA in 1953.
What is DNA? DNA is the chemical at the center of the cells of living things which controls structure and purpose of each cell and carries genetic information. DNA is the blueprint of life
DNA can be used to detect and help determine treatments of diseases, catch criminals, and many more exciting discoveries in agriculture too.
DNA is…….. in every cell of your body. DNA is the same in each and every cell; whether it is the liver, skin, blood, hair, pancreas, and so on the DNA is the exactly the same. (exception RBC’s don’t have a nucleus when mature) It identifies you!
Let’s take an animated tour of What DNA is……. our/ our/ Tour of Basics Q and A to be placed in notebook
Chromosomes and DNA Ours genes are on our chromosomes Chromosomes are made up of a chemical called DNA Each person has 46 chromosomes The base pairs of DNA are like sentences called genes. Genes tells cells to make proteins and proteins have the cell to perform specific functions.
DNA structure DNA is known as the double stranded helix. It resembles a twisted ladder.
The double strands The two strands of DNA are antiparallel. It is antiparallel because of the direction of the strands. When you look at the nucleotides they are heading one way along one stand and the other way along the other strand
For better understanding the antiparralel strands at their ends are lableled 5’ and 3’ (called 5prime and 3 prime).People who work with DNA and enzymes reading nucleotide sequence always read in the 5’to3’ direction. In a vertically oriented double helix, the 3' strand is said to be ascending while the 5' strand is said to be descending.
. Carbon atoms of the sugar are numbered (prime ‘ indicates carbon of the sugar) The phosphate of the nucleotide is attached to 3’ and to the 5’ of the adjacent nucleotide OH is attached to the terminal nucleotide. Gives DNA distinctive polarity
In deoxyribonucleic acid (DNA) replication, the 5′ to 3′ DNA strand that is synthesized with few or no interruptions is the leading strand. The leading strand, "reads" the DNA and adds nucleotides to it continuously. In deoxyribonucleic acid (DNA) replication, the 3′ to 5′ DNA strand that is discontinuously synthesized as a series of fragments (Okazaki) in the 5′ to 3′ direction is the lagging strand.
DNA What is it made of ? Phosphate Hydrogen bonds Deoxyribose sugar Four nitrogen bases: Adenine guanine Thymine cytosine
DNA components Deoxyribose (sugar) and phosphate make up the sides of the DNA molecule or ladder
Nucleotides One deoxyribose together with its phosphate base make a nucleotide One strand of DNA is a polymer of a nucleotide One strand of DNA has many millions of nucleotides
DNA components Nitrogen bases pair together to make what is called rungs of the ladder
DNA components 4 Nitrogenous Bases Adenine (A) always pairs with thymine (T) and guanine (G) always pairs with Cytosine (C)
Pyrimidine Bases Thymine Cytosine –Each have one ring of carbon and nitrogen atoms
Purine Bases Adenine Guanine –Have 2 rings of carbon and nitrogen atoms
Why A-T C-G? Each base pair is held together by hydrogen bonding A and T are held together by 2 hydrogen bonds G-C are held together by 3 hydrogen bonds The pairing of the bases is like a piece in a puzzle, this is just the way they fit!!!
DNA components Bases attach to the sugar on the sides of the DNA around 10 base pairs per turn
Functions of DNA The order of the nitrogen bases determines which proteins are produced by the cell Every aspect of life is determined by protein functions The proteins do all the work of the cell –Determine physical characteristics (genes) hair color, eye color, freckles, etc. –Play a part in chemical reactions in body
DNA Each cell has about 2m of DNA The average human has about 75 trillion cells sooo….. –DNA can go from earth to the sun more than 400 times
Now let’s see how we can extract DNA /extraction/ /extraction/