DNA Structure PDF

: nucleic acid DNARNA  After today, you should be able to:  Explain what each letter in DNA means  Discuss the shape of DNA and be able to label all parts of a DNA molecule  Name the parts of a nucleotide and the 4 bases  Explain the function of DNA in a cel...

: nucleic acid DNARNA  After today, you should be able to:  Explain what each letter in DNA means  Discuss the shape of DNA and be able to label all parts of a DNA molecule  Name the parts of a nucleotide and the 4 bases  Explain the function of DNA in a cell  DNA is the nucleic acid molecule that carries genetic information  A segment of DNA is called a gene Codes for proteins  So what does that really mean?  DNA stands for deoxyribonucleic acid Sugar inDNA category of molecule  We’ll come back to this one… The shape of the DNA molecule is called a 24 double helix Twisted  Think of DNA’s shape as a ladder that has been twisted 2nm Straight Twisted Ladder Ladder  It’s nice to think of DNA looking as simple as this:  But, it really looks more like this: Let’s break it down…  Back bone  Each side of the ladder is called a sugar-phosphate backbone and is connected by covalent bonds this part I Tig   The sugar-phosphate backbone…up close  Consists of: ▪ Phosphate group negativecharge ▪ Deoxyribose sugar 1 Pentagon valentbonds   The rungs of the ladder are made up of nitrogenous ATGC bases i i  Bonded to the sugar É  There are 4 different kinds of E bases in DNA… IE Hasnitrogen  Pyrimidines Purines (single-ringed) (double-ringed) Da ① ① fantasmmmmmmm  Building block of DNA  A deoxyribose sugar group, a phosphate group and a nitrogenous base make up a nucleotide 6 P P Adenine Cytosine P P Thymine Guanine  The deoxyribose sugar group of one nucleotide bonds to the phosphate group of another nucleotide to form the sugar- phosphate backbone  ALL bases are directly connected to a deoxyribose sugar  The nitrogenous bases of one sugar-phosphate backbone bond to the nitrogenous bases of the other sugar-phosphate backbone to make base pairs  A forms two hydrogen bonds with T (and ONLY T)  G forms three hydrogen bonds with C (and ONLY C)  Quick Practice: strand Complementary  If you had a strand of DNA where one side had this sequence of bases: ATAGGCAT TAT CC GTA  What would the other side’s sequence be???  P P C G P P A T P P G C P P A T One final look: Hydrogen bonds b/w bases Antiparallel DNA structure  Now that you know a little about the structure of DNA, let’s revisit its function…  Short version: DNA stores genetic information  Long version: The sequence (order) of bases on the strand of DNA is a code for a blueprint of hundreds of thousands of different proteins that, when made, make up living things