Presentation on theme: "DNA – What is it? A Rather Large Molecule That Encodes for Genetic Instruction * Deoxyribonucleic acid ** DNA is a polymer in the nuclei of cells **Made."— Presentation transcript:
A Rather Large Molecule That Encodes for Genetic Instruction * Deoxyribonucleic acid ** DNA is a polymer in the nuclei of cells **Made up of monomer subunits called nucleotides * Most of your cells have identical DNA but genes are “turned on” according to what proteins are made *Example: skin cells will not produce proteins for the liver
Nucleotides **DNA Nucleotides float in the cytoplasm and have three parts: Phosphate group Sugar (deoxyribose) Nitrogenous base **There are 4 nitrogen- containing bases: *Adenine (A) *Thymine (T) *Cytosine (C) *Guanine (G) The Backbone
For Simplicity Purposes – A Single Nucleotide A, G,T or C
Nitrogenous Bases Make Up The DNA “Alphabet” – A,G,T,C Adenine (A) Thymine (T) ALWAYS Pairs With Guanine (G) ALWAYS Pairs With Cytosine (C) PurinesPyrimidines ** Make notice that purines have 2 rings and pyrimidines have one. This is what will gives DNA molecules their shape!!
DNA ** All of the rungs of the DNA “ladder “are pairs of nucleotides, coiled into the shape of a double helix!! **Like a spiral staircase **“rungs” are held together by hydrogen bonds Nucleotides are held together by hydrogen bonds Remember base-pairing rules!!! A with T C with G
Structure of DNA’s Nucleotides Proposed by Watson and Crick in 1953
Genes are Found on Chromosomes (We’ll Discuss These a Little Later!)
Genes Made up of a series of DNA nucleotides –Only the 4 letters of DNA’s “alphabet” All of your genes make up a genome There are about 21, 000 genes About 3.2 billion base pair It is estimated that in one single human cell, if you uncoiled the double helix, it would be about 6 foot long!
Genes Can be several hundred to several thousand base-pair long Some genes carry the instructions to make proteins that give you traits, like eye color, hair color and freckles! Some genes are regulatory genes that may control other genes Some genes are promotor genes, sequences of DNA needed to turn genes “on” or “off”
On the Next Slide is an Example of Part of a Code for a Gene and is only one side of the “ladder”