DNA

What is DNA? Contains all genetic information of the entire organism Located in the nucleus of all cells (with a few exceptions!) mature red blood cells have no nucleus sex cells have half the amount of genetic information (haploid) A “full set” in humans is 46 chromosomes Made up of 23 pairs (diploid)

But not in all animals! Organism # of Chromosome Pairs Human 23 Drosophila (fruit fly) 4 E.coli (bacteria) Mosquito 3 Fly Frog 18 Cat 19 Chimpanzee 24 Horse 32 Dog 39 Onion 8 Peanut 12

DNA spends most of its time in a long string called chromatin During cell division, chromatin coils up tightly to form chromosomes

the section of DNA that codes for a protein is called a gene

DNA -> RNA -> Protein (made of amino acid)

DNA Structure DNA is made of nucleotides composed of 3 parts DNA: 5 carbon sugar: deoxyribose one nitrogenous base (4 possible options!) phosphate group DNA: Deoxyribo- Nucleic acid

There are two types of nitrogenous bases: 1. Purines -Adenine (A) and Guanine (G) -2 fused rings 2. Pyrimidines -Cytosine (C) and Thymine (T) -only one ring Adenine ALWAYS bonds with thymine Guanine ALWAYS bonds with cytosine -this is called complimentary base pairing

Computer information is stored as zeros and ones (binary) When we write information we use 26 letters (plus some extra numbers and symbols) Words can be short Computer information is stored as zeros and ones (binary) This takes a lot of zeros and ones to give useful information (very long “words”) E.g. the letter a is 0110001 How big is the human genome? Only uses 4 letters (A, C, G, and T)

How long do you think the human genome is? (in bases) The human genome has approx. 3 billion base pairs That’s 3,000,000,000 bases! Printing this out would take roughly 150,000 telephone book pages

DNA looks like a twisted ladder This arrangement is called a double helix

Alternating sugar and phosphates make up the backbone (the “rails” of the ladder) Bases make up the “rungs” and are held together by weak hydrogen bonds