DNA DNA is the Secret of Life!

Student goals The student will explain the functions of DNA identify the components of a DNA molecule summarize the events of DNA replication

DNA Functions o 1. Storage of genetic information o 2. Self-duplication & inheritance o 3. Expression of the genetic message. o DNA’s major function is to code for proteins.  Information is encoded in the order of the nitrogenous bases.

Discovering the structure of DNA Structure was discovered in 1953 by James Watson and Francis Crick

DNA: Structure and Function

DNA Structure One 'unit' in the structure of DNA is: A Phosphate (molecule made with phosphorus) A Sugar (the sugar's name is ribose) A Nitrogen base A- Adenine T-Thymine G-Guanine C-Cytosine

Types of Nucleotides A nitrogenous base is a carbon ring structure that contains one or more atoms of nitrogen. Adenine (A)Guanine (G)Cytosine (C )Thymine (T)

The Uprights of the DNA – Phosphate group – Sugar (deoxyribose) The Rungs of the DNA – Nitrogen Bases (A,G,T,C) Complimentary BasePairing: – A pairs with T – G pairs with C DNA is held together by: Sides - Strong Covalent Bonds Rungs – Weak Hydrogen Bonds DNA Structure

The middle of the DNA structure is the Nitrogen base of the nucleotide BONDED to the Nitrogen base of the nucleotide on the other side. A bond with T C bonds with G This is called complimentary "base pairing" Important concept

Adenine + Thymine Double H+ Bond Guanine + Cytosine Triple H+ Bonds Complementary Base Pairing

Discovering the structure of DNA Rosalind Franklin’s DNA image “Chargoff’s rule” A = T & C = G

TripletC odon Amino Acid A TripletC odon Amino Acid B TripletC odon Amino Acid C TripletC odon Amino Acid D TripletC odon Amino Acid E Makes a PROTEIN HOW IT WORKS DNA CODES FOR PROTEINS TO BE MADE

DNA codes for proteins Every 3 nucleotides makes a codon. Each codon is the code for an amino acid. A chain of amino acids is a protein. Your body runs on proteins!

An Analogy for better perspective… A Nucleotide (1 sugar, posphate & base) = 1 letter “t” 3 nucleotides = a codon = 1 word the A gene is a long string of codons = 1 paragraph DNA is a long string of genes = 1 chapter A chromosome is a VERY long string of DNA wrapped and bundled with proteins = 1 Book A genome is all the chromosomes in an organisme = 1 Entire Library

Quiz Yourself 1. Which one is NOT a function of DNA A. Stores Genetic information B. Codes for Proteins C. Is the energy of the cell D. Duplicates it's self. C. DNA is not the energy of the cell.

C, A, T and G are A. Sugars B. Nitrogen Bases C. Phosphates D. Proteins B. Nitrogen Bases

How many nucleotides in a codon? a. 1 b. 3 c. 6 d. Nucleotides don't make up a codon. B. 3

What is the shape of a DNA molecule? A. Rectangle B. Sphere C. Flat Chain D. Double Helix

What is true about complimentary base pairs? A. A bonds with T B. G bonds with A C. C bonds with T D. C bonds with G A & D

If a strand of DNA read AATGCC What would the complementary strand read? A. CCGATT B.TTAGAT C.TTACGG D.CCATGG B.TTAGAT