Goal for Today: Identify the structure and function of DNA

DNA The letters stand for deoxyribonucleic acid

Scientists James Watson & Francis Crick discovered the structure of DNA

Structure of DNA Twisted ladder / double helix Made of components (monomers) called “nucleotides” A nucleotide includes a nitrogen base, a five carbon sugar & a phosphate group

Structure of DNA The sides (backbone) of the ladder are alternating sugar and phosphate molecules The “rungs” are made up of 2 nitrogen bases The bases are connected to the sugar

Nitrogen Bases There are 4 nitrogen bases Adenine (A) Guanine (G) Cytosine (C) Thymine (T)

Chargoff’s Rule Any species contains equal amounts of adenine(A) and thymine(T) and also equal amounts of guanine(G) and cytosine(C)…..SO…..

A only pairs with T C only pairs with G They are connected by hydrogen bonds in the middle of the molecule

Brainpop With quiz!

Chromosomes are made of long strands of DNA(each chromosome is a single DNA molecule) DNA makes up genes DNA controls the production of proteins Proteins determine traits

Different genes produce different proteins *the human genome has 3 billion bases and 20,000 genes

Proteins Three nitrogen bases ( or 3 letters) make up a codon (a.k.a. triplet) One codon makes up one amino acid Several ( 2-?) amino acids make up one protein Proteins code for traits

Instructions for Paper DNA Model Guanine – Green Cytosine – Blue Thymine – Orange Adenine – Red Phosphate – Purple Deoxyribose – Yellow Cut out the nucleotides and then paste them on the construction paper

Cell Reproduction For a living thing to grow, it has to make new cells to get bigger It will go thru several mitotic divisions

Thru each division, an exact copy of a cell will be made The DNA is constantly being copied in the process of…

Replication