4. Effective communicators TODAY’S AGENDA: Warm Up (10) Structure of DNA (20) DNA Structure CYU (20) Tu Jan 8 DNA Structure CYU Today’ objectives: Students will be able to diagram the structure of DNA ESLRs Addressed: 1. + Citizenship 2. + relationships 3. Problem Solvers 4. Effective communicators

Describe the general structures and functions of DNA, RNA, and protein (5a) A DNA molecule is a large polymer made of two parallel chains of nucleotides twisted into a double helix In eukaryotes, DNA is organized into rods called chromosomes.

The details of the Structure of DNA – the parts DNA is a type of NUCLEIC ACID made up of smaller repeating subunits known as NUCLEOTIDE A nucleotide is made up of three smaller molecules, a SUGAR a PHOSPHATE and a NITROGEN BASE In DNA, there are four different kinds of nucleotides, each with a different NITROGEN BASE NITROGEN BASE PHOSPHATE SUGAR

The four different bases are ADENINE, GUANINE, CYTOSINE, & THYMINE. Structure of DNA The four different bases are ADENINE, GUANINE, CYTOSINE, & THYMINE. Two of these bases are PURINES and the other two are PYRIMADINES These classifications have to do with the size of each molecule

PURINES are made of two ring structures and include ADENINE & GUANINE Structure of DNA PYRIMIDINES are made of a single ring structures and include THYMINE & CYTOSINE PURINES are made of two ring structures and include ADENINE & GUANINE

Putting together the pieces – the double helix Untwisted the double helix can be thought of as a ladder… Sides of ladder: composed of Sugar and phosphate Rungs of ladder: composed of nitrogen bases P S-A --- T - S P P S-G --- C - S

Putting together the pieces – the double helix Things to notice: Base pairing rules: A-T G-C C-G T-A Why: A purine always pair with a pyrimidine P S-A --- T - S P P S-G --- C - S

Putting together the pieces – the double helix Things to notice: Strands are Complimentary: Nitrogen bases on each strand match up perfectly Strands are Antiparallel: One strand runs from 5 prime to 3 prime, while the other is 3’ to 5’ P S-A --- T - S P P S-G --- C - S

Base pairing rules practice What makes one person’s DNA different from another person’s? The order of these letters codes for amino acids. P S-C --- - S P P S- A --- - S S- T --- - S S- G --- - S

Another practice problem A certain strand of DNA has one strand with the following base pairs 5’ T-A-G-G-C-T 3’ What would its compliment be like?

Another practice problem A certain strand of DNA has one strand with the following base pairs 5’ G-G-C-A-C-A-T-A-G 3’ What would its compliment be like?