TODAY’S AGENDA:Warm Up (10)

Structure of DNA (20)

DNA Structure CYU (20)

Tu Jan 8

•DNA Structure CYU

Today’ objectives:1.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

SUGARPHOSPHATE

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

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

PS-A --- T - S

P PS-G --- C - S

P PS-G --- C - S

P PS-A --- T - S

P

Putting together the pieces – the double helix

Things to notice: Base pairing rules:

A-TG-CC-GT-A

Why:A purine always pair with

a pyrimidine

PS-A --- T - S

P PS-G --- C - S

P PS-G --- C - S

P PS-A --- T - S

P

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’

PS-A --- T - S

P PS-G --- C - S

P PS-G --- C - S

P PS-A --- T - S

P

Base pairing rules practice

What makes one person’s DNA different from another person’s?

The order of these

letters codes for amino acids.

PS-C --- - S

P PS- A --- - S

P PS- T --- - S

P PS- G --- - S

P

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?