All about DNAStructure, Building Blocks,

and Replication

DNA Structure-Review• REVIEW!

• Which type of organic molecule is DNA?• NUCLEIC ACID!!• DNA stands for

DEOXYRIBONUCLEIC ACID• Building Blocks of Nucleic Acids =

• NUCLEOTIDES• Or subunits

DNA Structure- Nucleotides• Each nucleotide is made of 3 parts:

1. Sugar (Deoxyribose)

2. Phosphate

3. 1 of 4 Nitrogenous Bases:• A = adenine • T = thymine• C = cytosine• G = guanine

4. So which part of a nucleotide changes??• THE NITROGEN BASE!!!!!

5. So how many different nucleotides are there for DNA?• Four (4)

Label a nucleotide!

DNA Shape and Form• DNA IS DOUBLE STRANDED• STRANDS TWIST TO FORM DOUBLE- HELIX• NITROGEN BASES BIND TOGETHER TO

MAKE TWO STRANDS• A always binds with T• C always binds with G****THIS IS CALLED THE BASE-PAIR RULE!

****• Now, on your notesheet, fill in the

COMPLEMENTARY strand using the BASE-PAIR rule!

Answer to Notesheet Practice

DNA Structure

• Let’s Practice Again!

• One strand of DNA has the sequence you see. What is the complimentary strand’s sequence???

G

G

T

A

C

G

C

C

T

-----C

-----C

-----A

-----T

-----G

-----C

-----G

-----G

-----A

Replication: The Video Clip

http://www.youtube.com/watch?v=z685FFqmrpo

DNA Replication (Copying)CLICK HERE FOR DEMO

• When does DNA need to be copied????• BEFORE any CELL DIVISION!

• DNA acts as a PATTERN or TEMPLATE to make copies of itself!

• Steps of DNA Replication:• First, two (2) strands are “unzipped” by enzymes• Second, other enzymes bring new subunits

(nucleotides) to these separated strands• Each strand acts as a template to build a new DNA

molecule• Third, you end up with 2 NEW identical double

helicesCLICK HERE FOR DEMO #2

DNA Replication Diagram

Free Floating Nucleotides

Parent Strands

New complimentary strands

Replication Practice- Step 1 “Unzip”

G

G

T

A

C

G

C

C

T

-----C

-----C

-----A

-----T

-----G

-----C

-----G

-----G

-----A

Enzymes UNZIP

G

G

T

A

C

G

C

C

T

C

C

A

T

G

C

G

G

A

Replication Practice- Step 2 Add Subunits using Base-Pair Rule

G

G

T

A

C

G

C

C

T

C

C

A

T

G

C

G

G

A

----C

----C

----A

----T

----G

----C

----G

----G

----A

G----

G----

T----

A----

C----

G----

C----

C----

T----

THE DNA RAP!!!!

• http://www.youtube.com/watch?v=d1UPf7lXeO8