DNA&

Replication Notes

DNA

A.k.a. Deoxyribonucleic AcidMolecule present in all living cells

Contains information that determines the traits that an organism inherits and needs to live

Rosalind Franklin

Took one of the first photos of DNA using X-Ray Diffraction

Watson & Crick

Two scientists who discovered the structure of DNA as a double helixWon a Nobel Prize for itMaurice Wilkins also won nobel prize for DNA structure

DNA Structure

DNA Structure

Double HelixTwisted ladder

Made up of nucleotidesNitrogenous base, phosphate, and sugar

DNA Structure

Sides of ladder = alternating phosphates and sugars

Rungs of ladder = nitrogenous bases

3D Model

DNA Picture

DNA Structure -Bases

There are 4 nitrogenous bases

Adenine (A)Thymine (T)Guanine (G)Cytosine (C)

Nitrogenous Bases

Certain bases match together

Guanine and Cytosine (C - G) pair together“Good Couples”

Adenine and Thymine (A - T) pair together“Always Together”

DNA Replication

DNA molecules are very long, nucleus of human cell has more than 1 meter of DNA.

DNA ReplicationEach side of the DNA strand has all of the information needed to reconstruct the other half of the strand through the process of base pairing.Due to this process (base pairing), the strands are said to be complementary.

DNA replication happens at hundreds of places along the strand- makes the process very fast!

Replication proceeds in both directions until each chromosome is completely copied.

Sites where separation and replication happen are called replication forks.

DNA Polymerase

Replication Fork

Nitrogen Bases

Original strandNew Strand

Replication Fork

Duplicating DNA

Replication- the copying process in which a cell duplicates its DNA, before it divides into 2 cells with complete sets of DNA molecules.

Step 1 --> Pull old DNA Apart

DNA molecule separates into two strands

DNA polymerase is the principle enzyme involved in DNA replication.It pulls apart the old DNA strand so that each side can be copied

Step 2 --> Base Pairing

Bases are added to each side following the rules of base pairing.

Each strand of the double helix DNA serves as a template, or model, for the new strand.

Step 3 =RESULT

Result is two DNA molecules identical to each other and the original molecule.

Each DNA molecule from replication has one original strand and one new strand.

Replication Example

Replication Example

Replication Example

Real Chromosome Pictures!

Real Chromosome Pictures!

DNA Replication Video

http://www.dnalc.org/resources/3d/DNAReplicationBasic_w_FX.html