DNA UNIT:Learning Outcomes

• It is expected that students will:• name the four bases in DNA and describe

the structure of DNA using the following terms: 

• nucleotide (sugar, phosphate, base) • complementary base pairing • double helix • hydrogen bonding 

DNA UNIT: Learning outcomes

• describe DNA replication with reference to three basic steps:

• "unzipping" • complementary base pairing • joining of adjacent nucleotides

FOUR DNA NUCLEOTIDES:

SUGAR

PHOSPHATEBASE

DNA is a polymer:

STRUCTURE OF DNA:

• Base pairs are bonded in a complementary fashion: A-T & C-G

• Bonds are hydrogen bonds

• Sides are made from phosphate and the sugar: deoxyribose

• Single sugar,phosphate and base unit are called nucleotides

DNA REPLICATION• DNA replicates

in a semi-conservative manner: each new helix contains one older (parent) strand and one new strand.

Enzymes help the process:DNA Polymerase,Helicase, and Ligase.

Replication occurs in three steps:

1.Unzipping of parent strand

2. Complementary pairing of new nucleotides

3. Hydrogen bonding between bases

•DNA being unzipped and copied:

DNA Unzipping:

1. The enzyme helicase unwinds the parent strand.

2. The enzyme DNA polymerase binds to each strand.

3. New nucleotides are matched in a complementary fashion A-T and C-G.

4. Ligase seals up the phosphate sugar bonds, hydrogen bonds form between nucleotides.

DNA REPLICATION VIDEO

DNAreplication.ram

Recombinant DNA

• DNA that has been recombined through genetic engineering is called Recombinant DNA.

• Often human DNA is combined with bacterial DNA to get the bacteria to make human proteins for medicine.

• This process of making Recom. DNA requires special enzymes: restriction enzymes (cut DNA); ligase glues DNA together and DNA polymerase copies DNA.

Please click here to launch the animation.