DNA Structure

OBJECTIVES

• Describe 3 parts of a NUCLEOTIDE

• Describe a DNA molecule

• Demonstrate COMPLIMENTARY base pairing

DNA is Genetic Material

• DNA stands for: DEOXYRIBONUCLEIC ACID

– Controls protein production in cells

– Made up of many genes which control traits

Why DNA is Important

• Passes genetic information from generation to generation

• Traits are controlled by DNA

• DNA replicates with little error

• Can’t live with out DNA because it part of everything in the body

DNA structure

• DNA is a double Helix • Meaning DNA has two

strands. It looks like a twisted ladder

• DNA is polymer made up of units called NUCLEOTIDES

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DNA StructurePO4

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A molecule of DNA is formed by millions monomers called nucleotides joined together in a long chain

Nucleotide Structure3 important parts:

1. Phosphate group

2. Sugar (Deoxyribose)

3. Nitrogenous base (G,C,A,T)

Phosphate &

sugar m

ake up

the “back

bone”.

4 Nitrogenous Bases

ADENINE (A)

THYMINE (T)

CYTOSINE (C)

GUANINE (G)

2 PURINES

The PURINES form hydrogen bonds with the PYRIMIDINES

PYRIMIDINES

Base Pairing

ADENINE always pairs with THYMINE

CYTOSINE always pairs with GUANINE

Notice the number of hydrogen bonds formed

DNA structure

Each strand is COMPLEMENTARY to the other

Complementary Strands

• If we know the DNA sequence of one strand, we can predict the DNA sequence of it’s complement

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C C GG A AT T

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C

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CPO4

A

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A

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T

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T

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G

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G

DNA Structure• DNA strands are

ANTI-PARALLEL– Phosphates run in

different directions

What to do next

• Complete worksheet in class

• When done call me over so I can stamp your sheet

• Homework: BRING YOUR BOOK TO CLASS!!

Replication

• http://highered.mcgraw-hill.com/sites/0072437316/student_view0/chapter14/animations.html#