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Let’s Review!

• What is a macromolecule?

• What are the four kinds of organic molecules?

• What are nucleic acids made of?

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- A large ___________ molecule (made of carbon!)

- Carbohydrates, lipids, proteins and _______________

- Phosphate group, _____________nitrogenous base

___________are the chemical link between generations dating back to the beginning of life on earth.

 

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• A nucleic acid is a complex macromolecule that stores information in cells in the form of a ________.

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• Nucleic acids are made of long chains of _______________.

 • ____________are made of three

components:

1. sugar

2. phosphate group

3. nitrogen base5

• Examples of nucleic acids are :

1. _____

2. RNA

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DNA = deoxyribonucleic acid

 

its components are:

1. deoxyribose (_____)

2. phosphate group

3. nitrogen base

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The Components and Structure of DNA

There are four kinds of bases in in DNA:

• adenine• guanine • ________• thymine

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• Rosalin Franklin, Maurice Wilkins,• James ______ and Francis _____

proposed the structure of DNA:

Chargaff proposed

Adenine (A) – Thymine (T)

Guanine (G) – Cytosine (C)

A and G are purines

C and T are pyrimidines 9

Watson & CrickDiscovered the structure of DNA

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 • Watson and Crick

also said the paired nitrogen bases formed ______long strands of nucleotides that compliment each other.

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• Nitrogen Bases are connected

between sugars and phosphates• They declared, “This structure is

a “__________________”.

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The Components and Structure of DNA

DNA Double Helix

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• DNA forms _________________, units of genetic information which pass from parent to offspring.

                        DNA is wound into structures called chromosomes during cell division (prophase)

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What are chromosomes???

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Nucleotides ___________DNA DNA winds into ChromatinChromatin condenses into ChromosomesChromosomes _________ GenesGenes are sections of DNADNA is made of nucleotides

Chromosomes contain Instructions for making YOU!!!

• If you unraveled all your chromosomes from all of your cells and laid out the DNA end to end, the strands would stretch from the Earth to the Moon about _______________.

                

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• RNA has a different sugar than DNA• RNA = ribonucleic acid

• It’s components are :

1. _________ (sugar)

2. phosphate group

3. nitrogen base

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• It also has different bases than DNA

adenine --- _________

cytosine --- guanine

 • RNA is also single stranded, not double

stranded like DNA.

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DNA RNA

- _________stranded - Single stranded

- Sugar = deoxyribose

- Sugar = ribose

- Adenine pairs with Thymine

- Adenine pairs with __________

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I. Why Must DNA Replicate? 

• Every time a cell divides, it must first make a copy of it’s ___________.

• Therefore, each cell can have a complete setof chromosomes.

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What are chromosomes???

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Nucleotides make up DNA DNA winds into ChromatinChromatin condenses into ChromosomesChromosomes contain GenesGenes are sections of DNADNA is made of nucleotides

Chromosomes contain Instructions for making YOU!!!

• Without replication, species could not survive and individuals could not successfully grow and _____________.

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II. How DNA Replicates

• DNA is a molecule composed of TWO strands, each consisting of a sequence of ___________.

• The order of the nitrogen bases on one strand mandates the sequence of bases on the ______________ strand. 24

If you know the bases on one strand, you can predict which bases will occur on the complementary strand.

A ----- G -----T -----C -----C -----C -----T -----

During Replication each strand serves as a template to create a new strand.

This is as easy as break dancing!

TCAGGGA

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III. Steps In Replication

1) __________ break down the hydrogen bonds between the two DNA strands, unzipping the molecule

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2) As the DNA unzips, free nucleotides (from surroundings in the nucleus) bond to the single strands by ________________(A-T, G-C)

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3) Another Enzyme bonds the new nucleotides into a chain

** The result of this process is the formation of TWO DNA molecules, each ____________to the original molecule.Replication! Rah,Rah, Rah!

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DNA Replication

Nitrogen Bases

Replication Fork

DNA Polymerase

Replication Fork

Original strandNew Strand

Growth

Growth

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1. What are the two types of nucleic acids?2. What are the three components of a

nucleotide?3. What are the similarities between DNA and

RNA? What are the differences?4. Describe the process of DNA replication.5. Why does a DNA molecule undergo

replication?

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