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DNADNA DNA stands for deoxyribose nucleic

acid Present in the nucleus of all cells in all

living organisms DNA controls all the chemical changes

within the body which take place in individual cells

DNA controls the kind of cell that is formed, (muscle, blood, nerve etc)

DNA also controls what kind of organism is produced (dog, cat, human, pine tree)

What is DNA? What is DNA?

A large molecule made of units A large molecule made of units called called nucleotidesnucleotides

Each nucleotide is made of:Each nucleotide is made of: A A sugar sugar (deoxyribose)(deoxyribose) A A phosphatephosphate A A nitrogen basenitrogen base

One NucleotideOne Nucleotide

Each nucleotide has Each nucleotide has one of four bases one of four bases Adenine (A)Adenine (A) Thymine (T)Thymine (T) Cytosine (C)Cytosine (C) Guanine (G)Guanine (G)

All nucleotides have All nucleotides have a phosphate and a a phosphate and a sugar but the bases sugar but the bases can changecan change

The Nitrogen BasesThe Nitrogen Bases

Adenine and Thymine bases are Adenine and Thymine bases are always paired together (see how the always paired together (see how the ends fit like a puzzle)ends fit like a puzzle)

Adenine (A)

Thymine (T)

The Nitrogen BasesThe Nitrogen Bases

Cytosine and Guanine bases are Cytosine and Guanine bases are always paired together (see how the always paired together (see how the ends fit like a puzzle)ends fit like a puzzle)Cytosine (C)

Guanine (G)

A DNA MoleculeA DNA Molecule

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

A DNA Molecule A DNA Molecule

DNA consists of a coiled double strand of nucleotides (called a double helix)

Sugar phosphate chains are on the outside and the nitrogen bases are on the inside joined together by chemical bonds

Get DNA coloring sheet and color Get DNA coloring sheet and color code itcode it

DNA ReplicationDNA Replication

Before a cell divides, the DNA strands unwind and separate

Each strand makes a new strand of DNA by adding the appropriate nucleotides that match the ones in the strand (makes it’s other puzzle piece)

DNA ReplicationDNA Replication

So that when the cell divides, each nucleus contains identical DNA

And this process is called replication

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The strands The strands separateseparate

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Each strand builds up its partner by adding the appropriate nucleotides

Genetic CodesGenetic Codes

The special programming in DNA are The special programming in DNA are actually codes.actually codes.

Each code in DNA is made up of 3 Each code in DNA is made up of 3 consecutive bases (3 in a row) called a consecutive bases (3 in a row) called a codon.codon.

Each Each codoncodon is in charge of making a is in charge of making a particular amino acid and a group of particular amino acid and a group of amino acids is called a amino acids is called a proteinprotein..

Genetic CodeGenetic Code

• There are 20 different amino acids that can be made

• The different amino acids and the order in which they are joined up determines the sort of protein being produced

• We know that proteins make up most of the structure of cells and tissues

Amino Acids and Amino Acids and ProteinsProteins

The The sequencesequence of codons are of codons are important to form a protein with a important to form a protein with a specific structure and functionspecific structure and function

The sequence is also written as:The sequence is also written as:

CGA - CAA - CCA - CCA - GCT - GGG - GAG - CCA -

Ala Val Gly Gly Arg Pro Leu Gly

Ala Val Gly Gly Arg Pro Leu Gly

DNA and GenesDNA and Genes

Each sequence of codons that form a Each sequence of codons that form a certain protein is the “gene” for that certain protein is the “gene” for that protein.protein.

Ex. Lets say this is the sequence for Ex. Lets say this is the sequence for of codons to form Protein A. It would of codons to form Protein A. It would be called Gene A.be called Gene A.

CGA - CAA - CCA - CCA - GCT - GGG - GAG - CCA -

Ala Val Gly Gly Arg Pro Leu Gly

Amino Amino Acids and Acids and

their their CodonsCodons