DNADeoxyribose Nucleic Acidsay: dee-ox-EAR-i-bose

new-CLAY-ik A-sid(Genetic Material)

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What is DNA?

• DNA is the genetic material of all living things on the planet.

• It is found in the nucleus of your cells.

• DNA holds the instructions to make all things in your body work properly.

Where is DNA found?• DNA is found

in the nucleus of all plant and animal cells.

• It is wound up in tight chromosomes.

What does DNA look like?• Shape of a double helix or a

twisted ladder.• The steps of the ladder are

called “base pairs”• The bases:

Adenine (A) say: A-da-nineGuanine (G) say: GWAY-nineThymine (T) say: THIGH-minCytosine (C) say: SITE-oh-seen

Base Pairs

• Each of the bases have a partner they pair off with.

• Adenine (A) always partners with Thymine (T)

• Cytosine (C) always partners with Guanine (G)

ACGTG

TGCAC

Complementary Strand

What is the complementary strand for the following sequence?

A A T C GG T C A GTT CA G A C

T T T T TA A A AG G G GCCCC

Mistakes Happen

• If the wrong bases pair off with one another it’s called a mutation.

• Most mutations are harmless.

• Some can be serious.

ACGTG

TGACC

DNA Replication

• This is when DNA makes a copy of itself.

• Usually when the cell divides, a copy of the instructions (DNA) is given to the new cell.

How does DNA control the cell?

• A cell’s DNA needs to change forms.• DNA cannot leave the nucleus to give

commands, so it needs to make a smaller copy of itself called RNA.

• RNA leaves the nucleus and is read by the ribosome. say: RYE-boh-sohm

• The ribosome then makes a protein.• The protein is DNA’s command.

Making RNA

DNA

RNA

DNA Unwinds

RNA is made

RNA has DNA’s instructions and can leave the nucleus

Changing DNA to RNA

• Transcription• To figure out the RNA sequence,

base pairs still need to match up.• A with T, C with G (for DNA)• In RNA the rules still apply, but

anywhere a T should be, it is replaced by Uracil (U). say: YUR-uh-sill

What is the RNA sequence?DNA RNA

T

A

T

C

G

T

G

A

A

U

A

G

C

A

C

U

What is a gene?

• A gene is a section of DNA that has instructions for a particular trait.

• Some genes are dominant (stronger)

• Some genes are recessive (weaker)

• Each organism inherits a gene from each parent.

• Each organism has 2 genes per trait.

Inheritance

• In the example, each flower has a trait for color: red or yellow.

• The offspring inherited a red gene from one parent and a yellow gene from the other parent.

• Red was the expressed color, so it is considered dominant.

Where did the color come from?

• There was a section of DNA which had the information for color.

• The RNA form is made and read into a protein that expresses the color.

DNA

RNA

Protein

Expressed color

References• http://www.pitt.edu/~hpsdept/images/double_helix.gif, Access Date: Dec. 12, 2006• http://www.bst.ntu.edu.tw/images/double%20helix%20c.jpg, Access Date: Dec. 12, 2006• http://www.chemsoc.org/ExemplarChem/entries/2003/imperial_Burgoine/origins.txt.html, Access Date:

Dec. 12, 2006• http://library.tedankara.k12.tr/chemistry/vol1/biochem/trans98.jpg, Access Date: Dec. 12, 2006• http://biology.unm.edu/ccouncil/Biology_124/Images/transcription.gif, Access Date: Dec. 13, 2006