What is DNA?
DNA
Deoxyribose Nucleic Acid
say: dee-ox-EAR-i-bose
new-CLAY-ik A-sid
(Genetic Material)
• 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.
Ka Hana ‘Imi Na‘auao – A Science Careers Curriculum Resource Go to: www.cds.hawaii.edu/kahana
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-nine
 Guanine (G) say: GWAY-nine
 Thymine (T) say: THIGH-min
 Cytosine (C) say: SITE-oh-seen
Base Pairs
A
C
G
T
G
T
G
C
A
C
• 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)
Complementary Strand
What is the complementary strand for the following sequence?
A A T G T C A T
G C
T A C G
G A
C
T
C G
A T
C T
G
T A C A G T A
G C
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Mistakes Happen
• If the wrong bases
pair off with one
another it’s called a
mutation.
• Most mutations are
harmless.
• Some can be serious.
DNA Replication
• This is when DNA
makes a copy of itself.
A
C
G
T
G
• Usually when the cell
divides, a copy of the
instructions (DNA) is
given to the new cell.
T
G
A
C
C
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
DNA Unwinds
RNA
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
A
U
T
A
C
G
C
G
T
A
G
C
A
U
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What is a gene?
Inheritance
• 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.
• 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.
References
Where did the color come from?
DNA
RNA
Protein
• 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.
•
•
•
•
•
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
Expressed color
3