6. 6
Why is DNADNA so important?
• Found in all organisms
(connects all living
things to one another)
• Medical research –
treatments and cures
• Agriculture, GMO
10. 10
One Strand (side) of DNAOne Strand (side) of DNA
• The backbone of the
molecule is alternating
– deoxyribose sugar
– Phosphates
• Bases attached to
sugars
phosphate
Deoxyribose
sugar
bases
11. 11
Four BasesFour Bases
• Adenine A
• Thymine T
•Cytosine C
• Guanine G
DNA has four different bases:
15. Knowledge CheckKnowledge Check
1. What are the 3 components that make up
DNA? (6 points)
2. Make a simple sketch of a DNA molecule. Use
different shapes to represent the 3 different
components and label one of each on your
sketch. (4 points)
15
17. How do you think DNA is replicated?How do you think DNA is replicated?
17
Considerations:
• Two identical copies of the DNA molecules come
from one original DNA molecule.
• Special enzymes are involved in DNA replication. (An
enzyme is a type of protein that can move, break
apart, or attach different molecules to one other.)
• The DNA molecule can be broken, torn, or split apart.
18. 18
•The DNA molecule unravels from
the histone proteins around which it
is spooled.
Step 1Step 1
19. 19
•A special enzyme called Helicase
“unzips” the DNA molecule,
breaking it down the middle.
Step 2Step 2
20. 20
•Another enzyme called DNA Polymerase
attaches new complimentary nucleotides
to each strand, completing two new DNA
strands.
Step 3Step 3
All life on earth uses a chemical called DNA to carry its genetic code or blueprint.
If you unravel all the DNA in the chromosomes of one of your cells, it would stretch out 2 meters. If you did this to the DNA in all your cells, it would stretch from here to sun and back more than 200 hundred times!
Why is DNA called the blueprint of life?
About better food crops, this area is controversial. There is a Dr. Charles Arntzen who is working on bioengineering foods with vaccines in them. People in poor countries could be immunized against diseases just by eating a banana, for instance.
{Show students a model of the double helix. Explain what a spiral is and a helix is.}
{Point to the 3-D mode, if you have one, to show the parts as you discuss them.}
These four bases are abbreviated by using their respective first letters.
{Point to the 3-D model to show the parts as you discuss them.}