DNA(Deoxyribonucleic Acid)

DNA Foldable Directions

• Make a shutter fold (lengthwise/hot dog)but overlap the left fold over the right.

• Fold the paper in half twice, make creases and cut the creases so you end up with 4 flaps per side

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DNA Foldable Directions• Label the left hand flaps A, T, C and G.• Label the right hand flaps T, A, G and C.• For each flap cut a

shape so they fit together like a puzzle– A: square (out)– T: square (in)– C: triangle (out)– G: triangle (in)

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It should look like this:

What is DNA?• Deoxyribonucleic Acid• GENES – • NUCLEOTIDES:• Double Helix

What is DNA?

• Important Scientists:– Rosalind Franklin:

• James Watson and Francis Crick:

What is DNA?DNA Nucleotide

P

Phosphate Group

Nitrogenous base (A, G, C, or T)CH2

O

C1C4

C3 C2

5

Sugar(deoxyribose)

“backbone”

“rungs” of DNA ladder

Nitrogenous Base Pairing•Bases held together by

•DNA had specific pairing between the nitrogen bases:

T A G C

Nitrogenous Base PairingChargaff’s Rule

• Their amounts in a given DNA molecule will be about the same and all 4 bases will equal to 100%

• If a DNA molecule contains 25% Adenine molecules how many Thymine molecules will there be? Guanine? Cytosine?

Nitrogenous Base PairingDNA Double Helix

P

P

P

O

O

O

1

23

4

5

5

3

3

5

P

P

PO

O

O

1

2 3

4

5

5

3

5

3

G C

T A

Nitrogenous Base PairingNitrogenous Bases

• PURINES1.

2.

• PYRIMIDINES3. Thymine (T)

4. Cytosine (C)

T or C

A or G

Nitrogenous Base PairingBASE-PAIRINGS

CG

H-bonds

T A

The Code of Life• The “code” of the chromosome is the SPECIFIC ORDER that bases occur.

• All living things contain DNA and reproduce– Kingdoms:

• Bacteria• Protists• Fungus• Plants• Animals

The Code of Life

Mushroom

Panda Bear Flower

E. coliVenus Fly Trap

Jellyfish Diatoms

Algae

Shark

Genetic Diversity…• Different arrangements

of NUCLEOTIDES in a nucleic acid (DNA) provides the key to DIVERSITY among living organisms.

Environmental factors that affect DNA

• Chemicals:– Addition of MgCl

causes fish to develop only 1 eye

• Drugs:– Causes deformities in

children

• Pollution– Asthma and

bronchitis

Environmental factors that affect DNA

• Temperature:

• Light:– Butterflies

exposed to red light have brighter colors

• Temp. Cont’d– Some reptiles change

sex based on temp.

AMAZING DNA FACTS…

• DNA from a single human cell extends in a single thread for almost 2 meters long!!!

• It contains information equal to some 600,000 printed pages of 500 words each!!!

(a library of about 1,000 books)

LET’S REVIEW DNA…

1. Summarize the relationship between genes & DNA.

2. Describe the overall structure of the DNA molecule.

3. What are the 4 kinds of bases?