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DNA Structure and Function
What is DNA and why is this molecule important?
A. DNA – Deoxyribonucleic Acid
B. Codes for our traits
Why is the structure of DNA important?
Structure must be able to be:
1.A “blueprint” for our traits
2.Easily copied
What does DNA look like?
What does DNA look like?
1953 – James Watson and Francis Crick discovered structure of DNA; later won Nobel Prize
What does DNA look like?
-“Twisted ladder” or “Spiral Staircase”
- Double helix
- 2 connected strands wrapped around each other
What is DNA made of?
A. Sugar “Deoxyribose”B. Phosphate
C. Base
Sugar + phosphate + base = 1 nucleotide
Four different nucleotides1. Deoxyribose2. Phosphate3. Base - Adenine
1. Deoxyribose2. Phosphate3. Base - Thymine
1. Deoxyribose2. Phosphate3. Base - Cytosine
1. Deoxyribose2. Phosphate3. Base - Guanine
DNA is shaped like a ladderRAILSRAILS
RUNGS
DNA is shaped like a ladder
Nucleotides are connected so:-Rails are alternating sugar - phosphate
-Bases are pointed to center
DNA is shaped like a ladder
DNA is made of:
-Two strands
-Strands connect at bases
Basepair rules
- Adenine always connects with Thymine
-Cytosine always connects with Guanine
Code of Life
- Order of bases spells out a code for your traits.
-Sequences of DNA which code for a trait are called “genes”.
-Change the order of the bases (mutation) and you may have a new trait.
Fun DNA Facts
-DNA is 1/10th width of human hair, but DNA in each cell is 6 feet long (over 3 billion nucleotides)!
-If all DNA from one person were connected end to end, it would stretch from the Earth to the Sun – 4 times!
Fun DNA Facts-Every person’s DNA sequence is unique (forensics, paternity tests).
-BUT . . . sequence is 99.8% IDENTICAL to any other person!
-Humans and Bananas – 50% identical
-Humans and Mice – 85% identical
Fun DNA Facts-Why is the DNA sequence of every living thing have almost the same DNA sequence?
-All are made of cells
-Cell division
-Making nutrients
Fun DNA Facts-Only 2% of our DNA codes for genes. Rest is . . .
“junk DNA” that may come from viruses!
Review Animations
• DNA structure review
• Base pair review
• DNA structure review #2
