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.

DNA Structure Summary Video – click here

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