dna structure and function. what is dna and why is this molecule important? a. dna –...

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