Dioxyribose Nucleic Acid Chapter 8 – Lesson 2

What is DNA? DNA is made of nucleic acids. DNA contains information that an organism needs to grow and function. DNA makes you who you are. DNA stands for dioxyribose nucleic acid.

Discoverers of DNA James Watson and Francis Crick made an accurate model of DNA in 1953. Rosalind Franklin discovered even more about DNA, but she died before she could become famous .

DNA Structure The structure of DNA is similar to a twisted ladder. Sugar Phosphate The structure of DNA is similar to a twisted ladder. The sides of the ladder are made up of sugar-phosphate molecules. The rungs of the ladder are made up of nitrogen bases. Nitrogen Bases

Nitrogen Bases T A C G Adenine – (A) Guanine – (G) Thymine – (T) Cytosine – (C) A always pairs with T G always pairs with C T A C G

A = Adenine T = Thymine G = Guanine C = Cytosine NITROGENOUS BASES A = Adenine T = Thymine G = Guanine C = Cytosine

Genes Genes are sections of DNA on a chromosome. Everyone has different patterns of A, T, C, G. These different patters allow for different genes. Or, a different genetic code. Gene 2 Gene 3

Examples A T G C A T G C A - T T - A G - C C - G A G C A - T G - C different genes = different traits!

Carl Sagan - DNA - The Language of Life Genes Did you know: - The majority of our DNA is considered “junk” - 98% of our genetic code is the same as apes - 50% of our genetic code is the same as a pig Carl Sagan - DNA - The Language of Life

DNA Replication Before a cell divides (MITOSIS!), its DNA duplicates itself by unwinding and separating its sides, then forming new sides.

RNA Think of DNA as a zipper. When it’s zipped up, you have plain DNA. When it’s unzipped, you have something known as RNA!

RNA C G G C T A In RNA, T (thymine) get replaced with U (uracil) T U A

RNA RNA carries the amino acid codes for making proteins. AMINO ACIDS  What are amino acids? The building blocks of proteins. Think legos… AMINO ACIDS PROTEINS

Amino Acids All amino acids have their own “three” digit code using nitrogen bases. Amino acids make proteins in your body. There are only 20 amino acids. U A G C U A G C U

MRNA RNA Video nucleus to… ribosome C U A G C U U A G Other Link MRNA Messenger RNA (mRNA) carries the amino acid code from the nucleus to the ribosomes in the cytoplasm. When the ribosomes get the code, they can start making proteins. nucleus to… ribosome C U A G C U RNA Video U A G A U C G A U C G A

Mutations Mutations are any permanent change in the DNA sequence of a cell’s gene or chromosome. (DNA is deleted, inverted or replaced) Can be caused by outside factors like x-rays, sunlight, and some chemicals. A change in a gene or chromosome can change the traits of an organism.

Mutations Mutations can be bad, but they are also responsible for diversity! Example: Giraffe Necks