1. The Structure of DNA

2. What is DNA? DNA - deoxyribonucleic acid
Holds all our cell’s information
Code for proteins that are essential for life

3. Where is it located? DNA is found in the nucleus
DNA is packaged into units known as chromosomes
Short sections of DNA are referred to as genes
Genes carry the instructions to make specific proteins
Proteins are what make up the characteristics of an organism.

4. Human Genome All of an organisms DNA is referred to as its genome
The human genome contains 23 pairs of chromosomes in almost every cell of the body
One pair of chromosomes determines the sex of an individual.
In males, the 23rd chromosome is the XY pair and in females, it is the XX pair.

5. Structure of DNA
DNA has double strands and consists of smaller molecules called nucleotides.
DNA looks like a spiral shape that scientists refer to as a double helix (looks like a twisted ladder).
A nucleotide is composed of three parts:
Deoxyribose Sugar Molecule
Phosphate Molecule
Nitrogenous Base

6. Nitrogenous Bases 1. Adenine 2. Guanine 3. Cytosine 4. Thymine
Each Nucleotide has one of the four different nitrogenous bases:
1. Adenine
2. Guanine
3. Cytosine
4. Thymine
Pairs of bases form a rung of the DNA ladder

7. Base Pairing Rule Adenine always pairs with Thymine (A-T)
Cytosine always pairs with Guanine (C-G)
Between each pair is a hydrogen bond that holds the pairs together.

9. DNA replication
One thing that makes DNA so amazing, is its ability to copy itself.
Before a cell divides, each DNA molecule makes a copy of itself.
DNA splits down the middle like a zipper and new bases join up with bases on each of the open ends.
The result is two new identical DNA strands. Each new DNA molecule has one new strand and one old strand.

10. DNA unzipping Nucleotides pair up according to the base pairing rules
Example: The “Thymine” will pair up with a new “Adenine” molecule
The two new DNA molecules are identical and each has an old and a new strand.

11. Two new identical DNA strands

12. Genetic Code
The bases in DNA molecules are like the numbers and letter in a Code.
DNA has a four character code.
The four characters are the Nitrogenous bases: A, T, G, C
The bases combine to form a three letter word called a ”CODON”, example ATG, CTA, TGA, etc…
Thus, when a DNA is replicated it has to follow the same three combinations throughout the DNA strand.

13. Genetic Code
Each 3 letter word (CODON) codes for the production of one of the 20 amino acids
Amino Acids are the Building Blocks of Protein.
Different combinations of amino acids results in the formation of different proteins.
The proteins determine the characteristics of an organism.

14. Protein synthesis
There are several steps involved in making a protein from DNA
Transcription
is when RNA is made from DNA. The information is copied from one molecule to the other. 
Translation
converts a mRNA (messenger rna) sequence into a string of amino acids that form a protein. 

15. Different Types of Proteins
Function
Hemoglobin
Carries oxygen in red blood cells
Insulin
Controls the level of sugar in the blood
Keratin
Makes up hair and nails
Enzymes
Controls chemical reactions in the body
Antibodies
Bind to foreign substances to protect the body against the foreign substance
Growth Hormone
Stimulates growth (cell division)

16. Transcription 1) DNA Unzips.
2) One strand of DNA is used to make another molecule called messenger ribonucleic acid (mRNA). The mRNA copies info from DNA using base pairings.
3) mRNA carries the genetic code from the nucleus to the ribosome in the cytoplasm

17. How is RNA different from DNA?
Single stranded, not double stranded
Sugar - Instead of deoxyribose, it has ribose
Base Pair - Instead of Thymine, it uses Uracil (Now A pairs with U)

18. Translation
1)  rRNA (ribosomal RNA) attaches to mRNA and starts reading the codons (3 nucleotides at a time) to produce one amino acid.
2) tRNA (transfer RNA) carries the produced amino acids and attaches them to the correct part of the growing amino acid chain. The chain is also known as a polypeptide.
3) When protein production is complete (the string of amino acids), the ribosome releases the protein chain (polypetide).

19. Protein Synthesis Review

20. Video Video on DNA Replication Video on Transcription and Translation.
Video on Transcription and Translation.

21. Assignment
Science Probe 9 – Page 47, Questions 1 – 16 exclude #9, #10, and #11.