Extra Credit due TOMORROW! Happy Thursday! Please do the following: pick up handouts have out your notebook Extra Credit due TOMORROW! https://www.youtube.com/watch?v=_POdWsii7AI

DNA (deoxyribonucleic acid)

DNA’s Role Revealed In 1952, Alfred Hershey and Martha Chase, proved that the DNA of a virus is injected into the bacterial cells. That then causes the bacterial cells to produce more viral DNA and proteins. Radioactive 32P was injected into bacteria!

Prokaryotes vs. Eukaryotes EVERY cell contains genetic material in the form of DNA. In prokaryotic cells, the DNA is contained within a singular, circular chromosome and exposed to the rest of the cell.

Prokaryotes vs. Eukaryotes In eukaryotes, the nucleus contains the genetic material of the cell, also in the form of DNA. While only eukaryotes keep their DNA in a nucleus, it is important to understand that every cell uses DNA. Nucleus

DNA stands for deoxyribonucleic acid. A nucleic acid is a long repeating chain of nucleotides.

Every nucleotide has 3 basic parts: 1. The phosphate group 2. A sugar named deoxyribose 3. One of the 4 nitrogen bases

A T G C The 4 nitrogen bases in DNA are: Adenine Thymine Guanine Cytosine 8

Why do you think they are called the nitrogen bases? Quick Question Why do you think they are called the nitrogen bases? Because they all contain the element nitrogen! 9

double-stranded molecule of DNA. DNA is a very long polymer! As you can see in the diagrams, two chains of nucleic acids join together to form a double-stranded molecule of DNA. DNA is a very long polymer!

These two strands spiral around one another to create a shape that scientists call a double helix.

DNA Double Helix DNA’s two strands run antiparallel 3’-5’ & 5’-3’ We will take apart the DNA molecule to see how it is put together. First, we will look at one strand.

The outside of the DNA is called the sugar-phosphate backbone The outside of the DNA is called the sugar-phosphate backbone. This gives the DNA its shape and structure. 13

The nitrogen bases are on the inside of the double helix The nitrogen bases are on the inside of the double helix. This is how the information is coded into the DNA. 14

The information in DNA is a blueprint for every cell The information in DNA is a blueprint for every cell. The information is found in the sequence of nitrogen bases. This information is used to make proteins according to a universal genetic code.

ALL living things use the SAME genetic code! EVERY cell uses the information in DNA to make proteins in the same way. The DNA is translated using the genetic code where a specific sequence of nitrogen bases codes for an amino acid in the protein being made. ALL living things use the SAME genetic code! 16

The Genetic Code is common to all… From the fish in the sea, To the mold on the wall! Photo by Brocken Inaglory Photo by Infrogmation

Chromosomes DNA is not found in many little pieces. Instead, large amounts of DNA are packaged together into chromosomes. Human cells hold 46 chromosomes that contain thousands of genes. Human Chromosomes The complete set of chromosomes with all of an organism’s DNA is known as its genome.

Chromosomes Chromosomes come in pairs, and there are hundreds, sometimes thousands, of genes in one chromosome. There are 46 chromosomes in each human cell. Except for gametes (egg and sperm) which have 23.

Genes are the sections of DNA that are located in a chromosome and that codes for a specific hereditary trait (protein).

A pairs with T G pairs with C DNA Base Pairing The nitrogen bases between the two strands of DNA pair together in a very specific way. A pairs with T G pairs with C

Watch the short video over Chargaff’s Rule.

A pairs with T G pairs with C Compare the letters in each pair. How can you remember that these go together? A pairs with T G pairs with C The letters made with straight lines go together. OR The letters made with curved lines go together.

Let’s Practice… What is the complimentary strand according to the base pairing rules? ATCCATTGGACGA

Two Kinds of Bases in DNA Pyrimidines are single ring bases; thymine and cytosine Purines are double ring bases; adenine and guanine The complimentary bases are held together by weak hydrogen bonds. T A G C