DNA

Genetic material is located in nucleus The genetic information is stored in Deoxyribonucleic acid, DNA Genetic information is copied from DNA and converted to protein

The Nucleus Most cells only have 1 nucleus. How ever a few cells have more than nuclei making them multinucleated. This only occurs in cells that have a large volume and there fore a large mass. One type of cell (Red Blood Cells) do not have a nucleus making them anucleated.

Nucleus The nucleus is bound by a membrane called the nuclear envelope. It’s a double layer membrane with fluid in between. At certain points the layers fuse and nuclear pores form. These pores are large and allow many molecules as well as mRNA to easily pass through.

Nucleus Inside of the nucleus there are the chromatin (pre-condensed Chromosomes) and a couple of nucleoli. The nucleoli are where ribosmomes are made.

Nucleus Chromatins are made up of DNA and histone proteins. Histone proteins are simply globular proteins that help DNA to keep it’s shape and be supported.

DNA ( Deoxyribo Nucleic Acid) DNA is two long chains of Nucleotides A Nucleotide consists of: A phosphate Group A five carbon sugar (deoxyribose) A Nitrogenous Base

DNA The sides of the DNA strand are the connection of the Phosphates to the Sugars. Each Phosphate is connected to deoxyribose by a covalent bond.

DNA There are four nitrogen bases that make up the “rungs” of the ladder Adenine Guanine Cytosine Thymine

Four bases... Each of the four bases has a specific shape. Purine bases Adenine and Guanine Two carbon rings Pyrimidine bases Thymine and Cytosine A single carbon ring A two carbon ring can only attach to a single carbon ring.

DNA Each base pair is held together by a hydrogen bond. Adenine only pairs with Thymine and Cytosine only pairs with Guanine. They are called complimentary base pairs.

DNA Molecules Two polynucleotide chains are joined Double helix, twisted in right handed way Full circle in every 10 bases

13 DNA Replication Preparing for mitosis or meiosis copyright cmassengale

14 Replication Facts DNA has to be copied before a cell dividesDNA has to be copied before a cell divides DNA is copied during the S or synthesis phase of interphaseDNA is copied during the S or synthesis phase of interphase New cells will need identical DNA strandsNew cells will need identical DNA strands copyright cmassengale

15 DNA Replication Enzyme Helicase unwinds and separates the 2 DNA strands by breaking the weak hydrogen bonds.Enzyme Helicase unwinds and separates the 2 DNA strands by breaking the weak hydrogen bonds. Two strands open forming Replication Forks (Y- shaped region)Two strands open forming Replication Forks (Y- shaped region) copyright cmassengale ReplicationFork Parental DNA Molecule 3’ 5’ 3’ 5’

16 DNA Replication An enzyme called DNA polymerase grabs new nucleotides found floating in the cell and adds the new complimentary nucleotides to the single DNA Strand.

DNA Replication As the new nucleotides are attached Covalent bonds form between the sugar of one nucleotide and the phosphate of the other nucleotide. copyright cmassengale17

DNA Replication In each new DNA strand one side of the double helix is the original molecule and the other side is the new strand. This is called Semi-Conservative replication. 18

Stages of Mitosis What are they????????