DNA & C ELL D IVISION Structure and Function of DNA Chromatin and Chromosome Role of Cell Division

S TRUCTURE OF DNA structure of DNA allows it to carry the genetic information for all different organisms DNA is a molecule arranged in a double helix with two backbones linked by bases order of the bases determines the genetic code

S TRUCTURE OF DNA

F UNCTION OF DNA gives the directions to the cell directs cell growth, cell death, responses to changes in the environment and message to other cells

C HROMATIN long strands of DNA found in the nucleus

C HROMOSOMES tightly coiled packages of DNA contain DNA and proteins found during cell division carry genes (small sections of DNA that give information about a specific trait or feature)

C HROMOSOMES different organisms have different numbers of chromosomes humans have 23 pairs or 46 chromosomes each kind of organism had a different number of chromosomes, a different set of genetic information, all composed of the same chemical, DNA OrganismNumber of Chromosomes dog78 mouse40 human46

F UNCTION OF C ELL D IVISION Healing and Tissue Repair cells need to be replaced as they are damaged or die prevents death of the organism Growth increase the number of cells an organism has as the number of cells in an organism increases, so does the size of the organism Reproduction of Organisms reproduction allows a species to continue to exist in future generations in unicellular organisms creates two new organisms used in reproduction of asexual organisms

C ELL D IVISION IN D IFFERENT T ISSUES every cell does not reproduce at the same rate or have the same lifespan some cells reproduce often and quickly, like red blood cells other cells, like liver and brain cells rarely divide Type of CellLifespan red blood cell120 days white blood cell1 day to 10 years platelets6 days stomach cell2 days brain celllifetime