DNA & CELL DIVISIONStructure and Function of DNA

Chromatin and Chromosome

Role of Cell Division

STRUCTURE 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

STRUCTURE OF DNA

FUNCTION OF DNA

gives the directions to the cell directs cell growth, cell death, responses to

changes in the environment and message to other cells

CHROMATIN

long strands of DNA found in the nucleus

CHROMOSOMES

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)

CHROMOSOMES

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

Organism Number of Chromosomes

dog 78

mouse 40

human 46

FUNCTION OF CELL DIVISION

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

CELL DIVISION IN DIFFERENT TISSUES

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 Cell Lifespan

red blood cell 120 days

white blood cell 1 day to 10 years

platelets 6 days

stomach cell 2 days

brain cell lifetime