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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
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
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
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