Transcript DNA and Cell Division - Student Note

DNA & CELL DIVISION
Structure 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
red blood cell
white blood cell
platelets
stomach cell
brain cell
Lifespan
120 days
1 day to 10 years
6 days
2 days
lifetime