Transcript Hormones for cell growth and division

HORMONES FOR CELL
GROWTH AND DIVISION
Science 9
DIFFERENCES FROM ONE ORGANISM TO
ANOTHER
 Cell growth and cell division are important for
understanding differences between organisms of the
same species
 Cells communicate with one another using chemical
messengers
 These messengers are called hormones
 Hormones are produced in cells in one part of the
body and can affect cell division and growth in
another part of the body
 Some hormones trigger cells to grow and divide
PLANT GROWTH HORMONES
Plants produce a variety of growth hormones
Auxins are plant hormones that cause cells to
grow longer
Cytokinins are plant hormones that stimulate
cell division
They are found in the roots but communicate
with all parts of the plant
ANIMAL GROWTH HORMONES
Growth hormone (GH) is produced in the
pituitary gland of humans
It is carried by blood to all areas of the body
It does not affect all parts of the body in the
same way
Low amounts of GH during childhood can
cause dwarfism and high amount can cause
gigantism
CELL DIVISION AND PATTERNS OF
GROWTH
Humans grow fastest during the nine months
before birth and the first three months after
Not all body parts grow at the same rate
AGING AND CELL DIVISION
 Very few of the cells you were born with are still
dividing
 Red blood cells live about 120 days
 Skin cells are replaced daily
 To stay alive, we rely on cell division
 There is a limit to how often a cell can divide
 Eventually, cells die and are not replaced
 Injuries are not repaired
 Accumulating damage and the function of organs are
compromised