Chapter 10 Cell Growth

							Chapter 10 Cell Growth

Limits to Cell Growth

" DNA "Overload"
" Exchanging Materials

Cells are limited in size by their SURFACE AREA and VOLUME ratio

CELL DIVISION - Process where a cell splits into two identical daughter cells

" Mitosis - division of the nucleus
" Cytokinesis - division of the cytoplasm

CHROMOSOMES

" Made of DNA
" Found in Nucleus
" Number depends on organism


CELL CYCLE - events cells go through as they grow and divide




Mitosis
Interphase

(technically not part of mitosis, but it is included in
the cell cycle)

Cell is in a resting phase, performing cell functions

DNA replicates (copies)

Organelles double in number, to prepare for division
Prophase

Spindle forms

Centrioles move to opposite poles

Chromosomes become visible



Metaphase

Chromosomes line up along the equator




Anaphase

Centromeres divide

Chromatids separate and move to opposite poles
                            Telophase

                            Nuclear membrane forms around each group of
                            chromosomes

                            Chromosomes unwind

                            Cytokinesis begins




Cytokinesis
The process by which the cytoplasm divides and one cell becomes two individual
cells. The process is different in plants and animals

Animals- cells pinches inward.

Plants - a new cell wall forms between the two new cells




Regulating the Cell Cycle
" Cells divide at different rates-
Nerve
& muscle cells usually stop dividing once developed

Skin & bone cells grow & divide rapidly throughout life

" Controls on Cell Division
       -Contact with other cells
" Cell cycle regulators
o Cyclin
o Internal regulators
o External regulators

" Cancer = uncontrolled cell growth
o Takes over the cell cycle
o Causes…environmental, genetic, viruses


STEM CELLS

" Unspecialized cells that have the potential to differentiate (to become any type
of cell)
" Found…
o Human embryos
o Some adult cells
o Cord blood

" Uses…
Repair injuries (brain & spinal cord)
Cure some diseases (diabetes)
Replace organs (liver tissue, heart valves)