Transcript Cell Growth and Division

Cell Growth and Division
The cell cycle and Mitosis.
When to Divide?
• Diffusion is a limiting factor
– Works well over short distances
– Takes too long to travel far
• Surface area to volume ratio
– All nutrients and waste must cross the cell membrane
– Larger the cell the smaller the surface area to volume ratio
(A larger cell produces more waste, but has less surface area for it to get
out of)
• DNA is a limiting factor
– Most cells have 1 nucleus and 1 set of DNA
– If the cell is too Big one copy of the DNA is not enough to make enough
proteins for a large cell
Diffusion and cell size
• Materials move through cells by diffusion.
Oxygen and food move into cells, while
waste products move out of cells.
• The size of a cell affects how efficiently
materials get to all parts of a cell.
• The larger the cell the less efficient
transport of materials across the cell
membrane is.
Surface area to Volume Ratio
Surface Area
(length x width x 6)
Volume
(length x width x height)
Ratio of Surface Area
to Volume
• The higher the surface area to volume ratio the
easier it is to get nutrients to the cell
Prokaryotic cell division
•
•
•
•
Binary fission
DNA replicates
No organelles to multiply
Cell divides cytoplasm, ribosomes and
DNA
• Cell wall divides two cells
The Cell Cycle
G1 phase
M phase
S phase
G2 phase
Interphase
• Interphase is when the cell is not dividing,
but is going about its normal daily
business. Ex. Nerve cells send
messages, muscle cells contract.
– G1- cell growth and day to day life
– S -Synthesis- DNA is replicating
– G2 –prepare for cell division, make extra
copies of organelles so both daughter cells
will get all the organelles.
Root words
• Look up what the following word pre-fixes
mean
• Inter• Pro• Meta• Ana• Telo-
Root Words… Defined
• Inter-Between, the cell is between
divisions
• Pro-Greek, from pro, before, before cells
divide they must prepare.
• Meta-Greek, from meta, beside,
Chromosomes are side by side
• Ana- Backward, Chromosomes are pulled
back
• Telo-From Greek telos, end
Correct order…
Prophase
Interphase
Spindle
forming
Centrioles
Nuclear
envelope
Cytokinesis
Chromatin
Centriole
Centromere
Chromosomes
(paired chromatids)
Spindle
Centriole
Individual
chromosomes
Nuclear
envelope
reforming
Anaphase
Telophase
Metaphase