1. “All living things grow and develop”
Cell Growth
“All living things grow and develop”

2. Cell Size Limitations Over burdened DNA Surface area to volume ratio
DNA = nucleic acid that provides instructions to ribosomes to produce protein
DNA controls activities of the cell within the nucleus
Surface area to volume ratio
Surface area increases slowly
Volume increases quickly
Just can’t get enough or get rid of enough
Cell membrane is site of material exchange
Diffusion, facilitated diffusion, osmosis too slow

3. DNA Overload There’s too much work!!!
Not enough information to go around in the cell
As a cell grows, it has more organelles and conducts more activities
Cellular activities require enzymes
Enzymes are proteins; therefore, must be produced through protein synthesis
Protein synthesis requires information from DNA

4. Just Can’t Get Enough
Can’t get enough oxygen, food and water across the cell membrane to supply the cell
Can’t get rid of waste products quickly enough to prevent self poisoning
Process of diffusion/osmosis is too slow

5. Surface Area to Volume Ratio
The surface area increases slower than the volume OR . . .
The volume increases faster than the surface area!!
Therefore, the surface area to volume ratio decreases!!
More volume = more demands because the rate of consumption increases
Surface area can’t keep up with demands

6. Surface Area

7. Surface Area vs. Volume
Surface area = 96 mm2
Volume = 64 mm3
Surface area to volume ratio:
6:1 or 6/1 = 6
Surface area to volume ratio:
24:8 or /8 = 3
Surface area to volume ratio:
96: or /64 = 1.5
As a cell grows, notice the value of the surface area to volume ratio!
It decreases!

9. So . . . What can cells do about that?
Cell division – the process used by cells to divide
Dividing rectifies the problem of putting too much demand on DNA
Dividing increases the surface area to volume ratio
Dividing reduces the size of the cell making it possible to distribute nutrients and remove waste!

10. Replication DNA makes copies of itself Review:
DNA unzips
Complementary nucleotides attach
Two new strands of identical DNA are produced
Each new strand has one strand from the original
DNA must be copied so that each new cell has a complete set of DNA of the original

11. Reproduction
Reproduction is the production of offspring or a new organism
There are two general methods/strategies of reproduction:
Asexual reproduction – production of offspring that requires only one parent
Sexual reproduction – production of offspring that requires the combination of two different cells

12. Asexual Reproduction Organisms produce offspring through one parent
Offspring have the same genetic information (information for making proteins) as the parent
They are, in essence, clones!!!
Unicellular organisms, like bacteria, usually reproduce asexually
Some multicellular organisms reproduce asexually

13. Asexual Reproduction & Multicellular Organisms
Organisms such as plants and protists can reproduce asexually
Hydra reproduce through budding!
Plants can reproduce asexually
Bulbs
Cuttings
Rhizomes
Roots/shoots/runners

14. Budding in Hydra

15. Binary Fission of Amoeba

16. Runners of Strawberry Plants

17. Asexual Reproduction in Plants

18. Asexual Reproduction = Clones

19. Sexual Reproduction
Sexual reproduction is a process where two cells (gametes) from different parents join together to form a new organism
Offspring of sexual reproduction have different genetic information from both parents
Most plants and animals and some unicellular organisms reproduce sexually

20. Sexual Reproduction

21. Asexual vs. Sexual Reproduction
No need to find mate; therefore, quicker
No genetic diversity; therefore, vulnerable
Sexual
Must find a mate; therefore, slower
Genetically diverse; therefore, healthy