Cell Growth Do Now: Do organisms get larger when they grow because each cell increases in size or...

Cell GrowthCell Growth

Do Now:Do Now:

Do organisms get larger Do organisms get larger when they grow because when they grow because

each cell increases in size or each cell increases in size or because it produces more of because it produces more of

them?them?

I. Why should cells I. Why should cells divide?divide?A.A. DNA overloadDNA overload

1.1. There is only one original copy of There is only one original copy of DNA in each cellDNA in each cell

2. If the cell gets too big, the DNA 2. If the cell gets too big, the DNA can not serve it.can not serve it.

3. A small library can only serve a 3. A small library can only serve a small town. More people = the small town. More people = the library needs more bookslibrary needs more books

B. Exchanging MaterialsB. Exchanging Materials

1. Food, O1. Food, O22, H, H22O into a cell, COO into a cell, CO22 and and waste out through the cell membranewaste out through the cell membrane

2. If the cell is too big, not enough 2. If the cell is too big, not enough nutrients will be moved in and too nutrients will be moved in and too much waste will build up.much waste will build up.

3. There would not be enough 3. There would not be enough surface area for the increasing surface area for the increasing volumevolume

II. Surface Area to II. Surface Area to VolumeVolume

A. Volume increases more rapidly A. Volume increases more rapidly than the surface area.than the surface area.

Surface area = (length x width)(number of sides)

Volume = length x width x height

Surface area/volume = ratio

Figure it out…Figure it out…

III. Cell DivisionIII. Cell Division

A. Before the cell becomes too A. Before the cell becomes too large:large:

1. It copies (replicates) it’s 1. It copies (replicates) it’s DNADNA

2. Divides into 2 equal and 2. Divides into 2 equal and identical identical daughter cellsdaughter cells

10-210-2Cell DivisionCell Division

That first cell had all the information That first cell had all the information and instructions to make you as you and instructions to make you as you

are now. are now. It was all in a secret code in the It was all in a secret code in the

middle of the cell. middle of the cell. This code is called DNA. It is a very This code is called DNA. It is a very long list of instructions that gives long list of instructions that gives

each cell in your body its own shape each cell in your body its own shape and function. and function.

That first cell grew a little and then That first cell grew a little and then "wiggly" bits called chromosomes could "wiggly" bits called chromosomes could clearly be seen.clearly be seen.Half of the chromosomes came from the Half of the chromosomes came from the egg cell, and half from the sperm cell and egg cell, and half from the sperm cell and each chromosome contained two copies of each chromosome contained two copies of that that secret code, the plans to make you , the plans to make you

The first cell then divided into two The first cell then divided into two separate cells using a process called cell separate cells using a process called cell division and this is how it happened... division and this is how it happened...

First the chromosomes lined up in First the chromosomes lined up in the center of the cell. the center of the cell.

Then each chromosome split into two Then each chromosome split into two identical halves. identical halves.

Next the cell made a fold down its Next the cell made a fold down its middle and... middle and...

HEY PRESTO!!!HEY PRESTO!!!

Two cells, which both had all the Two cells, which both had all the information and instructions to make information and instructions to make

you...and then...you...and then...

Those cells grew a bit...Those cells grew a bit...copied their chromosomes andcopied their chromosomes andthose became then became those became then became then became then became thenthen thenthen

thenthen

thenthen

Then:Then:

You get the You get the idea…idea…

Very soon there were Very soon there were

If one of your cells was really this size If one of your cells was really this size you'd be as big as the Empire State you'd be as big as the Empire State

Building in America. Building in America.

I. I. ChromosomesChromosomes

A. Made of DNA and proteinsA. Made of DNA and proteins

B. Invisible except during cell B. Invisible except during cell division division (chromatin(chromatinchromosomes)chromosomes)

C. Human cells have 46C. Human cells have 46

carrot cells have 18carrot cells have 18

http://www.youtube.com/watch?http://www.youtube.com/watch?v=Q6ucKWIIFmgv=Q6ucKWIIFmg

http://www.nobelprize.org/educational/http://www.nobelprize.org/educational/medicine/2001/cellcycle.htmlmedicine/2001/cellcycle.html

http://www.youtube.com/watch?http://www.youtube.com/watch?v=VRhz3DhjG5Mv=VRhz3DhjG5M

http://www.youtube.com/watch?http://www.youtube.com/watch?v=jk2RJm5RBEkv=jk2RJm5RBEk

http://www.youtube.com/watch?http://www.youtube.com/watch?v=z7I0mw4ZDJA&list=PL07B5D7AF5D381E65v=z7I0mw4ZDJA&list=PL07B5D7AF5D381E65