Chapter 10 Cell Growth and

Division

Cell Size

Why aren’t we just one GIANT cell?

Cell Size Limits

O Are whale cells the same size as sea stars cells?

Yes!

Limits to Cell SizeO Cells can only get so big for two reasons:1) Overloading the DNAO What does DNA do?

Limits to Cell Size2) Limited access ways in and out of

the cellO Only so much membrane space

O Remember it is across the cell membrane that materials move in and out of the cell

Cells want a large surface area to volume ratio

O What does this mean?O Smaller objects have more

“packaging” around a smaller volume than larger objects

How Do Cells Divide?

Put the Cartoon Frames in Order

Lets Start with a Simple Activity

Did you put them in the correct order?

How did you decide the order of the frames?

With your table partner, try to put the following stages of the cell cycle in

order.

Allium Root Tip Slides1. Look at the root tip slide under the microscope. Focus on

the tip of the root. This is where growth occurs.2. Try to find as many different looking cells as possible3. Sketch each different cell on a separate sheet of paper

As a class, we will sort the drawings like we did for the cartoon. The cells you are looking at are frozen in time the

same way each frame of a cartoon is.

Using the drawing, make a prediction on how cells divide in real time.

Using these diagrams, make a prediction on how cells divide in real time

So the big question is WHY do cells divide???

Take 1 minute and discuss this with your table partner

Growth and Repair

How Cells Divide:Put the following stages in order

2, 3, 1, 4, 5

Cell Division• At a certain point, our cells are at the right size to

divide.• What needs to happen for this to be successful?

The cells each need a complete copy of DNA

Types of ReproductionAsexual Reproduction - All you need is one! cell divides resulting in two identical copies. Common is single celled organisms.

Advantages: O No need for a mateO Very fastDisadvantages:-- More chance for error-- Lack of genetic diversity

Types of Reproduction Sexual Reproduction - fusion of two separate parent cells - inherit some genetic information from each parent

Advantages:-Increase genetic diversity-Dependent upon conditions/timingDisadvantages:-Slow-Requires 2!

ChromosomesGenetic information bundled into packages of DNA

Prokaryotic Cells• Lack nuclei and many of the organelles in eukaryotic

organisms• Most contain a singular, circular DNA chromosome in

the cytoplasm that contains nearly all the DNA• Reproduce by a process called binary fission. Once the

DNA duplicates it attaches to different regions of the cell membrane and, fibers form, and the cell pinches and forms two identical cells

Eukaryotic cells go through the process of either mitosis or meiosis

Mitosis – the division of the nucleus. This, combined with cytokinesis (the division of the cytoplasm) is known as the

cell cycle

Meiosis – Is the division of nucleus of your gametes (egg or sperm). This is different than mitosis because you end

of with half the DNA. This is NOT the same as sexual reproduction!