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 Size O Cells can only get so big for two reasons: 1) Overloading the DNA O What does DNA do?

Limits to Cell Size 2) Limited access ways in and out of the cell O 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 Slides 1.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 possible 3.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 Reproduction Asexual Reproduction - All you need is one!  cell divides resulting in two identical copies. Common is single celled organisms. Advantages: O No need for a mate O Very fast Disadvantages: -- 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/timing Disadvantages: -Slow -Requires 2!

Chromosomes Genetic 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 !