What Are Cells Made Of? 10.5 Cell Division Essential Question: Cells and Life Processes Ms. De Los Rios 6th Grade 10.5 Cell Division Essential Question: What Are Cells Made Of? What are the Functions of Cell Division? What Happens During the Cell Cycle? Pgs. 388-395

Vocabulary ch. 10.5 Cell Division- The series in which a cell grows, prepares for division, and divides to form daughter cells. Interphase-The first stage of the cell cycle that takes place before cell division(cell grows and makes a copy of DNA) Replication- The process by which a cell makes a copy of the DNA in its nucleus before cell division. Chromosome-A threadlike structure within a cell’s nucleus that contains DNA (passed from one generation to the next) Mitosis- The 2nd stage of the cell cycle. The cell nucleus divides into 2 new nuclei and one set of DNA for each daughter cell. Cytokinesis- the final stage of cell cycle. The cell’s cytoplasm divides, distributing organelles into each of the two new daughter cells.

The table below compares the length of different cell cycles. Cell Division pg. 388 Comparing Cell Cycles The table below compares the length of different cell cycles.

What are the Functions of Cell Division? Pg.389 Cell division allows organisms to: grow repair damaged structures reproduce. Different ways of Cell reproduction: Many single-celled organisms reproduce simply through cell division. Other organisms reproduce when cell division leads to the growth of new structures. Most organisms reproduce when specialized cells from two different parents combine, forming a new cell.

What Happens During the Cell Cycle? P. 390 The regular sequence of growth and division that cells undergo is known as the cell cycle. During the cell cycle: The cell grows ( ---) Prepares for division ( / ) Divides into two new cells “daughter cells” ( DC) and then the cycles begins again. The cell cycle consists of three main stages: Interphase , mitosis, and cytokinesis.

1st Stage-Interphase, the cell grows makes a copy of its DNA, in a process called replication. (DNA- holds of the info. that a cell needs to carry out its functions) and prepares to divide into two new cells. Produces structures that will help it divide in animal cells, a pair of centrioles is duplicated At the end of interphase, the cell is ready to divide.

Interphase: Preparing to Divide Fig. 2 Cell Division pg. 390 Interphase: Preparing to Divide The changes in a cell during interphase prepare the cell for mitosis.

The Cell Cycle pg. 392,3 The cell grows & produces organelles (plant=chloroplasts) (animal=ribosomes, & mitochondria) The replication process= cell makes an exact copy of the DNA in its nucleus. At the end of replication, = the cell contains two identical sets of chromosomes, which are the threadlike structures made up of proteins and DNA found in the nucleus.

Apply IT!!! Cell Division pg. 391 When one cell splits in half during cell division, the result is two new cells. Each of those two cells can divide into two more, and so on.

How does prophase look different from interphase? 2nd Stage—Mitosis Fig. 3 2nd Stage—Mitosis= is when the cell’s nucleus into 2 nuclei and 1 set of DNA is distributed to each nucleus of each daughter cell. Fig. 3 How does prophase look different from interphase?

There are four parts to mitosis: Prophase = the replicated chromosome condense. Can shape can be seen Microscope Metaphase- The chromosomes attaches to spindle fiber @ centromere anaphase – The centromere of chromosomes splits pulling chromatids apart= single chromosome Telophase- Nuclei forming- spindle fibers disappeared.

Cell Division pg. 391 Mitosis: Prophase Mitosis begins with prophase, which involves further changes to the cell.

Fig.4 Cell Division pg. 392-393 The Cell Cycle Answer all the questions and draw the missing parts of the stages in the spaces provided. Centriole pairs Spindle fiber Centromere Chromatids The Cell Cycle Cells undergo an orderly sequence of events as they grow and divide. What are the missing parts of the stages?

Final Stage Cytokinesis pg. 394 3rd The final stage of the cell cycle is cytokinesis. In animal cells, the cell membrane squeezes together around the middle of the cell, and the cell pinches in two. In plant cells, a structure called a cell plate forms across the middle of the cell and creates new cell membranes between the two daughter cells. New cell walls then form around the membranes. When cytokinesis is complete, two new cells have formed, each with the same number of chromosomes as the original parent cell.

DID YOU KNOW?? Pg. 394 Firmicutes Certain bacteria divide only once every 100 years! Bacteria known as Firmicutes live in certain rocks that are found 3 kilometers below Earth’s surface. The life functions of Firmicutes occur so slowly that it takes 100 years or more for them to store enough energy to split in two.

Do the Math!!! Cell Division pg. 395 Length of a Liver Cell Cycle Human liver cells generally reproduce less than once per year. At other times, they can complete one cell cycle in about 22 hours.

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