Cell Processes and EnergyDo Now:

Take the worksheet from the front of the

roomHomework:

1. Read pages 61-682. Cell definitions

Cell Processes and Energy

Cell Processes and Energy

Cell Division (2.3)

A. Cells reproduce by dividing

1. In order to divide, cells need to duplicate their

structures (organelles) or divide the structures

equally between the two new cells.

2. The regular sequence of growth and division is

called the cell cycle.

3. The cell cycle is divided into a series of phases.

4. At the end of the cell cycle, one “parent” cell

becomes two “daughter” cells.

Cell Processes and Energy

B. Interphase

1. Interphase is the period before cell division

occurs, the cell grows to its mature size, makes a

copy of its DNA and prepares to divide into two

cells.

2. The cell doubles in size and produces all

structures needed to carry out cell division

3. The cell makes a copy of its DNA through a

process called replication. Replication of the DNA

is very important because each daughter cell needs

a complete set of DNA to survive.

Cell Processes and Energy - Cell Division

Mitosis

During mitosis, the cell’s nucleus divides into two new nuclei. One copy of the DNA is distributed into each of the two daughter cells.

Cell Processes and Energy

C. Mitosis

1. the chromatin in the nucleus condenses to form

chromosomes.

2. structures called spindle fibers form a bridge

between

the ends of the cells

3. the nuclear membrane breaks down

4. the chromosomes line up across the center of the

cell

5. each chromosome attaches to a spindle fiber at its

centromere, which holds its chromatids together

Cell Processes and Energy

6. the centromeres split, the two chromatids separate

7. one chromatid moves along the spindle fiber to one

end of the cell, the other chromatid moves to the

opposite end

8. the cell becomes stretched out as the opposite ends

pull apart

9. the chromosomes begin to stretch out and lose their

rod like appearance

10. this occurs in two regions at the ends of the cell

11. a new nuclear membrane forms around each region

of chromosomes

Cell Processes and Energy

D. At the end of Mitosis, cytokinesis occurs

1. Cytokinesis is the division of the

cytoplasm

2. At the end of cytokinesis, the two new

daughter cells are exactly the same as the

original parent cell.

Cell Processes and Energy - Cell Division

The Cell Cycle

Cell Processes and Energy

Cell Cycle Activity

Click the Active Art button to open a browser window and access Active Art about the cell cycle.

- Cell Division

Cell Processes and Energy

Length of the Cell Cycle

How long does it take for a cell to go through one cell cycle? It all depends on the cell. A human liver cell, for example, completes one cell cycle in about 22 hours, as shown in the graph. Study the graph and then answer the following questions.

1.

- Cell Division

Cell Processes and Energy

Length of the Cell CycleHow long does it take for a cell to go through one cell cycle? It all depends on the cell. A human liver cell, for example, completes one cell cycle in about 22 hours, as shown in the graph. Study the graph and then answer the following questions.

- Cell Division

1. What do the three curved arrows

outside the circle represent?

2. In what stage of the cell cycle is the

wedge representing growth?

3. In human liver cells, how long does it

take DNA replication to occur?

4. In human liver cells, what stage in

the cell cycle takes the longest time?

Cell Processes and Energy

Length of the Cell Cycle

The longest curved arrow represents the cell’s interphase; the shortest represents cytokinesis; and the middle one represents mitosis.

Reading Graphs:

What do the three curved arrows outside the circle represent?

- Cell Division

Cell Processes and Energy

Length of the Cell Cycle

Interphase

Reading Graphs:

In what stage of the cell cycle is the wedge representing growth?

- Cell Division

Cell Processes and Energy

Length of the Cell Cycle

10 hours

Interpreting Data:

In human liver cells, how long does it take DNA replication to occur?

- Cell Division

Cell Processes and Energy

Length of the Cell Cycle

Interphase

Drawing Conclusions:

In human liver cells, what stage in the cell cycle takes the longest time?

- Cell Division