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During telophase, the cytoplasm begins dividing by the process of cytokinesis. In animal cells, cytokinesis begins with a pinching inward of the cell membrane midway between the dividing cell's two poles, as shown in Figure 8-8. The area of the cell membrane that pinches in and eventually separates the dividing cell into two cells is called the cleavage furrow. The cleavage furrow pinches the cell into two cells through the action of microfilaments.

Cleavage furrow

Cleavage furrow

Cleavage furrow figure 8-8

In animal cells, such as this frog cell, the cell membrane pinches in at the center of the dividing cell, eventually dividing the cell into two offspring cells. (SEM 78x)

Cleavage furrow figure 8-8

In animal cells, such as this frog cell, the cell membrane pinches in at the center of the dividing cell, eventually dividing the cell into two offspring cells. (SEM 78x)

Cell wa figure 8-9

Cell wa

Forming cell plate

In plant cells, such as this onion cell, a cell plate forms along the midline of the dividing cell, eventually dividing the cell into two offspring cells. (LM 4,104x)

In plant cells, such as this onion cell, a cell plate forms along the midline of the dividing cell, eventually dividing the cell into two offspring cells. (LM 4,104x)

Nuclei of new cells

Forming cell plate

Cell wall of original cell

Figure 8-9 shows cytokinesis in plant cells. In plant cells, vesicles from the Golgi apparatus join together at the midline of the dividing cell to form a cell plate. A cell wall eventually forms from the cell plate at the midline, dividing the cell into two cells.

In both animal cells and plant cells, offspring cells are approximately equal in size. Each offspring cell receives an identical copy of the original cell's chromosomes and approximately one-half of the original cell's cytoplasm and organelles.

Nuclei of new cells

Forming cell plate

Cell wall of original cell

Identifying Prefixes and Suffixes

Materials dictionary, 3 X 5 in.

index cards (18), pencil

Procedure

1. Write each of the following prefixes and suffixes on separate cards: pro-, meta-, ana-, telo-, cyto-, oo-, inter-, -kinesis, and -genesis.

2. Use a dictionary to find the definition of each prefix and suffix. Write the definitions on cards.

3. Play "Memory" with a partner. Mix the cards, and place each one face down on the table. Turn over two cards. If the two cards consist of a prefix or suffix and its definition, pick up the cards, and take another turn. If the two cards do not match, turn them face down again, and leave them in the same place.

4. Repeat step 3 until no cards remain on the table. The player with the most pairs wins.

Analysis How does knowing the meaning of a prefix or suffix help you understand a word's meaning?

Figure 8-9 shows cytokinesis in plant cells. In plant cells, vesicles from the Golgi apparatus join together at the midline of the dividing cell to form a cell plate. A cell wall eventually forms from the cell plate at the midline, dividing the cell into two cells.

In both animal cells and plant cells, offspring cells are approximately equal in size. Each offspring cell receives an identical copy of the original cell's chromosomes and approximately one-half of the original cell's cytoplasm and organelles.

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