"Cells produce new cells through division" How cells constitute organisms PPT courseware 3

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"Cells produce new cells through division" How cells constitute organisms PPT courseware 3

Section 1 Cells divide to create new cells

Why can't cells grow indefinitely?

Cell growth requires the cell surface to absorb nutrients from the outside world. The larger the surface area, the more nutrients it absorbs. As the cell grows, the ratio of its surface area to volume becomes smaller, that is, the surface area increases without increasing the volume. If there are too many, this will inevitably affect the absorption of nutrients by the cells, causing the cells to not get enough nutrients. Therefore, the cells can only grow to a certain size.

Cell division

animal cell division process

When an animal cell divides, the nucleus first divides into two, and then the cytoplasm divides into two parts, each containing a nucleus. Finally, a new cell membrane forms in the center of the original cell. One cell divides into two.

plant cell division process

When plant cells divide, first the nucleus is divided into two, then the cytoplasm is divided into two, and finally a new cell membrane and cell wall are formed.

Why are chromosomes called carriers of genetic material?

Those substances in cells that are stained darkly by basic dyes are called chromosomes. Chromosomes are composed of two substances, DNA and protein. DNA is genetic material, so it can be said that chromosomes are the carriers of genetic material.

result of cell division

Whether it is an animal cell or a plant cell, first the nucleus is divided into two, then the cytoplasm is divided into two, and finally the cell is divided into two cells. The result of division is that the number of cells in an organism increases.

The meaning of cell division

Promote normal life activities of organisms

Breed new individuals

New individuals grow from small to large

Renew aging and dead cells

During cell division, the most obvious changes in chromosomes

chromosomal changes

The replication of chromosomes doubles their number.

The chromosomes are divided equally into the two new cells.

The two new cells have the same chromosome shape and number.

The new cells have the same chromosome shape and number as the original cells.

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"Cells produce new cells through division" How cells constitute organisms PPT courseware 6:

"Cells produce new cells through division" How cells constitute living organisms PPT courseware 6 Review the past and learn the new 1. Inorganic substances and organic substances in cells 2. Cell membranes control the entry and exit of substances 3. Chloroplasts (the place of photosynthesis), the energy converters in cells Light energy change..

"Cells produce new cells through division" How cells constitute organisms PPT courseware 5:

"Cells produce new cells through division" How cells constitute organisms PPT courseware 5 1. Teaching objectives 1. Describe the basic process of cell division. 2. Say that the number of cells in an organism increases through cell division. 3. Name the roles of chromosomes before cell division..

"Cells produce new cells through division" How cells constitute organisms PPT courseware 4:

"Cells produce new cells through division" How do cells constitute an organism PPT courseware 4 1. Cell growth Cell growth: The cells that constitute an organism must constantly absorb nutrients from the surrounding environment and convert them into their own substances. The volume will change from Small becomes big. reason..

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Update Time: 2024-11-18

This template belongs to biology courseware People's Education Edition seventh grade biology volume 1 industry PPT template

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