Chapter 10

Does an animal get larger because each cell increases in size or because it produces more of them?

In most cases, living things grow by producing more cells

Identify the problems caused by growth of cells

Chromosomes are made of DNA (genetic information) and proteins (histones)

The cells of every organism have a specific number of chromosomes◦ Fruit flies = 8, human = 46, carrots = 18

Chromosomes are not visible in most cells except during cell division

Each chromosome consists of two identical sister chromatids which separate during cell division

Each pair of chromatids is attached in an area called the centromere

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The larger a cell becomes, the more demands a cell places on its DNA◦ If extra copies of DNA are not made, an “information

crisis” would occur The cell also has more trouble moving

nutrients and wastes across the cell membrane◦ Food, oxygen, water, and wastes move through the

cell membrane

Each cell has only one set of genetic information◦ must be copied before cell division begins

The first stage, division of the cell nucleus, is called mitosis

The second stage, division of the cytoplasm, is called cytokinesis

Reproduction by mitosis is classified as asexual

Interphase is the period in between periods of cell division

The cell cycle is the series of events that cells go through as they grow and divide

During the cell cycle, a cell grows, prepares for division, and divides to form two daughter cells, each of which then begins the cycle again

The cell cycle consists of four phases◦ M, S, G1, and G2

Mitosis

Mitosis

Cytokinesis is the division of the cytoplasm itself and usually occurs at the same time as telophase

In most animal cells, the cytoplasm is drawn inward until the cytoplasm is pinched into two nearly equal parts

In plants, a structure known as the cell plate forms midway between the divided nuclei

Not all cells move through the cell cycle at the same rate

The cells of the skin, digestive tract, and bone marrow grow and divide rapidly throughout life

How is the cell cycle regulated? How are cancer cells different from other

cells?

Proteins called cyclins - seemed to regulate the cell cycle

Proteins that respond to events inside the cell are called internal regulators

External regulators respond to events outside of the cell

Cancer is a disorder in which some of the body’s own cells lose the ability to control growth

They divide uncontrollably and form masses of cells called tumors that can damage the surrounding tissues

Causes include smoking, radiation, and viral infections