chapter 10. does an animal get larger because each cell increases in size or because it produces...
Post on 28-Dec-2015
217 Views
Preview:
TRANSCRIPT
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
Please use headphones.
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
top related