Cell Growth Does an animal get larger because each cell increases in size or because it produces...
-
Upload
april-ross -
Category
Documents
-
view
213 -
download
0
Transcript of Cell Growth Does an animal get larger because each cell increases in size or because it produces...
![Page 1: Cell Growth Does an animal get larger because each cell increases in size or because it produces more of them?](https://reader030.fdocuments.in/reader030/viewer/2022032605/56649e765503460f94b77aa0/html5/thumbnails/1.jpg)
Cell GrowthDoes an animal get larger because each cell increases in size or because it produces more of them?
![Page 2: Cell Growth Does an animal get larger because each cell increases in size or because it produces more of them?](https://reader030.fdocuments.in/reader030/viewer/2022032605/56649e765503460f94b77aa0/html5/thumbnails/2.jpg)
Cell Growth• As you might have guessed, living things grow
by producing more cells.
• The koalas have the same size cells, just one has more then the other.
![Page 3: Cell Growth Does an animal get larger because each cell increases in size or because it produces more of them?](https://reader030.fdocuments.in/reader030/viewer/2022032605/56649e765503460f94b77aa0/html5/thumbnails/3.jpg)
Limits to Cell growth• The larger a cell becomes, the more demands
the cell places on its DNA. In addition, the cell has more trouble moving enough nutrients and wastes across the cell membrane.
• The cell can’t grow. It must reproduce!
![Page 4: Cell Growth Does an animal get larger because each cell increases in size or because it produces more of them?](https://reader030.fdocuments.in/reader030/viewer/2022032605/56649e765503460f94b77aa0/html5/thumbnails/4.jpg)
Cell Division• The process by which a cell divides into two
new daughter cells is called cell division.
• Before cell division occurs, the cell replicates, or copies, all of its DNA. This replication solves the info. problem.
![Page 5: Cell Growth Does an animal get larger because each cell increases in size or because it produces more of them?](https://reader030.fdocuments.in/reader030/viewer/2022032605/56649e765503460f94b77aa0/html5/thumbnails/5.jpg)
Cell Division• What do you think would happen if a cell
were simply to split into two without any advance preparation?
![Page 6: Cell Growth Does an animal get larger because each cell increases in size or because it produces more of them?](https://reader030.fdocuments.in/reader030/viewer/2022032605/56649e765503460f94b77aa0/html5/thumbnails/6.jpg)
Chromosomes• In eukaryotic cells, the genetic
information that is passed on from one generation of cells to the next is carried by chromosomes.
• The cells of every organism have a specific number of chromosomes.
• Each chromosome consists of two identical “sister” chromatids. When the cell divides, the “sister” chromatids separate and go to each of the new cells.
![Page 7: Cell Growth Does an animal get larger because each cell increases in size or because it produces more of them?](https://reader030.fdocuments.in/reader030/viewer/2022032605/56649e765503460f94b77aa0/html5/thumbnails/7.jpg)
Chromosome• Each pair of chromatids is attached at an area
called a centromere.
• Centromeres are usually located near the middle of the chromatids, although sometimes can be found at each end.
![Page 8: Cell Growth Does an animal get larger because each cell increases in size or because it produces more of them?](https://reader030.fdocuments.in/reader030/viewer/2022032605/56649e765503460f94b77aa0/html5/thumbnails/8.jpg)
The Cell Cycle• 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 to daughter cells
![Page 9: Cell Growth Does an animal get larger because each cell increases in size or because it produces more of them?](https://reader030.fdocuments.in/reader030/viewer/2022032605/56649e765503460f94b77aa0/html5/thumbnails/9.jpg)
Events of the Cell Cycle p)245• There are four phases of the Cell Cycle.
• G1 phase – period where cell does most of their growing
• S phase – chromosomes are copied and the synthesis of DNA molecules takes place.
(DNA Replication)
• G2 phase – usually the shortest of the phases. The phase where essential organelles are constructed.
• and M phase – Cell Division.
![Page 10: Cell Growth Does an animal get larger because each cell increases in size or because it produces more of them?](https://reader030.fdocuments.in/reader030/viewer/2022032605/56649e765503460f94b77aa0/html5/thumbnails/10.jpg)
I P on a MAT C *preparation between split
Interphase
*mitosis
Prophase
Metaphase
Anaphase
Telophase
*cells split
Cytokenesis
Steps of Cell Division
![Page 11: Cell Growth Does an animal get larger because each cell increases in size or because it produces more of them?](https://reader030.fdocuments.in/reader030/viewer/2022032605/56649e765503460f94b77aa0/html5/thumbnails/11.jpg)
Interphase• Stage between cellular
division.
• Also known as the G1, S, and G2 stages of the cell cycle.
• In Interphase the cell is allowed to grow, copy its DNA and check for crucial genetic mistakes.
![Page 12: Cell Growth Does an animal get larger because each cell increases in size or because it produces more of them?](https://reader030.fdocuments.in/reader030/viewer/2022032605/56649e765503460f94b77aa0/html5/thumbnails/12.jpg)
![Page 13: Cell Growth Does an animal get larger because each cell increases in size or because it produces more of them?](https://reader030.fdocuments.in/reader030/viewer/2022032605/56649e765503460f94b77aa0/html5/thumbnails/13.jpg)
Mitosis• Mitosis (M phase) steps which include the
process for asexual cell division.
• Biologists divide the events of mitosis into four phases:
- Prophase
- Metaphase
- Anaphase
- Telophase
Depending on the type of cell, the four phases may last anywhere from a few minutes to several days.
![Page 14: Cell Growth Does an animal get larger because each cell increases in size or because it produces more of them?](https://reader030.fdocuments.in/reader030/viewer/2022032605/56649e765503460f94b77aa0/html5/thumbnails/14.jpg)
Prophase- The first and the longest phase of mitosis, prophase can take as much
as 50 to 60 percent of the total time required to complete mitosis.
- During prophase in animal cells, the centrioles separate and take up positions on opposite sides of the nucleus.
- The centrioles help organize the spindle, fanlike microtubule structure that helps separate the chromosomes.
![Page 15: Cell Growth Does an animal get larger because each cell increases in size or because it produces more of them?](https://reader030.fdocuments.in/reader030/viewer/2022032605/56649e765503460f94b77aa0/html5/thumbnails/15.jpg)
Prophase
• chromosomes appear-chromatin condenses to form chromosomes
• the nucleolus disappears
• the cell membrane begins to break down
![Page 16: Cell Growth Does an animal get larger because each cell increases in size or because it produces more of them?](https://reader030.fdocuments.in/reader030/viewer/2022032605/56649e765503460f94b77aa0/html5/thumbnails/16.jpg)
Metaphase
• chromosomes align along the equator of the cell pulled by the spindle fibers
• Spindle fiber that are attached to the poles connect to the centromeres
• Short Phase
![Page 17: Cell Growth Does an animal get larger because each cell increases in size or because it produces more of them?](https://reader030.fdocuments.in/reader030/viewer/2022032605/56649e765503460f94b77aa0/html5/thumbnails/17.jpg)
Early Anaphase
• chromosomes are pulled to the poles by the contraction of the spindle fibers chromatids are separated at the centromere
![Page 18: Cell Growth Does an animal get larger because each cell increases in size or because it produces more of them?](https://reader030.fdocuments.in/reader030/viewer/2022032605/56649e765503460f94b77aa0/html5/thumbnails/18.jpg)
Late Anaphase
• chromosomes begin to move to the opposite poles
• Karyokinesis• the energy for this
process is provided by the mitochondria
![Page 19: Cell Growth Does an animal get larger because each cell increases in size or because it produces more of them?](https://reader030.fdocuments.in/reader030/viewer/2022032605/56649e765503460f94b77aa0/html5/thumbnails/19.jpg)
Early Telophase
• the new cell wall begins to form to separate the new cell the chromosomes begin to form a nucleus
![Page 20: Cell Growth Does an animal get larger because each cell increases in size or because it produces more of them?](https://reader030.fdocuments.in/reader030/viewer/2022032605/56649e765503460f94b77aa0/html5/thumbnails/20.jpg)
Late Telophase
• the chromosomes start to uncoil and become less dense
• Nuclear membrane reassembles
• Nucelolus reappears• Plasma membrane
begins to separate• Cell plate forms• two new identical
cells are formed
![Page 21: Cell Growth Does an animal get larger because each cell increases in size or because it produces more of them?](https://reader030.fdocuments.in/reader030/viewer/2022032605/56649e765503460f94b77aa0/html5/thumbnails/21.jpg)
• Cytokinesis is the division of the cytoplasm of a parent cell.
• Microfilaments form a ring around the equator. When the microfilaments contract-pinches makes a furrow
Cytokinesis
![Page 22: Cell Growth Does an animal get larger because each cell increases in size or because it produces more of them?](https://reader030.fdocuments.in/reader030/viewer/2022032605/56649e765503460f94b77aa0/html5/thumbnails/22.jpg)
• You may either consider it the end of Mitosis or the beginning of Interphase.
• While each daughter cells gets identical sets of DNA, the cytoplasm and organelles are only roughly divided equally between the two cells.
• Parent chromosome #= Daughter chromosome#
Cytokinesis
![Page 23: Cell Growth Does an animal get larger because each cell increases in size or because it produces more of them?](https://reader030.fdocuments.in/reader030/viewer/2022032605/56649e765503460f94b77aa0/html5/thumbnails/23.jpg)
Mitosis • all four
stages of mitosis can be seen in this picture. note the process by which the red and blue chromosomes separate.
![Page 24: Cell Growth Does an animal get larger because each cell increases in size or because it produces more of them?](https://reader030.fdocuments.in/reader030/viewer/2022032605/56649e765503460f94b77aa0/html5/thumbnails/24.jpg)
MITOSIS
![Page 25: Cell Growth Does an animal get larger because each cell increases in size or because it produces more of them?](https://reader030.fdocuments.in/reader030/viewer/2022032605/56649e765503460f94b77aa0/html5/thumbnails/25.jpg)
://www.youtube.com/watch?v=VlN7K1-9QB0
![Page 26: Cell Growth Does an animal get larger because each cell increases in size or because it produces more of them?](https://reader030.fdocuments.in/reader030/viewer/2022032605/56649e765503460f94b77aa0/html5/thumbnails/26.jpg)
Regulating the Cell Cycle• If we grow by cell division, then why do we stop
growing?
• Multi-cellular organisms cell growth is controlled.
• For example, in the human body, most muscle and nerve cells don’t divide at all once they have developed, whereas skin cells and blood cells divide rapidly.
![Page 27: Cell Growth Does an animal get larger because each cell increases in size or because it produces more of them?](https://reader030.fdocuments.in/reader030/viewer/2022032605/56649e765503460f94b77aa0/html5/thumbnails/27.jpg)
Controls on Cell Division• Look at Fig 10-7 on page 250. What is
happening in this figure? What would happen if the cells continued to divide?
• When cells come into contact with other cells, they respond by not growing.
• How does this relate to how your body responds to a cut or a bone fracture?
![Page 28: Cell Growth Does an animal get larger because each cell increases in size or because it produces more of them?](https://reader030.fdocuments.in/reader030/viewer/2022032605/56649e765503460f94b77aa0/html5/thumbnails/28.jpg)
Cell Cycle Regulators• Scientists discovered
that cells in mitosis contain a protein called cyclin when injected in a non-dividing cell, would cause a miotic spindle to form.
• Cyclins regulate the timing of the cell cycle in eukaryotic cells.
![Page 29: Cell Growth Does an animal get larger because each cell increases in size or because it produces more of them?](https://reader030.fdocuments.in/reader030/viewer/2022032605/56649e765503460f94b77aa0/html5/thumbnails/29.jpg)
Other Cell Cycle Regulators
• Internal regulators- proteins that respond to events inside the cell.
For example: several regulatory proteins make sure that a cell does not enter mitosis until all its chromosomes have been replicated.
- External regulators- proteins that respond to events outside the cell.
For example: external regulators direct cells to either speed up or slow down the cell cycle.
![Page 30: Cell Growth Does an animal get larger because each cell increases in size or because it produces more of them?](https://reader030.fdocuments.in/reader030/viewer/2022032605/56649e765503460f94b77aa0/html5/thumbnails/30.jpg)
Uncontrolled Cell Growth• Why is cell growth regulated so carefully?
• Cancer- a disorder in which some of the body’s own cells lose the ability to control division. Cancer cells do not respond to the signals that regulate the division of most cells.
![Page 31: Cell Growth Does an animal get larger because each cell increases in size or because it produces more of them?](https://reader030.fdocuments.in/reader030/viewer/2022032605/56649e765503460f94b77aa0/html5/thumbnails/31.jpg)
Skin Cells