Transcript Chapter 10 Cell Growth and Division

Chapter 10 Cell Growth and Division
10-1 Cell Growth
A. Limits to Cell Growth
1. Larger the cell becomes the more demands
put on the cell’s DNA
a. Cell cannot and does not make more
DNA
-computer hard drive space/program
needs
2. Larger the cell the more problem the cell has
in moving materials/waste through
membrane
a. As cell increases in size:
-volume increases compared to surface
area
-less surface area to let things in/out
-ex. balloon
B. Division of the Cell
1. Cell Division
a. Process by which a cell divides into 2
new identical daughter cells
2. 2 Stages
a. Mitosis
-division of the nucleus
b. Cytokinesis
-division of the cytoplasm
10-2 Cell Division
A. Chromosomes
1. passes genetic info from gen. to gen.
2. composed of DNA and proteins
3. each species has specific number of
chromosomes
a. Fruit fly—8 chromosomes
carrot—18 chromosomes
humans—46 chromosomes
4. Invisible as chromatin—even under
microscope
5. As compacted chromatin (chromosomes)
visible under microscope
6. Replicates (make copies) and form identical
“sister” chromatids (2 chromosomes)
7. Chromatids are attached at the centromere
8. human cell entering cell division has 46
chromosomes which duplicates to
92 chromos. (46 chromatids)
9. Handout of sister chromatid
B. Cell Cycle
1. series of events cell goes through as it
grows and divides
a. Cell grows
b. Prepares for division
c. Divides to form 2 identical daughter
cells
d. cycles again
2. Handout
3. Events of cell cycle
Cell cycle has 2 stages:
--Interphase (G1, S, G2)
--cell division (mitosis
(PMAT) and
cytokinesis)
4. Interphase
Interphase
--may last a long time
--period between divisions
--cell is performing normal
life activities
--chromatin is present
--phases--Gap 1 (G1),
Synthesis phase (S),
Gap 2 (G2)
b. Phases of interphase
S phase
--DNA replication
--Synthesis of DNA
molecules
--Key proteins for
DNA is
synthesized
c. Phases of interphase
Gap 2 (G2)
--Organelles
required for
division are
produced
--Shortest of
interphase
--Preparation for
mitosis
5. M Phase
M
phase
M phase
--Prophase
--Metaphase
--Anaphase
--Telophase
--PMAT—division
of nucleus
--Cytokinesis—
Division of
cytoplasm
a. Phases of interphase
Gap 1 or G1—cells do
most of the growing
(increase in size),
synthesizes proteins
and organelles
C. Mitosis
1. 4 Phases
a. Prophase, metaphase, anaphase,
telophase (PMAT)
b. Phases last from a few minutes to
several days depending on cell type
c. Handout
10-3 Regulating the Cell Cycle
A. Controls on Cell Division
1. Human Body Cells
a. Muscle/nerve cells do not divide
once developed
--heart attacks, strokes, severed
nerves/spinal cord
b. Skin, digestive, bone divide rapidly
--repair, healing, replacement
2. cell growth can be “turned on/off”
B.
a. When cells come into contact with
each other they stop growing
b. When nutrients are gone growth
stops
Cell Cycle Regulators
1. cyclin
a. Protein (in the eukaryote cell) which
regulates cell cycle
-amount of cyclin rises and falls in cycle
2. Two types of regulatory proteins
a. Internal regulators
-respond to events inside the cell
-examples:
*ensures a cell does not enter mitosis
until chromosomes are duplicated
*cell does not enter anaphase until
chromosomes are attached to
spindles
b. External regulators
-responds to events outside the cell
-speeds up/slows down cell cycle
-examples:
*growth regulators
#embryonic development
#wound healing
#prevents excessive growth
3. Uncontrolled Cell Growth
a. Cancer
-cells lose their ability to control growth
-cells do not respond to signals that regulate
cell growth
-tumor
*mass of uncontrolled cells which damages
surrounding tissues
*cancer cells can break off and spread
throughout the body
-cancer cells have a defect in p53 gene
*p53 gene halts cell cycle until
chromosomes are duplicated
*lost or defective info in p53 causes cells
not to respond to info