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## 10-1 Cell Growth

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### Title: The Cell Cycle and Mitosis Author: xavier Last modified by: angusj Created Date: 1/23/2006 2:14:49 AM Document presentation format: On-screen Show – PowerPoint PPT presentation

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Title: 10-1 Cell Growth

1
10-1 Cell Growth
• Complete Guided Reading Workbook 10-1 and 10-2

2
By the end of today you will be able to
• Explain the problems that growth causes for
cells.
• Describe how cell division solves the problems of
cell growth.
• Name and describe the main events of the cell
cycle.

3
Lets do some math!!!!

• Calculate the surface area of each sphere.
• Calculate the volume of each sphere.
• Then, calculate the surface area to volume ratio.
Round s up or down to make it easier.

S.A. 4 (pi) r 2
Radius 2cm S.A. ________ V __________ Ratio
SAV ________
__33cm3____ Ratio SAV 5033_or 1.511
4
Radius 1cm S.A. _____ V ______ Ratio SAV
___
__33cm3____ Ratio SAV 5033_or 1.511
Radius 1cm S.A. __13cm2___ V __4cm3____ Ratio
SAV _134 or 3.251__
Radius 3cm S.A. _____ V ______ Ratio SAV
___
___113cm3___ Ratio SAV _113113 or 11__
S.A. 4 (pi) r 2
1. As the spheres get larger what happens to the
SAV ratio?

5
1st problem Cell size and material exchange
• The larger a cell grows the more trouble it has
• moving enough nutrients in
• Moving all the waste materials out

6
7
Checkpoint!!!!
• What are two problems that cell growth causes for
cells?
• The larger a cell becomes, the more demands the
cell places on its _____ and the more trouble the
cell has moving enough _________and _________
across the cell membrane.
• What is viable solution for cells solve these
problems?
• Cell Division A larger cell splits into two
smaller daughter cells.

8
The Cell Cycle and Mitosis
• Chapter 10-2
• Homework 10-2-3 in guided reading

9
The Cell Cycle - series of events that cells go
through as they grow and divide
• The cell cycle is divided into two halfs
• Interphase - period of the cell cycle between
cell divisions
• M phase period of time when mitosis and cell
division occurs

10
Parts of Interphase
• G1 Phase
• Growing
• Synthesize new proteins and organelles
• Doing their jobs
• Longest phase of cell cycle
• S Phase
• Chromosomes(DNA) are replicated
• Key proteins associated with replication are made
(centromeres)
• G2 Phase
• Shortest of the 3 phases of interphase
• Organelles and molecules for cell division are
produced (centrioles)
• Check-up phase before mitosis

11
Chromatin and Chromosomes
• Chromatin - A complex of DNA and proteins in the
cell nucleus that condenses to form chromosomes
during cell division.
• Chromosomes Condensed Chromatin
• They are the same stuff, just in different forms

12
Chromatin condenses in chomosomes before mitosis
begins
• Chromatin
• Chromosomes

13
Chromosomes
• Different organisms have different s of
chromosomes
• Humans cells 46
• Fruit Fly cells 8
• Carrot cells 18
• King Crab cells - 208

14
Chromosomes Replication
• During the cell cycle (before cell division can
take place) chromosomes are replicated to form an
identical copy of itself.
• Two identical copies of a chromosome are called
sister chromatids (one of two identical
sister parts of a duplicated chromosome)
• Centromere - area where the chromatids of a
chromosome are attached

15
M Phase, Cell Division and Mitosis
16
Mitosis
• Prophase
• Metaphase
• Anaphase
• Telophase

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22
Cytokinesis
-Cytoplasmic division and other changes exclusive
of nuclear division that are a part of mitosis or
meiosis.
23
In plant cells, a cell plate forms. The cell
plate is synthesized by the fusion of multiple
membrane-bounded vesicles. Their fusion supplies
new plasma membrane for each of the two daughter
cells. Synthesis of a new cell wall between the
daughter cells then occurs at the cell plate.
24
10-3 cell cycle regulation
• Homework 10-3 guided reading workbook

25
Checkpoint
• 1. The break down of a cells entire life is the
_______ ________.
• 2. The phase of the cell cycle when the cell is
growing, replicating DNA and getting ready for
mitosis is _____________.
• 3-6. What are the four phases of Mitosis?
• 7. The process of a cell actually splitting in
two is called _______________.

26
Controls on Cell Division
27
How do cells know when to divide and when not to?
• Internal regulators are proteins that respond
to events inside the cell.
• Some proteins make sure cells do not enter
mitosis until all of the chromosomes have been
replicated.
• What stage of the cell cycle do you think these
proteins work?
• G2 phase
• Cyclins (internal regulator) one of a family of
closely related proteins that regulate the cell
cycle in eukaryotic cells

28
Cyclins
Protein that periodically rises and falls in
concentration in step with the eukaryotic cell
cycle. Cyclins activate crucial protein kinases
(called cyclin-dependent protein kinases, or CDK)
and thereby help control the progression from one
stage of the cell cycle to the next. Cascade of
events!!
29
Cyclins
30
External Regulators
• External regulators - Proteins that respond to
events outside the cell are called external
regulators.
• External regulators direct cells to speed up or
slow down the cell cycle.
• Growth factors are among the most important
external regulators, which tell cells to speed up
division. When is this important?
• Molecules found on the surfaces of neighboring
cells often have an opposite effect, causing
cells to slow down or stop their cell cycles.

31
Uncontrolled Cell Growth
• Cancer cell
• Various forms of cancer have many causes
• Smoking
• Viral infections
• The common thread in all cancers is that control
over the cell cycle has broken down.
• Over 50 of cancer cells have a defect in the p53
gene.

32
Quiz on Thursday HO due wednesday
33
p53 antioncogene
• p53 is a tumor suppressor gene found mutated in
• It encodes a gene regulatory protein that is
activated by damaged DNA and is involved in
blocking further progression of the cell cycle.

34
Oncogenes SRC, proto-oncogene tyrosine-protein
kinase