Download presentation
Presentation is loading. Please wait.
1
Cell Growth and Division
Chapter 10
2
Why are cells so small? DNA Diffusion
Messages from the nucleus must be able to reach all parts of the cell Diffusion Nutrients must enter and wastes must leave If the cell was too big, diffusion would happen too slowly
3
Limits to cell Growth The larger the cell becomes the more demand it paces in its DNA. (DNA “overload) The cell has more trouble moving enough nutrients and wastes across the cell membrane.(Exchanging Materials).
4
Why are cells so small? Surface Area vs. Volume
As a cell grows larger, the volume increases faster than the Surface Area (SA) A bigger cell needs more nutrients, but has relatively less SA to take in those nutrients
5
Surface Area vs. Volume Cell Size 5 cm 10 cm Surface Area (l×w×6)
Volume (l×w×h) 125 cm3 1000 cm3 SA to Volume Ratio 150/125 = 6:5 600/1000 = 6:10
6
Cell Cycle It is a series of events that cells go through as they grow and divide.
7
Events of the Cell Cycle
Cells divide before growing too large Before dividing, cells must prepare Preparation =Interphase=G1, S, G2 phase G1 phase: Cell grows larger S phase: Cell makes new DNA for daughter cell –DNA replication G2 phase: Cell makes new organelles for daughter cell –preparation for mitosis
8
Events of the Cell Cycle
9
Chromosomes A DNA molecule & attached proteins
Centromere Sister Chromatids A DNA molecule & attached proteins Each chromosome is replicated during the S phase A replicated chromosome has two identical sister chromatids connected by a centromere
10
Chromosome A DNA molecule & attached proteins
Duplicated in preparation for mitosis one chromosome (unduplicated) one chromosome (duplicated)
11
Mitosis It is the division of the nucleus
12
Mitosis Four Stages: Prophase (pro- means first)
Metaphase (meta- means middle/after) Anaphase (ana- means apart) Telophase (telo- means far away/end)
13
Prophase Chromatin condenses into chromosomes
condensing Chromatin condenses into chromosomes Nuclear envelope and nucleolus disintegrate Centrioles migrate to opposite ends of the cell Spindle fibers form in foot ball shape across cell
14
Prophase
15
Metaphase Chromosomes line up in the middle (equator) of the cell
Spindle fibers attach to centromeres
16
Metaphase
17
Anaphase Sister chromatids separate
Spindle fibers shorten, pulling chromatids to opposite ends of cell Animal cells begin to pinch in Plant cells begin to form cell plate in the middle
18
Anaphase
19
Telophase Nuclear membrane built from ER around each set of chromosomes Nucleolus reforms in each nucleus Chromosomes become mass of chromatin
20
Two cells dividing into four
Telophase Two cells dividing into four
21
Cytokinesis Final division of cytoplasm (CM) resulting in two daughter cells Animals – CM pinches together Plants – Cell plate forms new CM dividing the daughter cells
22
Which phases can you see?
Anaphase Prophase Metaphase Telophase Interphase
23
Regulating the cell cycle Knowing when to divide
Cyclins Protein that regulates the cell cycle in eukaryotes Internal regulators – tell the cell when to enter mitosis External regulators – control the rate of the cell cycle
24
Cellular Response to Injury
25
Effect of Cyclins Cytoplasm is injected into a second cell in G2 phase
Cytoplasm is removed from cell in mitosis Second cell enters mitosis
26
Cancer Cancer results when cells do not respond to cell cycle regulators Cells grow unregulated, forming a tumor Tumor damages surrounding tissue
27
Web activities http://www.millerandlevine.com/intro.html
(stem cell activities)
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.