cell division mitosis chapter 10. why do cells divide, rather than continually grow forever? the...
TRANSCRIPT
Cell DivisionMitosis
Chapter 10
Why do cells divide, rather than continually grow forever?
• The larger a cell becomes, the more demands the cell places of its DNA.
• The cell also has more trouble moving enough nutrients and wastes across the cell membrane.
Division of the CellBefore it becomes too large, a
growing celldivides forming two “daughter cells.”
• The process by which a cell divides into new daughter cells is called cell division.
• Before cell division occurs, the cell replicates, or copies, all of its DNA. Thus, each daughter cell gets one complete set of genetic information.
Cell Division• Cell division is complex and occurs
in 2 main stages:– Mitosis-division of cell nucleus– Cytokinesis-division of cytoplasm
• Genetic information is carried by chromosomes. – Before cell division each chromosome
is replicated, or copied forming two identical sister “chromatids,” which will be separated from each other when the cell divides.
The Cell Cycle
The cell cycle is a series of events that
cells go through as
they grow and divide.
During the cell cycle, the following happens:
•Cell grows (interphase)
•Cell prepares for division (interphase)
•Cell divides to form 2 daughter cells (each of which further divide) (cell division)
Events of the Cell Cycle• Interphase
– G1 phase• Cell grows (increases in size and makes new
proteins and organelles)
– S phase• Replication of chromosomes/DNA synthesized
– G2 phase• Organelles and molecules needed for cell
division produced.
Centrioles
Chromatin
Interphase
Nuclear envelope
Cytokinesis
Nuclear envelope reforming
Telophase
Anaphase
Individual chromosomes
Metaphase
Centriole
Spindle
CentrioleChromosomes
(paired chromatids)
Prophase
Centromere
Spindle forming
Section 10-2
Figure 10–5 Mitosis and Cytokinesis
Mitosis (M phase)• When the events of the G2 phase
are completed, the cell is ready to enter the M phase and begin cell division.
• The events of mitosis are divided into four phases:– Prophase– Metaphase– Anaphase– Telophase
Prophase
•1st phase of mitosis where:–Centrioles take their place at opposite sides of the cell–Spindle fibers form–Chromatin coils to form chromosomes–Nuclear envelope breaks down
Centrioles
Chromatin
Interphase
Nuclear envelope
Cytokinesis
Nuclear envelope reforming
Telophase
Anaphase
Individual chromosomes
Metaphase
Centriole
Spindle
CentrioleChromosomes
(paired chromatids)
Prophase
Centromere
Spindle forming
Section 10-2Figure 10–5 Mitosis and Cytokinesis
Metaphase
•The chromosomes line up across the center of the cell
•Each chromosome is connected to a spindle fiber at its centromere.
Centrioles
Chromatin
Interphase
Nuclear envelope
Cytokinesis
Nuclear envelope reforming
Telophase
Anaphase
Individual chromosomes
Metaphase
Centriole
Spindle
CentrioleChromosomes
(paired chromatids)
Prophase
Centromere
Spindle forming
Section 10-2
Figure 10–5 Mitosis and Cytokinesis
Anaphase
•Sister chromatids separate into individual chromosomes and are moved apart
Centrioles
Chromatin
Interphase
Nuclear envelope
Cytokinesis
Nuclear envelope reforming
Telophase
Anaphase
Individual chromosomes
Metaphase
Centriole
Spindle
CentrioleChromosomes
(paired chromatids)
Prophase
Centromere
Spindle forming
Section 10-2Figure 10–5 Mitosis and Cytokinesis
Telophase
•The chromosomes gather at opposite ends of the cell and lose their distinct shapes.
•Two new nuclear envelopes will form.
Centrioles
Chromatin
Interphase
Nuclear envelope
Cytokinesis
Nuclear envelope reforming
Telophase
Anaphase
Individual chromosomes
Metaphase
Centriole
Spindle
CentrioleChromosomes
(paired chromatids)
Prophase
Centromere
Spindle forming
Section 10-2
Figure 10–5 Mitosis and Cytokinesis
Cytokinesis
• The cytoplasm pinches in half.
• Each daughter cell has an identical set of duplicate chromosomes.
How will I ever remember the phases?
•P•M•A•T
This is how you can remember the phases:
•Please•Make•Another•Touchdown