Cell Growth and Division Honors Biology Chapter 10.
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Transcript of Cell Growth and Division Honors Biology Chapter 10.
Cell Growth and Division
Honors Biology
Chapter 10
Cell Growth
Living things grow larger due to an increase in cells
Larger the cell, the more demands on the DNA and the more transport of water and nutrients across the membrane
The surface area to volume ratio must also be maintained.
Cell GrowthBefore the cell gets too big in size, it must
divide into 2 new daughter cells via a process known as cell division
In order to divide, the cell must make a copy of its DNA so each cell has a set of instructions of how the body functions
DNA Replication
Cell Division
Occurs in 2 main stages
1. mitosis – division of nucleus
2. cytokinesis – division of cytoplasmConsidered to be asexual since the two
daughter cells are genetically identical to the parent cell
Source of new cells as organism grows and develops
Chromosomes
Made of DNA and proteinsCells of every organism have a specific
number of chromosomes
humans = 46 carrot = 18 fruit fly = 8Chromosomes are only visible during cell
division, these structures form to compact the DNA to make it easy to divide
Chromosome Structure Each chromosome consists of 2 identical “sister” chromatids When the cell divides, the sister chromatids separate from
each other. One chromatid goes to each of the 2 new cells Each pair of chromatids are attached by the centromere. The
centromere is usually located near the middle of the chromatid The human body contains 46 chromosomes and 46
centromeres, each of which contain 2 chromatids
Short arm
Long arm
One chromosome with 2 identical sister chromatids
Cell Cycle
During the cell cycle, a cell grows, prepares for division, and divides to form 2 new identical daughter cells, each of which then begin the cycle again.
The cell cycle consists of 4 phases
1. M Phase: (mitosis phase) mitosis and cytokinesis
2. G1 Phase: (gap phase) growth and activity 3. S Phase: (synthesis phase) DNA replication
4, G2 Phase: (gap phase) growth and activity G1, S and G2 all used to be group together and
called interphase
Cell Cycle
M Phase
G1 Phase
S Phase
G2 Phase
Interphase
Cell spends more time in interphase than M phase
1. G1 Phase – Most growing occurs. Cells increase in size and synthesize new proteins and organelles
2. S Phase – Chromosomes are replicated. Key proteins are synthesized
3. G2 Phase – Shortest of the three phases. Organelles and molecules required for division are produced. When the cell completes this phase it is ready to enter the M phase and begin the process of cell division
Mitosis Involves the centrioles (cell organelles made of
proteins and microtubules) of the cell Occurs in four stages
1. prophase – chromosomes appear and nuclear envelope breaks down2. metaphase – chromosomes line up across center of cell 3. anaphase - sister chromatids separate into separate cells 4. telophase – chromosomes gather at opposite ends of two cells and two new nuclear envelopes begin to form
Centrioles
Chromatin
Interphase
Nuclear envelope
Cytokinesis
Nuclear envelope reforming
Telophase
Anaphase
Individual chromosomes
Metaphase
Centriole
Spindle
CentrioleChromosomes
(paired chromatids)
Prophase
Centromere
Spindle forming
InterphaseDuring Interphase the chromosomes are not visible. The cell grows and replicates its DNA and centrioles
Prophase
Longest phase of mitosis Chromatin condenses and chromosomes
become visible The nuclear envelope begins to break down Centrioles separate and take positions on
opposite sides of the cell The spindle, a microtubule structure that helps
separate the chromosomes, begins to form
Centrioles
Chromatin
Interphase
Nuclear envelope
Cytokinesis
Nuclear envelope reforming
Telophase
Anaphase
Individual chromosomes
Metaphase
Centriole
Spindle
CentrioleChromosomes
(paired chromatids)
Prophase
Centromere
Spindle forming
Prophase
Metaphase
Chromosomes line up across the center of the cell.
Microtubules connect the centromere of each chromosome to the two poles of the spindle
Centrioles
Chromatin
Interphase
Nuclear envelope
Cytokinesis
Nuclear envelope reforming
Telophase
Anaphase
Individual chromosomes
Metaphase
Centriole
Spindle
CentrioleChromosomes
(paired chromatids)
Prophase
Centromere
Spindle forming
Metaphase
Anaphase
The centromeres that join the sister chromatids of the chromosome split and allow the sister chromatids to separate and become individual chromosomes
The chromatids continue to move until they have separated into two groups near the poles of the spindle
Anaphase ends when the chromatids stop moving
Centrioles
Chromatin
Interphase
Nuclear envelope
Cytokinesis
Nuclear envelope reforming
Telophase
Anaphase
Individual chromosomes
Metaphase
Centriole
Spindle
CentrioleChromosomes
(paired chromatids)
Prophase
Centromere
Spindle forming
Anaphase
Telophase
Final stage of mitosis Chromosomes begin to loosen and into a tangle
of dense material Two new nuclear envelopes begin to reform
around the two clusters of chromosomes The spindle begins to break apart and a
nucleolus becomes visible in each daughter nucleus
Mitosis is now complete, 2 nuclei are formed, but the cells are not yet separated
Centrioles
Chromatin
Interphase
Nuclear envelope
Cytokinesis
Nuclear envelope reforming
Telophase
Anaphase
Individual chromosomes
Metaphase
Centriole
Spindle
CentrioleChromosomes
(paired chromatids)
Prophase
Centromere
Spindle forming
Telophase
Cytokinesis
Separation of cytoplasm within a single cell Typically occurs at the same time as telophase Cell membrane is drawn inward until the
separation of the cytoplasm into two nearly equal parts
Each part contains its own nucleus and organelles
In plants, a cell plate forms midway between the divided nuclei and a cell wall begins to appear in the cell plate
Centrioles
Chromatin
Interphase
Nuclear envelope
Cytokinesis
Nuclear envelope reforming
Telophase
Anaphase
Individual chromosomes
Metaphase
Centriole
Spindle
CentrioleChromosomes
(paired chromatids)
Prophase
Centromere
Spindle forming
Cytokinesis
Mitosis and Cytokinesis Video Segment
..\..\bio CD\Chapter 10A.mpg
Did you know????
All of the DNA in an adult human body could fit inside one ice cube, but if unwound, stretched out and joined end to end, it could reach from the earth to the sun and back again approximately 400 more times.
Homework Assignment
This will be due tomorrow, start it in class now because it is a long assignment!!!
Suppose you were small enough to hitch a ride on a chromosome located in an animal cell that goes through mitosis and cytokinesis. Describe what you would see happening during EACH phase of the process