Cell Division Mitosis replaces worn-out old cells with fresh new duplicates.
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Transcript of Cell Division Mitosis replaces worn-out old cells with fresh new duplicates.
Cell Division
Mitosis replaces worn-out old cells with fresh new duplicates
Generates ReplacementsCell divide to
a. Grow (increase in size)b. Repair (cells must be replaced with they die)c. Reproduction (new offsprings)
1. Asexual reproduction (one parent)2. Sexual reproduction (two parents
Each time a cell reproduces, the new cells contain all the essential cytoplasm, organelles, and chromosomes needed for an organism to develop, survive, and function.
CELL GROWTH
The cell cycle describes the series of phases that leads to
cell division
First Growth Phase
(G1)
Interphase – part of the cell cycle that occurs
between divisions G1, S, G2
G1: The cell’s primary growth phase. Normal cellular functions (making proteins, getting rid of waste, etc, take place.
2. Synthesis Replication
(S phase)
DNA is synthesis (S) –the
cell begins preparations
fordivision.
Every chromosome creates
an exact duplicate of itself in
a process called replication
Interphase – part of the cell cycle that occurs between divisions
Chromosome -compact X-shaped form of chromatin formed (and visible) during mitosis
Chromatid - single arm of an X-shaped chromosome
S- Synthesis/DNA Replication
Interphase part of the cell cycle that occurs between divisions (G1, S, and G2)
1. DNA appears like threadlike coils.
2. DNA coils to formChromosomes which appear as threadlike coils (chromatin) at start.
3. Chromosomes are copied (# doubles).
4. Sister chomatids at end of this phase
3. Second Growth Phase (G2)
Second period of growth and preparation for cell division
Interphase = G1 + S + G2
Interphase – part of the cell cycle that occurs between divisions
4. Mitosis - The cell’s nucleus duplicates, then divides
5. Cytokinesis Cytoplasm divides, forming two daughter cells
Mitosis Creates Duplicate Cells
Overview: Mitosis leads to
duplicate cells
Interphase
• Chromosomes condense
Mitosis - 1
• Chromosomes line up in the middle of the cell.
Mitosis 2
• Each chromosome is pulled away from its duplicate
Mitosis - 3
New membranes form around each complete set of chomosomes and the cell divides forming two new cells called daughter cells
Mitosis – 4
The Details: Mitosis is a four-step process
1 - Prophase
• Centrioles move to opposite poles of the cell
• Mitotic spindle, microtubules forms
• Chromosomes condense
• Nuclear envelope breakdown begins
Early Prophase
• Early prophase: chromosomes begin to condense and become visible.
Prophase: chromosomes are rod-shaped
• Sister chromatids line up at the center of the cell.
• Microtubules attach
sister chromatids to opposite poles of the spindle
2 - Metaphase
• Sister chromatids pairs are pulled apart by the spindle fibers. One full set of chomosomes goes to one side of the cell and another identical set goes to the other side.
3 - Anaphase
Anaphase: chromatids begin to separate and move away
• Spindle disperse
• Chromosomes are in opposite ends of the cell.
• Nuclear membrane forms around each set of chromatid
• Two new cells begin to form from the same parent.
4 - Telophase
Telophase: an envelop will arise around the daughter nuclei
Cytokinesis: Cytoplasm and organelles duplicate and are divided into equal parts. The cell splits in two
• Interphase is the time the cell spends between cell divisions, just doing its job in the body. Most of the time cells are in interphase.
Interphase
Mitosis - Stages
What stage of cell division is represented here?
What stage of cell division is represented here?
What stage of cell division is represented here?
What stage of cell division is represented here?
What stage of cell division is represented here?
What stage of cell division is represented here?
What stage of cell division does the cell
spend most of its time in?
What stage of cell division is represented by the cell at A?
What stage of cell division is represented by the cell at B?
What stage of cell division is represented by the cell at C?
What stage of cell division is represented by the cell at D?
What stage of cell division is represented by the cell at E?
What stage of cell division is represented here?
What stage of cell division is represented here?
What stage of cell division is represented here?
What stage of cell division is represented here?
What stage of cell division is represented here?
What stage of cell division is represented here?
What stage of cell division is represented here?
What structure is represented by A?
What cell organelle is found at A?
What term do we call the thread-like structures at B?
Meiosis I
Meiosos II
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Growth, Repair and Reproduction
Growth - is the result of cells producing new cells through cell division
• The number of cells making up the organism increases, and
• The organism grows.
• Chromosomes line up in the middle of the cell.
• Spindle fibers (microtubules) connect centrioles to chromosomes
3rd:Metaphase
Metaphase - chromosomes alined in central plane