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Growth and Cell Reproduction -. Growth is a characteristic of all living things. You started out as a single cell. That cell quickly divided into two cells. Two cells became four, then 8, and on to billions of cells. What is cell division?.
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Growth and Cell Reproduction - Growth is a characteristic of all living things. You started out as a single cell. That cell quickly divided into two cells. Two cells became four, then 8, and on to billions of cells.
What is cell division? • The process of one cell dividing into two identical daughter cells . • Each daughter cell contains an exact copy of the DNA found in the parent cell. • The process is a type of asexual cell reproduction.
What are chromosomes? • A chromosome is a structure made of DNA and protein in the nucleus of eukaryotic cell. • Chromosomes organize DNA into distinct units. • Different organisms have different numbers of chromosomes. Example : • humans have 46 chromosomes • chicken 78 chromosomes • house fly 12 Chromosomes • tomato 24 Chromosomes
Before Cell Division • The amount of DNA doubles and so do the chromosomes. The DNA and protein in the doubled chromosomes coil up tightly.
The Cell Cycle • As you grow from a infant to an adult, you pass through different stages of life cycle. Similarly, a cell passes through different stages of its life. • The life cycle of a cell is called a cell cycle.
Cell Cycle • The cell cycle has three stages: Interphase, Mitosis, and Cytokinesis.
Interphase -The longest stage -The cell grows, develops and performs its functions. -Towards the end, DNA doubles (chromosomes double)
Mitosis • Is the process in cell division where the nucleus divides into two nuclei. • The second stage of the cell cycle, has four phases, prophase, metaphase, anaphase, and telophase.
Prophase -Chromosomes are visible -Nuclear membrane disappears. -Nucleolus disappears
Metaphase -Chromosomes line upacross center. -Spindle fibers attach to center of each chromosome.
Anaphase -Chromosomes split. -Each half is pulled to opposite side of cell.
Telophase -Chromosomes cluster in the center of each new cell. -Nuclear membrane begins to form. -Cells begin to separate.
Cytokinesis -Cytoplasm divides -Two daughter cells form. -Same number of chromosomes as parent cell.
A mnemonic device • Helpful for memorizing the cell cycle and steps of mitosis. • Example: I play music at the concert. • Interphase, prophase, metaphase, anaphase, telophase, cytokinesis
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