Mitosis Flashcards
Main reason cells need to divide (3)
Reproduction
Growth
Repair
Reproduction
-All cells, including single-celled organisms, use cell division to reproduce
-Each time a parent cell divides it results in two new organisms
-Each new cell must have a complete set of genetic information
-Asexual reproduction only involves one parent cell
-All offspring are genetically identical to the parent cell
sexual reproduction
-the process of producing offspring by the fusion of two gametes
-Offspring have genetic information from each parent (unique)
-A gamete is a reproductive cell that contains only half of the DNA found in normal body cells (egg, sperm)
-When two gametes combine, the offspring inherits characteristics from both parents
growth
-all organisms grow
-as multicellular organisms grow, the number of cells increase
-Can’t just increase the size of cells, because when a cell gets too large, chemicals and water can’t move through it fast enough
-Important chemicals must be available to all parts of the cell, in the right amount of water, for the cell to function properly
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Diffusion
-Chemicals enter across the cell membrane and travel through the cell by diffusion (from an area of higher concentration to an area of lower concentration)
-Waste products must also diffuse out of the cell quickly so they don’t poison the cell
Osmosis
-Water enters and leaves cells by osmosis (movement of water across a membrane toward an area of higher solute concentration)
repair
-Organisms need to repair themselves to stay alive
-When part of an organism is damaged, the remaining cells divide to repair the injury
examples:
-Shed dead skin cells & replace with new ones
-Replace red blood cells every 120 days
-Cells divide to heal a broken bone
-Every cut & blister needs new cells to fill in gaps
cell cycle
-Interphase: cell performs its normal functions and its genetic material is copied in preparation for the cell division (the time between cell divisions)
-Mitosis: DNA in the nucleus is divided; the first part of cell division
-Cytokinesis: cytoplasm divides to form two identical cells (known as daughter cells—two genetically identical cells); the final part of cell division.
shouldn’t divide if..
-Signals from surrounding cells tell the cell not to divide
-There are not enough nutrients to provide for cell growth
-The DNA within the nucleus has not be replicated
-The DNA is damaged (cell can try to repair DNA or be destroyed)
Interphase
-longest stage
-Not a resting stage
-cell carries out all life activities except division (ex. Growth, cellular respiration)
-DNA is in very long thin invisible strands
-cell prepares for division by duplicating the chromosomes in the nucleus
-spindle fibres start to form
Mitosis (PMAT)
-prophase
-metaphase
-anaphase
-telophase
prophase
-First phase of mitosis
-Nuclear membrane begins to dissolve
-Long strands of DNA condense into a compact form
-Double-stranded chromosomes condense and become visible
-Each chromosome consists of two identical strands called sister chromatids
-Centrioles move to opposite poles
-Spindle fibres begin to form at the centrioles
Prophase Terminology
-Chromosome: a structure in the cell made up of a portion of the cell’s DNA, condensed into a structure that is visible under a light microscope
-Chromatid: one of two identical strands of DNA that make up a chromosome
-Centromere: the structure that holds chromatids together as chromosomes
Metaphase
-Double-stranded chromosomes line up in the middle of the cell
-All chromosomes must be line up for mitosis to continue
-Spindle fibres continue to extend from the centrioles and attach to the centromere of the chromosomes
Anaphase
-Centromere splits and the sister chromatids separate away from each other
-They are now called daughter chromosomes
-These chromosomes move to opposite sides of the cell
