Biology Notes 2 Mitosis vs Meiosis

Diagram Booklet Cell Cycle (bottom corner draw cell in interphase) Mitosis Meiosis l Meiosis ll

Cell Cycle

Interphase Cell spends the majority of its life in this phase (90%) 1rst phase – cell is growing making the necessary proteins and molecules for the cell to function. Some organelles duplicate. 2nd phase – DNA makes a copy of itself, (Replicating the DNA ensures that newly formed cells will be identical to the original) 3rd phase – cell continues to grow in preparation for mitosis

Checkpoints in the Cell Cycle •Proteins in the cell check the viability of the cell at certain points in the cell cycle. This information is directed to the nucleus, which decides whether or not the cell will divide. Cells will not divide if: 1)There are not enough nutrients to support growth 2)DNA has not been replicated 3)DNA has been damaged

Mitosis Is the process in which the contents of a cells nucleus divide. (Remember DNA duplicated in Interphase) This division results in two identical daughter cells, each with same number and kinds of chromosomes as the original cell Mitosis is used in the growth or replacement of all body cells (not sex cells – sperm and egg cells)

Phases of Mitosis Prophase Metaphase Anaphase Telophase (cytokinesis)

Prophase Double stranded chromosomes shorten and thicken and the nuclear membrane begins to fade.

Metaphase Chromosomes line up across the middle of the cell

Anaphase Chromosomes are pulled to opposite poles of the cell

Telophase Complete set of chromosomes at each pole of the cell. Nuclear membrane reappears Cell starts to pinch inward, eventually it will divide into two separate cells (cytokinesis)

If the original parent cell has 46 chromosomes, how many chromosomes will each new daughter cell have at the end of mitosis?

Mitosis Check Type of Cells Involved? Number of daughter cells produced? Genetic Material in each cell (# of chromosomes)?

Mitosis Worksheets - cell growth and division - cell stage identification

Meiosis Results in the production of sex cells (sperm and egg) 4 daughter cells that are not identical to the parent (each daughter cell contains half the number of chromosomes or genetic material as the parent cell)

Terms to Know Haploid – half the genetic content or chromosomes Diploid – genetic content or number of chromosomes is the same as the parent cell Homologous Pairs – are the same size and shape and have genes in the same location (Figure 6.5 Page 174) Gametes – sex cells ( sperm and egg cells)

Meiosis 1 Prophase l Metaphase l Anaphase l Telophase l

Prophase 1 Homologous chromosomes pair up Crossing over occurs. Exchange segments of DNA. This allows for genetic variation

Metaphase l Homologous chromosomes line up across the center of the cell (equatorial plate)

Anaphase l Homologous chromosomes separate and are pulled to opposite poles of the cell

Telophase l Homologous pairs have moved to opposite ends of the cell and the cell begins to divide

Interkinesis Stage between meiosis l and ll During this time the cell grows and makes proteins but does not replicate its DNA

Meiosis ll Prophase ll Metaphase ll Anaphase ll Telophase ll

Prophase ll Nucleus contains only 1 chromosome from the homologous pair in each cell

Metaphase ll Chromosomes line up across the center of the cell

Anaphase ll Half of the chromosomes are pulled to opposite poles of the cell

Telophase ll A nuclear membrane is formed around each set of chromosomes and the cell begins to divide to produce 4 haploid gametes (sex cells).

If the original parent cell has 46 chromosomes, how many chromosomes will each new daughter cell have at the end of meiosis ll?

Meiosis Check Type of cells involved? Number of daughter cells produced? Genetic material or the number of chromosomes in each cell?