Cell Reproduction This PowerPoint has many animated slide progressions. You may only want to print the following slides: 1-11, 14-15, 22-47 EQ: Why do cells double their DNA before they divide? 1 1

Remember the Cell Theory… All living things are made of cells. Cells are the basic unit of structure and function. All new cells come from pre-existing cells. Let’s figure out how that happens! 2 2

Let’s start with the basics… Every cell in an organism must have the same number of chromosomes. (Except sex cells) If a cell doesn’t, it will not be able to function properly. Human body cells have 46 (2n or diploid) chromosomes 3 3

More basics… Before a cell divides, the DNA must replicate or make a copy of itself… 46 chromosomes 46 chromosomes 46 chromosomes …so each new cell will have the correct number of chromosomes (DNA) 4 4

Cell Reproduction The process of producing new cells from existing cells This is asexual reproduction (only one parent cell involved) New cells are genetically identical to parent cell Parent cell Daughter cells Parent cell Daughter cells 5

Why Do Cells Divide? 1) Cell is too big 2) To replace damaged or dead cells Answers are animated so you can ask students the question before you reveal the answers Maintain workable surface area to volume - too big-can’t work!! Replace damaged cells Produce sex cells 3) For growth and development (embryo) 6 6

How can a cell be too big? Look at the 3 cells below. Which one looks like it would be most efficient at transporting nutrients within and removing waste from the cell? Answers are animated so you can ask students the question before you reveal the answers Maintain workable surface area to volume - too big-can’t work!! Replace damaged cells Produce sex cells 8 8

Cell Size Limitations Ratio of surface area to volume Surface area is the area covered by the cell membrane. Volume is the space taken up by the inner contents of the cell. As the cell gets bigger, its volume increases faster than its surface area. Cells with a larger surface area: volume ratios (smaller cell) can sustain themselves more easily. Answers are animated so you can ask students the question before you reveal the answers Maintain workable surface area to volume - too big-can’t work!! Replace damaged cells Produce sex cells 9 9

Cell Size Limitations Answers are animated so you can ask students the question before you reveal the answers Maintain workable surface area to volume - too big-can’t work!! Replace damaged cells Produce sex cells 10 10

Cell Reproduction through Mitosis: For Eukaryotes Only! Advantages are…. Replacement Speed Rapid production of offspring (bacteria) Replacement of lost body parts Desirable characteristics are continually passed on Clip Art Preserving desirable characteristics 11 11

The Cell Cycle A series of events that takes place during the life of a eukaryotic cell Interphase Have students notice that the majority of a cell’s life is spent in interphase and during that time, the cell is performing all it’s cellular processes needed to survive. Indicate that M is Mitosis, the small amount of time the cell spends dividing. Picture taken from http://www.sol.duke.edu/mitosis/cycle/ 12 12

The Cell Cycle Interphase = G1, S, G2 G1 – (Gap 1) Growth and development S – (synthesis) DNA Replication G2 – (Gap 2) Growth and development, prepare for mitosis G0 – Resting phase G0 Have students notice that the majority of a cell’s life is spent in interphase and during that time, the cell is performing all it’s cellular processes needed to survive. Indicate that M is Mitosis, the small amount of time the cell spends dividing. Picture taken from http://www.sol.duke.edu/mitosis/cycle/ 13 13

The Cell Cycle Interphase A series of events that takes place during the life of a eukaryotic cell Most of the cell cycle is called Interphase, a time of growth and development The “M” phase is Mitosis & Cytokinesis, a time when the nucleus and cell divides Have students notice that the majority of a cell’s life is spent in interphase and during that time, the cell is performing all it’s cellular processes needed to survive. Indicate that M is Mitosis, the small amount of time the cell spends dividing. Picture taken from http://www.sol.duke.edu/mitosis/cycle/ 14 14