The Cycle of the Cell! The six phases of the cell cycle - embryo of the marine worm Cerebratulus marginatus

Cell Cycle Why do cells have to divide? DNA Overload – the Nucleus (boss of cell) can’t get the messages out to organelles fast enough. Material Exchange– Food and waste in volume and cannot enter or leave the cell fast enough

Surface Area and Volume Let’s do Math! 1x1x1 SA: Volume: SA to Volume Ratio: 6x6x6 SA: Volume: SA to volume Ratio: 10x10x10 SA: Volume: SA to Volume Ratio: Prokaryotes - 1–10 µmµm Eukaryotes – 10–100 µmµm 6 x 2 1 x x x x x 3.6

What are new cells used for? Growth and Repair The development of a fertilized egg into a newborn child requires an average of 41 rounds of mitosis (2 41 = 2.2 x ). During this period, the cells produced by mitosis enter different pathways of differentiation; some becoming blood cells, some muscle cells, and so on.

Prokaryotic Cell Cycle – Binary Fission

Cell Division in eukaryotes

Forms of a chromosome Eukaryotic Cell Cycle There is more than one form of DNA!!! And they will all be found in a cell at some time.

Forms of a Chromosome Chromatin Definition: Long stringy form of DNA. DNA will be in this shape while the cell is in Interphase or the “normal” phase.

Forms of a Chromosome Chromosome (Sister Chromatids) Definition: Tightly condensed and coiled Chromatin. It looks kind of like an “X.” The center of the chromosome, where the two halves of the chromosome meet is called a centromere.

Forms of a Chromosome Chromatid Definition: ½ a side of a chromosome. Two Sisters

Centrioles – Important Vocabulary Cell Cycle ONLY FOUND IN ANIMAL CELLS! Have strings/fibers called spindles that will move chromosomes around in the cell.

Cell Plate – Important Vocabulary Cell Cycle Cleavage Furrow – Cytokinesis in Animal Cells. Pinches inward Cytokinesis in Plant cells. Starts in the middle and grows out.

Cell Cycle Phases: INTERPHASE Normal Cell – Does the job of the cell – Muscle! Nucleus not undergoing mitosis yet. Draw!

Cell Cycle Phases: PROPHASE The nuclear membrane disintegrates. The chromosomes are floating in the cytoplasm and are composed of two chromatids joined at the centromere. Centrioles have completed their migration to opposite poles. Draw!

Cell Cycle Phases: METAPHASE The chromosomes are lined up across the center. Spindle fibers develop and attach to the chromosomes at the centromere. Draw!

Cell Cycle Phases: ANAPHASE Chromatids are pulled apart and travel up the spindle fibers. The chromatids are now single stranded chromosomes. The cell membrane starts to pinch the cytoplasm. Draw!

Cell Cycle Phases: TELOPHASE Chromosomes uncoil and the nucleus begins to reform. Division of cytoplasm has begun Draw!

Cell Cycle Phases: CYTOKINESIS Mitosis and cell division are complete producing two new daughter cells. Normal nuclei are to be seen. Draw!

Phases of the Cell Cycle Draw!

Real Pictures of the Cell Cycle ANIMAL CELLS PLANT CELLS

Onion Root Tip Mitosis

Extras Pinocytosis- bringing water into the cell. Phagocytosis- bringing food into the cell. (think of your esophagus…) Homeostasis- maintaining a constant internal environment.