440 likes | 2.82k Views
Cell Division. The Cell Cycle: Interphase Mitosis Cytokinesis. Cell Cycle. When a cell grows to a certain---predetermined size—it divides in to two cells. One ‘parent’ cell divides into two ‘daughter’ cells There are three main stages to this process. Stage 1: Interphase.
E N D
Cell Division The Cell Cycle: Interphase Mitosis Cytokinesis
Cell Cycle • When a cell grows to a certain---predetermined size—it divides in to two cells. • One ‘parent’ cell divides into two ‘daughter’ cells • There are three main stages to this process.
Stage 1: Interphase • Period BEFORE cell division occurs. • Cell grows to its mature stage. • Cell makes a copy of its DNA (chromosomes). • Cell prepares to divide into two cells.
Stage 1: Interphase-continued • Replication—this is when the DNA in the nucleus reproduces itself with an exact copy. • If the DNA (chromosomes) did not reproduce itself….then each new cell would only have ½ of the chromosomes it should have………
Stage 2: Mitosis • In this stage, one copy of the DNA (chromosomes) is distributed into each of the two new ‘daughter’ cells. • Prophase---Metaphase---Anaphase---Telophase
Stage 2: Mitosis--continued • Prophase: Chromosomes look like fishing line wrapped around a ball. • Each chromosome is made up of the doubled strand (chromatid) held together by a centromere.
Stage 2: Mitosis--continued • Metaphase: Chromosomes line up across the middle of the cell. • Each chromosome attaches to a spindle fiber that holds them together.
Stage 2: Mitosis--continued • Anaphase: The two chromatids of the Chromosome separate and each moves to the opposite end. • The cell appears stretched out.
Stage 2: Mitosis--continued • Telophase: The chromosomes begin to stretch out and lose their appearance. • A new nuclear membrane starts to appear and divides the nucleus into two different but identical nuclei.
Stage 3: Cytokinesis • This refers to when the cell membrane pinches in around the middle of the cell. • This separates the cell into two different but identical cells. • All organelles are evenly distributed to the new cells.
Stage 3: Cytokinesis-continued • Cytokinesis starts around the time of Telophase.
Structure of DNA • “double helix’ refers to a ladder that has sugars and phosphates as the sides and nitrogen bases as the steps.