Cell Division Chapter 2 Section 3

The Cell Cycle The regular sequence of growth and division that cells undergo

Stage 1: Interphase Growth DNA Replication Cell grows to mature size Endoplasmic reticulum produces more ribosomes Produces enzymes Mitochondria and chloroplasts duplicate Replication process Cell makes copies of DNA in nucleus Each cell has 2 identical copies of the DNA One set will go to each daughter cell

Stage 1: Interphase Preparation for Division Cell produces structures needed for cell division Cell is now ready to divide Longest phase of cell division

State 2: Mitosis Mitosis: Four parts of Mitosis Cell nucleus divides One copy of the DNA distributed to each daughter cell Four parts of Mitosis Prophase Metaphase Anaphase Telophase

Stage 2: Mitosis Prophase Chromatin condense Look like tiny rods Chromatid Since DNA is replicated there are 2 rods chromosome Two strands tied together by a centromere Nuclear membrane breaks down

Stage 2: Mitosis Metaphase Chromosomes line up along the center of the cell Each chromosome attaches to a spindle fiber at its centromere

Stage 3: Mitosis Anaphase Centromeres split Chromatids separate Chromatins move along spindle fibers Chormatids move to opposite ends of cells. Cell become stretched and moves apart

Stage 2: Mitosis Telophase Chromosomes stretch out Lose rod like appearance Occurs at two regions At either ends of the cell New nuclear membrane forms around each region of chromosome

Stage 3: Cytokinesis Cytokinesis Cytoplasm divides organelles are distributed to each cell Cell membrane pinches around the middle of the cell The cell pinches into to separate cells Two identical daughter cells are formed

Length of Cell Cycle Duration of cell division on the type of cell Human liver cell 22 hours Sea urchin cell 2 hours Human brain Never divides

DNA Replication Each daughter cell has all genetic information necessary

Structure of DNA Double Helix Twisted ladder shape of DNA 2 sides of DNA ladder made of deoxyribose alternate with phophates Each rung is made of nitrogen bases

Nitrogen Bases Molecules containing nitrogen Rungs on the double helix Four types A- Adenine T- Thymine G- Guanine C-Cytosine

Nitrogen Bases Bases on one side of the helix match in a specific way to the other side A matches with T C matches with G This pairing is the key to DNA replication

Replication Process Two sides of DNA unwind (unzip) and separate Molecules separate between nitrogen bases Floating nitrogen bases pair up with corresponding nitrogen base on the DNA New DNA is produces once nitrogen bases pair up The two DNA are exact matches DNA presentation