The Cell Cycle Notes
Cell Replacement and Development
-Cells continue to divide as you continue to grow.
-Muscle & nerve cells usually do not continue to divide in adult.
The Cell Cycle
-Life of cell = divided into 3 stages called cell cycle.
-Stages = Interphase, Mitosis and Cytokinesis
-Interphase= cells carry out functions necessary for survival and cells that divide prepare for reproduction.
-Mitosis divides duplicated contents of cell’s nucleus into 2 equal parts.
-Cytokinesis separates 2 nuclei & cell contents into 2 daughter cells.
-Interphase = largest stage of cell cycle.
Growth and Preparation
-During 1st phase of interphase, cell increases in size & makes proteins necessary for cell to function.
-Some organelles begin to dispute.
-Replication, cell copies the 3 billion base pairs of DNA info in nucleus of cell.
- Then cell temporarily has 2 complete sets of DNA.
-Enzymes control (above) process.
-To replicate itself, DNA molecule unwinds and steps of DNA ladder break apart.
-Each side then becomes a pattern or template on which new side forms.
- Continued growth and preparation
- After DNA replicates, cell continues to grow & is active making materials such as proteins for new cells that will be formed after cytokinesis.
- These cells= daughter cells
- Chromatin = Contains replicated DNA = loosely coiled form.
- In loosely coiled form, DNA can be copied into RNA. So proteins = made during preparation for cell division.
-During (above) final phase before cell division, organelles ; mitochondria & chloroplasts = duplicated.
* Next stage of cell cycle & usually the shortest. * Process in which contents of cell’s nucleus divides. * Division results in 2 daughter nu kinds of chromosomes as original cell. * As nucleus prepares to divide, DNA molecules that replicated during interphase join together to form sister chromatids of chromosome.