Chapter 12 The Cell Cycle

Today we took a vocab quiz (yay!) then played with the NEW Active Expressions (double yay!) and then took some notes on Chapter 12. Added notes from the book are in green. But before we get to the notes...how much did you really pay attention today in class?

1. What is the reproduction of cells called?

A. Cell cycle B. Cell Division C. Chromosomes

2. What molecule is packaged into chromosomes?

A. Carbon Dioxide B. RNA C. DNA

3. What is another name for reproductive cells?

A. Somatic cells B. Gametes C. Chromatin

True or False?

1.Gametes are somatic cells.

2. Chromatin is made of only DNA

Answers: B, C, B, False, False

Unicellular organisms reproduce by cell division; multicellular organisms depend on cell division for their development from a fertilized egg and for growth and repair.

Overview: The Key Roles of Cell Division

• The ablity of organisms to reproduce best distinguishes living things from nonliving matter
  
• The continuity of life is based on the reproduction of cells, or CELL DIVISION - Rudold Virchow states that "Where a cell exists, there must have been a preexisting cell"
  
• In unicellular organisms, division of one cell reproduces the entire organism
  
• Multicellular organims depend on cell divsion for-
  
  1. Development from a fertilized cell

2. Growth

3. Repair

• Cell division is an integral part of the CELL CYCLE-the life of a cell from formation to its own division
  
  

12.1 Cell Division results in genetically identical daughter cells

• most cell division results in daughter cells with identical genetic information, DNA



• a special type of division produces nonidentical daughter cells (gametes-sperm or egg) which are not genetically identical
  
  

Cellular Organization of the Genetic Material

• All the DNA in a cell constitutes the cell's GENOME


• A genome can consist of a single DNA molecule (common in prokaryotic cells) or a number of DNA molecules (common in eukaryotic cells)


• Before the cell can divide to form genetically identical daugher cells, all DNA must be copied and then separated
  
• DNA molecules in a cell are pachaged into CHROMOSOMES


• Every eukaryotic species has a charactersitic number of chromosomes in each cell nucleus


• SOMATIC cells (nonreproductive cells) have 2 sets of chromosomes (each set containing 23 chromosomes to make up 46 total)


• GAMETES (reproductive cells-sperm and egg) have half as many chromosomes as somatic cells (one set of 23 chromosomes)


• eukaryotic chromosomes consist of CHROMATIN- a complex of DNA and protein that condenses during cell division


• each chromosome contains on long DNA molecule that carries several hundred to a few thousand genes-specify an organism's inherited traits