Chapter 10: Cell Growth and Division -...
Transcript of Chapter 10: Cell Growth and Division -...
Chapter 10: Cell Growth and Division
10.2 - The Process of Cell Division
Mr. M. Varco Saint Joseph High School
Chromosomes• What role do chromosomes have in cell division?
• Prior to cell division, parent cells must undergo DNA replication so that each daughter cell gets a complete copy of genetic information.
• All cells, including bacteria, have a tremendous amount of DNA that must be carefully packaged.
Chromosomes• The cell’s genetic information is bundled into packages of DNA known as
chromosomes
• Chromosomes make it possible to separate DNA precisely during cell division
• The cells of every organism have a specific # of chromosomes
ChromosomesProkaryotic Chromosomes
• Most prokaryotes contain a single, circular DNA chromosome that contains nearly all of the cell’s genetic information
ChromosomesEukaryotic Chromosomes
• Eukaryotic cells generally have more DNA than prokaryotes and therefore contain multiple chromosomes
• Humans cells have 46 chromosomes
ChromosomesEukaryotic Chromosomes
• Chromosomes are located in the nucleus and are made up of chromatin
• Chromatin is composed of chromosomes and histone proteins
ChromosomesEukaryotic Chromosomes
• DNA tightly coils around histone proteins, forming nucleosomes
• Cells package their information in chromosomes to ensure equal division of DNA when a cell divides
The Cell Cycle• During the cell cycle, a cell: grows, prepares for division, and divides to form
two daughter cells
The Cell CycleProkaryotic Cell Cycle
• The prokaryotic cell cycle is a regular pattern of growth, DNA replication, and cell division
• The process of cell division is a form of asexual reproduction called binary fission
The Cell CycleEukaryotic Cell Cycle
• The eukaryotic cell cycle consists of 4 phases: G1, S, G2, and M
The Cell CycleEukaryotic Cell Cycle
• During the G1 phase, cells do most of their growing, which includes increasing in size, as well as synthesis of proteins and organelles
The Cell CycleEukaryotic Cell Cycle
• During the S phase, new DNA is synthesized when the chromosomes are replicated.
• The cell contains twice as much DNA as it did at the beginning of the cell cycle
The Cell CycleEukaryotic Cell Cycle
• During the G2 phase, many of the organelles and molecules required for cell division are reproduced
• The is the shortest of the three phases, and marks the cell as ready for division
The Cell Cycle
Eukaryotic Cell Cycle
• The M phase, which follows interphase, produces two daughter cells
• Unlike interphase, the process of cell division occurs very quickly
The Cell CycleEukaryotic Cell Cycle
• In eukaryotes, cell division occurs in two main stages:
- Mitosis: the division of the cell nucleus
- Cytokinesis: the division of the cytoplasm
MitosisProphase:
• The first phase of mitosis, in which chromatin condense and become visible chromosomes
• The duplicated strands of DNA attach at an area called the centromere
• Each DNA strand in the duplicated chromosome is referred to as a chromatid
MitosisProphase:
• The cell starts to build a spindle, used to help separate the chromosomes at the centromere
• Spindle fibers extend from regions where tiny paired structures called centrioles are located
MitosisMetaphase:
• The second phase, where centromeres of the duplicated chromosomes line up across the center of the cell
• Spindle fibers connect the centromere of each chromosomes to the two poles of the spindle
MitosisAnaphase:
• The third phase, when centromeres are pulled apart and the sister chromatids separate to become individual chromosomes
• The chromosomes move along spindle fibers to opposite ends of the cell
MitosisTelophase:
• The forth phase, during which the chromosomes begin to spread out into a tangle of chromatin
• Spindle fibers break apart, and the nuclear envelope re-forms around each cluster of chromosomes