1. The Process of Cell Division (10.2)

2. Chromosomes Chromosomes: packages of DNA, or genetic information
Before dividing, the cell needs to prepare and copy its DNA
Prokaryotic Chromosomes
DNA is found in the cytoplasm due to no nucleus
Most contain a single, circular DNA chromosome that contains all the genetic information

3. Chromosomes Cont. Eukaryotic Chromosomes
Eukaryotes have more genetic information compared to prokaryotes → more chromosomes
Chromatin: unraveled for of DNA
composed of chromosomes and histone protein
DNA + chromosomes = nucleosomes
Chromosomes make it possible to separate DNA precisely during cell division

4. Eukaryotic Chromosomes

5. Cell Cycle
Cell Cycle: The cell grows, prepares for division, and divides to form two daughter cells
Prokaryotic Cell Cycle (Binary Fission)
Once they grow to a certain size, the cell copies its DNA
the 2 DNA chromosomes attach to different regions of the cell membrane
a network of fibers forms between them stretching to the opposite side of the cell
the fibers constrict and pinch inwards dividing the cytoplasm and chromosomes
Binary fission: the production of two genetically identical cells

6. Binary Fission

7. Cell Cycle Eukaryotic Cell Cycle
Interphase: one division after another separated by an “in-between” variation of growth
G1--Cell Growth: most cell growth happens now with increased cell size and protein production
S--DNA Replication: new DNA is synthesized when chromosomes are replicated
G2--Preparing for Cell Division: is the shortest phase when organelles need for replication are produced
M--Cell Division: quick cell division in the form of mitosis
Mitosis: division of the nucleus
Cytokinesis: division of the cytoplasm

8. Eukaryotic Cell Cycle

9. Mitosis Mitosis: the division of the cell nucleus
Divided into 4 phases:
Prophase
Metaphase
Anaphase
Telophase

10. Prophase
Prophase: the genetic material inside the nucleus condenses and the duplicate chromosomes become visible. Outside the nucleus, a spindle starts to form.
Usually the longest (½ time)
Centromere: the area where the duplicate DNA strands connect
Chromatid: each DNA strand in the duplicate chromosome
when mitosis is complete, the chromatids will separate between the two new daughter cells
Centrioles: parts made of microtubules that are built like a spindle and extend from the centrosome
Centrioles begin to move towards opposite poles and the nucleolus disappears towards the end

11. Prophase

12. Metaphase
Metaphase: the centromeres of the duplicated chromosomes line up across the center of the cell Spindle fibers connect the centromere of each chromosome to the two poles of the spindle.
Generally the shortest phase

13. Anaphase
Anaphase: the chromosomes (sister chromatids) separate and move along spindle fibers to opposite ends of the cell
sister chromatids are considered individual chromosomes when anaphase begins
end: when the sister chromatids are completely separated into two sides

14. Telophase
Telophase: the chromosome, which are distinct and condensed, begin to spread out into a tangle of chromatin
nuclear envelope reforms around each set of chromosomes
spindle fibers begin to break apart
nucleolus becomes visible

15. Cytokinesis
Cytokinesis: the division of cytoplasm; splitting one cell into two completely separate cells (daughter cells)
Animal Cells → cell membrane draws inward creating a cleavage furrow until the two cells pinch apart
Plant Cells → a cell plate forms halfway between the divided nuclei; the cell plate develops into a cell membrane and separates the two cells; a cell wall forms between the two membranes completing the process

16. Plant vs. Animal Cytokinesis