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Learning Target:Know the reasons for why cells
divide.Learning Outcome:
I will know limitations to cell growth and structure of chromosomes.
Cells divide rather than get larger because…….
1. Demands on DNA would be too great.
2. Cell would have trouble moving food and waste across the cell membrane.
Each organism has a specific number of chromosomes.
During cell division chromatin condenses into chromosomes.
In order for each cell to get the right number the chromosomes have to double
Therefore, since cells can not become too large they need to divide into “daughter cells”
To do this the DNA first copies itself so each daughter cell receives exact copies of the genetic info needed for the cell
Also the ratio of surface area to volume increases which is a very good thing!
Learning Target:Know the phases of mitosis.
Learning Outcome:I will complete the “Mitosis
Flipbook.”
G1 – Growth phase #1. Cells increase in size and
make new proteins and organelles.
S – Synthesis. Chromosomes are replicated.
G2 – Growth Phase #2 Cell division organelles
are produced. Short phase.
Cell division is made up of 2 parts.1. Mitosis – division of the nucleus.
Divided into 4 phases.2. Cytokinesis – division of the
cytoplasm.
The opposite of prophase occurs. Chromosomes disappear back to chromatin Nuclear membrane reforms Spindle fibers break apart and disappear