Cell Division
All cells are derived from pre-existing cells. Also, new cells are produced for growth and to replace damaged or old cells. Cells differ in prokaryotes (bacteria) and eukaryotes (protists, fungi, plants, & animals)
The Eukaryotic Chromosome
All eukaryotic cells store genetic information in chromosomes. Most eukaryotes have between 10 and 50 chromosomes in their body (somatic) cells. To be precise, human body cells have 46 chromosomes or 23 homologous pairs. Each chromosome is composed of a single, tightly coiled DNA molecule. Chromosomes can’t be seen in a microscope when cells aren’t dividing and are called chromatin. Duplicated chromosomes are called chromatids & are held together by the centromere.
Chromosomes - The Basics
A Single strand is called an Unduplicated Chromosome. Two strands attached together at the centromere are referred to as 1 duplicated chromosome or 2 chromatids (Please refer to the figure below). While teaching, ensure that these terms are not mixed up as they may be a cause of confusion.
Figure retrieved from: http://www.google.ca/imgres?imgurl=http://www.clt.astate.edu/mhuss/chromosome.jpg&imgrefurl=http://en.convdocs.org/docs/index-13737.html&h=480&w=640&sz=41&tbnid=eI8dXacoSAmL8M&tbnh=194&tbnw=259&zoom=1&usg=__NnOIicxbzIV82Pd5GXNYE7I19Q4=
Cell Cycle
- G1 - primary growth phase
- S – synthesis; DNA replicated
- G2 - secondary growth phase
- M - Mitosis
- C - Cytokinesis
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Interphase
During Interphase, the cell undergoes growth and develops into a mature, functioning cell. It also copies its DNA and prepares for division.
Interphase is divided into 3 stages called G1, S and G2.
The cell spents majority of its time in this phase. After Interphase, the cell undergoes Mitosis.
Interphase is divided into 3 stages called G1, S and G2.
The cell spents majority of its time in this phase. After Interphase, the cell undergoes Mitosis.