BISC 101 Lecture Notes - Lecture 9: Organelle, Cleavage Furrow, Nuclear Space

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BISC 101 – Lecture 9 – The Cell Cycle: Part I
The Key Roles of Cell Division
The ability of organisms to reproduce best distinguishes living things from non –
living matter
The continuity of life is based on the reproduction of cells or cell division
Cell division reproduces an entire organism
oEx: A single celled amoeba dividing into two cells; each an individual
Cell division allows multi – cellular organisms to develop from single cells
oEx: Embryo development in a sea urchin
Cell division functions in renewal and repair
oDividing bone marrow cells give rise to new blood cells
Cell Division Results in Genetically Identical Daughter Cells
Most cell division results in daughter cells with identical genetic information or
A special type of division produces non – identical daughter cells
oInvolves gametes, aka, eggs and sperm cells
Cellular Organization of the Genetic Material
Genome: All the DNA in a cell or the cell’s total genetic information
A genome can consist of a single DNA molecule
oProkaryotic cells
A genome can consist of multiple DNA molecules
oEukaryotic cells
Chromosome: A molecule in which DNA is packaged into
Chromatin Fiber: The long, thin form of chromosome F
oFound in this form when the cell is not dividing
Every eukaryotic species has a characteristic number of chromosomes in each
cell nucleus
Humans have 46 chromosomes
o22 pairs of autosomes
o1 pair of sex chromosomes
Somatic Cells: Non – reproductive cells that have two sets of chromosomes
Gametes: Reproductive cells like sperm and eggs that have half as many
chromosomes as somatic cells
Potatoes have 46 chromosomes
Horsetails have over 200 chromosomes
The common house fly, or the Drosophita, have 8 chromosomes
The complexity or size of an organism, does not determine the amount of
chromosomes it may possess
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